Multi-channel diffuser

Abstract

A multi-channel diffuser (MCD) has multiple radial inlets in an annular configuration, a tangential outlet, a single discharge passage, and multiple individual passages extending from the radial inlets toward the outlet. The individual passages are fluidically isolated from each other at their upstream ends and merge at one or more confluences upstream of the single discharge passage. Therefore, the fluid flow entering the radial inlets is first separated within the individual passages, merges in the single discharge passage, and then flows out of the MCD collectively through the outlet. Both mixing losses and viscous losses are reduced.

Description

Description of Related Application

[0001] This application claims priority from and relates to U.S. Patent Application No. 18 / 213,990, filed on June 26, 2023, entitled "Multi-channel Diffuser", the entire content of which is incorporated herein by reference. Technical Field

[0002] The present technology generally relates to pumps or compressors, and more particularly to diffusers for pumps or compressors. Background Art

[0003] In pumps such as turbopumps and compressors, a diffuser is generally used to convert the dynamic pressure of the fluid flow discharged from the pump or compressor into an increase in static pressure at the volute outlet. There are three commonly used diffuser types: vaneless diffusers, airfoil diffusers, and island diffusers. The largest loss in a turbopump occurs in the diffuser, and diffuser loss may account for more than 20% of the total pressure loss discharged from the impeller to the volute. Such losses are caused by leading edge (incidence loss), trailing edge (expansion loss), mixing loss, and / or surface friction loss. Among these losses, mixing loss is the largest, accounting for more than 90% of the total loss.

[0004] Mixing loss reaches its maximum value because of the large pressure gradient and velocity gradient between the diffuser and the volute. An additional contributing factor to loss is the asymmetry induced by the volute tongue, which also generates a circumferential static pressure gradient around the volute that propagates through the diffuser to the impeller. The volute tongue is the main cause of radial lateral load on the impeller that is borne by the bearing. However, eliminating the tongue and the circumferential pressure gradient eliminates this lateral load, thereby increasing the service life and reliability of the bearing.

[0005] In addition, the radial component of kinetic energy, once it enters the vortex along with the meridional dynamic pressure, is almost irrecoverable. Leading-edge loss or injection loss is due to stagnation caused by the misalignment between the leading edge and the streamlines of the flow field. Even if these were perfectly adjusted at the design point conditions (which is impossible), injection loss will occur under out-of-design conditions. Trailing-edge loss is caused by the pressure gradient between the pressure side and the intake side of the diffuser. This loss exists even in symmetrical blades, but is greater in asymmetrical blades because the pressure and velocity gradients between the pressure side and the intake side increase. Surface friction loss is due to the velocity of the fluid flowing in contact with the stationary wall. This loss can be significant when viscous fluids are used in the pump. However, these losses are negligible for cryogenic fluids such as hydrogen, oxygen, and methane, as they are almost non-viscous. Even low-viscosity, non-cryogenic fluids, including rocket propellants and water, will have relatively low surface friction loss. To emphasize the magnitude of mixing loss, it should be noted that bladeless diffusers, despite having no leading-edge or trailing-edge loss, are the least efficient diffusers due to their high mixing loss. [Overview of the project]

[0006] Some embodiments provide useful MCDs, such as multi-flow diffusers (MCDs) for turbomachinery.

[0007] In one embodiment, the MCD comprises a plurality of inlets and outlets arranged in a ring, and a plurality of individual passages extending from the plurality of inlets toward the outlets, each having an increasing flow area, being fluidly isolated from one another at its upstream end, and converging at one or more confluence locations upstream of the outlet.

[0008] In one embodiment of the above-described embodiment, the plurality of individual passages are configured as a plurality of rows, each having a plurality of diffuser passages.

[0009] In one embodiment of the above-described embodiment, the plurality of inlets are radial inlets.

[0010] In one embodiment of the above-described embodiment, the outlet is a tangential outlet.

[0011] In one embodiment of the above-described embodiment, the outlet has a square or circular cross-section.

[0012] In one embodiment of the above-described embodiment, each of the plurality of individual passages has one of the following cross-sectional shapes: a straight cross-section, a hexagonal cross-section, or an elliptical cross-section.

