Passive cooling of high-temperature turbomachine components

Abstract

A supersonic diffuser is provided. The supersonic diffuser includes a vaned zone having a flow area to pass a process fluid at supersonic velocity and a shock zone fluidly coupled to the vaned zone to pass the process fluid that exits the vaned zone. The supersonic diffuser also includes a mixing and subsonic diffusion zone fluidly coupled to the shock zone, the mixing and subsonic diffusion zone configured to decelerate process fluid from the shock zone to a reduced subsonic speed prior to discharge of the process fluid through an exit of the supersonic diffuser. The vaned zone includes a plurality of vanes interposed between an outer wall and an inner wall of the supersonic diffuser, where one or more of a pressure surface and a suction surface of each of the plurality of vanes includes a step-down portion.

Description

PASSIVE COOLING OF HIGH-TEMPERATURE TURBOMACHINE COMPONENTSBACKGROUND0001] Disclosed embodiments relate generally to the field of turbomachinery, and, more particularly, to turbomachinery arranged to impart thermal energy to a process fluid, such as for carrying out an endothermic process in connection with the process fluid, and, even more particularly, to vanes having a geometry to promote passive cooling adapted for use in such turbomachinery.

[0002] An endothermic process refers to a thermochemical process that absorbs heat from the environment. The endothermic process may be used in connection with various industrial operations for fractioning or “cracking’’ of molecules that may be constituents of the process fluid. Thermal cracking may involve the separation of chemical bonds of relatively complex molecular species to form simpler molecular species or form more complex molecules as an end product. For example, an endothermic process can be used to absorb heat that was added to a process fluid during a cracking process.SUMMARY

[0003] In one aspect a supersonic diffuser is provided. The supersonic diffuser includes a vaned zone configured to define a passageway having a flow area to pass a flow of a process fluid at supersonic velocity and a shock zone fluidly coupled to the vaned zone to pass the flow of the process fluid that exits the vaned zone, the shock zone configured to support a system of shock waves that increases static temperature of the process fluid downstream of the system of shock waves. ’The supersonic diffuser also includes a mixing and subsonic diffusion zone fluidly coupled to the shock zone, the mixing and subsonic diffusion zone configured to decelerate process fluid from the shock zone to a reduced subsonic speed prior to discharge of the process fluid through an exit of the supersonic diffuser. The vaned zone comprises a plurality of vanes interposed between an outer wall and an inner wall of the supersonic diffuser, and wherein one or more of a pressure surface and a suction surface of each of the plurality of vanes includes a step-down portion

[0004] The foregoing has broadly outlined some of the technical features of the present disclosure so that those skilled in the art may better understand the detailed description that follows. Additional features and advantages of the disclosure will be described hereinafter that form the subject of the claims. Those skilled in the art will appreciate that they may readily use the conception and the specific embodiments disclosed as a basis for modifying or designing other structures for carrying out the same purposes of the present disclosure. Those skilled in the art will also realize that, such equivalent constructions do not depart from the spirit and scope of the disclosure in its broadest form.

[0005] Also, before undertaking the Detailed Description below, it should be understood that various definitions for certain words and phrases are provided throughout this patent document, and those of ordinary skill in the art will understand that such definitions apply in many, if not most, instances to prior as well as future uses of such defined words and phrases. While some terms may include a wide variety of embodiments, the appended claims may expressly limit these terms to specific embodiments.BRIEF DESCRIPTION OF THE DRAWINGS

[0006] FIG. 1 is a schematic representation of one embodiment of a turbomachine arranged to impart thermal energy to a process fluid

[0007] FIG. 2A is a fragmentary cut away view' of one embodiment of a supersonic diffuser that may form part of a turbomachine, such as the turbomachine illustrated in FIG. 1.

[0008] FIG. 2B is a fragmentary cut away view of one embodiment of a vane of a turning vane upstream of the diffuser that may form part of a turbomachine, such as the turbomachine illustrated in FIG. I.

