Patent Publication Number: US-10760487-B2

Title: Inlet particle separator systems and methods

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application is a divisional application of application Ser. No. 15/092,820, filed Apr. 7, 2016. Application Ser. No. 15/092,820 is a continuation in part of application Ser. No. 13/621,764, filed Sep. 17, 2012, and issued as U.S. Pat. No. 9,314,723 on Apr. 19, 2016. This application claims priority to application Ser. No. 15/092,820 and application Ser. No. 13/621,764, which are both hereby incorporated by reference. 
    
    
     STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT 
     This invention was made with Government support under W911W6-08-2-0001 awarded by the U.S. Army. The Government has certain rights in this invention 
    
    
     TECHNICAL FIELD 
     The present invention generally relates to fluid inlets for vehicle engines, and more particularly relates to methods and systems for separating particles flowing into vehicle engines, such as aircraft engines. 
     BACKGROUND 
     During operation, fluids such as air are pulled from the atmosphere into an engine and used to generate energy to propel the vehicle. The fluids may contain undesirable particles, such as sand and dust, which may cause issues for engine components. In order to prevent such issues, at least a portion of the undesirable particles are removed from the fluids using an inertial inlet particle separator. 
     A conventional inertial inlet particle separator typically includes a duct system with a fluid inlet that transitions into 1) a scavenge channel that forms an in-line fluid path with the fluid inlet and 2) a clean channel that branches off from the in-line fluid path. As the name suggests, inertia tends to cause the particles to travel in a straight line rather than follow the curved fluid flow path. This being the case, particles and a portion of the air carrying the particles tend to flow straight into the scavenge channel rather than curve into the clean intake channel. As such, the clean air is separated from the contaminated air and guided into the engine. The contaminated air is guided from the scavenge channel into a blower or other type of suction source and discharged. Approximately 15-25% of the fluid entering the fluid inlet typically enters the scavenge channel, while the remaining fluid and lighter particles enter the clean channel. As designed, the fluid entering the scavenge channel includes most of the larger particles such that only a small percentage of particles enter the engine through the clean channel, thereby protecting engine components. 
     Although some conventional inertial inlet particle separators are successful in providing relatively clean fluid to the engine, they may also have the adverse impact of increasing the pressure loss of the air entering the engine, with the attendant decrease in engine power output and increase in fuel consumption. 
     Accordingly, it is desirable to provide improved methods and systems for separating particles from inlet fluid for a vehicle engine. Furthermore, other desirable features and characteristics of the present invention will become apparent from the subsequent detailed description of the invention and the appended claims, taken in conjunction with the accompanying drawings and this background of the invention. 
     BRIEF SUMMARY 
     In accordance with an exemplary embodiment, an inertial inlet particle separator system for a vehicle engine is provided. The system includes a separator assembly defining a fluid inlet for receiving inlet air, and a scavenge flow path and an engine flow path configured to separate the inlet air into scavenge air and engine air such that the scavenge air is directed into the scavenge flow path and the engine air is directed into the engine flow path. The system further includes a collector assembly coupled to the scavenge flow path and configured to receive the scavenge air. The collector assembly includes a collector inlet coupled to the scavenge flow path. The collector inlet has a throat extending from a first throat end to a second throat end to define a throat length. The throat defines a cumulative throat area at each position along the throat length from the first throat end to the second throat end. The collector assembly further includes a collector body coupled to the collector inlet along the throat length. The collector body defines a cross-sectional area associated with each position along the throat length between the first throat end and the second throat end. The collector assembly further includes a collector outlet coupled to the collector body such that scavenge air flows into the collector inlet, through the collector body, and out through the collector outlet. At a first position between the first throat end and the second throat end, the respective cross-sectional area of the collector body is greater than or equal to the respective cumulative throat area. 
