Compressor with a stabilizer and turbomachine including the same

Abstract

A stabilizer (10) of a compressor (20), in particular of a radial compressor or diagonal compressor, is described. The stabilizer (10) includes an annular stabilizer chamber (12), which surrounds a main flow channel (13) in the intake region of a compressor wheel (21) and is delimited with respect to the main flow channel by an annular web (14). The annular stabilizer chamber is connected to the main flow channel via a downstream flow inlet (15) and an upstream flow outlet (16). Further, a plurality of first flow guiding elements (17) are circumferentially provided at a radial inner surface (142) of the annular web (14). The plurality of first flow guiding elements (17) are provided closer to the downstream flow inlet (15) than to the upstream flow outlet (16). Additionally, the plurality of first flow guiding elements at least partially overlap with the compressor wheel in the axial direction.

Description

COMPRESSOR WITH A STABILIZER AND TURBOMACHINE INCLUDING THE SAMETECHNICAL FIELD

[0001] Embodiments of the present disclosure relate to compressors, particularly radial or diagonal compressors. In particular, embodiments of the present disclosure related to a stabilizer at the compressor inlet for improving the map width and the characteristic curve slope of the compressor. Further embodiments of the present disclosure relate turbomachines including a stabilizer according to embodiments described herein.BACKGROUND

[0002] Exhaust turbochargers are used to increase the performance of internal combustion engines, particularly reciprocating engines. Typically, an exhaust turbocharger has a radial or diagonal compressor and a radial or axial turbine.

[0003] The operational range of radial and axial compressors is limited towards lower mass flows by the surge limit / flow instability: As the compressor is throttled, the incidence angles progressively worsen until the flow separates and surging occurs. The permissible incidence angle range, within which the flow remains attached, decreases with increasing flow Mach number. This means that the operating range tends to narrow in stages with high pressure ratios and / or high swallowing capacity.

[0004] As a measure to stabilize the performance curves, a bypass in the form of an annular cavity within the compressor housing can be providedabove the contour of the compressor wheel, parallel to the intake duct. Such a bypass is also known as a stabilizer chamber or recirculator. Using a recirculator can artificially increase the mass flow at the compressor wheel inlet near the surge limit. A portion of the mass flow is diverted from the compressor wheel into the side chamber (bypass). This mass flow has a strong swirl component (in the direction of the impeller rotation - co-rotating swirl). This co-rotating swirl reduces the work transfer in the compressor, resulting in flatter performance curves near the surge limit.

[0005] Flat performance curves near the surge limit can lead to unexpected surging in applications with pressure pulsations (e.g., due to the valve movement of the turbocharged internal combustion engine). For this reason, there is a requirement to provide a minimum pressure increase between the operating point and the surge point on the operating speed line. This requirement can hardly be met in stages with a high pressure ratio and conventional bypass / stabilizer channel, due to the high work transfer and the flat performance curve over the mass flow at constant speed.

[0006] The objective of the present invention is to provide a stabilizer for a compressor, particularly a radial or diagonal compressor, that is improved in at least one aspect compared to the known disadvantages of the prior art. Furthermore, the objective of the present invention is to provide an improved compressor and an improved turbomachine, particularly an improved turbocharger.SUMMARY

[0007] In light of the above, a stabilizer of a compressor according to claim 1 is provided. Additionally, a compressor including a stabilizer according any embodiments described herein and a turbomachine including such a compressor are provided. Further aspects, advantages, and features areapparent from the dependent claims, the description, and the accompanying drawings.

[0008] According to an aspect of the present disclosure, a compressor, in particular a radial compressor or diagonal compressor, including a compressor wheel and a stabilizer is provided. The stabilizer includes an annular stabilizer chamber. The annular stabilizer chamber surrounds a main flow channel in the intake region of a compressor wheel. The annular stabilizer chamber is delimited with respect to the main flow channel by an annular web. The annular web has a radial outer surface that provides a wall of the annular stabilizer chamber. The annular web has a radial inner surface that provides a wall of the main flow channel. The annular stabilizer chamber is connected to the main flow channel via a downstream flow inlet and an upstream flow outlet. Further, a plurality of first flow guiding elements are circumferentially provided at the radial inner surface of the annular web. The plurality of first flow guiding elements are provided closer to the downstream flow inlet than to the upstream flow outlet. Additionally, the plurality of first flow guiding elements at least partially overlap with the compressor wheel in the axial direction. Moreover, the stabilizer includes a plurality of second flow guiding elements different from the plurality of first flow guiding elements. The plurality of second flow guiding elements at least partially overlap with a flow entry portion of the compressor wheel.