[0009] FIGS 2C and 2D are plots obtained from a model of a vane of a turning vane upstream of the diffuser illustrating the spatial distribution of static temperature in a process fluid that flows over the vanes.

[0010] FIG. 2E shows a partial solid view of an alternative embodiment of a turning vane upstream of a diffuser

[0011] FIG. 3 is a fragmentary cut away view of another non-limiting embodiment of a supersonic diffuser.

[0012] FIG. 4 is an isometric view of the embodiment illustrated in FIG. 3

[0013] FIG. 5 shows respective example plots for conceptualizing a shock zone in a disclosed supersonic diffuser, where the shock zone is configured to support a system of shock waves that increases the static temperature of the process fluid.

[0014] FIG. 6 is a fragmentary cut away view of another embodiment of a supersonic diffuser that may form part of a turbomachine, such as the turbomachine illustrated in FIG. I.

[0015] FIG. 7 is an isometric view of the embodiment illustrated in FIG. 6.

[0016] FIG. 8 is a schematic representation of another embodiment of a turbomachine arranged to impart thermal energy to a process fluid.DETAILED DESCRIPTION

[0017] In exemplary embodiments, a supersonic diffuser is configured to diffuse internal supersonic flows of elastic fluids, such as may be used in turbomachines arranged to impart thermal energy to a process fluid to carry out various industrial processes, such as may involve thermochemical reactions for fractioning or ‘‘cracking” relatively complex molecular species (e.g., precursor molecular species) into simpler molecular species that, for example, may have a relatively lower molecular weight than the precursor molecular species.

[0018] In exemplary embodiments, the geometry of vanes, and optionally other portions, of the turbomachine are configured to reduce the heating effect of primary working fluids on the metal components of a turbomachine processing high temperature fluids and undergoing endothermic reactions. One application of this is to use these features in olefin producing turbomachines wherein the olefins are generated from hydrocarbons via an endothermic pyrolysis reaction mechanism.

[0019] It will be appreciated that disclosed supersonic diffuser embodiments not only convert the kinetic energy of the fluid into internal energy, but also provide a shock zone where a desiredincrease of the static temperature of the fluid is achieved to initiate certain thermochemical reactions. Disclosed embodiments exhibit a robust and compact topology that can appropriately handle a broad range of back pressures while substantially isolating the upstream fluid flow regimes.

[0020] Before disclosed embodiments are explained in detail, it is to be understood that disclosed embodiments are not limited in applicability to the details of construction and the arrangement of components set forth in this description or illustrated in the following drawings. The underlying principles embodied in disclosed embodiments may be realized by way of further embodiments and of being practiced or of being carried out in various ways. Also, it is to be understood that the phraseology and terminology used herein is for the purpose of description and should not be regarded as limiting

[0021] Various technologies that pertain to apparatuses and / or methodologies will now be described with reference to the drawings, where like reference numerals represent like elements throughout. The drawings discussed below, and the various embodiments used to describe the principles of the present disclosure in this patent document are by way of illustration only and should not be construed in any way to limit the scope of the disclosure. Those skilled in the art will understand that the principles of the present disclosure may be implemented in any suitably arranged apparatus. It is to be understood that functionality that is described as being carried out by certain elements may be performed by multiple elements. Similarly, for instance, an element may be configured to perform functionality that is described as being carried out by multiple elements. The numerous innovative teachings of the present application will be described with reference to exemplary' non-limiting embodiments.

[0022] It should be understood that the words or phrases used herein should be construed broadly, unless expressly limited in some examples. For example, the terms “including,” “having,” and “comprising,” as well as derivatives thereof, mean inclusion without limitation. The singular forms “a”, “an” and “the” are intended to include the plural forms as well, unless the context clearly indicates otherwise Further, the term “and / or” as used herein refers to and encompasses any and all possible combinations of one or more of the associated listed items. The term “or” is inclusive, meaning and / or, unless the context clearly indicates otherwise. Thephrases "‘associated with1’ and “associated therewith,” as well as derivatives thereof, may mean to include, be included within, interconnect with, contain, be contained within, connect to or with, couple to or with, be communicable with, cooperate with, interleave, juxtapose, be proximate to, be bound to or with, have, have a property of, or the like. Furthermore, while multiple embodiments or constructions may be described herein, any features, methods, steps, components, etc. described with regard to one embodiment are equally applicable to other embodiments absent a specific statement to the contrary.