     In accordance with an exemplary embodiment, an inertial inlet particle separator system for a vehicle engine includes a separator assembly defining a fluid inlet for receiving inlet air. The separator assembly further includes a scavenge flow path and an engine flow path and configured to separate the inlet air into scavenge air and engine air such that the scavenge air is directed into the scavenge flow path and the engine air is directed into the engine flow path. The system further includes a collector assembly coupled to the scavenge flow path of the separator assembly. The collector assembly is bifurcated to form a first collector assembly portion configured to receive a first portion of the scavenge air and a second collector assembly portion configured to receive a second portion of the scavenge air. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The present invention will hereinafter be described in conjunction with the following drawing figures, wherein like numerals denote like elements, and wherein: 
         FIG. 1  is a block diagram of an inlet particle separator system for supplying clean air to an engine in accordance with an exemplary embodiment; 
         FIG. 2  is a partial, more detailed cross-sectional view of the separator system of  FIG. 1  in accordance with an exemplary embodiment; 
         FIG. 3  is a partial isometric view of the separator system of  FIG. 1  in accordance with an exemplary embodiment; 
         FIG. 4  is a front view of a collector of the separator system of  FIG. 1  in accordance with an exemplary embodiment; 
         FIG. 5  is a partial isometric view of the collector of  FIG. 4  in accordance with an exemplary embodiment; and 
         FIG. 6  is a chart illustrating collector body cross-sectional area and cumulative throat area, each as a function of circumferential collector position; 
         FIG. 7  is an isometric view of an inlet particle separator system of  FIG. 1  in accordance with another exemplary embodiment; 
         FIG. 8  is a further isometric view of the inlet particle separator system of  FIG. 7  in accordance with an exemplary embodiment; and 
         FIG. 9  is an isometric view of a collector assembly of the inlet particle separator system of  FIG. 7  in accordance with an exemplary embodiment. 
     
    
    
     DETAILED DESCRIPTION 
     The following detailed description is merely exemplary in nature and is not intended to limit the invention or the application and uses of the invention. Furthermore, there is no intention to be bound by any theory presented in the preceding background or the following detailed description. 
     Embodiments described herein provide inertial inlet particle separator systems and methods for separating particles from an inlet fluid and providing the clean fluid to an engine. Particularly, the systems and methods bifurcate the collector flow paths to reduce the distance that the scavenge flow must travel to the outlet. The system and methods additionally have a geometric configuration in which a collector body cross-sectional area is greater than a cumulative collector inlet throat area. As a result, such systems and methods may reduce pressure loss and increase separation and operation efficiency. 
       FIG. 1  is an exemplary block diagram of an inertial inlet particle separator system  100  coupled to an engine  102 . The engine  102  may be, for example, a turbine engine of an aeronautical vehicle such as a helicopter. The engine  102  receives air from the separator system  100 , compresses the air to elevate the air pressure, adds fuel, ignites the mixture, and uses the combustion gases to drive a series of turbines, the work from which may be used to propel the vehicle or generate electricity. 
     Particularly, and as discussed in further detail below, the separator system  100  receives inlet air  104  and provides relatively clean air  106  for use by the engine  102 . The separator system  100  includes an inertial inlet particle separator assembly  110  that receives the inlet air  104 . The separator assembly  110  separates the inlet air  104  into the engine air  106  provided to the engine  102  and the scavenge air  108 . The scavenge air  108  is drawn into a collector assembly  150  by a fan  152  and then exhausted into the atmosphere as exhaust air  112 . In one embodiment, the fan  152  may be electric and function to induce the scavenge air  108  into the separator system  100 . Although not shown, the separator system  100  may include sensors, controllers, adjustment mechanisms and/or other components. 
     Since the scavenge air  108  must be separated and exhausted, drawing scavenge air  108  in addition to engine air  106  through the inlet results in some pressure loss to the engine  102 . If unaddressed, excess pressure loss may contribute to degraded performance of the engine  102  and/or require increased operation of the fan  152  with the associated energy cost. As described in greater detail below, the collector assembly  150  may be configured to enable a more efficient operation of the separator system  100 , and thus, a more efficient operation of the engine  102 . 
