Abstract:
An apparatus and method for generating cavitation in fluids is disclosed. The apparatus includes a housing for receiving a rotor, which is driven by a motive force. Multiple embodiments of the rotors are disclosed including, but not limited to, centrally feed, centrally drained, face feed, and face drained rotors. In one preferred embodiment, cavitation is enhanced by inducing tensile stress in the fluid by subjecting the fluid centrifugal force or centripital force depending upon the flow of the fluid.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS  
       [0001]     The present application claims the benefit of the following U.S. Provisional Patent Applications: Ser. No. 60/414,238, filed Sep. 26, 2002; Ser. No. 60/419,751, filed Oct. 18, 2002; Ser. No. 60/428,073, filed Nov. 21, 2002; Ser. No. 60/441,623, filed Jan. 21, 2003; Ser. No. 60/463,689, filed Apr. 16, 2003; Ser. No. 60/448,017, filed Feb. 18, 2003; Ser. No. 60/453,139, filed Mar. 10, 2003; Ser. No. 60/478,881, filed Jun. 16, 2003; and Ser. No. 60/482,707, filed Jun. 20, 2003, all of which are hereby incorporated by reference. 
     
    
     BACKGROUND OF THE INVENTION  
       [0002]     Hydrodynamic cavitation is a physical phenomenon that involves the formation and collapse of cavities within a liquid. The cavities (bubbles) are often filled with a vapor-gas mixture and are typically created by reducing a fluid&#39;s local pressure. The vapor bubbles, once formed, cannot hold their shape, being formed by fluid walls, and their rapid collapse creates mixing, emulsification, dispersion, and kinetic effects which may be useful. Since the fluid is typically near its particular phase transformation at the inception of cavitation, the process can be used for particle dispersion, atomization, and emulsion formation. Sufficient agitation can be imparted such that full vaporization can be accomplished, if so desired. In addition, the cavitation of certain substances create desired chemical reactions. For example, the cavitation of water produces OH radicals and peroxides which serve to attack any biological contaminants within the water, providing a level of disinfection of the water through the occurrence of cavitation.  
         [0003]     The mechanism of the bubble collapse, as described in the field, is that a “finger” of fluid is pulled through the surface of the bubble, which has lower pressure than the surrounding fluid, from a single point (or a small local region) of the bubble&#39;s surface. This finger forms a micro-jet of fluid, which strikes the opposing surface of the bubble with great force and speed (measured as being supersonic). This collision creates forces that can be disruptive to the chemical structure of the fluid. Sonochemistry involves the studying of such forces to facilitate various chemical reactions and efforts, including atomization.  
         [0004]     Traditionally, hydrodynamic cavitation is created by pumping a fluid through a venturi of some sort. The restrictive portion of the venturi creates the necessary local velocity increase and corresponding pressure drop, which precipitates cavitation. A venturi may be formed by a fixed diameter throat that is smaller in diameter than an upstream inlet, smoothly transitioned from the inlet and onward to the outlet, or it may be formed by a simple restriction placed inside a fluid flow field which has a similar effect of raising the fluid&#39;s velocity and thus lowering its pressure. This occurs in accordance with Bernoulli&#39;s principle which states that for steady flow of an incompressible fluid the pressure will decrease if the velocity increases, and visa versa. In the case of a venturi, the restriction causes an increase in the fluid&#39;s local velocity and thus lowers its pressure. This can be accomplished through the use of a simple restrictive element as well, although flow losses will be greater. Conventional ventrui systems are held fixed and a fluid is passed through them.  
         [0005]     The pressure reduction created by venturis (or restrictive elements in passages) has been utilized to create cavitation in fluids by reducing a fluid&#39;s local pressure to a level below its vaporization pressure, causing vapor bubbles to form in the fluid. These bubbles collapse, in the case of a venturi, once the pressure of the fluid recovers downstream of the venturi throat, the higher relative fluid pressure causing the vapor bubble to implode upon itself with great force.  
         [0006]     It is also observed in experiments that do no involve centrifugal or centripetal forces such as experiments involving stretching a fluid using a piston and cylinder or by cooling a fluid in a fixed volume that vapor bubbles may be created within a fluid through the application of tensile stresses to the fluid. Due to the weak molecular bonds existing within a fluid, once the tensile strength of the fluid is exceeded, the fluid “fractures” and forms a vapor bubble. If the tensile stress within the fluid is removed in a sufficiently rapid fashion, the bubble will collapse, completing the cavitation cycle.  
       SUMMARY OF THE INVENTION  
       [0007]     Embodiments, among others, of the present invention provide an apparatus and method for facilitating cavitation in a fluid.  
         [0008]     Briefly described, in architecture, one embodiment of the apparatus, among others, can be implemented as follows. The apparatus includes a housing that has a generally hollow interior for receiving a rotor. A rotor having an exterior surface is disposed in the housing, and the rotor defines a first opening disposed on the exterior surface and a second opening with a fluid passage extending therebetween. The fluid passage facilitates cavitation in a fluid.  
         [0009]     In another embodiment, an apparatus includes a rotor having a front face, an opposed rear face, and an exterior surface extending therebetween. The exterior surface of the rotor defines an plurality of irregularly spaced cavities disposed thereon.  
         [0010]     Embodiment of the present invention can also be viewed as providing methods for inducing cavitation. In this regard, one embodiment of such a method, among others, can be broadly summarized by the following steps: providing a fluid; and inducing tensile stress in the fluid for facilitating controlled cavitation through rotation.  
         [0011]     Other systems, methods, features, and advantages of the present invention will be or become apparent to one with skill in the art upon examination of the following drawings and detailed description. It is intended that all such additional systems, methods, features, and advantages be included within this description, be within the scope of the present invention, and be protected by the accompanying claims. 
     
    
     DESCRIPTION OF THE DRAWINGS  
       [0012]      FIG. 1A  is an isometric view of a roto-dynamic fluidic system.  
         [0013]      FIG. 1B  is an exploded view of a roto-dynamic fluidic system.  
         [0014]      FIG. 2A  is an cross sectional view of a roto-dynamic fluidic device.  
         [0015]      FIG. 2B  is an cross sectional view of a roto-dynamic fluidic device.  
         [0016]      FIG. 3A  is an perspective view with a partial cut away of a rotor.  
         [0017]      FIG. 3B  is an cross sectional view of a rotor.  
         [0018]      FIG. 3C  is an cross sectional view of a rotor.  
         [0019]      FIG. 3D  is an cross sectional view of a rotor.  
         [0020]      FIG. 4A  is an cross sectional view of a roto-dynamic fluidic device.  
         [0021]      FIG. 4B  is an cross sectional view of a roto-dynamic fluidic device.  
         [0022]      FIG. 4C  is an cross sectional view of a roto-dynamic fluidic device.  
         [0023]      FIG. 5  is an cross sectional view of a roto-dynamic fluidic device.  
         [0024]      FIG. 6  is an cross sectional view of a roto-dynamic fluidic device.  
         [0025]      FIG. 7  is an cross sectional view of a roto-dynamic fluidic device.  
