Patent Description:
It is desirable to incorporate radial diffusers where possible to save on space, weight, and materials costs. However, conventional diffusers are not able to respond to or control the flow rate of the working fluid passing through the diffuser.

According to one aspect of the present invention, a radial diffuser for a heat exchanger system includes a diffuser inlet section, a diffuser outlet section, a diffuser wall, and a movable diffuser hub. The diffuser inlet section is upstream of the heat exchanger system and oriented along a central flow axis of the radial diffuser. The diffuser inlet section has a cylindrical shape which extends along the central flow axis and a circular cross section along an inlet section plane perpendicular to the central flow axis. The diffuser outlet section is downstream of the diffuser inlet section with respect to the central flow axis. The diffuser wall includes a diffuser wall inner surface defining a fluid flow path which is non-linear. The diffuser wall inner surface includes a convex curved section and a concave curved section. The convex curved section is adjacent to the diffuser inlet section and has a convex curvature with respect to the central flow axis. The concave curved section is adjacent to the diffuser outlet section and has a concave curvature with respect to the central flow axis. The concave curved section is adjacent to and downstream of the convex curved section with respect to the central flow axis. The movable diffuser hub is configured to move with respect to the central flow axis relative to the diffuser wall and can thereby alter a fluid flow through the radial diffuser.

According to another aspect of the present invention, an air cycle machine includes a turbine oriented along a central flow axis, a heat exchanger downstream of the turbine with respect to the central flow axis, and a radial diffuser. The turbine includes a turbine outlet. The radial diffuser includes a diffuser inlet section, a diffuser outlet section, a diffuser wall, and a movable diffuser hub. The diffuser inlet section is upstream of the heat exchanger system and oriented along a central flow axis of the radial diffuser. The diffuser inlet section has a cylindrical shape which extends along the central flow axis and a circular cross section along an inlet section plane perpendicular to the central flow axis. The diffuser outlet section is downstream of the diffuser inlet section with respect to the central flow axis. The diffuser wall includes a diffuser wall inner surface defining a fluid flow path which is non-linear. The diffuser wall inner surface includes a convex curved section and a concave curved section. The convex curved section is adjacent to the diffuser inlet section and has a convex curvature with respect to the central flow axis. The concave curved section is adjacent to the diffuser outlet section and has a concave curvature with respect to the central flow axis. The concave curved section is adjacent to and downstream of the convex curved section with respect to the central flow axis. The movable diffuser hub is configured to move with respect to the central flow axis relative to the diffuser wall and can thereby alter a fluid flow through the radial diffuser. The radial diffuser is downstream of the turbine and upstream of the heat exchanger with respect to the central flow axis. The radial diffuser is configured to receive a fluid flow from the turbine through the turbine outlet, diffuse the fluid flow, and direct the fluid flow into the heat exchanger.

According to yet another aspect of the present invention, a method of manufacturing a radial diffuser includes manufacturing a diffuser inlet section of the radial diffuser. A diffuser wall of the radial diffuser is manufactured adjacent to the diffuser inlet section. A diffuser outlet section of the radial diffuser is manufactured adjacent to the diffuser wall. A movable diffuser hub of the radial diffuser is manufactured such that the movable diffuser hub is configured to move relative to the diffuser wall during operation of the radial diffuser.

The following descriptions of the drawings should not be considered limiting in any way.

Radial diffusers perform approximately as well as conical diffusers with respect to pressure drop and flow distribution, while using less material and taking up less space than a conventional conical diffuser. The efficiency and advantages of a radial diffuser can be further improved by allowing the diffuser hub to move axially or rotationally, as well as by additively manufacturing the radial diffuser. Axial movement of the diffuser hub varies the ratio of the diffuser outlet area to the diffuser inlet area, which can allow for more efficient diffusion of air (or another working fluid) and can help to achieve reduced losses. Additionally, axial movement of the diffuser hub can further increase the pressure ratio of the radial diffuser while avoiding or reducing shock experienced by the fluid flow.

<FIG> is a schematic depiction of air cycle machine <NUM>. Air cycle machine <NUM> includes diffuser <NUM>, heat exchanger <NUM>, turbine <NUM>, and load <NUM>. Diffuser <NUM> includes diffuser inlet section <NUM> and diffuser outlet section <NUM>. Heat exchanger <NUM> includes heat exchanger inlet section <NUM> and heat exchanger outlet section <NUM>. Turbine <NUM> includes turbine outlet <NUM>.