       FIG. 2  is a partial, more detailed cross-sectional view of the separator system  100  of  FIG. 1  in accordance with an exemplary embodiment. In particular,  FIG. 2  illustrates a portion of the separator assembly  110  and the collector assembly  150 . As described above, inlet air  104  enters the separator assembly  110  and is separated into scavenge air  108  and engine air  106 . Scavenge air  108  with debris and dirt particles flows into the collector assembly  150 , while relatively clean engine air  106  flows from the separator assembly  110  into the engine  102  ( FIG. 1 ), as described in more detail below. As used herein, the term “axial” generally refers to an orientation or direction parallel to the engine centerline and the term “radial” generally refers to an orientation or direction perpendicular to the engine centerline. The axial and radial directions are indicated by legend  200  in  FIG. 2 . 
     The separator assembly  110  is defined by a hub  210  and a shroud  220 . The shroud  220  typically circumscribes the hub  210  to define an annular flow path  230  for the inlet air  104  in an upstream portion of the separator assembly  110 . A splitter  240  is positioned to divide the flow path  230  into a scavenge flow path (or channel)  232  and an engine (or clean) flow path (or channel)  234 . As such, the scavenge flow path  232  is defined by the splitter  240  and the shroud  220 , and the engine flow path  234  is defined by the splitter  240  and the hub  210 . As described in greater detail below, the scavenge flow path  232  is fluidly coupled to the collector assembly  150 , and the engine flow path  234  is fluidly coupled to the engine  102 . 
     The hub  210  and shroud  220  are configured to separate the inlet air  104 , which may include dirt and other debris, into the relatively clean engine air  106  and scavenge air  108 , which carries the debris into the collector assembly  150 . Particularly, the hub  210  includes a radial element  212  that forces the inlet air  104  from a generally axial orientation into a partially outward radial direction. As the inlet air  104  flows radially outward, the debris that forms the scavenge air  108  tends to engage the shroud  220  and maintain a flow along the shroud  220  into the scavenge flow path  232  as a result of inertia. However, the relatively clean engine air  106  may flow radially inward and radially around the radial element  212 , closer to the hub  210 , and into the engine flow path  234 . As such, the engine air  106  is separated from the scavenge air  108 . 
     As shown in  FIG. 2 , the scavenge flow path  232  is coupled to an inlet  250  of the collector assembly  150 . The collector assembly  150  generally includes a radial passage  252  extending from the inlet  250  and defined by a vortex fence  254  and a downstream wall  256 . The collector assembly  150  further includes a collector body  258  extending from the radial passage  252 . In particular, the collector body  258  is coupled to the radial passage  252  at a throat  260 , which may be defined at the termination of the vortex fence  254 . The radial passage  252  and the throat  260  may be considered as part of the inlet  250  or the collector body  258 . The collector body  258  may be at least partially defined by a portion of the downstream wall  256 , an outer circumferential wall  262 , an upstream wall  264 , an inner circumferential wall  266 , and the vortex fence  254 . The vortex fence  254  generally prevents flow circulating through the collector body  258  from blocking flow from the throat  260  from entering the collector body  258 , thereby reducing pressure losses in the collector assembly  150 . As an example, vortex flow  202  is depicted in  FIG. 2  flowing through the collector body  258 . Although the vortex flow  202  is generally depicted as a vortex in  FIG. 2 , as described above, the flow  202  is also flowing circumferentially around the collector assembly  150 . In any event, the configuration of the inner circumferential wall  266  and the vortex fence  254  function to maintain the vortex shape of the flow  202  as the flow  202  flows close to the throat  260 . In other words, the flow  202  is directed along the inner circumferential wall  266  in a generally radial and axial direction, and as the flow  202  meets the vortex fence  254 , the flow  202  is directed generally radially outward. As a result of this arrangement, the flow  202  is directed past the throat  254  instead of flowing towards the downstream wall  256  and avoid and/or mitigates interference of the flow  202  with the flow through throat  260 , e.g., by directing flow  202  to a location adjacent to the throat  260  and/or in the same radially outward direction as the flow through the throat  260 . As described below, the collector body  258  may be a scroll or partial scroll to collect and discharge the scavenge air  108 . 
