Abstract:
A Mixer-Ejector Prop System (MEPS) is presented as a new, unique and improved concept for injecting power and producing force in flowing fluids such as air or water. MEPS incorporates advanced flow mixing technology, single and multi-stage ejector technology, aircraft and propulsion aerodynamics and noise abatement technologies in a unique manner to fluid-dynamically improve the operational effectiveness and efficiency for subsonic flow velocities.

Description:
RELATED APPLICATION 
       [0001]    This application claims priority from U.S. Provisional Patent Applications Ser. No. 60/919,588, filed Mar. 23, 2007. Applicants hereby incorporate the disclosure of that application by reference. 
     
    
     BACKGROUND OF INVENTION 
       [0002]    A propeller rotor device, termed the “prop”, is a series of aerodynamic blades that are rotated by a power source such that energy is added to the flow passing through the prop. In most applications such added energy is used to generate an axial, propulsive force at speeds less than 300 miles per hour, hereinafter “low speed flow”. The number, shape and design of the rotating prop blades can vary. Two example applications of such props are in the propulsion systems of aircraft and watercraft. Variations of such props are used in axial flow rotors of a compressor. They are also used to drive blower and vacuum systems. 
         [0003]    The ability of a prop to convert power to force when placed in a stream of very large width compared to its diameter is limited by the amount and speed of the fluid it draws into and through the area swept by the propeller. To increase beyond this level, shrouds or ducts surrounding the propeller have been used. There has been considerable effort and discussion in the literature by Kort, Abella, Hollmann, Kuchemann, Lazareff and de Piolenc concerning the potential for such shrouded propeller propulsion. Additionally, while ejector-based propulsion augmentation has been studied extensively for over 60 years (see Prandtl, Heiser, Presz and Werle), only limited attention has been given its application to subsonic/incompressible propeller propulsors. 
         [0004]    Properly designed shrouds cause the oncoming flow to speed up as it is concentrated into the center of the duct containing the prop. In general, for a properly designed rotor and shroud combination, this increased flow speed at the prop causes increased force, termed “amplification”, on the combined system of the prop and shroud. A significant portion of the total force can occur on the shroud. Amplification values 1.5 and 2 have been recorded for such shrouded rotors. 
         [0005]    Ejectors are well known and documented fluid jet pumps that draw flow into a system and thereby increase the flow rate through that system. Mixer/ejectors are short compact versions of such jet pumps that are relatively insensitive to incoming flow conditions and have been used extensively in high speed jet propulsion applications involving flow velocities near or above the speed of sound. See, for example, U.S. Pat. No. 5,761,900 to Dr. Walter M. Presz, Jr, which also uses a mixer downstream to increase thrust while reducing noise from the discharge. Dr. Presz is a co-inventor in the present application. 
         [0006]    It is a primary objective to present a force generating shrouded axial flow prop system for low speed flow that employs advanced flow mixing and control devices to increase its amplification and minimize the impact of its attendant flow field on the surrounding environment and/or other props in its near vicinity. 
         [0007]    It is another primary object of the current invention to present a force generating axial flow prop system that employs advanced fluid dynamic ejector principles to cause force amplification. 
         [0008]    It is a more specific objective, commensurate with the above-listed objectives, to combine ejector concepts with high efficiency flow mixing devices, hereinafter “mixer-ejector”, concepts in a force generating shrouded axial flow prop system for low speed flows. 
       SUMMARY OF INVENTION 
       [0009]    A mixer-ejector prop system (nicknamed the “MEPS”) for generating force is disclosed that combines fluid dynamic ejector concepts, advanced flow mixing and control devices and an adjustable prop system. 