         [0026]      FIG. 8  is an cross sectional view of a roto-dynamic fluidic device.  
         [0027]      FIG. 9  is an cross sectional view of a roto-dynamic fluidic device.  
         [0028]      FIG. 10A  is an cross sectional view of a roto-dynamic fluidic device.  
         [0029]      FIG. 10B  is an cross sectional view of a roto-dynamic fluidic device.  
         [0030]      FIG. 10C  is a perspective view of a rotor.  
         [0031]      FIG. 11  is an cross sectional view of a roto-dynamic fluidic device.  
         [0032]      FIG. 12  is an cross sectional view of a roto-dynamic fluidic device.  
         [0033]      FIG. 13  is an cut away/cross sectional view of a rotor. 
     
    
     DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS  
       [0034]     Many aspects of the preferred embodiments, among others, of the invention can be better understood with reference to the following drawings. The components in the drawings are not necessarily to scale, emphasis instead being placed upon clearly illustrating the principles of the present invention. Moreover, in the drawings, like reference numerals designate corresponding parts throughout the several views. Except for some embodiments in which like numbers denote elements having at least one structural or functional similarity.  
         [0035]     For the purposes of this disclosure the following definitions are provided: 
    Vaporization: the formation of vapor bubbles within a fluid at a temperature lower in value than its normal boiling point for a given pressure.     Cavitation: the formation and subsequent collapse of vapor bubbles within a fluid at a temperature that is below its normal boiling point for a given pressure.     Centrifugal force: the component of apparent force on a element in curvilinear motion, as observed in the non-inertial reference frame of the element, that is directed away from the axis of rotation in a direct radial vector.     Centripetal force: the component of force acting on a body in curvilinear motion that is directed toward the center of the axis of rotation as viewed from an inertial reference frame.     Inertia: the tendency of an element in motion to remain in motion, or for an element at rest to remain at rest, or for an element traveling in one direction to remain traveling along that vector or direction.     Sonochemistry: the use of the high levels of acoustic energy created within a cavitation bubble collapse event to affect chemical reactions, and applies to cavitation caused by any process, be it ultrasonic excitation of a fluid, or the hydrodynamic manipulation of a fluid to induce cavitation in same, or any other means of creating cavitation within fluids.    
 
         [0042]     Refer now in more detail to the drawings, in which like numerals indicate corresponding parts throughout the several views. Referring to  FIGS. 1A and 1B  and  FIGS. 2A and 2B , a roto-dynamic system  1  includes a roto-dynamic fluidic device  2  and motor  6 . In  FIG. 1A  the roto-dynamic system  1  is shown in perspective view, and in  FIG. 1B  the roto-dynamic fluidic device  2  is shown in exploded from the motor  6 . In  FIG. 2A  the roto-dynamic fluidic device  2  is shown and a portion of a shaft  16  in longitudinal cross section, and in  FIG. 2B  the roto-dynamic fluidic device is shown in cross section as viewed from line A-A of  FIG. 2A . The roto-dynamic fluidic device  2  includes a housing  2 , and the housing  2  is coupled to the motor  6  via bolts. The housing  4  includes a front plate  8 , which is bolted onto a base portion  10 . The base portion  10  defines a cavity  12 , which is generally cylindrical. Disposed within the cavity  12  is a rotor  14 , which is held by the shaft  16 . The solid line  91  passing through the roto-dynamic fluidic device  2  denotes the center of rotation of the rotor  14 .  
         [0043]     The shaft  16  is longitudinally rotatable and driven by the motive source  6 . A sealing element  18  abuts the shaft  16  and prevents fluid from escaping rearward from the cavity  12 . Preferably, the sealing element includes a rubber ring member  113  held in place by tension from a ring member  115  of metal nature. Of course, other embodiments include other types of seals as would be understood by those skilled in the art. A support bearing  20  supports the shaft  16 .  
         [0044]     The rotor  14  is approximately cylindrical in shape having a front face  22  and a rear face  24  and a longitudinal exterior  26  extending therebetween. A center void  28  extends from the front  22  of the rotor rearward. The region between the center void  28  and the rear face  24  is a boss  105 , and the boss  105  defines an opening  29  that extends between the center void  28  and the rear face  24 . Typically, a threaded bolt  30  extends from the center void  28  rearward through the opening  29  to the shaft  16 . The shaft  16  defines a threaded opening  31 , for engaging the bolt  30 . Typically, the bolt  30  and shaft  16  are threaded such that during operation, when the rotor  14  is spun, the bolt  30  is tightened. In another embodiment, the opening  29  is threaded and the shaft  16  has threads on its exterior surface so that the shaft  16  can be threadably received by the rotor  14 . Those skilled in the art will recognize other ways of coupling the rotor  14  to the shaft  16 , such as, but not limited to, pressing, brazing, welding, press-fit, using keys and keyways, splines, geometrically shaped shaft, set screws, clamping elements, bonded, and in addition, the shaft may be formed as part of the rotor, and all such ways of coupling are intended to be within the scope of the invention.  
         [0045]     In alternative embodiments, the rotor  14  can be spherical or have an exterior surface of any other predetermined shape.  
         [0046]     Typically, the boss  105  has an exterior  107  that is generally cylindrical shape that tapers inward to a flat head  109  for abutting against the bolt  30 . The interior  111  of the boss  105  is adapted to receive the shaft  16  such that when the shaft  16  is beveled or tapered the interior  111  of the boss  105  is complementary configured.  
         [0047]     In one embodiment, the rotor  14  is plastic and is formed using injection molding known to those skilled in the art. The rotor  14  can also be made from, but is not limited to, metal, which may be made using manufacturing methods such as, but not limited to, die-cast methods, or machining methods, among others known to those skilled in the art. The rotor  14  can also be made from ceramics using known methods or from other rigid materials.  
         [0048]     The rotor  14  defines fluid passages  32  having walls  34 . The fluid passages  32  extend outward from a first opening  36  to a second opening  38 , which are disposed along the longitudinal exterior  26  of the rotor  14 . The rotor  14  is illustrated as having multiple fluid passages  32  with second openings  38  approximately longitudinally aligned. A first set of fluid passages  32  proximal to the front face  22 ; a second set of fluid passages  32  proximal to the rear face  24 ; and a third set of fluid passages  32  interposing the first and second set of fluid passages. However, this is merely one embodiment, and in alternative embodiments, the rotor may more, fewer, or no sets of approximately longitudinally aligned second openings  38  or third openings.  
         [0049]     The base portion  10  defines an exterior surface  50  and an interior surface  52  having an opening  54  formed therethrough. An outlet/inlet pipe  56  extends outward from the opening  54  and is in communication with the cavity  12 . When fluid flows into the cavity  12  from an inlet/outlet pipe  48 , the fluid flows out the outlet/inlet pipe  56 .  
         [0050]     The base portion  10  also includes a rear wall  11  and a longitudinal wall  101  having an inner surface  103 . The rear wall  11  defines an opening  19 , which extends through the rear wall  11 . The opening  19  is adapted to receive the shaft  16  so that the shaft  16  can extend from the motive source  6  to the rotor  14 .  