       FIG. 3  is a partially transparent, isometric view of the separator system  100  of  FIGS. 1 and 2 . A portion of the air flowing through the separator system  100  is depicted in the view of  FIG. 3 . As shown in  FIG. 3  and introduced above, inlet air  104  flows into the separator assembly  110  in which the inlet air  104  is separated into relatively clean engine air  106  and relatively dirty scavenge air  108 . The clean engine air  106  flows out of the separator assembly  110  into the engine (not shown). The scavenge air  108  flows into the collector assembly  150 . For example, the scavenge air  108  flows into the inlet  250 , through the radial passage  252 , and into the collector body  258 . 
       FIG. 3  particularly shows the annular nature of the separator assembly  110 . As described above, in one exemplary embodiment, the collector body  258  at least partially wraps around separator assembly  110 . The collector body  258  is coupled to an outlet  270 , which is oriented in a generally axial direction such that the scavenge air  108  flowing through the collector body  258  is exhausted out of the collector assembly  150  through the outlet  270 . 
     Although  FIG. 3  shows a slice of inlet air  104  in a radial-axial plane, the separator assembly  110  generally has an annular inlet such that the inlet air  104  flows into the separator assembly  110 . As the inlet air  104  is separated, the scavenge air  108  continues to flow into the collector body  258 . In other words, the collector body  258  continues to receive additional scavenge air  108  along the circumferential length of the collector body  258 , as discussed in greater detail below. 
     Additional details about the collector assembly  150  are provided below with reference to  FIGS. 4 and 5 .  FIG. 4  is a front (or upstream) side view of the collector assembly  150  according to an exemplary embodiment.  FIG. 4  particularly illustrates the outer circumferential wall  262 , the upstream wall  264 , and the inner circumferential wall  266 .  FIG. 4  additionally shows the inlet  250  and outlet  270  of the collector assembly  150 . As noted above and additionally referring to  FIGS. 2 and 3 , the scavenge air  108  flows into the inlet  250 , through the radial passage  252 , through the collector body  258 , and out of the outlet  270 . 
     In one exemplary embodiment, the collector assembly  150  may be bifurcated. In other words, as shown in  FIG. 4 , the collector assembly  150  may include a partition  400 . In one exemplary embodiment, the partition  400  may be a wall positioned within the collector body  258  and generally extending in an axial-radial plane to circumferentially divide the collector body  258  into a first collector body portion  410  and a second collector body portion  420 . The throat  260  defining the entry of the body portions  410 ,  420  may be similarly considered respective first and second throat portions  460 ,  470  (e.g., the body portions  410 ,  420  and throat portions  460 ,  470  respectively form collector assembly portions). Each of the throat portions  460 ,  470  may be considered to have a first throat portion end at the partition  400  and a second throat portion end at the outlet  270  to define respective throat portion lengths. In some embodiments, the partition  400  may additionally extend through the radial passage  252  and/or inlet  250  to circumferentially divide the entire collector assembly  150 . In any event, as shown in  FIG. 4 , the partition  400  is typically arranged at a circumferential position approximately 180° from the outlet  270  such that the first and second collector body portions  410 ,  420  have approximately the same circumferential lengths, e.g., using the outlet  270  as a reference point (labeled 0° in  FIG. 4 ), each of the collector body portions  410 ,  420  has a length of approximately 180°. 
     During operation, if scavenge air  108  enters the collector assembly  150  on a circumferential first side of the partition  400 , the scavenge air  108  flows through the first collector body portion  410  in a first circumferential direction, as indicated by arrows  414 . If scavenge air  108  enters the collector assembly  150  on a circumferential second side of the partition  400 , the scavenge air  108  flows through the second collector body portion  420  in a second circumferential direction, as indicated by arrows  424 . In the view of  FIG. 4 , the first circumferential direction of air flowing through the first collector body portion  410  is clockwise, and the second circumferential direction of air flowing through the second collector body portion  420  is counter-clockwise. The first and second body portions  410 ,  420  are each coupled to the outlet  270  such that the air flowing through each body portion  410 ,  420  flows out through the common outlet  270 , although other embodiments may have separate outlets. 
