Patent Publication Number: US-2004045291-A1

Title: Flow laminarizing device

Description:
CROSS REFERENCE TO RELATED APPLICATIONS  
     [0001] The present invention claims priority under 35 U.S.C. § 120 to U.S. Provisional Patent Application Serial No. 60/408,838, filed Sep. 6, 2002 and hereby incorporated herein by reference in its entirety. 
    
    
     
       BACKGROUND  
       [0002] Turbochargers are commonly known devices for increasing the air mass in the combustion chambers (cylinders) of an internal combustion engine, particularly, but not limited to, diesel engines. The turbocharger is most frequently driven by exhaust gasses which are used to drive an impeller. The impeller is attached by a shaft or other coupling to a compressor wheel, which is used to compress ambient air which is then provided to the combustion chambers of the engine. Other kinds of fluid impelling devices use one of more impellers to induce fluid flow through centrifugal force.  
       [0003] Therefore, it is desirable to improve the performance of turbochargers and other kinds of fluid impelling devices.  
       SUMMARY  
       [0004] One embodiment provides for a turbocharger including an impeller, a fluid inlet to the impeller, and an outlet from the impeller. A flow laminarizing device is disposed within the inlet to the impeller, or the outlet from the impeller, or flow laminarizing devices are disposed within both the inlet and the outlet. The flow laminarizing device includes a plurality of walls, which define a plurality of passageways, the passageways being substantially mutually parallel and configured to permit fluid flow there through.  
       [0005] Another embodiment provides for a diesel engine including a plurality of combustion chambers, each combustion chamber being configured to receive ambient air and to discharge combustion gases. The diesel engine further includes a turbocharger, which is configured to receive the ambient air, compress the ambient air, and to provide the compressed ambient air to the plurality of combustion chambers. The turbocharger is also configured to receive, and be driven by, the combustion gasses discharged by the diesel engine. The diesel engine further includes a flow laminarizing device, which is configured to laminarize a flow of one of the ambient air to the turbocharger, or the combustion gasses to the turbocharger.  
       [0006] Yet another embodiment provides for a flow laminarizing device that includes a first plurality of first walls defining a plurality of passageways, the plurality of passageways being substantially, mutually parallel and disposed as an array. Each of the passageways includes open opposite ends, and is configured to permit fluid flow there through. The flow laminarizing device also includes a second plurality of second walls defining a plurality of channels, the plurality of channels being substantially parallel with each other and the plurality of passageways. Each of the channels includes at least one open side and open opposite ends, and is configured to permit fluid flow there through. The flow laminarizing device further includes a retainer configured to support the flow laminarizing device in a substantially fixed position with respect to a location of use. The retainer optionally includes a ring.  
       [0007] Still another embodiment provides for a method of using a diesel engine that includes a turbocharger. The method includes receiving a flow of combustion gasses from the diesel engine at the turbocharger, receiving a flow of ambient air at the turbocharger, and laminarizing at least one of the flow of combustion gasses or the flow of ambient air prior to the receiving at the turbocharger using a flow laminarizing device.  
       [0008] These and other aspects and embodiments will now be described in detail with reference to the accompanying drawings, wherein: 
     
    
    
     DESCRIPTION OF THE DRAWINGS  
     [0009]FIG. 1 is a schematic view depicting an engine and turbocharger combination in accordance with the prior art.  
     [0010]FIG. 2 is a schematic view depicting an engine and turbocharger combination including a pair of flow laminarizing devices in accordance with one embodiment of the invention.  
     [0011]FIG. 3 is a perspective view depicting a flow laminarizing device in accordance with another embodiment of the invention.  
     [0012]FIG. 4 is a perspective view depicting a turbocharger and the flow laminarizing device of FIG. 3.  
     [0013]FIG. 5 is an end plan view depicting a flow laminarizing device in accordance yet another embodiment of the invention.  
     [0014]FIG. 6 is a side elevational view depicting the flow laminarizing device of FIG. 5.  
     [0015]FIG. 7 is a side elevation sectional view depicting a portion of a turbocharger in combination with the flow laminarizing device of FIG. 5.  
     [0016]FIG. 8 is a schematic view depicting a flow laminarizing device in combination with a fluid impelling device in accordance with yet another embodiment of the invention.  
     [0017] FIGS.  9 A- 9 F are linearized graphs respectively depicting various performance characteristics associated with a flow laminarizing device in accordance with the present invention.  