         [0051]     The rotor  14  and cavitation housing  4  have an interstitial clearance  40  that is typically greater than (including magnitudes greater than, in some embodiments) approximately 0.005 inches. For the purposes of this disclosure, the interstitial clearance is defined as the distance between the longitudinal exterior surface  26  of the rotor  14  and the inner surface  103  of the longitudinal wall  101  of the base portion  14 . The interstitial clearance  40  is typically large enough so that there is no fluid flow restriction, which might reduce the cavitation effect within the fluid passages  32 . In some embodiments, the interstitial clearance  40  is on the order of multiple feet. For example, a roto-dynamic fluidic system for treating municipal waste waster may have interstitial clearances in the range of multiple feet. In addition, the interstitial clearance is typically large enough so that fluid disposed between the rotor  14  and the housing  4  is not generally cavitated by shear forces induced by spinning the rotor  14 . Typically, the distance between the front and rear faces of the rotor is approximately the same as the interstitial distance  40 .  
         [0052]     The front plate  8  defines an exterior face  42  and an interior face  44  having an opening  46  formed therethrough. A fluid inlet/outlet pipe  48  extends outward from the opening  46  and partially into the cavity  12 . Typically, the fluid inlet/outlet pipe  48  threadably mates with the opening  46 . A fluid flows from a reservoir (not shown) through a hose or pipe, etc. (not shown) into the cavity  12 . The inlet/outlet pipe  48  and the center void  28  are operationally aligned such that fluid flowing through the inlet/outlet pipe  48  flows into the center void  28  and, from there, through the fluid passages  32 .  
         [0053]     The front face  22  defines a notch  115  that circumscribes the center void  28 . A sealing element  58  is pressed into the notch  115  and extends thereform to the inlet/outlet pipe  48 . The sealing element  58  provides an essentially fluid tight seal between the front plate  8  and the rotor  14  so that fluid flowing from the inlet/outlet pipe  48  is directed into the center void  28 . Examples of sealing elements  18  and  58  include, but are not limited to, lip seals, carbon-element spring loaded seals, packing elements, labyrinth seals, etc.  
         [0054]     For the purposes of this disclosure, the roto-dynamic fluidic device  2  will include three fluid regions: a central region (I); a peripheral region (II); and an intermediate region (III). In the embodiment illustrated in  FIG. 1 , the central region is defined by the inlet/outlet pipe  48 , the sealing element  58 , and the void  28 . The peripheral region is the region between the interior surfaces  44  and  52  and the exterior of the rotor  14 . The intermediate region is defined as the regions that fluidically connect the central region (I) with the peripheral region (II). If not for the passages  32 , the sealing element  58  would essentially prevent proper fluidic communication between the central region (I) and the peripheral region (II).  
         [0055]     In operation the roto-dynamic fluidic device  2  can be operated such that there is a pressure differential between the pressure of the fluid flowing through the inlet/outlet pipe  48  and the pressure of the fluid flowing out of the outlet/inlet pipe  56 . When the pressure of the fluid in the inlet/outlet pipe  48  is beneath a given value, the given value depending upon the fluid, the fluid entering the roto-dynamic fluidic device  2  experiences tensile stress induced by the pressure “stretching” the fluid. Typically, the fluid is not “stretched” to the point that vapor bubbles will form in the fluid prior to the fluid beginning to flow through the passages  32 . For a fluid such as water, the pressure at the inlet/outlet pipe  48  is typically within the range of 0 to 100 psi.  
         [0056]     It should be noted that although the fluid flow into the roto-dynamic fluidic device  2  has been described as flowing from the inlet/outlet pipe  48 , through the rotor  14 , and out the outlet/inlet pipe  56  that this was done for exemplary purposes only. In another preferred embodiment, the fluid flow is reversed such that fluid flows into the roto-dynamic fluidic device  2  from the outlet/inlet pipe  56  and out the inlet/outlet pipe  48 .  
         [0057]     The rotor  14  is spun at rpm levels typically ranging from 70 to 65,000 rpm depending on the dimensional parameters of the rotor  14  itself and the fluid being cavitated. In operation, fluid flows into the passages  32  through the first openings  36  as the rotor  14  is being spun, and the fluid in the passages  32  experiences centrifugal force induced by the rotation of the rotor  14 . The fluid within the passages  32  experience centrifugal force, which results in tensile stresses being developed in the fluid column present within the passage  32 . Generally, the tensile stress serves as the primary or one of many components that cause vapor bubbles to form within the fluid. The fluid exits the passages  32 , and generally the vapor bubbles collapse within the interstitial clearance  40 . However, in some modes of operation, some or all of the vapor bubbles may collapse within the passages  32  prior to their exiting the passages  32 . It should be also understood that, in other embodiments, when fluid flows radially inward (from the second openings  38  to the first openings  36 ) through the rotor  14 , the fluid undergoes centripetal acceleration which creates a low pressure field proximate to the center of rotation, thereby promoting cavitation in the fluid.  
         [0058]     Furthermore, it should be understood that although the first opening  36  and the second opening  38  of the passages  32  within the rotor  14  have been shown as being circular in cross section, this is simply in accordance with at least one embodiment. In alternative preferred embodiments, the cross section of the first openings  36 , the second openings  38 , and the passages  32  may be, but are not limited to, a circular, or square, or rectangular, or oval, or irregular shape. Furthermore, alternative preferred embodiments, the passages  32  are defined by walls  34  that may be diverging or converging or a combination of both, among others.  
         [0059]     Although the motive source  6  is illustrated as being proximal to the cavitation housing  4 , this is for illustrative purposes only and is a non-limiting example. In other embodiments, the shaft  16  having the rotor  14  coupled thereto can be powered by other sources such as, but not limited to, a belt, chain, gear, hydraulic, air, or similar drive means. In other embodiments of the invention, the motive force for the rotor  14  is provided through the provision within the rotor for it to also act as an armature for a brush-type or inductive electric motor with the corresponding components being provided within the housing  4 . In other preferred embodiments of the invention, water pressure from an outside source is used as the motive force for the rotor  14  through the use of a water driven turbine connected rotationally to the rotor  14  of the roto-dynamic fluidic device  2 . In some implementations of the invention, it is advantageous to use a magnetic bearing to reduce the frictional losses within the roto-dynamic fluidic device  2 . In other implementations of the invention, the rotor  14  is supported by the fluid within the housing  4  by a hydrodynamic bearing through the dimensional configurations of the rotor and housing construction. Furthermore, in other implementations, the roto-dynamic fluidic device  2  may act as both a turbine and a cavitation facilitator.  
         [0060]     In an alternative embodiment, the roto-dynamic fluidic device  2  includes a hollow rotatable shaft (not shown) that extends through the opening  46 . The hollow shaft is supported by a support bearing (not shown), and a sealing element (not shown) abuts the hollow shaft and the interior face  44  of the front plate  8 . The hollow shaft is coupled to the rotor  14  pressing the hollow shaft into the void  28 . Those skilled in the art are familiar with other ways of coupling the hollow shaft to the rotor  14 , and the other ways are included within the scope of the invention.  