     A conventional collector assembly may have a complete scroll collector body. As such, conventional collector assemblies require the scavenge air to travel potentially 360° from an initial circumferential scroll position to the collector outlet. The relatively long distance may result in a pressure drop along the length of the collector scroll body, thereby requiring increased power in the fan to draw scavenge air along the length and/or compromised performance with respect to the scavenge air removed from the engine air. 
     By comparison, the collector assembly  150  in  FIG. 4  is bifurcated such that the maximum circumferential path that the scavenge air  108  must travel is only 180° (e.g., from the partition  400  along the first circumferential length of the body portion  410  to the outlet  270  or from the partition  400  along the second circumferential length of the body portion  420  to the outlet  270 ). Since the bifurcated circumferential flow path is only half that of conventional collector assemblies, the pressure drop through the collector body  258  is improved. As such, collector assembly  150  may provide an improvement in separation performance and/or reduction in power to the fan  152 . An additional or alternative mechanism to improve performance is discussed below with reference to  FIG. 5 . 
       FIG. 5  is a partially transparent schematic, isometric view of the collector body  258  of the collector assembly  150  of  FIGS. 1-4  in accordance with an exemplary embodiment.  FIGS. 1-4  are referenced below in the description of  FIG. 5 . As described above, the scavenge air  108  flows into the collector body  258  through the throat  260 .  FIG. 5  illustrates a visual representation of a throat area (A thr ) and one collector body cross-sectional area (A x-sec ). As described in greater detail below, a cumulative throat area (A cum_thr ) and collector body cross-sectional area (A x-sec ) may be manipulated to provide improved performance. In one exemplary embodiment, the ratio of collector body cross-sectional area (A x-sec ) to cumulative throat area (A cum_thr ) is at least one (e.g., A x-sec /A cum_thr ≥1). In some embodiments, the ratio of collector body cross-sectional area (A x-sec ) to cumulative throat area (A cum_thr ) is generally constant along the length of the collector assembly. In other embodiment, the ratio of collector body cross-sectional area (A x-sec ) to cumulative throat area (A cum_thr ) is varies along the length of the collector assembly. 
     An example of the relationship between collector body cross-sectional area (A x-sec ) and cumulative throat area (A cum_thr ) is provided with reference to  FIG. 6 , which is a chart illustrating exemplary calculations. Reference is additionally made to  FIGS. 2 and 5 . In the example provided by  FIG. 6 , the collector body cross-sectional area (A x-sec ) and cumulative throat area (A cum_thr ) are considered with respect to 15° increments in which the partition  400  is considered 180° and the outlet  270  is considered 0°. In this example, the bifurcated collector body  258  is circumferentially symmetric, e.g. the first body portion  410  has generally identical characteristics to the second body portion  420 , such that only half (or) 180° of the collector body  258  needs to be illustrated. 
       FIG. 2  illustrates one exemplary position of a throat width (b thr ) and throat radius (R thr ) to calculate the cumulative throat area (A cum_thr ) and the collector body cross-sectional area (A x-sec ). As an example, for a 15° segment length, the throat area (A thr ) may be expressed as Equation (1), as follows:
 
 A   thr =2*π* R   thr *15°/360 °*b   thr   Equation (1)
 
     The collector body cross-sectional area (A x-sec ) is a local, radial cross-section represented by the shaded area in  FIG. 2  and may be calculated based on the dimensions of the downstream wall  256 , outer circumferential wall  262 , upstream wall  264 , inner circumferential wall  266 , and the vortex fence  254 . In the discussion below, the collector body cross-sectional area (A x-sec ) is the cross-sectional area at the respective circumferential position.  FIG. 5  additionally illustrates an exemplary collector body cross-sectional area (A x-sec )  500  and a corresponding cumulative throat area (A cum_thr )  502 . Although the collector body cross-sectional area (A x-sec ) generally increases along the length of the collector body  258 , the area may be limited by packaging and overall size considerations for the separator system  100 . As such, considering that the collector assembly  150  is designed such that the collector body cross-sectional area (A x-sec ) is greater than the cumulative throat area (A cum_thr ), the throat width (b thr ) must typically decrease along the throat length to maintain this relationship. 