Air cycle machine <NUM> can be part of an environmental control system within an aircraft. Diffuser <NUM> can be a conventional conical diffuser, such as conical diffuser <NUM> (described below in reference to <FIG>), or a radial diffuser, such as radial diffuser <NUM> (described below in reference to <FIG>). Heat exchanger <NUM> can be a plate heat exchanger or other suitable heat exchanger. In the example depicted in <FIG>, heat exchanger <NUM> is a crossflow heat exchanger. Load <NUM> can be a section or component of the aircraft requiring cooling.

Turbine <NUM>, diffuser <NUM>, and heat exchanger <NUM> are oriented along central flow axis C-C. Turbine <NUM> is located upstream of diffuser <NUM> and heat exchanger <NUM> with respect to central flow axis C-C. Turbine outlet <NUM> is adjacent to diffuser inlet section <NUM>. Diffuser <NUM> is located downstream of turbine <NUM> and upstream of heat exchanger <NUM>. Diffuser outlet section <NUM> is adjacent to heat exchanger inlet section <NUM>. Diffuser <NUM> has a larger cross-sectional area at diffuser outlet section <NUM> than at diffuser inlet section <NUM>.

During operation of air cycle machine <NUM>, a flow of a working fluid passes through turbine <NUM>, diffuser <NUM>, and heat exchanger <NUM> along central flow axis C-C. This working fluid can be air or another fluid. Working fluid leaves turbine <NUM> at turbine outlet <NUM> and flows into diffuser inlet section <NUM>. Diffuser <NUM> diffuses the working fluid received from turbine <NUM>, decreasing its velocity as it travels along the length of diffuser <NUM>. Diffuser outlet section <NUM> directs the working fluid out of diffuser <NUM> and into heat exchanger <NUM>. Heat exchanger <NUM> transfers heat between the working fluid from diffuser <NUM> and a second fluid. The working fluid then exits heat exchanger <NUM> at heat exchanger outlet <NUM>. The working fluid and the second fluid can be exhausted to ambient, to another section of the aircraft or can enter load <NUM> to heat or cool a component of the aircraft.

<FIG> is a perspective view of heat exchanger system <NUM>. Heat exchanger system <NUM> includes conical diffuser <NUM>, heat exchanger <NUM>, and turbine outlet <NUM>. Conical diffuser <NUM> includes diffuser inlet section <NUM>, diffuser outlet section <NUM>, diffuser wall <NUM>, and diffuser hub <NUM> (all shown in <FIG>).

Heat exchanger <NUM> and turbine outlet <NUM> can operate in substantially the same way as heat exchanger <NUM> and turbine outlet <NUM> (described above in reference to <FIG>). As described in more detail below, conical diffuser <NUM> directs a working fluid flow along the length of conical diffuser <NUM>. As the cross-sectional area of conical diffuser <NUM> increases, the velocity of the fluid flow through conical diffuser <NUM> decreases.

<FIG> is a side view of conical diffuser <NUM>. <FIG> is a perspective view of conical diffuser <NUM>. <FIG> will be discussed concurrently. Conical diffuser <NUM> includes diffuser inlet section <NUM>, diffuser outlet section <NUM>, and diffuser wall <NUM>.

The velocity of fluid flow through conical diffuser <NUM> is highest at diffuser inlet section <NUM>. As the cross-sectional area of conical diffuser <NUM> increases, the velocity of the fluid flow along central flow axis C-C decreases. In this way, the passage of working fluid through a diffuser, such as conical diffuser <NUM>, converts a portion of the working fluid's kinetic energy into potential energy. This conversion causes the working fluid to increase in pressure as it travels along the length of conical diffuser <NUM>.

<FIG> is a perspective view of heat exchanger system <NUM>. Heat exchanger system <NUM> includes conical diffuser <NUM>, heat exchanger <NUM>, and turbine outlet <NUM>. Radial diffuser <NUM> includes diffuser inlet section <NUM>, diffuser outlet section <NUM>, diffuser wall <NUM>, and diffuser hub <NUM> (all shown in <FIG>). Heat exchanger system <NUM> can operate in substantially the same way as heat exchanger system <NUM> (described above in reference to <FIG>).

<FIG> is a side view of radial diffuser <NUM>. <FIG> is a perspective view of radial diffuser <NUM>. <FIG> will be discussed concurrently. Radial diffuser <NUM> includes diffuser inlet section <NUM>, diffuser outlet section <NUM>, diffuser wall <NUM>, and diffuser hub <NUM>. Diffuser wall <NUM> includes diffuser wall inner surface <NUM> which defines a fluid flow path and which includes convex curved section <NUM> and concave curved section <NUM>.