[0023] Also, although the terms “first”, “second”, "‘third” and so forth may be used herein to refer to various elements, information, functions, or acts, these elements, information, functions, or acts should not be limited by these terms. Rather these numeral adjectives are used to distinguish different elements, information, functions or acts from each other. For example, a first element, information, function, or act could be termed a second element, information, function, or act, and, similarly, a second element, information, function, or act could be termed a first element, information, function, or act, without departing from the scope of the present disclosure.

[0024] In addition, the term “adjacent to” may mean that an element is relatively near to but not in contact with a further element, or that the element is in contact with a further portion, unless the context clearly indicates otherwise. Further, the phrase "‘based on” is intended to mean “based, at least in part, on” unless explicitly stated otherwise. Terms "‘about” or “substantially” or like terms are intended to cover variations in a value that are within normal industry manufacturing tolerances for that dimension. If no industry standard is available, a variation of twenty percent would fall within the meaning of these terms unless otherwise stated.

[0025] Referring now to FIG. 1, a schematic representation of one non-limiting embodiment of a turbomachine 100 arranged to impart thermal energy to a process fluid is shown. As shown in FIG. 1, a number of rows of rotatable blades 102 are coupled to a rotor shaft 104 that in turn is coupled to and driven by a shaft-rotating power source or driver 106, such as an electric motor, steam or gas turbine, or another turbomachine.

[0026] The rows of rotatable blades 102 impart kinetic energy to the process fluid through a well-understood momentum transfer process. In FIG. 1, there are three rows of rotatable blades102 for adding kinetic energy to the process fluid It will be appreciated that the number of rows of rotatable blades shown in FIG. 1 should be construed as an example and not as a limitation since such a number can be adapted based on the needs of any given application. The process fluid is then processed by a supersonic diffuser 110 to decelerate the flow and convert kinetic energy in the process fluid into thermal energy, as described in greater detail below.

[0027] In exemplary embodiments, the varied zone 202 is formed by a plurality of circumferentially positioned vanes 210 that collectively span 360 degrees of the annulus defined by outer wall 212 and inner wall 214, where a respective passageway 203 is defined between two adjacent vanes 210 for a respective stream or jet of the process fluid. That is, the plurality of circumferentially positioned vanes 210 collectively define the series of circumferentially arranged individual flow passageways 203 leading to the shock zone 204.

[0028] Referring now to FIG 2 A, a fragmentary cut away view of an embodiment of a supersonic diffuser 110 fluidly coupled to receive process fluid flow exiting from the most downstream row of rotatable blades 102 (FIG 1) is shown. Supersonic diffuser 110 includes a vaned zone 202, a shock zone 204, and a mixing and subsonic diffusion zone 206. The vaned zone 202 is configured to define a passageway 203 having a flow area to pass the flow of the process fluid at supersonic velocity. In exemplary embodiments, the vaned zone 202 is formed by a series of circumferentially arranged vanes 210 that define individual flow passageways 203 leading to the shock zone 204. That is, shock zone 204 is located downstream from vaned zone 202. For simplicity, just one of such passageway 203 is pointed to in the figures since the structural and / or operational relationships would be the same for each passageway 203.