         [0061]     In yet another embodiment, the shaft  16  is a through shaft that extends through the rotor  14 . In this case, the front plate  8  may also include a support bearing for supporting the through shaft. As those skilled in the art will recognize, a through shaft can also have a hollow interior, and if the through shaft defines a hollow interior for communicating fluid into (or out of) the roto-dynamic fluidic device  2 , then the through shaft includes ports for communicating fluid. In some embodiments, a through shaft may be used to communicate a first fluid from one end of the through shaft into the roto-dynamic fluidic device  2  and a second fluid or gas or gaseous-fluid mix into the roto-dynamic fluidic device  2 . The ports in the through shaft may be located such that one of the fluids is communicated between the center void  28  and the through shaft and the second fluid is communicated between the region that is exterior to the rotor  14  and the through shaft such that the fluids mix after cavitation. Alternatively, the ports can be disposed on the through shaft such that the two fluids mix prior to or during cavitation.  
         [0062]     In yet another embodiment, the inlet/outlet pipe  48  can include a plurality of tubes such that multiple fluids, gases, types of particulate matter, etc. can be injected into the roto-dynamic fluidic device  2 . The tubes can be co-axial, and the tubes can be used to inject the substances into different regions of the roto-dynamic fluidic device  2  such that mixture can occur before, during, or after cavitation.  
         [0063]     In some embodiments of the invention, the cavitation housing  4  is an open structure presented to the rotor  14  such that fluid can flow into and out of the interior cavity  12  of the cavitation housing  4 . In some implementations of this embodiment, the rotor  14  is immersed in an open reservoir, wherein the fluid enters the center void  28  of the rotor and exits the passages  32  via the second opening  38 .  
         [0064]     The roto-dynamic fluidic device  2  preferably provides for controlled cavitation such that when vapor bubbles collapse, the vapor bubbles collapse in predetermined zones such that the mechanical components of the roto-dynamic fluidic device  2  are not harmed. Typically, this is accomplished by providing for substantial laminar flow between the first opening  34  and the second opening  38  or the passage  32 . Generally, in some embodiments, if the passages  32  are narrow or any portion of a passage is narrow, then the walls  34  of that portion are smooth so as to facilitate laminar fluid flow. Alternatively, in portions of the passages  32  that are wide, the walls can be rough. Fluid flowing in a wide passage having a rough wall can form a turbulent boundary layer proximal to the rough wall, which promotes vapor bubble travel within the flow field region away from the walls.  
         [0065]     The following figures illustrate, alternative embodiments, among others, of the rotor  14 . The following embodiments are intended to be non-limiting and are provided for, among other things, exemplary purposes.  
         [0066]      FIG. 3A  shows a perspective cutaway view of a rotor  14 A having an inducer  60 , which is disposed within a center void  28 , and  FIG. 3B  shows the rotor  14 A in cross section as seen from line B-B. The inducer  60  aids the transition of the fluid flow from longitudinal to radial. The inducer  60  includes vanes  61  that extend outward from the center of the inducer  60 . The inducer  60  and rotor  14  spin as one element on the shaft  16  (not shown, but the shaft is connectable to the rear of the rotor  14 A, as with the boss  105  illustrated in  FIG. 2A ), and the vanes  61  impart rotational momentum to the fluid in the center void  28 , which enhances fluid flow from the center void  28  into the first openings  36  of the passages  32 . The passages  32  extend non-radially from the center void  28  to the exterior surface  26 . However, the passages  32  could also extend radially from the center void  28  to the exterior surface  26 . In various embodiments, passages  32  are preferably circular cylindrical but could be otherwise in other embodiments. In other embodiments, an inducer may be formed by passages formed to impart rotational momentum to the fluid.  
         [0067]     Refer to  FIG. 3C , which is cross sectional view of another embodiment of a rotor  14 B, the rotor  14 B defines passages  32  that are formed along a curved or irregular path. Preferably, the curvature of the passages  32  is such that when fluid flows through the passages  32 , the fluid helps rotate the rotor  14   c.    
         [0068]     Refer to  FIG. 3   d , which is cross sectional view of another embodiment of a rotor  14 C, the rotor  14   c  defines a plurality of fluid passages  62  having walls  64 . Each of the fluid passages  62  includes a feed passage  66  having an inlet opening  67  and a cavitation passage  68  having an outlet opening  69 . The feed passage  66  is formed at an angle with respect to the normal of the outer surface  26  of the rotor  14  and extends partially inward towards the center of the rotor  14 . At the inner most portion  70  of the fluid passage  62 , the feed passage  66  communicates with the cavitation passage  68 . The cavitation passage  68  extends from the inner most portion  70  to the exterior surface  26  of the rotor  14   c . In operation, the spinning rotor  14   c  allows fluid to flow from the interstitial clearance  40  down the feed passage  66  and out the cavitation passage  68  back to the interstitial clearance  40 . As fluid flows through the cavitation passages  68 , the fluid experiences tension, thereby producing cavitation in the fluid. The cavitation passage  68  can extend radially or non-radially from the inner most portion  70  to the surface  26 . In addition, it is preferable that the minimum distance (d 1 ) between the inner most portion  70  and a given point  71  on the exterior surface  26  be less than the minimum distance (d 2 ) between the center of rotation  73  of the rotator  14   c  and the given point on the exterior surface  26 , where the given point  71  lies upon the shortest line on the surface (d 3 ) extending between the inlet opening  67  and the outlet opening  69 .  
         [0069]     In alternative embodiments, the fluid passages  62  can include a longitudinal component. For example, for a given fluid passage  62 , the feed passage  66  could extend tangentially inward (toward the shaft  16 ) and rearward (toward the rear face  24 ) to the inner most portion  70 , and the cavitation passage  68  would extend outward from the inner most portion  70  back to the exterior surface  26 . The cavitation passage  68  could also include a longitudinal component such that the cavitation passage  68  could extend both outward from the inner most portion  70  and toward either the front face  22  or the rear face  24 .  
         [0070]     Refer to  FIG. 4A  and  FIG. 4B , in  FIG. 4A  the housing  4  and a rotor  14 D are shown in cross section, and in  FIG. 4B  the housing  4  and the rotor  14 D are shown in cross section as viewed from line C-C. The rotor  14 D comprises a hub  74  and a plurality of hollow tubes  72  that extend outward from the hub  74 . Each of the tubes  74  is defined by a proximal end  76  and a distal end  78 , relative to the hub  74 . The hub  74  defines a generally hollow interior  80  for receiving a fluid via the inlet/outlet pipe  48 . In this embodiment, the inlet/outlet pipe  48  extends partially into the cavity  12 , and the sealing element  58  extends from a notch  82  formed in the hub  74  to the inlet/outlet pipe  48 . In this embodiment, the peripheral region (II) includes all of the volume of the cavity  12  outside of the rotor  14  and the inlet/outlet pipe  48 . The central region (I) is defined by the volume of the inlet/outlet pipe  48  and the hollow interior  80  of the hub  74 .  