     [0018]FIG. 10 is a perspective view depicting a flow laminarizing device in accordance with still another embodiment of the invention. 
    
    
     DETAILED DESCRIPTION  
     [0019] Currently, the air entering the compressor wheel (i.e., impeller) of a turbocharger in automotive (and other) applications passes through an air filter and air passageways with various bends and restrictions before entering the impeller. These restrictions and bends in the air passageway cause the air actually entering the impeller intake to be turbulent, resulting in less than optimum efficiency (i.e., performance) of the impeller of the turbocharger. Consequently, a given turbocharger typically provides, for example, an air compression ratio (i.e., the ratio of outlet pressure to inlet pressure) that is less than optimum for the given turbocharger.  
     [0020] This less-than-optimum performance generally extends to other kinds of fluid impelling devices for reasons similar to those presented above. Such other fluid impelling devices include, but are not limited to, the following: superchargers; centrifugal pumps; centrifugal fans; single-stage gas compressors; multistage gas compressors; and other kinds of devices which generally use one or more rotating elements to compress gases and/or induce fluid flow.  
     [0021] In representative embodiments, the present teachings provide methods and apparatus for laminarizing a fluid flow to a turbocharger or other fluid impelling device, typically improving the performance of the fluid impelling device.  
     [0022] Turning now to FIG. 1, a schematic view depicts an engine  20  and an associated turbocharger  22 , in accordance with the prior art. The engine  20  can be a diesel engine or a conventional gasoline engine. Generally, the engine  20  can be any type of internal combustion engine requiring an inlet flow of combustion air and producing an outlet flow of combustion exhaust gasses. The engine  20  is fluidly coupled to the turbocharger  22  by way of an exhaust gas conduit  24  and a combustion air conduit  26 .  
     [0023] The turbocharger  22  includes a turbine chamber  28 , which houses a turbine  30 . The turbocharger  22  further includes a compression chamber  32 , which houses an impeller  34 . The turbine  30  is mechanically coupled to the impeller  34  by way of a rotatable shaft  36 . The turbocharger  22  further includes an exhaust gas outlet  38  and an ambient air inlet  40 .  
     [0024] Cooperation of the engine  20  and the turbocharger  22  is performed generally as follows: The engine  20  produces a flow of combustion exhaust gasses  44  that are coupled to the turbine chamber  28  by way of the exhaust conduit  24 . The flow of exhaust gasses  44  drives a rotation  42  of the turbine  30 . The exhaust gasses  40  continue to flow through the turbine chamber  28  and out of the turbocharger  22  by way of exhaust gas outlet  38 .  
     [0025] The rotation  42  of the turbine  30  is coupled to the impeller  34  by way of the shaft  36 . The impeller  34 , thus rotating, impels (i.e., drives or induces) a flow of ambient air  46  into the compression chamber  32  by way of inlet  40 . As shown in FIG. 1, the ambient air  46  is drawn through a filter  48  prior to flowing into the compression chamber  32 . The ambient air  46  then continues to flow from the turbocharger  22  by way of the combustion air conduit  26 , and is consumed in combustion by the engine  20 .  
     [0026] The impeller  34  generally compresses the ambient air  46  within the compression chamber  32 , resulting in an increase in pressure of the ambient air  46  at the combustion air conduit  26  (i.e., outlet pressure), relative to that of the ambient air inlet  40  (i.e., inlet pressure). As discussed briefly above, the performance of the turbocharger  22  (or any other fluid impelling device) can be expressed as a ratio of the outlet pressure to the inlet pressure, referred to herein as the performance ratio. Moreover, the performance ratio can be considered as indicative of the overall efficiency (or efficacy) of the turbocharger  22  (or another fluid impelling device).  
     [0027] As introduced above, turbulence within a fluid flow can result in a less-than-optimum performance ratio for a given fluid impelling device. In one case, for example, a swirling of the fluid in a direction counter to the rotation of the impeller can result in excessive drag. In another exemplary case, the fluid flow has a velocity profile relative to the cross-section of the flow-containing conduit, which is less than ideal for introduction to an impeller. Other aspects of turbulence within a fluid flow can have an undesired effect on the performance ratio of a fluid impelling device.  