     Equation (1) described above generally provides an equation for throat area (A thr ) in a radial passage, such as that shown in  FIG. 2 . However, in alternate embodiments, the throat and/or collector body may be axial and/or axial and radial. In general, exemplary embodiments may represent a throat cross-sectional area (A thr ) for a 15° segment as expressed in Equation (2), as follows:
 
 A   thr =π*( R   thr_o   +*R   thr_i )15°/360 °*b   thr   Equation (2)
 
     where 
     R thr_o  is the outer radius of the throat, and 
     R thr_i  is the inner radius of the throat. 
     In one exemplary embodiment, the throat width (b thr ) may be linearly reduced along the length of the throat, e.g., a reduction of about 60%, although any reduction may be provided. However, in other embodiments, the throat width (b thr ) may be reduced to any width and/or in a non-linear manner. In further embodiments, the throat width (b thr ) may remain constant and/or increase. 
       FIG. 6  depicts an exemplary plot  650  in which the cross-sectional area (A x-sec ) of the collector body  258  and cumulative throat width (A cum_thr ) are plotted as a function of circumferential position, which additionally illustrates that the cross-sectional area (A x-sec ) of the collector body  258  is greater than the cumulative throat width (A cum_thr ) throughout the length of the collector body  258 . It should be noted that this ratio may be maintained even if the collector body  258  is not bifurcated, e.g., for lengths greater than 180°, including 360°. 
       FIGS. 2-6  depict embodiments in which the circumferential flow path is bifurcated into two path portions such that the maximum circumferential path that the scavenge air must travel is 180°. However, other embodiments may be provided the divide the circumferential flow path into more than two path portions, as will be discussed in greater detail below with reference to  FIGS. 7-9 . 
       FIG. 7  is an isometric view of an inlet particle separator system  700  in accordance with another exemplary embodiment. Unless otherwise noted, the system  700  of  FIG. 7  may correspond to the system  100  of  FIGS. 1-6 . As shown in  FIG. 7 , the system  700  may include a separator assembly  710  and a collector assembly  750 . Generally, the view in  FIG. 7  is an external view of the separator assembly  710  and collector assembly  750  in an upstream direction.  FIG. 7  additionally depicts the FADEC (full authority digital engine control) unit  752  that receives the scavenge air from the collector assembly  750 . 
       FIG. 8  is further isometric view of the inlet particle separator system  700  of  FIG. 7  in accordance with an exemplary embodiment. Relative to  FIG. 7 ,  FIG. 8  depicts the system  700  without the FADEC unit  752 .  FIG. 9  is an isometric view of the collector assembly  750  removed from other portions of the system  700 . 
     The separator system  710  depicted in  FIGS. 7 and 8  generally corresponds to the separator assembly  110  depicted in  FIGS. 1-3  that receives the inlet air and separates the inlet air into the engine air provided to the engine and the scavenge air drawn into the collector assembly  750 . Also similar to the previous exemplary embodiments, and using  FIG. 9  as a reference, the collector assembly  750  may be considered to have an outer circumferential wall  862 , an upstream wall  864 , and an inner circumferential wall  866 .  FIG. 9  additionally shows the inlet  850  and outlet  870  of the collector assembly  750 . As noted above (additionally referring to  FIGS. 2 and 3 ), the scavenge air  108  flows from the separator assembly  710  (or  110 ) into an inlet  250 , through a radial passage  252 , through the collector body  858 , and out of the outlet  870 . Contrary to the collector assembly  150  depicted in  FIGS. 2-6 , however, the collector assembly  750  of  FIGS. 7-9  separates the scavenge air into more than two path portions. 
     In particular, and referring to  FIG. 9 , the collector assembly  750  may be divided into four path portions. For example, the collector assembly  750  may include four partitions  901 - 904  that divide aspects of the collector assembly  750  into the respective portions. Each partition  901 - 904  may be a wall, strut, or other separating element positioned within the collector assembly  750 . As shown, partitions  901 - 904  function to divide the collector assembly  750  into first, second, third, and fourth inlet or throat portions  911 - 914 . In some embodiments, the partitions  901 - 904  function to divide the collector assembly  750  into first, second, third, and fourth collector body portions  921 - 924 . Generally, a “partition” refers to any element that functions to separate two portions. For example, a closed end on a structure may be considered a partition with respect to an adjacent structure. In the depicted embodiment, each of the throat portions  911 - 914  and/or collector body portions  921 - 924  extend approximately 90° along the circumference of the collector assembly  750 . 