         [0071]     The front face  22  defines a discharge port  84  that extends from the interior face  44  to the exterior face  42 . The discharge ports  84  enable excess fluid to be discharged from the roto-dynamic fluidic device  2 . In this embodiment, the front face  22  also defines an opening for receiving an outlet/inlet pipe  56 .  
         [0072]     Refer to  FIG. 4B , a fluid  86 A flows into the hollow interior  80  of the hub  74  via the inlet/outlet pipe  48  and through the tubes  72  into the cavity  12 . The spinning of the rotor  14   d  causes the fluid  86   b  in the cavity  12  to spin in conjunction with the rotor  14   d . Thus, the spinning fluid  86   b  experiences centrifugal force, which causes it to push against the interior face  52  of the base portion  10  away from the center of rotation, which for the present embodiment is shaft  16 . Fluid that cannot move proximal to the interior face  52  is drained from the cavity  12  via the discharge ports  84 . Due to the centrifugal force experienced by the spinning fluid  86   b , a pressure gradient develops across the spinning fluid. Maximum pressure is experienced at the interior face  52  of the base portion  10  and decreases radially inward toward the axis of rotation. The spinning liquid  86   b  defines a liquid ring that extends from a fluid-vapor boundary  88  to the interior face  52 . Typically, the rotational speed of the rotor  14  and the locations of the discharge ports  84  are such that the pressure acting on the fluid at the fluid-vapor boundary  88  is approximately the vapor pressure of the fluid.  
         [0073]     In operation, the distal ends  78  are immersed in the fluid ring  86   b , and fluid  86   c  in the tubes  72  experiences tensile stress as the rotor  14   d  is rotated, thereby causing the formation of vapor bubbles in the fluid in the tubes  72 . The vapor bubbles formed by tensile stresses acting on the fluid within the tubes  72  are exposed to the high pressure fluid  86   b  when the fluid  86   c  exits the distal end  78  of the tubes  72 . The high pressure fluid  86   b  enhances the collapsing of the vapor bubbles.  
         [0074]     Refer to  FIG. 4C , in this embodiment, the housing  4  defines a longitudinal center  90 , and the shaft  16  is offset from the longitudinal center  90 . The shaft  16  defines a center of rotation  91  that is offset to the left from the longitudinal center  90 , and consequently, the tubes  72   a  that are currently in the left half of the housing  4  extend deeper into the fluid ring  86   b  than do the tubes  72   b  that are currently in the right half of the housing  4 . In this embodiment, the fluidic pressure exerted on a vapor bubble exiting the distal end  78  of a tube  72  depends upon the instantaneous position of the distal end  78 .  
         [0075]     Refer to  FIG. 5 , which shows the housing  4  and a rotor  14 E in cross sectional view, the rotor  14 E includes a plurality of passages  32  having first openings  36  disposed front face  22  of the rotor  14 E and second openings  38  disposed on the longitudinal surface  26 . The interior surface  52  of the base portion  10  defines a notch  93  that extends circumferentially around the rotor  14 E. A sealing element  95  extends from the base portion  10  to the longitudinal surface  26 . Here, region I is defined to include the inlet/outlet pipe  48  and the volume of space between the interior face  42  of the front plate  16  and the sealing element  58  and the front face  22  of the rotor  14 E. Region III is defined as the volume behind the sealing element  95 . The passages  32  define region II, and the passages  32  include both straight and curved passages. In one preferred implementation, fluid flows into Region I of the roto-dynamic fluidic device  2 , through region II into region III, and from region III out of the roto-dynamic fluidic device  2 . In another implementation, the fluid flow is reversed. The spinning of the rotor  14 E induces tensile stress in fluid within the region II, thereby causing vapor bubble formation in the fluid therein.  
         [0076]     Refer to  FIG. 6 ,  FIG. 6A  shows the housing  4  and a rotor  14 F in cross section. The rotor  14 F defines passages  32 A- 32 C, each of the passages  32  have a restrictive section  94 A- 94 C, respectively, where a restrictive section is defined as a region having a relatively narrow cross section or having an obstruction therein. Typically, the restrictive section  94  is the narrowest region along the length of the passage  32  and is typically narrower than the cross sections of the first opening  36  and the second opening  38 . The flow area for the fluid is reduced at the restrictive section  94  which results in an increase in the velocity of the fluid in the restrictive section  94 . As the fluid has passes through the restrictive section  94 , the fluid experiences a drop in local fluid pressure. This pressure reduction in cooperation with the tensile stresses already present in the liquid act to cause the fluid to form vapor bubbles which typically collapse after passing through the restrictive section  94 , thereby completing the cavitation process. The region upstream from the restrictive section  94  is defined as the converging section  114 , and the region downstream from the restrictive section is defined as the diverging section  116 . The restrictive section  94  may be placed anywhere along the passages  32 , but it is preferably located proximal to the second opening  38 . In some embodiments, the diverging section  116  may be eliminated and the passage  32  can discharge directly into the interstitial region  40 . The vapor bubbles typically collapse because the pressure partially recovers after the restrictive section  94  as the fluid enters the diverging section  116 .  
         [0077]     In passage  32 A, the restrictive section  94 A is defined by a pin  97 A that extends from the front face  22  through a hole  99  into the passage  32 A. Typically, the pin  97 A is pressed into the hole  99 , but the pin  97 A can also be welded, threaded, glued or otherwise affixed to the rotor  14 F.  
         [0078]     In passage  32 B, the restrictive section  94 B is defined by the walls  34  tapering inward in a converging section  114  to a minimum clearance section  95   a  and then tapering outward as the diverging section  116 .  
         [0079]     The passage  32 C is hexagonal in cross section, and the restrictive section  94 C is defined by a triangularly shaped pin  97 B. The pin  97 B extends from the rear face  24  through a hole (not shown) into the passage  32 C. The pin  97 C is pressed into the hole, but the pin  97 B can also be welded, threaded, glued or otherwise affixed to the rotor  14 F.  
         [0080]     In one preferred implementation, there are a series of restrictive sections  94  placed in succession to one another to process the working fluid multiple times. Ports and passageways can be provided for the introduction or removal of elements at given points in the process to affect chemical and physical reactions. The multiple restrictive sections  94  are placed linearly one after the other inside the passageways  32  which are used to direct the fluid from one pressure reduction section to the next.  
         [0081]     In passage  32   c , the restrictive section  94   c  is defined by one or more restrictive elements  94  placed in the passage  32   c . Non-limiting examples of a restrictive element  94  include a cylinder and other geometrical objects whose cross-sectional area is smaller than the passageway&#39;s flow area at the point of insertion such that the fluid is forced through a narrower passage as it passes the restrictive element.  