         [0010]    The MEPS uses aerodynamically contoured shrouds and ejectors surrounding an axial flow prop system which consists of one or more rows of blades to inject power into an oncoming fluid stream. The shrouds and ejectors are designed and arranged so as to draw the maximum amount of fluid through the prop and to minimize impacts to the environment (such as noise) and other props in its vicinity. Unlike the prior art, MEPS contain shrouds with advanced flow mixing and control devices such as lobed or slotted mixers and/or one or more ejector pumps. Additionally, it may contain sound absorption materials on the interior surfaces, internal flow blocker doors for reversing the flow and force direction, multiple flow inlet and outlet ports which may be noncircular and inlet and outlet ports whose axes are not coincident with the axis of rotation of the prop. First-principles-based theoretical analysis of MEPS indicate that they can produce three or more time the force of their un-shrouded counterparts for the same power level and frontal area. 
         [0011]    In the first preferred embodiment, the MEPS comprises: an axial flow prop surrounded by an aerodynamically contoured prop shroud incorporating mixing devices in its terminus region and a separate ejector duct overlapping but generally aft of said prop shroud, which itself may incorporate advanced mixing devices in its terminus region. 
         [0012]    In the second preferred embodiment, the MEPS comprises: an axial flow prop surrounded by an aerodynamically contoured prop shroud incorporating mixing devices in its terminus region. 
         [0013]    Other objects and advantages of the current invention will become more readily apparent when the following written description is read in conjunction with the accompanying drawings. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS  
         [0014]      FIGS. 1 ,  2 A,  2 B,  3 A,  3 B show MEPS, constructed in accordance with the present invention, having a single stage ejector incorporating either lobed or slotted mixers; 
           [0015]      FIGS. 4A ,  4 B,  5 A,  5 B show MEPS constructed in accordance with the present invention, having a multistage ejector incorporating either lobed or slotted mixers; 
           [0016]      FIGS. 6 ,  7 ,  8 ,  9 A,  9 B,  10 A,  10 B,  11 A,  11 B,  12 ,  13  show MEPS incorporating mixing devices in the non-circular inlets and outlet combinations; 
           [0017]      FIGS. 14A ,  14 B,  15  show MEPS with a adjustable rotor and stator combinations; 
           [0018]      FIG. 16  shows a MEPS constructed with the rotor blade power transmitted at the rotor inner ring; 
           [0019]      FIG. 17  shows a MEPS constructed with the rotor blade power transmitted at the rotor outer ring and sound absorption in the inner surface of the shrouds; 
           [0020]      FIG. 18  shows a MEPS constructed with blocker doors incorporated in the shroud to reverse or deflect the thrust generated; 
           [0021]      FIGS. 19A ,  19 B,  20 A,  20 B show a MEPS constructed with articulating ejector shrouds for thrust vectoring; 
           [0022]      FIGS. 21A ,  21 B present a variation of Applicant&#39;s MEPS wherein the system has two separate and independent inlet sections; 
           [0023]      FIGS. 21A ,  21 B,  22 , present variations of Applicant&#39;s MEPS wherein the axes of the various flow inlets and outlets are offset; 
           [0024]      FIGS. 23 ,  24 A,  24 B present variations of Applicant&#39;s MEPS wherein it is embedded in another entity, such as an aircraft wing; 
       
    
    
     DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS 
       [0025]    Referring to the drawings in detail, Applicants&#39; novel mixer-ejector propeller system (nicknamed the “MEPS”) is disclosed and like reference numerals refer to like elements. MEPS combines advanced flow mixing devices (hereinafter “MIXERS”), ejector pumps (hereinafter “EJECTORS”) and propellers (hereinafter “PROPs”) elements for increasing force generated in a fluid stream. 
         [0026]    The MEPS uses aerodynamically contoured shrouds and ejectors surrounding a propeller system which consists of one or more rows of blades to input power to the oncoming fluid stream. The shrouds and ejectors are designed and arranged so as to draw the maximum amount of fluid through the propeller for maximum propulsion efficiency. First-principles-based theoretical analysis of MEPS indicate that they can increase propulsion by fifty percent or more when compared to the thrust produced by un-shrouded counterpart propellers for the same frontal area and power input. 