[0029] Referring now to FIG 2B, a fragmentary cut away view of one embodiment of a turning vane 210 (also referred to herein as a turning vane 210) upstream of diffuser that may form part of a turbomachine is shown. In exemplary embodiments, each vane 210 includes a tip 221 and a trailing edge 218. Each vane 210 also includes a first surface 222 (also referred to herein as a pressure surface) and a second surface 224 (also referred to herein as a suction surface) that extends from the tip 221 to the trailing edge 218. In exemplary embodiments, one or more of the first surface 222 and the second surface includes a step-down portion 226. As illustrated the step¬ down portion 226 includes a discontinuity 228 in the first surface 222 or the second surface 224that, extends towards an inner portion of the vane 210 The step-down portion 226 also includes a ramp portion 230 that extends from an inner end of the discontinuity 228 to the first or second surface 222, 224

[0030] In exemplary embodiments, the process fluid flows from the tip 221 of the vane 210 towards the trailing edge 218 of the vane and over the step-down portions 226 disposed on one or more of the first surface 222 and the second surface 224 In exemplary embodiments, the step-down portions 226 cause a reduction in the velocity of the process fluid downstream of the step-down portions 226 on the first and / or second surfaces 222, 224 of the vane 210. The reduction in velocity leads to an increase in static temperature and initiates and / or advances the pyrolysis reaction. The endothermic pyrolysis reaction causes a reduction in the total temperature of the process fluid and thus reduces the heating effect on the component In addition to the change in total temperature, the heat transfer coefficient is also positively affected by the reduction in flow velocity.

[0031] Referring now to FIGS. 2C and 2D, plots obtained from models of exemplary turning vanes upstream of the diffuser illustrating the spatial distribution of static temperature in a process fluid that flows over the vanes are shown. As illustrated in FIG. 2C, a first vane 210-1 includes one step-down portion 226 disposed on a pressure surface 222 and one step-down portion 226 disposed on a suction surface 224. Both of the step-down portions 226 are disposed relatively close to the tip 221 of the first vane 210-1. As il lustrated in FIG. 2D, a second vane 210-2 includes multiple step-down portions 226 disposed on a pressure surface 222 and multiple step-down portions 226 disposed on a suction surface 224. As shown in FIGS 2C and 2D, each of the step-down portion 226 creates a low velocity region in the flow of the process fluid immediately downstream of the step-down portion 226

[0032] In exemplary embodiments, the number and location of the step-down portions 226 on each of the vanes 210 in the vaned zone 202 can be configured based on a desired reduction in the speed of the flow of the process fluid. Likewise, the geometry' of each of the step-down portions 226 on each of the vanes 210 in the vaned zone 202 can be configured based on a desired reduction in the speed of the flow of the process fluid. For example, the length and angle of both the discontinuity 228 and the ramp portion 230 that define each step-down portion 226can be configured based on the desired reduction in the speed of the flow'- of the process fluid. In exemplary embodiments, different step-down portions 226 located on different areas of the vane may have different geometries. In one embodiment, the length of the discontinuity 228 may increase as the distance of the step-down portion 226 increases from the tip 221 of the vane 210. In exemplary embodiments, the geometry of each of vanes 210 in the vaned zone are configured to be the same Regardless of the specific implementation, the step-down portion 226 provides a sudden increase to the flow area at a given location and slows the velocity of the process fluid which in turn increases the static temperature of the process fluid.

[0033] An alternative embodiment is shown in FIG.2E. In exemplary embodiments, a surface texture with overlapping triangular facets 240 that provide localized and customizable depressions along the surface 224 to allow thermal relief equivalent to the effect of the prismatic cavities of the embodiment shown in FIG.2B. These scale-like facets can be tailored to address local flow conditions along the blade surfaces, especially due to variations along the vane height. This texture can be applied across the entire vane or end wall surfaces, or selectively in areas requiring thermal relief.

[0034] In one example embodiment, the vaned zone 202 includes spaced apart vanes 210 interposed between an outer wall 212 and an inner wall 214 of the supersonic diffuser. In this embodiment, the vanes 210 are configured to turn the flow direction of the process fluid to be parallel or approximately parallel along an axial direction of supersonic diffuser 110, schematically represented by center line 216. In another embodiment, the vanes are not parallel to the axial direction and are arranged at a desired angle to the axial direction The vanes 210 each have a blunt trailing edge 218 (e.g., truncated trailing edge) that circumferentially defines a step-change to the flow area of passageway 203 In one embodiment, the location of the stepchange may be conceptualized to be at the intersection of vaned zone 202 and shock zone 204.