     [0028]FIG. 2 is a schematic view depicting an engine  120  and an associated turbocharger  122 , in accordance with an embodiment of the present invention. The engine  120  and the turbocharger  122  are coupled by way of an exhaust conduit  124  and a combustion air conduit  126 . The turbocharger  122  includes a turbine chamber  128 , a turbine  130 , a compression chamber  132 , an impeller  134 , and a rotatable shaft  136 , which function and cooperate substantially as described above for elements  28 ,  30 ,  32 ,  34  and  36 , respectively.  
     [0029] Further depicted in FIG. 2 are a pair of flow laminarizing devices  100 A and  100 B, respectively. The flow laminarizing device  100 A is shown installed in an ambient air inlet  140 , generally in close adjacency to the impeller  134  of the turbocharger  122 . The flow laminarizing device  100 B is installed in an exhaust gas conduit  124 , in generally close adjacency to the turbine  130  of the turbocharger  122 .  
     [0030] Cooperation of the engine  120 , the turbocharger  122  and the flow laminarizing devices  100 A and  100 B is performed generally as follows: Exhaust gasses  144  flow from the engine  120  and toward the turbine chamber  128  by way of the exhaust gas conduit  124 . The exhaust gasses  144  flow through the flow laminarizing device  100 B, which operates to substantially laminarize, or reduce any turbulence within, the flow of gasses  144  resulting in a laminarized exhaust gas flow  154 . The laminarized gas flow  154  enters the turbine chamber  128  and drives a rotation  142  of the turbine  130 . The exhaust gasses  144  then flow from the turbocharger  122  as exhaust discharge flow  160 , by way of an exhaust gas outlet  138 .  
     [0031] The impeller  134 , rotating by way of the shaft  136 , impels ambient air  146  to flow through a filter  148  and toward the compression chamber  132 . The ambient air  146  flows through the flow laminarizing device  100 A, which operates to laminarize the flow of air  146 , resulting in a laminarized air flow  156 . The laminarized air flow  156  enters the compression chamber  132  and is compressed by the impeller  134 . The compressed ambient air  158  flows from the turbocharger  122  by way of the combustion air conduit  126 , and is consumed by the engine  120 .  
     [0032] The flow laminarizing device  100 A generally increases the performance ratio (i.e., pressure ratio of compressed air  158  to laminarized air  156 ) of the turbocharger  122 . Similarly, the flow laminarizing device  100 B generally increases the efficiency of the turbine  130 , such that the exhaust gasses  144  impart a reduced back pressure against the engine  120 . In any case, the flow laminarizing devices  100 A and  100 B serve to generally improve, and can substantially optimize, the overall performance (i.e., the performance ratio) of the turbocharger  122 .  
     [0033] As depicted in FIG. 2, the turbocharger  122  operates in conjunction with both flow laminarizing devices  100 A and  100 B. In another embodiment (not shown in FIG. 2), only the flow laminarizer  100 A or  100 B can be present, with the flow laminarizer  100 A typically being selected for installation in a single-laminarizing-device embodiment. Other arrangements associated with other embodiments are possible.  
     [0034]FIG. 3 is a perspective view of a flow laminarizing device  100 , in accordance with another embodiment of the present invention. Embodiments of the flow laminarizing device  100  can be utilized, for example, as devices  100 A and/or  100 B of FIG. 2.  
     [0035] The flow laminarizing device  100  includes a plurality of tubes  102 , which are coupled in a mutually parallel arrangement, generally defining a single array or cluster  104 . Each of the tubes  102  includes a wall (or sidewall)  106 , defining a passageway  108  that is configured to permit a fluid to flow there through. Each passageway  108  further has a length L and a cross-sectional area A, defined by the wall  106  of the corresponding tube  102 . The plurality of tubes  102  can be formed of stainless steel, aluminum, or another suitable metal. Alternatively, the tubes  102  can be formed from plastic, nylon, a fiber and resin composite, or any other natural or synthetic material that is suitable for the application at hand (i.e., use with a turbocharger or another fluid impelling device).  
     [0036] The flow laminarizing device  100  further includes a plurality of retaining elements  110 . The retaining elements  110  of the device  100  are typically uniformly spaced about the periphery of the array  104 , and extend radially away there from. As depicted in FIG. 3, the retaining elements  110  have an overall “L” shape; it is understood that other forms of retaining elements corresponding to other embodiments of the invention are possible. The retaining elements  110  are configured to support, or maintain, the flow laminarizing device  100  in a substantially fixed position with respect to a location of use (not shown in FIG. 3; refer to FIG. 4). The retaining elements  110  can be formed from any material suitable for use with the plurality of tubes  102  and/or the application at hand.  