[0013] In one embodiment, the multi-flow diffuser (MCD) comprises a plurality of inlets and outlets arranged in a ring, and a plurality of individual passages extending from the plurality of inlets toward the outlets, each having an upstream end and a downstream end, the upstream end of which is located at a corresponding one of the plurality of inlets, each having an increasing flow area from the upstream end toward the downstream end, being fluidly isolated from each other at the upstream end, and converging at one or more confluence locations upstream of the outlet.

[0014] In one embodiment of the above-described embodiment, the plurality of individual passages are configured as a plurality of rows, each having a plurality of diffuser passages.

[0015] In one embodiment of the above embodiment, one or more confluence locations include an upstream confluence location and a downstream confluence location. In one embodiment of the above embodiment, the MCD further includes a single discharge passage between the downstream confluence location and the outlet. In one embodiment of the above embodiment, at least two of the plurality of individual passages confluence at the upstream confluence location, and at least two other of the plurality of individual passages confluence at the downstream confluence location.

[0016] In one embodiment of the above-described embodiment, each of the plurality of individual passages has one of the following cross-sectional shapes: a straight cross-sectional shape, a hexagonal cross-sectional shape, and an elliptical cross-sectional shape.

[0017] In one embodiment of the above-described embodiment, the multi-flow diffuser defines an opening, which is sized to accommodate at least a portion of the impeller of a pump. In one embodiment of this embodiment, a plurality of inlets arranged in an annular pattern spread out around the opening. In one embodiment of this embodiment, a plurality of individual passages spread out around the opening. [Brief explanation of the drawing]

[0018] For a more complete understanding of the embodiments described herein, and the associated advantages and features, it is easiest to refer to the following detailed description in conjunction with the accompanying drawings. [Figure 1] Cross-sectional view of an exemplary embodiment of a multi-channel diffuser (MCD) according to this disclosure. [Figure 2] A side perspective view of the MCD structural model shown in Figure 1, as disclosed in this disclosure. [Figure 3] Figure 1 is a perspective view showing the flow rate of the MCD. [Figure 4] Front view of the MCD in Figure 1, showing the main discharge and confluence passages as disclosed herein. [Modes for carrying out the invention]

[0019] Before describing the exemplary embodiments in detail, note that these embodiments primarily relate to combinations of components and processes of devices associated with diffusers for pumps or compressors, and more specifically, to multi-flow diffusers (MCDs) for pumps or compressor turbomachinery. The MCD has an annular radial inlet and a tangential outlet, with multiple passages separated from each other to restrict fluid mixing, but converging at one or more locations upstream of the MCD outlet. Accordingly, components of the systems and methods are represented in the drawings by conventional symbols where appropriate, and only specific details relevant to understanding the embodiments of this disclosure are shown, so as not to obscure the disclosure by details readily understandable to those skilled in the art who enjoy the description herein.

[0020] Herein, referring to drawings where similar elements use similar reference symbols, exemplary embodiments of the MCD are shown in Figures 1-4. In one embodiment, the MCD10 generally comprises an outlet 12 and a plurality of inlets 14. In one embodiment, the MCD10 further comprises a plurality of individual passages 16 extending from each of the plurality of inlets 14 to the outlet 12. However, the plurality of individual passages 16 merge into a single discharge passage 18 at at least one confluence position 20 upstream of the outlet 12. In one embodiment, the plurality of individual passages 16 include nine passages 16 (for example, as shown in the cross-sectional view of Figure 1 and the flow diagram of Figure 3, which shows the path the fluid takes within the MCD10 shown in Figures 1, 2, and 4). However, it will be understood that there may be more or fewer passages. In one embodiment, the MCD10 is stationary, and an impeller rotates within the MCD10, discharging fluid outwards in a ring-shaped arrangement into multiple inlets of the MCD10.

[0021] Continuing to refer to Figures 1-4, in one embodiment, the MCD10 is generally ring-shaped and constructed to spread out around an impeller, defining an opening 22 into which the impeller is mounted. In one embodiment, each of the multiple inlets 14 is arranged radially around a virtual center point 24 of the opening 22 within the MCD10 (radial inlets). In one embodiment, the MCD10 is stationary, and the impeller rotates within the MCD10 (for example, at its position within the opening 22), discharging fluid outward in the multiple inlets of the MCD10 in an annular arrangement.