[0035] Regardless of the specific implementation, the step-change provides a sudden increase to the flow area at a given location and leads to the formation of a system of shock waves into shock zone 204 that in turn increases the static temperature of the process fluid, as elaborated in greater detail below. That is, the step-change to the flow area of each passageway constitutes a specific, discontinuous change in flow area at the interface between vaned zone 202 and shockzone 204 to initiate the shock wave system. In general, the transition between vaned zone 202 and shock zone 204 is defined by the step-change to the flow area and then shock zone 204 may or may not continue with defined passages.

[0036] In another embodiment, as shown in FIG. 3 and 4, vane 210 may include an axial extension (schematically represented by twin-headed arrow 218) featuring a tapering section 220 that allows some area expansion in the passageway 203 before the process fluid exits the varied zone. Depending on the needs of a given application, this embodiment permits greater tolerance to backpressure variation that may be encountered in the given application. In this example, the total increase in the flow area may be up to approximately 200%. Although not illustrated, the vanes 210 of the embodiment shown in FIG. 3 and 4 include one or more step-down portions 226 such as shown in FIGS. 2B, 2C, and 2D

[0037] In exemplary embodiments, the outer wall of the diffuser includes a step-change 232 in radius that increases the flow area of passageway 203. Although the step-change 232 is illustrated in the shock zone 204, the step-change may be disposed in the turning zone 202, at the transition from the turning zone 202 to the shock zone 204, or in the diffusion zone 206. In addition, although the step-change 232 is shown as being disposed only on the outer wall, those of ordinary skill in the art will appreciate that, the step-change 232 may also be disposed on the inner wall of the diffuser For example, in one embodiment, vaned zone 202 may be configured to define a step-change to the inner wall and outer wall of the diffuser at a location where the flow of the process fluid exits the vaned zone, as best shown in FIGS. 6 and 7.

[0038] FIG. 5 shows respective example plots for conceptualizing a system of shock waves 302 that may be formed in shock zone 204 that may be part of a disclosed supersonic diffuser, where the system of shock waves 302 permits to increase the static temperature of the process fluid downstream of the system of shock waves. As can appreciated in FIG. 5, in one example embodiment, a respective intensity of successive shock waves in the system of shock waves 302 becomes progressively attenuated as the system of shock waves propagates in shock zone 204.

[0039] In another embodiment, as shown in FIG. 6 and 7, vaned zone 202 includes a plurality of low camber vanes 610. Each of the low camber vanes 610, by way of example, may have a camber angle of approximately 20 degrees or less Although not illustrated, the low cambervanes 610 of the embodiment shown in FIG 6 and 7 include one or more step-down portions 226 such as shown in FIGS. 2B, 2C, and 2D. The low camber vanes 610 are interposed between outer wall 212 and inner wall 214 of the supersonic diffuser. The low camber vanes 610 are arranged to guide the flow of the process fluid to meet a step-change to the flow area of passageway 203. In this embodiment, at. least one of outer wall 212 and inner wall 214 has a step-change in radius (labeled Ar) that radially defines the step-change to the flow area of passageway 203

[0040] In this embodiment, as noted above, vaned zone 202 is formed by a plurality of circumferentially positioned low camber vanes 610 that collectively span 360 degrees of the annulus defined by outer wall 212 and an inner wall 214, where a respective passageway is defined between each pair of adjacent low camber vanes 610 for a respective stream or jet of the process fluid. That is, the plurality of circumferentially positioned low camber vanes 610 collectively defines the series of circumferentially arranged individual flow passageways 203 leading to the shock zone 204.