     [0037]FIG. 4 is a perspective view depicting the flow laminarizing device  100  of FIG. 3, in typical usage combination with a turbocharger  112 . As depicted, the turbocharger  112  includes an inlet or throat  114 . The flow laminarizing device  100  is received in the inlet  114 , being maintained in place by cooperation of the retainer elements  110  with an edge or lip  116  of the inlet  114 .  
     [0038] In typical operation, an ambient air conduit (not shown) fluidly couples air with the flow laminarizing device  100  and the turbocharger  112 . At least a portion of the air flowing toward the inlet  114  of the turbocharger  112  passes through the passageways  108  and exits the flow laminarizing device  100  as a substantially laminar air stream. The laminar air stream continues through the remainder of the inlet  114 , and into an air compression chamber  116  of the turbocharger  112 . An impeller (not shown) of the turbocharger  112  generally compresses the air flow, and discharges it along a path  118  for consumption by an engine (not shown).  
     [0039] Performance of the flow laminarizing device  100  can be generally characterized as follows: An increase in the number of tubes  102  (i.e., increase in the number of corresponding passageways  108 ) within an array  104  of a substantially constant overall size typically increases the flow laminarizing effect of the device  100 , but also typically increases drag on the fluid flowing there through (i.e., fluid drag) due to an increase in the surface area (tube length times tube inside circumference) which the air can contact in passing through the device. An increase in the length “L” of the tubes typically increases both the flow laminarizing effect and the fluid drag of the particular passageway  108 . An increase in the surface roughness of the wall  106  defining the passageway  108  will decrease the flow laminarizing effect. Conversely, an increase in the cross-sectional area A typically results in a decrease of both the flow laminarizing effect and the fluid drag of the particular passageway  108 .  
     [0040] Other effects resulting from the number of tubes  102  (i.e., passageways  108 ) and their associated characteristics and dimensions can also be present; however, it those effects stated above that are of primary concern herein. In any case, it is generally desirable to realize an embodiment of the flow laminarizing device  100  such that a ratio of the flow laminarizing effect, to the fluid drag there produced, is optimized for the application at hand—that is, the kind and size of fluid impelling device, type of flowing fluid, location of the flow laminarizing device relative to the fluid impelling device, etc. Such design optimization typically requires an iterative approach, and the acquisition of empirical data associated with the application at hand. This topic will be discussed more fully below with respect to FIGS.  9 A- 9 F.  
     [0041]FIG. 10 is a perspective view depicting a flow laminarizing device  400  in accordance with still another embodiment of the invention, which is generally similar to the flow laminarizing device  100  described above. The flow laminarizing device  400  includes a plurality of tubes  402 , which are coupled in a mutually parallel arrangement, defining an array or cluster  404 . Each of the tubes  402  includes a wall  406 , defining a passageway  408  that is configured to permit fluid flow there through. Each of the tubes  402  further includes a length L4 and cross-sectional area A4, defined by the corresponding wall  406 .  
     [0042] The tubes  402  of the cluster  404  are further generally arranged about the periphery of, and thus define, a central passageway  412 . Function of the central passageway  412  will be described in detail here after. The flow laminarizing device  400  further includes a plurality of retaining elements  410 . The plurality of retaining elements  410  are typically coupled to and are uniformly distributed about the periphery of the cluster  404  of the tubes  402 . The plurality of retaining elements  410  are configured to support the flow laminarizing device  400  in a substantially fixed position relative to a location of use, such as, for example, the fluid inlet (or throat) of a turbocharger (not shown) or other fluid impelling device (not shown).  
     [0043] The tubes  402  and the retaining elements  410  of the flow laminarizing device  400  can be formed from any material or materials suitable for the intended use, such as, for example, any of the materials described above in regard to the formation of the flow laminarizing device  100 . Optionally, the flow laminarizing device  400  can be formed as a single-piece entity, of any suitable material, and by any correspondingly suitable method of formation. For example, the flow laminarizing device  400  can be formed as a single-piece, injection-molded plastic entity. In another example, the flow laminarizing device  400  can be at least partially formed of an extruded metal. Other materials and/or methods for producing the flow laminarizing device  400  are possible.  