Diffuser inlet section <NUM> extends along central flow axis C-C. Diffuser inlet section <NUM> can be approximately cylindrical in shape and can have an approximately circular cross section along inlet section plane I perpendicular to central flow axis C-C. Diffuser outlet section <NUM> is downstream of diffuser inlet section <NUM> with respect to central flow axis C-C. In the example shown in <FIG>, diffuser outlet section <NUM> has an approximately rectangular prism shape and an approximately square cross section along outlet section plane O perpendicular to central flow axis C-C. Diffuser outlet section <NUM> can have an approximately circular cross section along outlet section plane O, or can have another suitable cross sectional shape. Diffuser wall <NUM> is downstream of diffuser inlet section <NUM> and upstream of diffuser outlet section <NUM> such that diffuser wall <NUM> is between diffuser inlet section <NUM> and diffuser outlet section <NUM> with respect to central flow axis C-C. Convex curved section <NUM> is adjacent to and downstream of diffuser inlet section <NUM> such that convex curved section <NUM> is an upstream end of diffuser wall <NUM>. Convex curved section <NUM> has a convex curvature with respect to central flow axis C-C and curves away from central flow axis C-C. Concave curved section <NUM> is downstream of convex curved section <NUM>, and is adjacent to and upstream of diffuser outlet section <NUM> such that concave curved section <NUM> is a downstream end of diffuser wall <NUM>. Concave curved section <NUM> has a concave curvature with respect to central flow axis C-C and curves towards central flow axis C-C. The fluid flow path is defined by diffuser wall inner surface <NUM> and is non-linear. In this way, radial diffuser <NUM> diffuses working fluid along a non-linear path.

Radial diffuser <NUM> can operate in substantially the same way as conical diffuser <NUM> (described above in reference to <FIG>) in that radial diffuser <NUM> diffuses a working fluid flow by decreasing its velocity and, ideally, maintaining laminar flow. The working fluid flow enters radial diffuser <NUM> at diffuser inlet section <NUM>. The working fluid then flows along the fluid flow path around diffuser hub <NUM>. The diffused working fluid then exits radial diffuser <NUM> at diffuser outlet section <NUM>. The use of convex curved section <NUM> and concave curved section <NUM> help to avoid pressure losses of the flow of working flow through radial diffuser <NUM>. Additionally, radial diffuser <NUM> can be approximately nine inches shorter than a conical diffuser with a comparable diffusion rate.

<FIG> depicts the change in pressure along the length of conical diffuser <NUM> (described above in reference to <FIG>). Gradient G depicts the static pressure of working fluid within conical diffuser <NUM> in pounds per square inch (psi).

The static pressure of working fluid within conical diffuser <NUM> is lowest at diffuser inlet section <NUM>. The static pressure gradually increases along diffuser wall <NUM> and is fairly constant along diffuser outlet section <NUM>. As described above in reference to <FIG>, this increase in static pressure is accompanied by a drop in the velocity of the working fluid flow. A uniform and slower-moving working fluid flow is desirable to increase the efficiency of a heat exchanger.

<FIG> depicts the change in pressure along the length of radial diffuser <NUM> (described above in reference to <FIG>). Gradient G depicts the static pressure of working fluid within radial diffuser <NUM> in pounds per square inch (psi).

The change in static pressure along the length of radial diffuser <NUM> is substantially the same as the change in static pressure along the length of conical diffuser <NUM> shown in <FIG>. The static pressure of the working fluid within radial diffuser <NUM> is lowest at diffuser inlet section <NUM>, gradually increases as the working fluid flows between diffuser wall <NUM> and diffuser hub <NUM>, and is fairly constant along diffuser outlet section <NUM>. In this way, radial diffuser <NUM> achieves a substantially similar outcome as conical diffuser <NUM> across a shorter length.

<FIG> is a schematic depiction of radial diffuser <NUM> having an actuated diffuser hub in an initial state. <FIG> is a schematic depiction of radial diffuser <NUM>, with the actuated diffuser hub in an extended state. <FIG> will be discussed in turn below. Radial diffuser <NUM> includes diffuser inlet section <NUM>, diffuser outlet section <NUM>, diffuser wall <NUM>, and actuated diffuser hub <NUM>. Diffuser wall <NUM> includes diffuser wall inner surface <NUM> which defines fluid flow path F and which includes convex curved section <NUM> and concave curved section <NUM>. Diffuser inlet section <NUM> includes inlet inner surface <NUM>. Actuated diffuser hub <NUM> includes diffuser hub surface <NUM>. Actuated diffuser hub <NUM> can include translational actuator <NUM>.