         [0027]    In the first preferred embodiment, the MEPS, as shown in  FIGS. 1 ,  2 A,  2 B comprises:
       f. ( FIG. 1 ) a shrouded propeller with a single stage mixer/ejector jet pump attached to the downstream section of the propeller shroud  50 . The area ratio of the ejector pump, as defined by the ejector shroud exit area  91  over the turbine shroud exit area  90  will be between 1.5 and 3.0. The number of lobes  92  would be between six and fourteen. Each lobe will have inner  94  and outer  93  trailing edge angles  95  between 5° and 25° degrees. The primary lobe exit location  96  will be at, or near the entrance location of the ejector shroud. The height  97  to width  98  ratio of the lobe channels will be between 0.5 and 4.5. The mixer penetration  99  will be between 50% and 80%. The length  101  to diameter  102  (L/D) of the overall MEPS system will be between 0.5 and 1.25;   g. a shroud entrance area  66  and exit area  67  ( FIG. 2A ) that is equal or greater than that of the annulus surrounding the prop.   h. an aerodynamically contoured center-body  61  ( FIG. 2A ) that has downstream flow angles  103  ( FIG. 2B ) between five and thirty degrees when measured with respect to the axial direction;   i. a propeller shroud  62  that is aerodynamically shaped (spline surfaces) with camber directed towards the centerline with a minimum area occurring at the plane of the prop  60  and an internal surface  63  that varies smoothly from the entrance plane to the exit plane. Any internal shroud diffusion angles  69  will be less than six degrees when measured with respect to the axial direction. The shroud is aerodynamically shaped to assist guiding the flow into the prop shroud entrance  66 , eliminating any flow separation, and delivering smooth flow into the ejector entrance  92 . The propeller shroud L/D will be between 0.25 and 1.0.   j. An ejector shroud  65  that is aerodynamically shaped (spline surfaces) with camber directed towards the centerline and an internal surface that varies smoothly from the entrance plane to the exit plane. Any internal shroud diffusion angles will be less than six degrees when measured with respect to the axial direction. The shroud is aerodynamically shaped to assist guiding the flow into the ejector entrance and eliminating any flow separation. The ejector shroud L/D will be between 0.25 and 1.0.
 
This first preferred MEPS embodiment will increase propulsion by fifty percent or more when compared to the thrust produced by un-shrouded counterpart propellers for the same frontal area and power input.
       
 
         [0033]    Applicants&#39; second preferred embodiment of MEPS, shown in  FIGS. 3A ,  3 B incorporates slots  105  as mixer enhancing devices instead of forced mixer lobes. The number of slots around the perimeter will be between 6 and 16. Each slot will have a depth to width ratio of 2.0. Such slots increase mixing and shorten the required ejector shroud length. 
         [0034]    Applicants&#39; third preferred embodiment of MEPS, shown in  FIGS. 4A ,  4 B,  5 A,  5 B incorporates two-stage ejectors  65 ,  68  to pump more flow through the propeller for higher thrust benefits. Two ejector stages means two ejector secondary flow inlets  46 ,  47  which allow more flow to be pumped into the system for higher thrust augmentation. Lobes or slots are used to enhance ejector mixing. Each ejector shroud  65 ,  68  is aerodynamically shaped (spline surfaces) with camber directed towards the centerline and an internal surface that varies smoothly from the entrance plane to the exit plane. Any internal shroud diffusion angles  69  will be less than six degrees when measured with respect to the axial direction. The shroud is aerodynamically shaped to assist guiding the flow into the ejector entrance and eliminating any flow separation. The ejector shroud L/D will be between 0.25 and 1.0. 