     [0044] The operation and performance characteristics of the flow laminarizing device  400  are substantially similar to those described above in regard to the flow laminarizing device  100  of FIG. 3. Furthermore, the central passageway  412  is configured to permit the flow laminarizing device  400  to be positioned in relatively close, non-contacting proximity to an impeller of a turbocharger (not shown) or other fluid impelling device (not shown). This can be accomplished, for example, by receiving a portion of the impeller (not shown) into the central passageway  412 . In this way, fluid (i.e., air) is introduced to the impeller (not shown) immediately upon exiting the flow laminarizing device  400 , while the fluid flow still retains most or all of the laminarizing characteristic provided by the flow laminarizing device  400 .  
     [0045]FIG. 5 is an end plan view depicting a flow laminarizing device  200  in accordance with yet another embodiment of the invention. The flow laminarizing device  200  includes a first plurality of first walls  202 . The first walls  202  are coupled so as to define a plurality of passageways  206 . The plurality of passageways  206  are substantially mutually parallel and arranged as an array  204 . As depicted, each of the passageways  206  has a generally square cross-sectional area A2, in accordance with the arrangement of the particular walls  202  defining each passageway  206 . It is understood that other passageways (not shown) having different cross-sectional geometries such as, for example, triangular, hexagonal, octagonal, etc., associated with other embodiments of the invention (not shown), can also be used. Accordingly, the term “wall” or “walls” as used herein should not be considered as limiting structures to open planar shapes, but is also meant to include closed shapes (such as circular, square, polygonal, elliptical, etc.)  
     [0046] The flow laminarizng device  200  further includes a second plurality of second walls  208 . The second walls  208  are coupled with each other and with the first walls  202 , and thus define a plurality of channels  210 . The channels  210  are generally disposed about the periphery of the array  204  of the passageways  206 . Each of the channels  210  is further defined by an open side  212 . As depicted, each of the channels  210  has a generally rectangular, or triangular, open, cross-sectional area A3, in accordance with the second walls  202 , the open side  212 , and the first wall  202  (where applicable) defining each channel  210 . It is understood that other channels (not shown) having different cross-sectional geometries such as, for example, hexagonal, octagonal, etc., associated with other embodiments of the invention, can also be used.  
     [0047] The flow laminarizing device  200  further includes a retaining element  214 , coupled to the first and second walls  202  and  208 , respectively. In this example, the retaining element  214  is formed as a ring, or annulus, and is configured to support or hold the flow laminarizing device  200  in a substantially fixed position during typical operation (shown and described hereafter).  
     [0048]FIG. 6 is a side elevational view depicting the flow laminarizing device  200  of FIG. 5. The flow laminarizing device  200  further is of a length L2, as defined by the first and second walls  202  and  208 , respectively. Thus, each of the passageways  206  and channels  210  are of this length L2. The fluid laminarizing device  200  further includes a fluid entrance end  216  and a fluid exit end  218 . As depicted, the fluid entrance end  216  is generally proximate to the retaining element  214 , while the fluid exit end  218  is generally distal to the retaining element  214 . The plurality of second walls  208  are formed (i.e., angled) such that the flow laminarizing device  200  includes a taper T, from the entrance end  216  to the exit end  218 .  
     [0049] The flow laminarizing device  200  can be formed from any material suitable for the intended use, and is preferably formed as a single-piece entity (i.e., not from an assemblage of discrete pieces). In one preferred embodiment, the flow laminarizing device  200  is formed as a single, injection-molded plastic entity. In another embodiment, the flow laminarizing device  200  is formed in a metallic extrusion process. Other materials and methods of formation, associated with other embodiments of the flow laminarizing device  200 , are possible.  
     [0050] Furthermore, the flow laminarizing device  200  exhibits performance characteristics that are substantially similar to those described above for the flow laminarizing device  100 . For example, an increase of the length L2 of the device  200  generally corresponds to increasing both the flow laminarizing effect and the fluid drag of the device  200 . As another example, an increase of the cross-sectional areas A2 and A3 generally corresponds to a decrease in both the flow laminarizing effect and fluid drag of the flow laminarizing device  200 . Other general characteristic similarities can exist between the respective flow laminarizing devices  100  and  200 .  