[0022] In one embodiment, each of the plurality of individual passages 16 has an upstream end 16A and a downstream end 16B, and the upstream end 16A of each of the plurality of individual passages 16 intersects with the corresponding inlet of the plurality of inlets 14, is located near the inlet, and / or at least partially defines the inlet and is in fluid communication with the inlet. In one embodiment, each of the plurality of individual passages 16 has a cross-sectional area that gradually increases from the associated inlet 14 at the upstream end 16A toward the downstream end 16B and the outlet 12. Furthermore, each of the plurality of individual passages 16 is fluidically isolated from each of the other individual passages 16 until the plurality of individual passages 16 intersect at one or more confluence positions 20. Thus, the fluid in each of the plurality of individual passages 16 remains isolated from the fluid in any of the other individual passages 16, but then mixes with the fluid from at least one of the other individual passages 16 at a position upstream of the single discharge passage 18 and outlet 12. All individual passages 16 merge by the time they intersect with the single discharge passage 18 and the fluid can be discharged collectively from the outlet 12. Each of the multiple individual passages 16 functions as an individual diffuser, remaining separate from the other fluid until it reaches the confluence point 20 and the single discharge passage 18 (where the fluids mix along parallel streamlines, eliminating mixing losses). In some embodiments, mixing losses are eliminated by the fluid isolation of the multiple individual passages 16 from the multiple inlets 14. However, viscous losses are also reduced when the fluid flows merge in the single discharge passage 18 before being discharged from the outlet 12.

[0023] With continued reference to FIGS. 1 to 4, in one embodiment, the MCD 10 has a plurality of merging positions 20, and the most downstream merging position is located in the upstream portion 18A of the single discharge passage 18. In one embodiment, the downstream portion 18B of the single discharge passage 18 defines the outlet 12. By way of example, in one embodiment, some (less than all) of the plurality of individual passages 16 merge at at least one upstream position 20A, and other (less than all) of the plurality of individual passages 16 merge at the downstream or most downstream merging position 20B located in or adjacent to the upstream portion 18A of the single discharge passage 18 (for example, as shown in FIG. 1). Regardless of the number of merging positions 20, fluid flows as a merged fluid from the plurality of individual passages 16 through the length of the single discharge passage 18 before being discharged from the MCD 10 through the outlet 12. In one embodiment, when these passages are located at sufficient circumferential and axial positions to form a common uniform structural wall, the spacing between individual passages 16 is eliminated; for example, two of the individual passages 16 can merge before reaching a common merging position, such as the upstream merging position 20A or the downstream merging position 20B located in or adjacent to the discharge passage 18. These merging positions occur at a certain proportion of the total length of the passages relative to the position of the inlet 14 and the discharge passage 18, and until merging occurs, a larger passage length occupies a smaller proportion of the total length. In other words, in some embodiments, each of the individual passages 16 travels a certain proportion of the total length before merging with another individual passage 16. In one non-limiting example, this proportion decreases based on the total length of the individual passage 16: the shortest individual passage 16 may travel about 100% (±5%) of its length before merging, while the longest individual passage 16 may only travel about 10% (±5%) of its length before merging.

[0024] Such an exemplary configuration is shown in the front view of the MCD10 in FIG. 4. When viewed through the outlet 12, a single discharge passage 18 that terminates at a downstream portion 18B at the outlet 12 is visible. Some of the plurality of individual passages 16 are visible in the single discharge passage 18. Some of the passages merge at a downstream merging position 20, while other passages of the plurality of individual passages 16 merge at an upstream merging position 20 (for example, as shown in FIG. 1), and individual passages 16 are no longer visible through the outlet 12 near the single discharge passage 18. Furthermore, as shown in FIGS. 3 and 4 and described in more detail below, in some embodiments, the plurality of individual passages 16 start in a radial arrangement of the plurality of inlets 14, spread spirally in a slightly helical arrangement, and form a more matrix-like or grid-like arrangement at or adjacent to the upstream portion 18A of the single discharge passage 18. In one example, the plurality of individual passages 16 are arranged to form a plurality of rows each including one or more individual passages 16, thereby forming a matrix-like or grid-like arrangement.