[0041] Referring now to FIG. 8, a schematic representation of an embodiment of a turbomachine 800 arranged to impart thermal energy to a process fluid is shown. As shown in FIG. 8, a first portion 802 of the turbomachine includes a number of rows of rotatable blades 102 are coupled to a rotor shaft 104 The rotor shaft 104 is coupled to and driven by a shaft-rotating power source or driver 106, such as an electric motor, steam or gas turbine, or another turbomachine. The rows of rotatable blades 102 impart kinetic energy to the process fluid through a well-understood momentum transfer process. The process fluid is then fluidly coupled to be provided from the first portion 802 to a supersonic diffuser 110 to decelerate the flow and convert kinetic energy in the process fluid into thermal energy, as described in greater detail above. In exemplary embodiments, a step-change 804 in the flow area between the first portion 802 and the supersonic diffuser 110. As described in more detail above, the step-change 804 creates a sudden increase in the flow area of the process fluid, which causes a reduction in the velocity of the process fluid downstream of the step-change 804. The reduction in velocity leads to an increase in static temperature and initiates and / or advances the pyrolysis reaction. The endothermic pyrolysis reaction causes a reduction in the total temperature of the process fluid and thus reduces the heating effect on the component. In addition to the change in totaltemperature, the heat transfer coefficient is also positively affected by the reduction in flow velocity.

[0042] It will be appreciated that the embodiments described above in the context of FIGS. 1 through 8, may be combined with one another in various manners. That is, one or more of the step-down portions of the vanes 210(FIGS. 2B-2D), the step-change to the flow area of the passageway may be implemented by way of a combination of blunt trailing edges 218 of vane pairs 210 (FIGS. 3-4), the step-change in radius (Ar) (FIGS. 6-7), and the step-change 804 may be combined in various embodiments.

[0043] In one example embodiment, the process fluid subjected to the thermochemical reaction may comprise ammonia to produce a mixture of ammonia and hydrogen. As would be appreciated by one skilled in the art, the mixture of ammonia and hydrogen constitutes a carbon- free fuel. In another example embodiment, the process fluid subjected to the thermochemical reaction may comprise saturated hydrocarbons, such as propane, naphtha, or ethane to produce ol efins.

[0044] In one example embodiment, the train of shock waves is effective in raising the static temperature of the process fluid downstream of the train of shock waves by at least ten percent (10%), within ten milliseconds (10 MS), without changing static pressure by more than plus or minus 25 percent (25%).

[0045] In operation, disclosed supersonic diffuser embodiments are effective in realizing a desired increase of the static temperature of the fluid to initiate certain thermo-chemical reactions Disclosed embodiments exhibit a robust and compact topology that can handle a broad range of back pressures while isolating the upstream fluid flow regimes.

[0046] Although an exemplary embodiment of the present disclosure has been described in detail, those skilled in the art will understand that various changes, substitutions, variations, and improvements disclosed herein may be made without departing from the spirit and scope of the disclosure in its broadest form.

[0047] None of the descriptions in the present application should be read as implying that any particular element, step, act, or function is an essential element, which must be included in theclaim scope. The scope of patented subject matter is defined only by the allowed claims.Moreover, none of these claims are intended to invoke a means plus function claim construction unless the exact words "means for" are followed by a participle.

Claims

CLAIMSWhat is claimed is.

1. A supersonic diffuser comprising:a vaned zone configured to define a passageway having a flow area to pass a flow of a process fluid at supersonic velocity;a shock zone fluidly coupled to the vaned zone to pass the flow of the process fluid that exits the vaned zone, the shock zone configured to support a system of shock waves that increases static temperature of the process fluid downstream of the system of shock waves; anda mixing and subsonic diffusion zone fluidly coupled to the shock zone, the mixing and subsonic diffusion zone configured to decelerate process fluid from the shock zone to a reduced subsonic speed prior to discharge of the process fluid through an exit of the supersonic diffuser,wherein the vaned zone comprises a plurality of vanes interposed between an outer wall and an inner wall of the supersonic diffuser, and wherein one or more of a pressure surface and a suction surface of each of the plurality of vanes includes a step-down portion.