     [0051] It is therefore desirable to realize an embodiment of the flow laminarizing device  200  such that a ratio of the flow laminarizing effect, to the fluid drag there produced, is optimized for the application at hand—typically, laminarizing an ambient air flow into a compression chamber of a turbocharger. In one non-limiting example, the flow laminarizing device  200  includes: a length L of about 30 mm; a total of sixteen passageways  206 , each having a cross-sectional area A2 of about 0.81 cm{circumflex over ( )}2; and a total of twenty channels  210 , each having an entrance end  216  cross-sectional area A3 in the range of about 0.18 cm{circumflex over ( )}2 to about 1.1 cm{circumflex over ( )}2. Other dimensions and pluralities of passageways  206  and channels  210 , associated with other embodiments of the flow laminarizing device  200 , are also possible.  
     [0052]FIG. 7 is a side elevation sectional view depicting the flow laminarizing device  200  of FIG. 5 in cooperation with a portion of a turbocharger  250 . The turbocharger  250  includes a housing  252 , which defines an inlet  254  and a compression chamber  256 . The flow laminarizing device  200  is received within the inlet  254 , with the retainer element  214  cooperating with the housing  252  (in addition to other possible elements, not shown) to hold the flow laminarizing device  200  in a generally fixed position. The turbocharger  250  further includes an impeller  258  that is supported within the compression chamber  256  by way of coupling to a rotatable shaft  260 .  
     [0053] Cooperation of the flow laminarizing device  200  and the turbocharger  250  is performed typically as follows: The shaft  260  is driven to rotation by an attached turbine (not shown) of the turbocharger  250 , which in turn rotates the impeller  258 . The rotating impeller  258  impels a flow of generally turbulent ambient air  262  toward the fluid entrance end  216  of the flow laminarizing device  200 . The flow of the ambient air  262  divides to form a plurality of individual flow streams  264 , which respectively enter the plurality of passageways  206  and channels  210  of the flow laminarizing device  200 .  
     [0054] The individual flow streams  264  are laminarized (i.e., made more laminar, or reduced in turbulence) as they flow from the entrance end  216  to the exit end  218  of the flow laminarizing device  200 . The plurality of flow streams  264  then exit the flow laminarizing device  200  and flow into the compression chamber  256  of the turbocharger  258 , where they interact with the impeller  258 . The impeller  258  generally compresses the ambient air  262  of the plurality of flow streams  264 , such that a single, combined flow stream  266  of ambient air  262  is discharged from the turbocharger  250 .  
     [0055] As depicted in FIG. 7, the inlet  254  of the turbocharger  250  has a general taper leading into the compression chamber  256 . It is noted that this taper is accommodated by the taper T of the flow laminarizing device  200 , such that the housing  252  of the inlet  254  cooperates to substantially close the open sides  212  of the channels  210  of the flow laminarizing device  200 . In this way, the respective cross-sectional areas A3 of the channels  210  effectively decrease along a path from the entrance end  216  to the exit end  218 . It is well known to those of skill in the art that fluid flow generally accelerates under such conditions, leading to a higher velocity at the exit end  218  than at the entrance end  216 , for those flow streams  264  that flow through the channels  210 . The relative velocity of the individual flow streams  264  is shown in the form of corresponding vector length within FIG. 7.  
     [0056] Furthermore, the individual air streams  264  flowing from the central passageways  206  typically have the lowest exit velocities, with the exit velocity of the air streams  264  generally increasing when flowing from the peripheral passageways  206  and the channels  210 . This general exit-velocity characteristic is believed to improve the overall performance of the flow laminarizing device  200  in at least the following ways:  
     [0057] 1) The higher velocity air streams  264  tend to draft, or boost, the lower velocity air streams  264 , due to respectively different static pressures; and  
     [0058] 2) The peripheral, higher velocity air streams  264  tend to desirably interact with the features of the impeller  258  which are moving with the greatest linear (i.e., tangential) velocity.  
     [0059] Other performance benefits attributable to the taper T of the flow laminarizing device  200  can also be present or realized. In any case, the flow laminarizing device  200  generally improves, and can substantially optimize, the performance ratio of the turbocharger  250  for reasons similar to those described above for the flow laminarizing device  100  of FIG. 2.  
     [0060] Although the flow laminarizing devices  100  and  200  have been exemplarily shown as being used with a turbocharger, it will be appreciated that the devices can also be used on the air inlet to a supercharger (which is directly mechanically driven by a belt or gears or the like, rather than being driven by exhaust gasses).  