Diffuser wall <NUM>, diffuser inlet section <NUM>, and/or diffuser outlet section <NUM> can have a partially porous internal structure. In the example shown in <FIG>, diffuser wall <NUM> is at least partially composed of an internal lattice structure <NUM>. In some examples, diffuser inlet section <NUM> and/or diffuser outlet section <NUM> can additionally or alternatively be at least partially composed of a similar lattice structure. In some examples, diffuser inlet section <NUM>, diffuser outlet section <NUM>, and/or diffuser wall <NUM> can include internal voids within their respective structures. These voids can be repeating, non-repeating, evenly or unevenly distributed, and similarly or dissimilarly shaped. Actuated diffuser hub <NUM> can include a variety of surface features, such as those shown in <FIG>.

Radial diffuser <NUM> can operate in substantially the same way as radial diffuser <NUM> (described above in reference to <FIG>) in that radial diffuser <NUM> diffuses a working fluid flow. Actuated diffuser hub <NUM> is configured to translate along central flow axis C-C, thereby moving closer to or further from diffuser wall <NUM>.

The translational movement of actuated diffuser hub <NUM> along the central flow axis C-C allows the alteration of the diffusion rate of working fluid through radial diffuser <NUM> and can adjust the fluid flow rate within an air cycle machine. This axial movement also allows for the alteration of the working fluid's expansion rate and pressure ratio within radial diffuser <NUM>. The change in geometry of radial diffuser <NUM> caused by translational movement of actuated diffuser hub <NUM> allows the shape of radial diffuser <NUM> to be optimized to different conditions or operating requirements. A smaller path for fluid flow within radial diffuser <NUM> can be desirable at lower flow rates, while a wider path for fluid flow can be desirable when the flow rate through the air cycle machine is higher. In this way, an actuated diffuser hub can optimize flow rates through an air cycle machine by tailoring the size of the fluid flow path to the developed fluid flow rate. Additionally, if diffused working fluid is fed back into the turbine after exiting the heat exchanger, an adjusted flow rate may be desirable for increased turbine performance and efficiency.

<FIG> are schematic depictions of radial diffuser <NUM>. Radial diffuser <NUM> includes diffuser inlet section <NUM>, diffuser outlet section <NUM>, diffuser wall <NUM>, and rotatable diffuser hub <NUM>. Diffuser wall <NUM> includes diffuser wall inner surface <NUM> which defines fluid flow path F and which includes convex curved section <NUM> and concave curved section <NUM>. Diffuser inlet section <NUM> includes inlet inner surface <NUM>. Rotatable diffuser hub <NUM> includes diffuser hub surface <NUM>. In the example shown in <FIG>, rotatable diffuser hub <NUM> includes bearing system <NUM>. In the example shown in <FIG>, rotatable diffuser hub <NUM> includes control system <NUM>. <FIG> will be discussed concurrently.

Radial diffuser <NUM> can operate in substantially the same way as radial diffuser <NUM> (described above in reference to <FIG>) in that radial diffuser <NUM> diffuses a working fluid flow by increasing its static pressure. In some examples, radial diffuser <NUM> can contain a partially porous internal structure, such as internal voids or internal structures similar to internal lattice structure <NUM> (described above in reference to <FIG>). Rotatable diffuser hub <NUM> is configured to rotate about central flow axis C-C. Bearing system <NUM> allows rotatable diffuser hub <NUM> to freely rotate in the working fluid flow within radial diffuser <NUM>. A freely rotatable diffuser hub <NUM> will rotate when it experiences a shear force of the working fluid flow through radial diffuser <NUM>. Control system <NUM> can be an electrical connection, a pneumatic system, or other suitable control mechanism. A rotatable diffuser hub <NUM> with a control system <NUM> can be actively controlled, and can electrically or pneumatically rotate about central flow axis C-C. Because a diffuser hub rotating in the same direction as the working fluid flow can reduce the velocity of the working fluid flow relative to the diffuser hub, the rotational movement of rotatable diffuser hub <NUM> can allow for an additional decrease in velocity of the working fluid flow through radial diffuser <NUM>.

<FIG> depict surface features for use on various surfaces of a radial diffuser, such as radial diffusers <NUM>, <NUM>. <FIG> will be discussed in turn below. <FIG> depicts grooves <NUM> on surface <NUM>. <FIG> depicts raised surface features <NUM> on surface <NUM>. <FIG> depicts swirled pattern <NUM> on surface <NUM>.