2. The supersonic diffuser of claim 1, wherein the plurality of vanes are configured to turn a flow direction of the process fluid to be parallel along an axial direction.

3. The supersonic diffuser of claim 1, wherein the step-down portion includes a discontinuity that extends towards an inner portion of the vane.•4 The supersonic diffuser of claim 1, wherein the pressure surface of each of the plurality of vanes includes at least one step-down portion.5 The supersonic diffuser of claim 1, wherein the suction surface of each of the plurality of vanes includes at least one step-down portion.

6. The supersonic diffuser of claim 1, wherein one or more of the pressure surface and the suction surface of each of the plurality of vanes includes two or more step-down portions.

7. The supersonic diffuser of claim 6, wherein a geometry of the two or more step-down portions disposed on the one or more of the pressure surface and the suction surface of each of the plurality of vanes are distinct from one another.

8. The supersonic diffuser of claim 1, wherein the vaned zone configured to define a stepchange to the flow area of the passageway.

9. The supersonic diffuser of claim 8, wherein each of the plurality of vanes each has a blunt trailing edge that circumferentially defines the step-change to the flow area of the passageway.

10. The supersonic diffuser of claim 8, wherein the step-change to the flow area of the passageway is at a location where the flow of the process fluid exits the vaned zone.

11. The supersonic diffuser of claim 8, wherein at least one of the outer wall and the inner wall has a step-change in radius that radially further defines the step change to the flow area of the passageway.

12. The supersonic diffuser of claim 8, wherein a location of the step-change to the flow area is at an intersection of the vaned zone and the shock zone.

13. The supersonic diffuser of claim 1, wherein the flow area is located between an outer wall and an inner wall of the supersonic diffuser, wherein at least one of the outer wall and the inner wall has a step-change in radius that radially defines the step-change to the flow area of the passageway.

14. A turbomachine comprising:a driver;a plurality of rotatable blades coupled to the driver by a rotor shaft, wherein the plurality of rotatable blades are configured to impart kinetic energy to a process fluid through the turbomachine; anda supersonic diffuser configured to receive the process fluid, the supersonic diffuser comprising:a vaned zone configured to define a passageway having a flow area to pass a flow of the process fluid at supersonic velocity;a shock zone fluidly coupled to the vaned zone to pass the flow of the process fluid that exits the vaned zone, the shock zone configured to support a system of shock waves that increases static temperature of the process fluid downstream of the system of shock waves; anda mixing and subsonic diffusion zone fluidly coupled to the shock zone, the mixing and subsonic diffusion zone configured to decelerate process fluid from the shock zone to a reduced subsonic speed prior to discharge of the process fluid through an exit of the supersonic diffuser,wherein the vaned zone comprises a plurality of vanes interposed between an outer wall and an inner wall of the supersonic diffuser, and wherein one or more of a pressure surface and a suction surface of each of the plurality of vanes includes a step-down portion.

15. The turbomachine of claim 14, wherein the plurality of vanes are configured to turn a flow direction of the process fluid to be parallel along an axial direction.

16. The turbomachine of claim 14, wherein the step-down portion includes a discontinuity that extends towards an inner portion of the vane.

17. The turbomachine of claim 14, wherein the pressure surface of each of the plurality of vanes includes at least one step-down portion.

18. The turbomachine of claim 14, wherein the suction surface of each of the plurality of vanes includes at least one step-down portion.

19. The turbomachine of claim 14, wherein one or more of the pressure surface and the suction surface of each of the plurality of vanes includes two or more step-down portions.

20. The turbomachine of claim 19, wherein a geometry of the two or more step-down portions disposed on the one or more of the pressure surface and the suction surface of each of the plurality of vanes are distinct from one another.

21. The turbomachine of claim 14, wherein another step-down portion is located on one or more of a rotating blade, endwalls of rotating and stationary components upstream of the plurality of vanes in the supersonic diffuser.

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