[0025] In addition, the embodiment of the MCD10 shown in FIGS. 1 to 4 includes a radial inlet (that is, a plurality of radially arranged inlets) with a tangential outlet. However, in other embodiments, the MCD10 includes axial inlets (that is, a plurality of axially arranged inlets) and a non-tangential outlet. For example, an axial flow pump or compressor may discharge a fluid flow into an annularly arranged axial inlet, each having passages spaced from one another, such that each discharges into a single discharge passage 18 that is not tangential to the axis of the pump or compressor.

[0026] Continuing to refer to Figures 1-4, in one embodiment, the outlet 12 of the MCD 10 has a round or circular cross-sectional shape. However, it will be understood that the outlet 12 may have any suitable cross-sectional shape, including, but not limited to, a circle, square, polygon (e.g., hexagon), straight line, ellipse, etc. Furthermore, each of the multiple individual passages 16 is shown to have a square cross-sectional shape. However, it will be understood that other suitable cross-sectional shapes, including, but not limited to, a circle, polygon, straight line, ellipse, etc., may be used.

[0027] In some embodiments, the MCD10 has one or more additional features. For example, in one embodiment, one or more of the multiple individual passages 16 are separated from the other individual passages 16 to define an extraction passage for a portion of the fluid flow. In some embodiments, one or more second-stage discharge configurations are used, so that the MCD10 comprises multiple single discharge sections, one or more outlets, and one or more sets of individual passages 16.

[0028] Continuing to refer to Figures 1-4, in one embodiment, the leading edge 26 of the MCD 10 is similar to that of an airfoil diffuser, except that each of the multiple individual passages 16 is unique and extends as it encloses the opening 22 and impeller (when in use), and expands continuously so that the cross-sectional diameter increases (thus expanding the fluid flow). Each of Figures 1-4 shows how the multiple individual passages 16 are distributed internally to achieve the matrix or grid arrangement partially shown in the front view of Figure 4. In the deployed state (i.e., unfolded or flattened to eliminate the opening 22), in one embodiment, the MCD 10 is a conical diffuser having a square, rhombic, trapezoidal, rectangular, or other suitable cross-sectional shape. In one embodiment, the expansion angle is very small due to the length, which allows for highly efficient diffusion with minimal loss. For example, in some embodiments, the expansion angle is between about 0° and about 15° (±0.05°), depending on the requirements of the particular application. In one embodiment, after the dynamic pressure is diffused and the static pressure rises, the multiple individual passages 16 then merge in a single discharge passage 18, resulting in a swirling discharge section having an appearance and function similar to that of a discharge section used in currently known diffusers. In addition, since each of the multiple individual passages 16 is independent of the other individual passages 16, these individual passages 16 can be bundled or separated and reoriented for other purposes or configurations. For the same reason, the multiple individual passages 16 can be configured additionally or alternatively to a planar arrangement rather than bundled, thereby enabling a variety of packaging configurations.

[0029] The MCD10 eliminates mixing and viscous losses and further increases pressure recovery. In some embodiments, the dynamic pressure of the impeller discharge pressure is increased stepwise and efficiently within a plurality of fluidically isolated individual passages 16. Once the fluid flow is fully expanded, it merges and combines with the adjacent passages after a confluence point 20 in a single discharge passage 18. However, because the flow is fully expanded (and without reversal of direction), no significant pressure or velocity gradients that would cause mixing losses are generated. By keeping the turbopump, engine size, and number of stages constant, this results in increased chamber pressure for additional stage capabilities (higher orbits, higher orbital inclination angles, and / or heavier payloads). Alternatively, by keeping the specific impulse and thrust constant, both the maximum diameter and overall length are significantly reduced, resulting in smaller and lighter stages while greatly increasing mission capabilities.