As shown in <FIG>, grooves <NUM> are arranged on surface <NUM>. Surface <NUM> can be a surface of the radial diffuser, such as the diffuser hub surface, diffuser wall inner surface, and/or inlet inner surface. Grooves <NUM> can be oriented along the fluid flow path and can thereby be aligned with the working fluid flow through the radial diffuser. Alternatively, grooves <NUM> can be arranged perpendicular to the fluid flow path or otherwise arranged in a pattern which is not aligned with the fluid flow path. Grooves <NUM> which are not aligned with the anticipated fluid flow path and which are incorporated onto the surface of the diffuser wall or diffuser inlet section can further reduce the velocity of working fluid flow through the radial diffuser. In some examples, grooves <NUM> can be micro-grooves. Grooves <NUM> can be incorporated into the surface of the diffuser hub, diffuser wall, and/or diffuser inlet section during additive manufacturing.

As shown in <FIG>, raised surface features <NUM> are arranged on surface <NUM>. Surface <NUM> can be a surface of the radial diffuser, such as the diffuser hub surface, diffuser wall inner surface, and/or inlet inner surface. In the example shown in <FIG>, raised surface features <NUM> are cylindrical prisms which are approximately uniform in shape and size and which are arranged in a repeating grid pattern on surface <NUM>. In other examples, raised surface features <NUM> can be varied in shape, size, and/or pattern. In some examples, raised surface features <NUM> can be micro-features. Raised surface features <NUM> can vary the surface roughness of the radial diffuser and can help to further decrease the velocity of the working fluid flow through the radial diffuser. Raised surface features <NUM> can be incorporated into the surface of the diffuser hub, diffuser wall, and/or diffuser inlet section during additive manufacturing.

As shown in <FIG>, swirled pattern <NUM> is arranged on surface <NUM>. Surface <NUM> can be a surface of the radial diffuser, such as the diffuser hub surface. In the example shown in <FIG>, swirled pattern <NUM> is formed of evenly-spaced grooves which partially encircle surface <NUM>. In other examples, swirled pattern <NUM> can be formed of unevenly-spaced grooves, or of evenly- or unevenly-spaced raised lines. When combined with a freely rotatable diffuser hub, a swirled pattern <NUM> which is aligned with an anticipated swirl direction of incoming working fluid flow can further reduce the velocity of the working fluid. Swirled pattern <NUM> can be incorporated into the surface of the diffuser hub during additive manufacturing.

The surfaces features depicted in <FIG> can be included on the surface of a diffuser hub, such as diffuser hub surfaces <NUM>, <NUM> of movable diffuser hubs <NUM>, <NUM>. The surface features can additionally and/or alternatively be included on an inner surface of a diffuser inlet section, such as diffuser inlet inner surfaces <NUM>, <NUM> of diffuser inlet sections <NUM>, <NUM>, and/or an inner surface of a diffuser wall, such as diffuser wall inner surfaces <NUM>, <NUM> of diffuser walls <NUM>, <NUM>.

<FIG> depicts method <NUM> of manufacturing a radial diffuser having a movable diffuser hub, such as radial diffusers <NUM>, <NUM>. Method <NUM> includes steps <NUM>-<NUM>. As described in more detail below, a radial diffuser as described herein can be additively or conventionally manufactured, or can be partially additively manufactured.

In step <NUM>, a diffuser inlet section, such as diffuser inlet sections <NUM>, <NUM>, is manufactured. In some examples, the diffuser inlet section can be additively manufactured. Surface features can be formed on an inner surface of the diffuser inlet section, such as inlet inner surfaces <NUM>, <NUM>. The diffuser inlet section can be manufactured to include a porous internal structure, such as a lattice or series of voids.

In step <NUM>, a diffuser wall, such as diffuser walls <NUM>, <NUM>, is manufactured adjacent to the diffuser inlet section. In some examples, the diffuser wall can be additively manufactured. Surface features can be formed on an inner surface of the diffuser wall, such as diffuser wall inner surfaces <NUM>, <NUM>. The diffuser wall can be manufactured to include a porous structure, such as a lattice or series of voids.

In step <NUM>, a diffuser outlet section, such as diffuser outlet sections <NUM>, <NUM>, is manufactured adjacent to the diffuser wall. In some examples, the diffuser outlet section can be additively manufactured. The diffuser inlet section, diffuser wall, and diffuser outlet section can be additively manufactured as a single monolithic piece. The diffuser outlet section can be manufactured to include a porous structure, such as a lattice or series of voids.

In step <NUM>, a movable diffuser hub, such as movable diffuser hubs <NUM>, <NUM>, is manufactured. In some examples, the movable diffuser hub can be additively manufactured. Surface features can be formed on a surface of the movable diffuser hub, such as diffuser hub surfaces <NUM>, <NUM>. The movable diffuser hub can be manufactured to include a porous structure, such as a lattice or series of voids.