     The collector assembly  750  in  FIGS. 7-9  may also be considered to have an outlet  870  with two outlet portions  931 ,  932  (or two outlets  931 ,  932 ). The first outlet portion  931  is positioned in between the first and second throat portions  911 ,  912  and in between the first and second body portions  921 ,  922  (e.g., at partition  902 ). The second outlet portion  932  is positioned in between the third and fourth throat portions  913 ,  914  and in between the third and fourth body portions  923 ,  924  (e.g., at partition  904 ). During operation, air flowing into the first and second throat portions  911 ,  912  respectively flow through the first and second body portions  921 ,  922  and out through the first outlet portion  931 . Similarly, air flowing into the third and fourth throat portions  913 ,  914  respectively flow through the third and fourth body portions  923 ,  924  and out through the second outlet portion  932 . Air flowing through the first, second, third, and fourth body portions  921 - 924  are respectively depicted schematically by arrows  941 - 944 . As shown in  FIG. 9 , the maximum path traveled by the air within each portion  921 - 924  is 90°. 
     Similar to the embodiments of  FIGS. 2-6 , the embodiments of  FIGS. 7-9  are subject to a particular relationship between collector body cross-sectional area (A x-sec ) and cumulative throat area (A cum_thr ), Specifically, the ratio of collector body cross-sectional area (A x-sec ) to cumulative throat area (A cum_thr ) is at least one (e.g., A x-sec /A cum_thr ≥1). In some embodiments, the ratio of collector body cross-sectional area (A x-sec ) to cumulative throat area (A cum_thr ) is generally constant along the length of the collector assembly. In other embodiments, the ratio of collector body cross-sectional area (A x-sec ) to cumulative throat area (A cum_thr ) varies along the length of the collector assembly. 
     In one exemplary embodiment, this relationship holds true for each of the throat portions  911 - 914  and collector body portions  921 - 924 , particularly for any position between a partition  901 - 904  and an outlet portion  931 ,  932 , such as any position between a first end at a respective partition  901 - 904  to a second end at a respective outlet portion  931 ,  932 . For example, for any position between partition  901  and outlet  931  in the direction of air flow (e.g., from 0° to 90°), the collector body cross-sectional area (A x-sec ) of the body portion  921  will be at least as large as the cumulative throat area (A cum_thr ) at that position. Moreover, for any position between partition  903  and outlet  931  in the direction of air flow (e.g., from 180° to 90°), the collector body cross-sectional area (A x-sec ) of the body portion  922  will be at least as large as the cumulative throat area (A cum_thr ) at that position. This relationship is also applicable from 180° to 270° and from 0° to 270°. As described in greater detail above, this relationship between cumulative throat area (A cum_thr ) and collector body cross-sectional area (A x-sec ) provides improved performance by improving pressure drop as air flows through the collector body. 
     Although exemplary embodiments are described above with respect to an inertial inlet particle separator system operating in air and therefore separating contaminated air from clean air, the present invention may be applied to inertial particle separators operating in or utilizing other fluids. For example, a fluid may be in the form of a liquid rather than air, as may be used in ships, submarines, and/or other watercraft. 
     While at least one exemplary embodiment has been presented in the foregoing detailed description of the invention, it should be appreciated that a vast number of variations exist. It should also be appreciated that the exemplary embodiment or exemplary embodiments are only examples, and are not intended to limit the scope, applicability, or configuration of the invention in any way. Rather, the foregoing detailed description will provide those skilled in the art with a convenient road map for implementing an exemplary embodiment of the invention. It being understood that various changes may be made in the function and arrangement of elements described in an exemplary embodiment without departing from the scope of the invention as set forth in the appended claims.