         [0082]     In some preferred implementations there may be provided a moveable restrictive element  94  placed at a chosen location within the fluid passage and held in place by the flow field acting on the exterior surfaces of the moveable restrictive element. In other implementations of the invention the moveable restrictive elements  94  may be acted upon by centrifugal or centripetal force which serve to close off the passageway but are prevented from totally shutting off the flow due to the external geometry of the restrictive element  94 , thus providing a changeable means of decreasing the fluid flow area at a chosen point in the passageway and increasing the fluid velocity in this region. In other preferred embodiments the moveable restrictive element  94  may be affixed to a spring or springing medium such that the force of the spring acting on the restrictive element acts to maintain a near-constant pressure or flow within the passageway, such as is known to those skilled in the art. In other preferred embodiments the moveable restrictive element  94  may be vibrated at a chosen frequency to impart cyclic pressure fluctuations in the fluid, such as is known to those skilled in the art.  
         [0083]     In this embodiment, the front  22  of the rotor  14  defines a notch  97  that circumscribes the center void  28  and has the sealing element  58  affixed thereto. The sealing element  58  extends from the notch  82  to the inlet/outlet pipe  48 , which extends partially into the cavity  12  and partially past the front  22  of the rotor  14 .  
         [0084]     Here, region I is defined to include the inlet/outlet pipe  48  and the center void  28 . Region III is defined as the volume between interior of the housing  4  and the rotor  14   f  and the inlet/outlet pipe  48 . The passages  32  define region II, and the passages  32  include both straight and curved passages. In one preferred implementation, fluid flows into Region I of the roto-dynamic fluidic device  2 , through region II into region III, and from region III out of the roto-dynamic fluidic device  2 . In another implementation, the fluid flow is reversed. The spinning of the rotor  14 F induces tensile stress in fluid within the region II, thereby causing vapor bubble formation in the fluid therein.  
         [0085]     Refer to  FIG. 7 , which shows the housing  4  and a rotor  14 G in cross section, the interior face  52  of the housing  2  defines multiple circumferential troughs  96 . The design of the circumferential troughs  96  is such that the fluid exiting the rotor  14 G fills the troughs  96  and is brought into rotation around the inside of the cavitation housing  4  by the motion of the rotor  14 . A rotating fluid ring  86  forms within the circumferential trough  96  and fluid pressure builds up within the trough  96  in relation to the speed of the rotor. The pressure of the fluid within the trough  96  is higher than the pressure of the fluid in the passages  32 , and the higher pressure facilitates the violent collapse of vapor bubbles. The liquid ring  86  is driven into rotation by the shearing action of the rotor against the fluid within the housing, and the whirling effect of the fluid exiting the passageways.  
         [0086]     Refer to  FIG. 8 , which shows the housing  4  and a rotor  14 H in cross section, the rotor  14 H includes passages  32 , which have a restrictive section  94 . In this embodiment, the width between the walls  34  of the passages  32  abruptly narrows in a step like manner at the beginning of the restrictive section  94 , and the restrictive section  94  ends at the exterior surface  26 . Thus, as the fluid flows out of the passages  32 , the fluid is no longer confined by the restrictive section  94 . In other words, the interstitial region  40  is a diverging section where cavitation occurs. In other implementations, the diverging section  116  may be provided within the passage  32 .  
         [0087]     Refer to  FIG. 9 , which shows a cross sectional view of the housing  2 , a hollow shaft  102 , and a rotor  14 I, the rear  24  of the rotor  14 I defines an opening  100  for receiving the hollow shaft  102 . Typically, the opening  100  is configured to receive the hollow shaft  102  such that when the shaft  102  is pressed onto the rotor  14 I, the hollow shaft  102  and rotor  14  move as one element. The rotor  14 I includes a plurality of channels  104  that extend outward from a cavity  106 , which is in fluidic communication with the hollow shaft  102 . Each one of the channels  104  intersects and is in fluidic communication with one of the passages  32  at an intersection point  108 .  
         [0088]     In operation, the center void  28  receives a first fluid  86   d  via the inlet/outlet pipe  48 , which then flows towards the interstitial region  40  via the passages  32 . The hollow shaft  102  communicates a second fluid  86   e  into the cavity  106 , and the second fluid then flows through the channels  104  to the intersection points  108 . At each intersection point  108 , the first fluid  86   d  and the second fluid  86   e  mix together and the resultant fluid  86   f  discharges into the interstitial region  40 . It should be noted that having the intersection point  108  in proximity to the restrictive section  94  enhances mixing because of the energitics of the destruction of the vapor bubbles formed in the restrictive section  94 . However, in alternative embodiments, the intersection point  108  may be before or after the restrictive section  94 .  
         [0089]     Refer to  FIG. 10A , which shows a cross sectional view of the housing  2 , the hollow shaft  102 , and a rotor  14 J, the rotor  14 J is comprised of a front section  110  and a rear section  112  whose cross sections form a converging section  114  and diverging section  116  in passage  32 . The interstitial clearance  40  between rotor front section  110  and rotor rear section  112  is typically greater than 0.010 inches to prevent fluid friction from “choking” the device. The front section  110  and rear section  112  each define a plurality of aligned pairs holes  118  and  120 , respectively, and each pair of aligned holes is for receiving a connecting member  122 . The connecting members  122  extend rigidly between the front section  110  and the rear section  112  such that the front section  110   x  and rear section  112  rotate as essentially one element. The connecting members  122  are formed in a manner such that they do not substantially block fluid flowing from region I to region II. Non-limiting examples of connecting members  122  include rods, pins, bolts, and the like.  
         [0090]     Together the front section  110  and the rear section  112  define a cavity  124  that is in fluid communication with the inlet/outlet pipe  48  and the hollow shaft  102 . A first fluid  86   d  is passed into the cavity  124  of the rotor  14 J via the inlet/outlet pipe  48 . Another fluid  86   e  is passed into the cavity  124  of the rotor  14 J via the hollow shaft  102 , and the two fluids are mixed in the passage  32 . The mixed fluid  86   f  exits the passages  32  into the cavity  12 .  
         [0091]     In this embodiment, the rear section  112  is attached to the shaft  102  by aligning the opening  100  with the shaft  102  and pressing the rear section  112  onto the shaft  102 . Those skilled in the art will recognize other ways of coupling the shaft  102  and the rear section  112  such as, but not limited to, the ways previously described hereinabove, all of which are included within the scope of the invention.  
         [0092]     For operation with a single fluid, the fluid experiences centrifugal force as the rotor is spun because the fluid in the rotor spins in conjunction with the rotor. The rotational movement of the fluid results in tensile stresses being developed in the fluid. The converging section  114  leads to a minimal clearance section  126  which results in an increase in the velocity of the fluid, thereby reducing the local fluid pressure. This pressure reduction in cooperation with the tensile stresses already present in the liquid act to cause the fluid to form vapor bubbles which collapse in the diverging section  116  of the passage  32  downstream of minimal clearance section  126 , wherein the pressure partially recovers, completing the cavitation process. The same process applies when two fluids are mixed.  