The components of the radial diffuser can be formed of metal, plastic, fiber, a combination of these materials, or other suitable materials. In examples where the radial diffuser is at least partially additively manufactured, the radial diffuser can be partially or entirely manufactured with a heat exchanger, the turbine casing, and/or the movement mechanism as a monolithic structure. Additively manufacturing one or more components of the radial diffuser provides advantages over conventionally manufacturing the radial diffuser by allowing the formation of surface features such as micro-grooves or micro-features, decreasing the number of parts needed by integrating the radial diffuser with the heat exchanger and/or turbine casing, and decreasing the weight of the radial diffuser by incorporating a partially porous internal structure.

A radial diffuser with a movable diffuser hub as described herein provides numerous advantages. A movable diffuser hub can increase the efficiency of the radial diffuser by increasing the diffusion rate, and can control the pressure ratio and expansion rate of the working fluid through axial actuation. A movable diffuser hub can additionally increase the efficiency of other components by altering and/or controlling the mass flow rate. A movable diffuser hub can furthermore help to avoid shock experienced by the working fluid as it flows through the radial diffuser, and allows the radial diffuser's geometry to change in response to the characteristics of the flow of working fluid. These improvements can help to optimize the performance of the radial diffuser and the expansion of the working fluid. Additively manufacturing the movable diffuser hub can allow for material combinations to be implemented, and can additionally allow for the reliable formation of complex and/or fine surface features on various surfaces of the radial diffuser. Additive manufacturing can further allow for a porous structure to be incorporated into parts of the radial diffuser to reduce material use and weight, as well as reducing associated time and materials costs. Additionally, the radial diffuser can be built monolithically with other components, such as a heat exchanger or the movement mechanism of the movable diffuser hub. The manufacturing advantages of additively manufacturing a radial diffuser include reduced cost, reduced number of parts needed, decreased weight, reduced assembly time and complexity, and improved structural performance.

A radial diffuser for a heat exchanger system includes a diffuser inlet section, a diffuser outlet section, a diffuser wall, and a movable diffuser hub. The diffuser inlet section is upstream of the heat exchanger system and oriented along a central flow axis of the radial diffuser. The diffuser inlet section has a cylindrical shape which extends along the central flow axis and a circular cross section along an inlet section plane perpendicular to the central flow axis. The diffuser outlet section is downstream of the diffuser inlet section with respect to the central flow axis. The diffuser wall includes a diffuser wall inner surface defining a fluid flow path which is non-linear. The diffuser wall inner surface includes a convex curved section and a concave curved section. The convex curved section is adjacent to the diffuser inlet section and has a convex curvature with respect to the central flow axis. The concave curved section is adjacent to the diffuser outlet section and has a concave curvature with respect to the central flow axis. The concave curved section is adjacent to and downstream of the convex curved section with respect to the central flow axis. The movable diffuser hub is configured to move with respect to the central flow axis relative to the diffuser wall and can thereby alter a fluid flow through the radial diffuser.

The radial diffuser of the preceding paragraph can optionally include, additionally and/or alternatively, any one or more of the following features, configurations, and/or additional components:
A radial diffuser for a heat exchanger system according to an exemplary embodiment of this disclosure, among other possible things includes a diffuser inlet section, a diffuser outlet section, a diffuser wall, and a movable diffuser hub. The diffuser inlet section is upstream of the heat exchanger system and oriented along a central flow axis of the radial diffuser. The diffuser inlet section has a cylindrical shape which extends along the central flow axis and a circular cross section along an inlet section plane perpendicular to the central flow axis. The diffuser outlet section is downstream of the diffuser inlet section with respect to the central flow axis. The diffuser wall includes a diffuser wall inner surface defining a fluid flow path which is non-linear. The diffuser wall inner surface includes a convex curved section and a concave curved section. The convex curved section is adjacent to the diffuser inlet section and has a convex curvature with respect to the central flow axis. The concave curved section is adjacent to the diffuser outlet section and has a concave curvature with respect to the central flow axis. The concave curved section is adjacent to and downstream of the convex curved section with respect to the central flow axis. The movable diffuser hub is configured to move with respect to the central flow axis relative to the diffuser wall and can thereby alter a fluid flow through the radial diffuser.

A further embodiment of the foregoing radial diffuser, further comprising a translational actuator. The translational actuator is configured to control an axial separation between the diffuser hub and the diffuser wall along the central flow axis, thereby altering a diffusion rate of the fluid flow through the radial diffuser.