     [0061]FIG. 8 is a schematic view depicting a flow laminarizing device  300 , operating in conjunction with a generic fluid impelling device  302 . The flow laminarizing device  300  is understood to be generic to the instant invention, and includes a plurality of passageways and/or channels (not shown), which are formationally and characteristically similar to those described above for the flow laminarizing devices  100  and  200 .  
     [0062] In operation, a fluid (i.e., liquid or gas)  304 , having a generally turbulent flow characteristic, flows toward the flow laminarizing device  300 , and passes there through. The flow laminarizing device  300  substantially reduces the turbulence (i.e., laminarizes) of the fluid, resulting in the generally laminarized flow  306  of the fluid  304 . The laminarized flow  306  of the fluid  304  enters the fluid impelling device  302 , where it interacts with an impeller (not shown), resulting in compression and/or flow induction of the fluid  304 . The fluid  304  then exits the fluid impelling device  302  as an exit flow  308 .  
     [0063] The fluid  304  of the exit flow  308  generally has a higher static pressure, upon exiting the fluid impelling device  302 , than does the fluid  304  of the laminarized flow  306 . As described above, the ratio of the exit flow  308  pressure, to the laminaried (i.e., inlet) flow  306  pressure, is referred to herein as the performance ratio of the fluid impelling device  302 , and is generally considered to provide an overall benchmark, or standard, by which to evaluate the performance of the generic fluid impelling device  302 .  
     [0064] The flow laminarizing device  300  is used in conjunction with the fluid impelling device  302 , so as to increase, or optimize, the performance ratio of the fluid impelling device  302 , by substantially reducing or eliminating the undesired effects of introducing the turbulent flow of fluid  304  directly to the generic fluid impelling device  302 . These undesired effects can include, but are not limited to, drag due to counter-rotation of the fluid flow with respect to the rotation of the impeller, and a less-than-optimum velocity profile of the fluid flow, etc.  
     [0065]FIG. 9A is a linearized, graphical representation depicting the general correspondence between the laminarizing effect, and the passageway or channel length, of a flow laminarizing device (not shown) generic to the instant invention. In general, an increase of passageway or channel length typically results in an increase of the laminarizing effect of the associated flow laminarizing device.  
     [0066]FIG. 9B is a linearized, graphical representation depicting the general correspondence between the laminarizing effect, and the passageway or channel cross-sectional area, of a flow laminarizing device (not shown) generic to the instant invention. In general, an increase of passageway or channel cross-sectional area typically results in a decrease in the laminarizing effect of the associated flow laminarizing device.  
     [0067]FIG. 9C is a linearized, graphical representation depicting the general correspondence between the static pressure of a laminarized fluid entering a generic fluid impelling device (not shown), and the passageway or channel length of a flow laminarizing device (not shown) generic to the instant invention. In general, an increase in the passageway or channel length results in a decrease in the static pressure of the fluid entering the fluid impelling device (and after passing through the flow laminarizing device).  
     [0068]FIG. 9D is a linearized, graphical representation depicting the general correspondence between the static pressure of a laminarized fluid entering a generic fluid impelling device (not shown), and the passageway or channel cross-sectional area of a flow laminarizing device (not shown) generic to the instant invention. In general, an increase in the passageway or channel cross-sectional area results in an increase in the static pressure of the fluid entering the fluid impelling device (and after passing through the flow laminarizing device).  
     [0069]FIG. 9E is a linearized, graphical representation depicting the general correspondence between the static pressure of a laminarized fluid entering a generic fluid impelling device (not shown), and the drag on that fluid (resulting from wall roughness) as it flows through a flow laminarizing device (not shown) generic to the instant invention. In general, an increase in drag on the flowing fluid (corresponding to an increase in the coefficient of drag on the wall surface) results in a decrease in the static pressure of that fluid as it enters the fluid impelling device.  
     [0070]FIG. 9F is a linearized, graphical representation depicting the general correspondence between the static pressure of a laminarized fluid entering a generic fluid impelling device (not shown), and the rate of flow of that fluid through a flow laminarizing device (not shown) generic to the instant invention. In general, an increase in rate of fluid flow results in a decrease in the static pressure of that fluid as it enters the fluid impelling device after passing through the flow laminarizing device.  