         [0093]     In this embodiment, the base portion  10  also defines a single circumferential trough  96 . In operation, the fluid  86   f  in the trough  96  experiences centrifugal force as the rotor  14 J is spun. As previously described hereinabove, the pressure on the fluid  86   f  in the trough  96  is higher than the pressure on the fluid in the diverging section  116  of the rotor  14 J, and the pressure on the fluid in the diverging section  116  is less than the pressure on the fluid in the converging section  14 J. The local pressure reduction in the diverging section  116  along with the tensile stresses already present in the fluid (the tensile stresses being due to the fluid&#39;s rotational movement imparted by the rotor) act to cause the fluid to form vapor bubbles. Some of the vapor bubbles collapse in the diverging section  116  of the passage  32  downstream of minimal clearance section  126 . Bubbles that do not collapse in the rotor  14 J are directed by fluid flow and radial momentum into the relatively higher pressure zone of the circumferential trough  96 , and the increase in pressure as the bubbles move from the lower pressure diverging section  116  into the higher pressure circumferential trough  96  enhances the destruction of the bubbles in the trough  96 .  
         [0094]     Refer to  FIGS. 10B and 10C ,  FIG. 10B  shows a cross sectional view of the housing  2 , the hollow shaft  102 , the rotor  14 J, and a volute ring  128 , and  FIG. 10C  shows an isometric view of the rotor  14 J. The volute ring  128  is attached to the front section  110  and rear section  112  and spins in conjunction with the front section  110  and rear section  112 . In cross section, the volute ring  128  includes opposed ends  130  and a peak region  132  that is approximately half-way between the opposed ends  130 . The opposed ends  130  are attached to the front section  110  and rear section  112  such that the peak region  132  is approximately aligned with the passage  32 . Typically, the opposed ends  130  are attached by fasteners and/or adhesives such as, but not limited to, screws, bolts, rivets, welds, and spot welds to the longitudinal surface  26 . The volute ring  128  defines a plurality of bleed-off ports  134  for communicating fluid from the region between the volute ring  128  and the rotor  14 J to the exterior of the volute ring  128 . The bleed-off ports  134  are configured to drain the volute ring  128  at a chosen rate that maintains a desired pressure within the cavity  12  and maintains a desired pressure gradient in the fluid  86 F trapped by the volute ring  128 . In an alternative embodiment, one or both of the opposed ends  130  may be raised from the longitudinal exterior  26  by spacers (not shown) or the like such that fluid can escape from the volute ring element  128  by flowing between the volute ring element  128  and the rotor  14 J.  
         [0095]     In this implementation, the volute ring element  128  has the same rotational speed as the front section  110  and rear section  112 , thereby reducing the fluidic shear present in the embodiment shown in  FIG. 7  and  FIG. 10   a . With the reduction in fluidic shear provided by the volute ring element in  FIG. 10   b , the pressure within the circumferential ring of fluid  86   f  formed inside the volute ring element will be greater, which facilitates more violent bubble collapse. In some implementations of the invention it may be desirable to have the volute element  128  driven at a speed higher than that of the rotor  14 J to increase the pressure within the fluid  86   f  trapped by the volute ring  128 ; the increased pressured caused by the increased rotational speed of the volute ring element  128 . In that case, the volute ring  128  is not attached to the rotor  14 J and is driven by an outside motive force. In a preferred implementation of the invention, the volute ring  128  is supported by a bearing element (not shown) surrounding the main input shaft  16  of the roto-dynamic fluidic device  2 , and the volute ring  128  is driven by a planetary gear transmission (not shown) to spin at a chosen rpm higher than that of the rotor  14 J. The center gear of the planetary gear transmission being affixed to the input shaft  16  of the device.  
         [0096]     In alternative embodiments, the volute ring element  128  may have a sequence of peaks and valleys between the opposed ends  130 ; the number of peaks related to the type of rotor  14  that the volute ring element  128  is used with. For example, in one non-limiting embodiment, the rotor  14  (see  FIG. 2A ) includes three sets of fluid passages  32 , each set of passages having second openings  38  that are approximately longitudinally aligned on the longitudinal exterior  26 . (A first set proximal to the front face  22 ; a second set proximal to the rear face  24 ; and a third set between the first and second set.) In this case, a volute ring element  128  for use with the rotor  14   a  would preferably include three peaks so that each of the peaks is aligned with one of the sets of openings. However, in this embodiment, the volute ring element  128  could also include fewer or more peaks because even though it is preferable to coincide the peaks with the sets of openings, it is not is required that the peaks and sets of openings coincide, and a single peak could be wide enough to traverse more than one set of openings. For the purposes of discussing a non-limiting embodiment of the volute ring element  128 , the rotor  14   a  was described as having sets of openings that are approximately longitudinally aligned. However, it should be remembered that the second openings  38  disposed on the longitudinal exterior  26  need not be disposed such that they are approximately longitudinally aligned. The second openings  38  in any of the non-limiting rotors  14  described hereinabove may disposed in any predetermined configuration or random configuration.  
         [0097]     In another embodiment, the front section  112  and rear section  1110  may spin at different speeds to each other, or the two elements may counter-rotate with respect to one another through known means, all of which will serve to create small vortices within the minimal clearance  126 , thereby aiding bubble formation.  
         [0098]     In yet another preferred implementation of the invention, the input shaft  102  is connected to the volute element  128  and the rotor  14 J is supported by a bearing mounted on the shaft  102  and allowed to freewheel such that the motive force for the rotor becomes the shearing effect of the fluid between the volute element and the rotor&#39;s external surfaces. In this manner, the speed of the volute element will always be higher than the speed of the rotor and a control means such as a brake (not shown) actuated by control means known to those skilled in the art of speed control. The brake is provided to maintain the rotor at a chosen rotational speed, such speed being advantageous for creating the level of cavitation desired within the device, said speed alterations being able to be performed without interfering with the rotation of the volute element and the established circumferential liquid ring therein.  
         [0099]     Refer to  FIG. 11 , which shows a cross sectional view of the housing  2  and a partial cut away view of a rotor  14 K, the rotor  14 K includes a plurality of cavities  136  that extend inward from the exterior surface  26  of the rotor  14 K. The cavity  12  of the roto-dynamic fluidic device  2  is essentially filled by both the rotor  14 K and fluid, which enters via inlet/outlet port  48 , and exits via outlet/inlet port  56 . In operation, as the fluid fills an individual cavity  136  within the spinning rotor  14 K, tension is created in the fluid due to centripetal force and a vapor bubble is created within cavity  136 . Due to centrifugal forces acting on the fluid, the fluid contained within the now filled cavity  136  is propelled in an outwardly radial direction, carrying the recently formed vapor bubble with the fluid flow. In this way the vapor bubble is ejected from cavity  126  and sent into interstitial clearance region  40 . Typically, the expelled bubbles experience a high pressure field due to the centrifugal force acting on the total fluid mass, which facilitates the implosion of the vapor bubble upon itself, thus completing the cavitation cycle. In some modes of operation, the vapor bubbles may collapse within the cavity  136  prior to their reaching the interstitial clearance  40 . It should be understood that cavities  136  within the rotor may have any predetermined shape. Non-limiting examples of cross sections for cavity  126  include circular, or square, or rectangular, or an irregular shape. Furthermore, the cavities may have diverging or converging walls which facilitate the creation of tensile stress within the fluid to enhance the formation of vapor bubbles. Typically, the cavities  136  are disposed on the exterior surface  26  in a irregular/quasi-random or random manner. The irregularity or randomness of the cavities  136  promotes cavitation over regularly spaced cavities  136  because the fluid between the rotor  14 K and the housing  4  is more turbulent than when the cavities  136  are evenly/regularly spaced. Furthermore, it is preferred that the opening for a cavity  136  have an abrupt wide edge, instead of a curved round edge, at the upstream portion of the cavity  136 .  