A further embodiment of any of the foregoing radial diffusers, wherein the movable diffuser hub is configured to rotate about the central flow axis, thereby decreasing a relative velocity of the fluid flow with respect to the movable diffuser hub.

A further embodiment of any of the foregoing radial diffusers, wherein the radial diffuser further comprises a bearing system. The movable diffuser hub is connected to the bearing system, and the movable diffuser hub is configured to rotate about the central axis when a diffuser hub surface of the movable diffuser hub experiences a shear force of the fluid flow.

A further embodiment of any of the foregoing radial diffusers, wherein the radial diffuser further comprises at least one electrical connection and the movable diffuser hub is configured to be electrically rotated about the central flow axis.

A further embodiment of any of the foregoing radial diffusers, wherein the radial diffuser further comprises a pneumatic system and the movable diffuser hub is configured to be pneumatically rotated about the central flow axis.

A further embodiment of any of the foregoing radial diffusers, wherein the movable diffuser hub is additively manufactured and the diffuser hub surface comprises a plurality of surface features.

A further embodiment of any of the foregoing radial diffusers, wherein the plurality of surface features comprises grooves, raised surface features, or a swirled pattern.

A further embodiment of any of the foregoing radial diffusers, wherein the diffuser inlet section, the diffuser wall, and the diffuser outlet section are additively manufactured as a monolithic piece.

A further embodiment of any of the foregoing radial diffusers, wherein at least one of the diffuser inlet section, the diffuser wall, and the diffuser outlet section comprises an internal lattice structure.

A further embodiment of any of the foregoing radial diffusers, wherein at least one of an inlet inner surface of the inlet section and the diffuser wall inner surface comprises a plurality of surface features.

A further embodiment of any of the foregoing radial diffusers, wherein the diffuser outlet section has a rectangular prism shape and a square cross section along an outlet section plane perpendicular to the central flow axis.

An air cycle machine includes a turbine oriented along a central flow axis, a heat exchanger downstream of the turbine with respect to the central flow axis, and a radial diffuser. The turbine includes a turbine outlet. The radial diffuser includes a diffuser inlet section, a diffuser outlet section, a diffuser wall, and a movable diffuser hub. The diffuser inlet section is upstream of the heat exchanger system and oriented along a central flow axis of the radial diffuser. The diffuser inlet section has a cylindrical shape which extends along the central flow axis and a circular cross section along an inlet section plane perpendicular to the central flow axis. The diffuser outlet section is downstream of the diffuser inlet section with respect to the central flow axis. The diffuser wall includes a diffuser wall inner surface defining a fluid flow path which is non-linear. The diffuser wall inner surface includes a convex curved section and a concave curved section. The convex curved section is adjacent to the diffuser inlet section and has a convex curvature with respect to the central flow axis. The concave curved section is adjacent to the diffuser outlet section and has a concave curvature with respect to the central flow axis. The concave curved section is adjacent to and downstream of the convex curved section with respect to the central flow axis. The movable diffuser hub is configured to move with respect to the central flow axis relative to the diffuser wall and can thereby alter a fluid flow through the radial diffuser. The radial diffuser is downstream of the turbine and upstream of the heat exchanger with respect to the central flow axis. The radial diffuser is configured to receive a fluid flow from the turbine through the turbine outlet, diffuse the fluid flow, and direct the fluid flow into the heat exchanger.

The air cycle machine of the preceding paragraph can optionally include, additionally and/or alternatively, any one or more of the following features, configurations, and/or additional components:.

An air cycle machine according to an exemplary embodiment of this disclosure, among other possible things includes a turbine oriented along a central flow axis, a heat exchanger downstream of the turbine with respect to the central flow axis, and a radial diffuser. The turbine includes a turbine outlet. The radial diffuser includes a diffuser inlet section, a diffuser outlet section, a diffuser wall, and a movable diffuser hub. The diffuser inlet section is upstream of the heat exchanger system and oriented along a central flow axis of the radial diffuser. The diffuser inlet section has a cylindrical shape which extends along the central flow axis and a circular cross section along an inlet section plane perpendicular to the central flow axis. The diffuser outlet section is downstream of the diffuser inlet section with respect to the central flow axis. The diffuser wall includes a diffuser wall inner surface defining a fluid flow path which is non-linear. The diffuser wall inner surface includes a convex curved section and a concave curved section. The convex curved section is adjacent to the diffuser inlet section and has a convex curvature with respect to the central flow axis. The concave curved section is adjacent to the diffuser outlet section and has a concave curvature with respect to the central flow axis. The concave curved section is adjacent to and downstream of the convex curved section with respect to the central flow axis. The movable diffuser hub is configured to move with respect to the central flow axis relative to the diffuser wall and can thereby alter a fluid flow through the radial diffuser. The radial diffuser is downstream of the turbine and upstream of the heat exchanger with respect to the central flow axis. The radial diffuser is configured to receive a fluid flow from the turbine through the turbine outlet, diffuse the fluid flow, and direct the fluid flow into the heat exchanger.