         [0035]      FIGS. 6 ,  7 ,  8 ,  9 A,  9 B,  10 A,  10 B,  11 A,  11 B,  12  present Applicants&#39; MEPS with non-circular flow inlets  30  and/or outlets  31  on either the turbine shroud or ejector shroud so as to allow better control of the flow source and impact of its wake. Lobes or slots can be used to enhance ejector mixing. Each shroud is aerodynamically shaped (spline surfaces) with camber directed towards the centerline and an internal surface that varies smoothly from the entrance plane to the exit plane. Any internal shroud diffusion angles  69  will be less than six degrees when measured with respect to the axial direction. The shroud L/Dh (Dh is the hydraulic diameter) will be between 0.25 and 1.0 
         [0036]      FIG. 13  presents a variations of Applicant&#39;s MEPS wherein the prop is made up of a row rotating blades  71  (hereinafter “ROTOR”) and guide vanes (hereinafter “STATOR”)  70  in conjunction.  FIG. 13  shows a configuration with a single rotor and stator but the concept could include variants with multiple rotors and/or stators as shown in  FIGS. 14A ,  14 B,  15 ,  16  to better control the flow and force produced for a wide range of velocities at the inlet. The rotors may, or may not, have the outer ring  71  attached for rigidity and strength. Stator rotor stages allow more energy to be added to the flow at higher efficiencies at higher aircraft flight speeds. 
         [0037]    As shown in  FIG. 17 , MEPS may contain sound absorbing material  73  affixed to the inner surface of its shrouds to absorb and thus eliminate any the sound waves produced by either the power source or prop system. The sound absorption surface will be a porous plate with chambers behind designed to act as a Helmholtz resonator absorbing the key noise frequencies generated by the fan. The blade passage frequency will be one of the key sound frequencies to be absorbed. 
         [0038]      FIGS. 16 ,  17  present variations of Applicant&#39;s MEPS concept to include different means of transmitting power to the rotor.  FIG. 16  shows power transmitted to the inner ring  72  containing the rotor  71 .  FIG. 17  shows power transmitted to the outer ring  86  containing the rotor  71 .  FIG. 17  shows a rack (gears) attached to the outer ring of the rotor  71 . The rack  86  will be driven by a pinion gear. This outer drive mechanism will reduce the complexity of any gear box needed. 
         [0039]      FIG. 18  present variations of Applicant&#39;s MEPS concept to include movable flow blockage doors  74  that are stored in the shrouds and/or the plug. The length of the flaps will be close to one half the radius of the shroud as shown. As such, the flaps can be used to divert the flow, or reverse the flow for the actuated positions shown in  FIG. 18 . The reverse flow will exit the inlet section of the ejector. 
         [0040]      FIGS. 19A ,  19 B,  20 A,  20 B present variations of Applicant&#39;s MEPS wherein the mixer/ejector shrouds are articulated about the turbine shroud to allow swivel of the flow outlet so as to produce a force in a direction not aligned with that of the prop axis of rotation (herein after “VECTORING”). The mechanical drives,  89 , for controlling the vectoring may be either interior to the shrouds or on their exterior surfaces.  FIGS. 19A ,  19 B show a single stage vectoring system where the shroud is pivoted about an attachment point  85 .  FIGS. 20A ,  20 B show a two stage, articulating ejector system. The two stage system can be combined with rotation planes sequenced at 90 degrees to provide 360 degrees of thrust vectoring. 
         [0041]      FIG. 21  (A) presents a variation of Applicant&#39;s MEPS wherein the system has two separate and independent inlet sections  87 , and  88 . The offset can allow the system to be mounted closer to the ground, or closer to aircraft structure. Test data has shown very little loss in performance when using such mixer ejector systems. 
         [0042]      FIGS. 21A ,  21 B,  22 , present variations of Applicant&#39;s MEPS wherein the axes of the various flow inlets  106  and outlets  107  are offset  87  so as to accommodate placement of other devices not directly associated with the MEPS . The offset shown in  FIG. 22  could allow better, or closer, placement to support or aircraft structure. 
         [0043]      FIGS. 23 ,  24  present variations of Applicant&#39;s MEPS wherein it is embedded in another entity, such as an aircraft wing,  75  and may or may not contain inlet and outlet closure doors,  76  and  77  to be employed when MEPS is not operational.  FIGS. 23 ,  24 A show the entire MEPS system stowed in the wing.  FIG. 24B  shows the same configuration in which the ejector shroud,  78 , is actuated so as to slide outward from the wing or entity  75  when MEPS is made operational. The stowed position provides lower airplane cruise drag. The actuated configuration provides using the MEPS system for vertical takeoff and landing situations.