         [0100]     The cavities  136  are defined by inner walls  138 , which is coated with a lining material  140 . The lining material  140  can be rough, or smooth, or threaded, or have ridges, or include one or more materials that are different than the rotor material to enhance or hinder reactions that occur when cavitation is present, or have magnetic properties. In one preferred embodiment, the material  140  includes one or more permanent or electrical magnets that affect chemical processes within the roto-dynamic fluidic device  2 . The magnets can be placed upstream or downstream from where vapor bubbles are formed or from where the vapor bubbles collapse. Typically, electrical magnets are controllable such that their magnet fields can be controlled for strength for the purpose of, among other things, affecting chemical processes within the device.  
         [0101]     Further, the housing may be fitted with such permanent and/or electric magnets in the fluid flow between the surface of the rotor and inner surface of the housing to affect the chemical processes within the device.  
         [0102]     In addition, in one embodiment, the material  140  includes a membrane. The membrane may be located upstream or downstream from where vapor bubbles are formed or from where the vapor bubbles collapse.  
         [0103]     Furthermore, in one embodiment, the material  140  includes metal alloys that affect specific chemical reactions or physical elements within the fluid as it passes through the cavity, with or without cavitation occurring. Further, in these embodiments, one or more cavity(ies) may include a chemical process tube such as disclosed in U.S. Pat. No. 5,048,499; 5,197,446; 5,482,629; or 6,106,787 which are incorporated herein by reference.  
         [0104]     In other preferred embodiments of the invention, there are mechanical or pizeo-electric or electrical ultrasonic transducers placed proximate to the cavities, either within the cavities themselves or in the housing&#39;s inner wall, and the transducers enhance or hinder reactions that occur when cavitation is present. Typically, the units or transducers are activated at frequencies that will intensify the cavitation of fluid within one or more selected cavities.  
         [0105]     In yet in another embodiment, the inner walls  136  are not lined by material  140 , but are instead themselves rough, or smooth, or threaded, or have ridges, or include one or more materials that are different than the rotor material to enhance or hinder reactions that occur when cavitation is present, or have magnetic properties.  
         [0106]     Refer to  FIG. 12 , which shows a rotor  14 L and the housing  2  in cross section, the rotor  14 L defines undulating passages  32 . For each one of the passages, the passage  32  extends radially outward from the central void  28  to a point of inflection  119  where the passage  32  then extends inward to a second point of inflection  121 . From the second point of inflection  121 , the passage  32  extends to the surface  26 . In alternative embodiments, the passage  32  can define more than two points of inflection. Typically, the rotor  14 L acts as a pump as a fluid is flowing from the center void  28  to the first point of inflection, and the formation of vapor bubbles typically occurs in the region of the second point of inflection. If the passage  32  defines more than one pair of points of inflection, then cavitation may occur in the regions where the flow of the fluid changes from inward to outward.  
         [0107]     Refer to  FIG. 13 , which shows a portion of a rotor  14 M in cross section, the rotor  14 M is used for, among other things, vaporizing a fluid. The rotor  14 M defines a passage  32  having a first restrictive element  119  such as for example a nozzle. Preferably, the passage  32  in non-uniformly shaped within the rotor, and preferably, the restrictive element  119  is located at the exterior surface  26 . The passage  32  defines a second restrictive element  94  and a diverging section  116  that is down stream from the second restrictive element  94 . In the preferred embodiment, fluid flows through the second restrictive element  94 , and consequently, the fluid cavitates in the diverging section  116 . The fluid is chosen such that the cavitation process creates a phase change in the fluid, or facilitates the combustion of a monopropellant, or of a fuel when air or oxygen is added by additional passages (not shown), such that high pressure is created, whereupon the partially or fully affected fluid is exhausted from the rotor  14 M via the first restrictive element  119 . Combustion may be precipitated by known ignition or catalysis means. Preferably, the fluid or gases exiting through the surface of the rotor are directed such that a jet is formed and a force vector that is generally tangential to the surface of the rotor is formed. In alternative embodiments, the second restrictive element  119  can be disposed inside of the rotor  14 M Furthermore, in alternative embodiments, the rotor  14 M can include secondary channels that intersect with the passage  32 . The secondary passages can be used for, among other things, introducing a second fluid, or gas, or exhausting the combusted fluid.  
         [0108]     It should be emphasized that a fluid can include gases such as, but not limited to, argon, which can be premixed with the fluid before the fluid is received by the roto-dynamic fluidic device or the gas(es) can be mixed with a fluid in the roto-dynamic fluidic device prior to or after the formation of vapor bubbles. Typically, gases are mixed with the fluid to facilitate (or hinder) certain chemical reactions. In addition, particulate matter can also be mixed with the fluid. The particulate matter may be introduced to facilitate (or hinder) certain chemical reactions.  
         [0109]     In yet another alternative embodiment, the roto-dynamic fluidic device  2  may include mechanical components such as a ratchet and pawl assembly for, among other things, vibrating the rotor  14 .  
         [0110]     The roto-dynamic fluidic system  1  can be used for, among other things, modifying or aerating fuels, sonochemical reactions, production of nano-materials or nano-fluids, separation/mixing of gases or fluids or particulates, steam production, purification of water, combustion of fuels, and creating special alloys.  
         [0111]     It should be emphasized that the above-described embodiments of the present invention, particularly, any “preferred” embodiments, are merely possible examples of implementations, merely set forth for a clear understanding of the principles of the invention and that the embodiments disclosed hereinabove are non-limiting embodiments. Many variations and modifications may be made to the above-described embodiment(s) of the invention without departing substantially from the spirit and principles of the invention. Alternative embodiments may include more or fewer elements than were illustrated in the various non-limiting described embodiments. For example, the inducer  60  could be included in any one or none of the described embodiments. Similarly, it should be remembered that in the interest of brevity and clarity fluid flow was normally described in one direction, but the fluid flow can be reversed in each of the embodiments described hereinabove with appropriate modification where necessary. For example, if the fluid flow were reversed in rotor  14   f , then the passage  32   b  would also be reversed such that the walls  34  would taper inward from the second opening  38  to the minimum clearance  95   b  and then expand in a step like manner. All such modifications and variations are intended to be included herein within the scope of this disclosure and the present invention and protected by the following claims.