A method of manufacturing a radial diffuser includes manufacturing a diffuser inlet section of the radial diffuser. A diffuser wall of the radial diffuser is manufactured adjacent to the diffuser inlet section. A diffuser outlet section of the radial diffuser is manufactured adjacent to the diffuser wall. A movable diffuser hub of the radial diffuser is manufactured such that the movable diffuser hub is configured to move relative to the diffuser wall during operation of the radial diffuser.

The method of the preceding paragraph can optionally include, additionally and/or alternatively, any one or more of the following features, configurations, and/or additional components:.

A method of manufacturing a radial diffuser according to an exemplary embodiment of this disclosure, among other possible things includes manufacturing a diffuser inlet section of the radial diffuser. A diffuser wall of the radial diffuser is manufactured adjacent to the diffuser inlet section. A diffuser outlet section of the radial diffuser is manufactured adjacent to the diffuser wall. A movable diffuser hub of the radial diffuser is manufactured such that the movable diffuser hub is configured to move relative to the diffuser wall during operation of the radial diffuser.

A further embodiment of the foregoing method, wherein manufacturing the movable diffuser hub comprises additively manufacturing the movable diffuser hub and forming a plurality of surface features on a diffuser hub surface of the movable diffuser hub.

A further embodiment of any of the foregoing methods, wherein manufacturing the diffuser inlet section comprises additively manufacturing the diffuser inlet section. Manufacturing the diffuser wall comprises additively manufacturing the diffuser wall. Manufacturing the diffuser outlet section comprises additively manufacturing the diffuser outlet section. The diffuser inlet section, the diffuser wall, and the diffuser outlet section are additively manufactured as a monolithic piece.

A further embodiment of any of the foregoing methods, further comprising forming a plurality of surface features on at least one of an inlet inner surface of the diffuser inlet section and a diffuser wall inner surface of the diffuser wall.

A further embodiment of any of the foregoing methods, further comprising forming a plurality of surface features on at least one of an inlet inner surface of the diffuser inlet section and a diffuser wall inner surface of the diffuser wall. Manufacturing the movable diffuser hub comprises additively manufacturing the movable diffuser hub and forming a plurality of surface features on a diffuser hub surface of the movable diffuser hub. Manufacturing the diffuser inlet section comprises additively manufacturing the diffuser inlet section. Manufacturing the diffuser wall comprises additively manufacturing the diffuser wall. Manufacturing the diffuser outlet section comprises additively manufacturing the diffuser outlet section. The diffuser inlet section, the diffuser wall, and the diffuser outlet section are additively manufactured as a monolithic piece.

Claim 1:
A radial diffuser for a heat exchanger system, the radial diffuser comprising:
a diffuser inlet section (<NUM>, <NUM>, <NUM>, <NUM>, <NUM>) which is upstream of the heat exchanger system and oriented along a central flow axis of the radial diffuser, the diffuser inlet section (<NUM>, <NUM>, <NUM>, <NUM>, <NUM>) having a cylindrical shape which extends along the central flow axis and a circular cross section along an inlet section plane perpendicular to the central flow axis;
a diffuser outlet section (<NUM>, <NUM>, <NUM>, <NUM>, <NUM>) which is downstream of the diffuser inlet section (<NUM>, <NUM>, <NUM>, <NUM>, <NUM>) with respect to the central flow axis;
a diffuser wall comprising a diffuser wall inner surface defining a fluid flow path which is non-linear, the diffuser wall inner surface comprising:
a convex curved section adjacent to the diffuser inlet section (<NUM>, <NUM>, <NUM>, <NUM>, <NUM>) and having a convex curvature with respect to the central flow axis; and
a concave curved section adjacent to the diffuser outlet section (<NUM>, <NUM>, <NUM>, <NUM>, <NUM>) and having a concave curvature with respect to the central flow axis, wherein the concave curved section is adjacent to and downstream of the convex curved section with respect to the central flow axis; and
a movable diffuser hub which is configured to move with respect to the central flow axis relative to the diffuser wall, thereby altering a fluid flow through the radial diffuser.