[0030] Diffusers and volute chambers typically have thick housings to accommodate high pressure. Discharge pressure is the same regardless of the size of the diffuser or passages. Therefore, wall thickness depends only on the passage size. A large volute chamber requires thick walls, while smaller passages, especially individual passages 16 located outside other passages, require only thin walls. Individual passages 16 located internally, or individual passages 16 surrounded by other individual passages 16, can be designed to be even thinner because no pressure gradient is created on the wall surface by adjacent passages. As a result, further weight reduction is possible from the diffuser and volute housing of the MCD10, in addition to the weight reduction effect of the smaller engine. Furthermore, the MCD10 lacks the tongue-like structure found in conventional volute chamber and diffuser combinations, thereby virtually eliminating the rotor-side load that occurs in current diffuser systems, thus improving rotor dynamics and system life.

[0031] As used herein, relational terms such as “first” and “second,” “upper” and “lower” are used merely to distinguish one entity or element from another, and do not necessarily require or imply any physical or logical relationship or order between those entities or elements. The terminology used herein is for the sole purpose of describing a particular embodiment and is not intended to limit the concepts described herein. In this specification, the singular forms “a,” “an,” and “the” are interpreted to include the plural form unless the context clearly indicates otherwise. Furthermore, it should be understood that the terms “comprises,” “comprising,” “includes,” and / or “including,” as used herein, identify the presence of the described features, integers, steps, operations, elements, and / or components, but do not exclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and / or groups thereof.

[0032] Unless otherwise defined, all terms used herein (including technical and scientific terms) have the same meaning as those commonly understood by those skilled in the art to which this disclosure belongs. Furthermore, terms used herein should be construed to have meanings consistent with their meanings in the context of this specification and the relevant art, and it will be further understood that, unless expressly defined herein, they should not be interpreted in an idealized or overly formal sense.

[0033] Those skilled in the art will recognize that the present invention is not limited to what has been specifically shown and described above. Furthermore, it should be noted that not all of the accompanying drawings are to scale unless otherwise specifically mentioned above. In light of the above teachings, various modifications and variations are possible without departing from the scope and spirit of the invention. [Explanation of Symbols]

[0034] 10. Multi-channel diffuser (MCD) 12 Exit 14 Entrance 16 Individual aisles 18 Single discharge passage 20A Upstream confluence location 20B Downstream confluence position 22 Virtual Center Point

Claims

1. Multiple entrances arranged in a ring, Exit, and A plurality of individual passages extending from the plurality of inlets toward the outlet, each of the plurality of individual passages having an upstream end and a downstream end, the upstream end of each of the plurality of individual passages being at the corresponding inlets of the plurality of inlets, each of the plurality of individual passages having an increasing flow area from the upstream end toward the downstream end, the plurality of individual passages being fluidly isolated from each other at the upstream end and converging at one or more confluence locations upstream of the outlet, A multi-channel diffuser equipped with [a specific feature].

2. The multi-flow diffuser according to claim 1, wherein the plurality of individual passages are configured as a plurality of rows, each row having a plurality of diffuser passages.

3. The multi-flow diffuser according to claim 1, wherein the plurality of inlets are radial inlets.

4. The multi-flow diffuser according to claim 1, wherein the outlet is a tangential outlet.

5. The multi-flow diffuser according to claim 1, wherein the outlet has a square or circular cross-section.

6. The multi-flow diffuser according to claim 1, wherein each of the plurality of individual passages has one of the following cross-sectional shapes: a straight cross-section, a hexagonal cross-section, or an elliptical cross-section.

7. The multi-flow diffuser according to claim 1, wherein the one or more confluence positions include an upstream confluence position and a downstream confluence position.

8. The multi-flow diffuser according to claim 7, further comprising a single discharge passage located between the downstream confluence point and the outlet.

9. The multi-flow diffuser according to claim 8, wherein at least two of the plurality of individual passages merge at the upstream confluence position, and at least two other of the plurality of individual passages merge at the downstream confluence position.

10. The multi-channel diffuser according to claim 1, wherein the multi-channel diffuser defines an opening, the opening being sized to accommodate at least a portion of the impeller of a pump.

11. The multi-flow diffuser according to claim 10, wherein the plurality of inlets arranged in an annular shape spread out around the opening.

12. The multi-flow diffuser according to claim 11, wherein the plurality of individual passages spread out around the opening.

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