     [0071] FIGS.  9 A- 9 F are not intended as representing empirical data, but are only depicted to show the general relationship between the design variables and the performance characteristics of a flow laminarizing device in accordance with the present invention. In designing such a flow laminarizing device, the length of the walls (or fluid passageways), as well as the inner circumference of the passageways, are optimized to increase the laminarizing effect on the fluid, and thus efficiency of a device using the laminarized flow, while at the same time reducing the pressure loss imposed on the fluid by the flow laminarizing device. Surface roughness of the wall surfaces of the flow laminarizing device should be reduced whenever practical, and can be achieved by using materials have low drag coefficients after being formed (such as extruded TFE), or by being polished.  
     [0072] One method for designing a flow laminarizing device in accordance with the present invention is to select a number of fluid passageways and a length for the device. The length is preferably selected to be longer than is believed reasonable. The device can then be placed in the inlet to a centrifugal compressor, and the compressor driven at a fixed rotational speed. The pressure of the air exiting the compressor (discharge pressure) is then measured as is compared to a base-line measurement made without the device in place. The length of the device can then be shortened by a selected increment (as by cutting, for example), and the discharge pressure measured again with the shortened device in place. Generally, the discharge pressure will increase as the length of the device is shortened. However, at a certain point the discharge pressure will start to drop as the device becomes “too short” to produce a useful laminarizing effect. When this occurs, then the last selected length is the near-optimum length of this device.  
     [0073] Once a near-optimum length for the device is determined (as just discussed), then the near-optimum number of passageways can be determined. Preferably, the initial number of passageways selected is greater than what is believed to be practical. The number of passageways can then be incrementally decreased, and the effect on the discharge pressure observed with the altered device. As with the length determining process, the discharge pressure will be observed to increase as the number of passageways is decreased. However, at a certain point the discharge pressure will start to decrease as the number of passageways are decreased, indicating a loss of flow laminarizing benefit fro the device. The last-used number of fluid passageways will then be the near-optimum number of fluid passageways.  
     [0074] It will be appreciated that the above iterative design method is practical for designing a flow laminarizing device in accordance with the present invention due to the variables inherent in the system in which the device will be used, as well as the difficulties of performing fluid flow calculations for compressible fluids. However, the design process can also be performed on a computer using compressible fluid flow design software, such as “PIPE-FLO Compressible”, available from Engineered Software, Inc. of Lacey, Wash., U.S.A.  
     [0075] It will also be appreciated that a similar design methodology is applied when the flow laminarizing device under consideration is to be used on the inlet side of a turbine, when energy is to be extracted from the fluid (such as on the driving side of a turbocharger, or the inlet to a turbine in a hydraulic power generator), rather than energy being input into the fluid. In the instance where energy is being extracted from the fluid, rather than driving the turbine at a fixed speed and measuring outlet pressure of the fluid from the turbine, the turbine can be free-wheeling and the rotational speed of the turbine can be measured as the flow laminarizing device is altered (i.e., length shortened and number of passageways decreased). In general, the rotational speed will increase as these two variables are altered up to a certain point, at which point the rotational speed will start to decrease as the flow laminarizing effect is lost. The design points where the rotational speed ceases to increase and starts to decrease are the near-optimal design points.  
     [0076] From the foregoing it will be appreciated that another embodiment of the present invention provides for a method for using a turbocharger including an impeller. The method includes laminarizing a flow of air or gas using a flow laminarizing device, and providing the laminarized flow of air or gas to the impeller of the turbocharger. Yet another embodiment provides for a method for using a diesel engine including a turbocharger. In this latter embodiment a flow of combustion gasses is received from the diesel engine at the turbocharger, and a flow of ambient air is received at the turbocharger. The method includes laminarizing at least one of the flow of combustion gasses or the flow of ambient air prior to the receiving at the turbocharger using a flow laminarizing device. Still another embodiment of the present invention provides for a method for using a fluid impelling device. This method includes laminarizing a fluid flow using a flow laminarizing device, and providing the laminarized fluid flow to the fluid impelling device.  
     [0077] While the above methods and apparatus have been described in language more or less specific as to structural and methodical features, it is to be understood, however, that they are not limited to the specific features shown and described, since the means herein disclosed comprise preferred forms of putting the invention into effect. The methods and apparatus are, therefore, claimed in any of their forms or modifications within the proper scope of the appended claims appropriately interpreted in accordance with the doctrine of equivalents.