[0009] Accordingly, the compressor with the stabilizer described in the present disclosure offers improvements over conventional compressors with stabilizers, particularly in terms of the operating range and the performance curve slope of a compressor stage.

[0010] According to another aspect of the present disclosure, a turbomachine, in particular a turbocharger, including a compressor according to any embodiments of the present disclosure is provided.BRIEF DESCRIPTION OF THE DRAWINGS

[0011] So that the manner in which the above recited features of the present disclosure can be understood in detail, a more particular description of the disclosure, briefly summarized above, may be had by reference to embodiments. The accompanying drawings relate to embodiments of the disclosure and are described in the following:Figs. 1 and 2 show schematic longitudinal sectional views of a stabilizer according to exemplary embodiments described herein;Fig. 3 shows a schematic transversal sectional view along line A-A indicated in Fig. 2;Fig. 4 shows schematic transversal sectional view according to an alternative configuration according to embodiments described herein;Fig. 5 shows a schematic longitudinal sectional view of a stabilizer according to further embodiments described herein;Fig. 6 shows a sectional view along line B-B indicated in Fig. 5;Fig. 7 shows a sectional view along line C-C indicated in Fig. 5;Fig. 8 shows a schematic longitudinal sectional view of a stabilizer according to yet further embodiments described herein; andFig. 9 shows schematic transversal sectional views of a stabilizer according to further exemplary embodiments described herein.DETAILED DESCRIPTION OF EMBODIMENTS

[0012] Reference will now be made in detail to the various embodiments, one or more examples of which are illustrated in each figure. Each example is provided by way of explanation and is not meant as a limitation. For example, features illustrated or described as part of one embodiment can be used on or in conjunction with any other embodiment to yield yet a further embodiment. It is intended that the present disclosure includes such modifications and variations.

[0013] Within the following description of the drawings, the same reference numbers refer to the same or to similar components. Generally, only the differences with respect to the individual embodiments are described. Unless specified otherwise, the description of a part or aspect in one embodiment can apply to a corresponding part or aspect in another embodiment as well.

[0014] With exemplary reference to Figs. 1 to 9, a stabilizer 10 of a compressor 20 according to embodiments of the present disclosure is described. For instance, the compressor 20 can be a radial compressor or a diagonal compressor.

[0015] According to embodiments, which can be combined with other embodiments described herein, the stabilizer 10 includes an annular stabilizer chamber 12. The annular stabilizer chamber 12 surrounds a main flow channel 13 in the intake region of a compressor wheel 21. The annular stabilizer chamber 12 is delimited with respect to the main flow channel by an annular web 14. The annular web 14 has a radial outer surface 141 that provides a wall of the annular stabilizer chamber 12. Further, the annular web 14 has a radial inner surface 142 that provides a wall of the main flow channel 13. The annular stabilizer chamber 12 is connected to the main flow channel 13 via a downstream flow inlet 15 and an upstream flow outlet 16. Additionally, a plurality of first flow guiding elements 17 are circumferentially provided at the radial inner surface 142 of the annular web14. As exemplarily shown in Fig. 1, the plurality of first flow guiding elements 17 are provided closer to the downstream flow inlet 15 than to the upstream flow outlet 16. Further, the plurality of first flow guiding elements 17 at least partially overlap with the compressor wheel 21 in the axial direction x.

[0016] Accordingly, the stabilizer according to embodiments of the present disclosure is improved compared to stabilizers of compressors according to the state of the art. In particular, the stabilizer beneficially combines a recirculator, (which may include flow guiding elements, particularly swirlregulating elements such as axial struts, blades, etc.) to generate a counterswirl at the impeller inlet with a casing treatment measure, namely the plurality of first flow guiding elements, that acts locally in the blade tip area near the leading edge and relieves the blade tip section. In particular, the casing treatment is used to reduce the relative Mach number and the incidence angle deviation at the blade tip section, both with and without co-swirl. By using circumferentially separated (partial) areas provided by the plurality of first flow guiding elements, direct tip leakage flows and the associated losses can be reduced. A compact axial extension and local effectiveness of the casing treatment beneficially minimizes mixing with the counter-swirl- affected, radially inner main flow. Accordingly, beneficially the surge margin and efficiency level can be further improved.

[0017] In the present disclosure, a “stabilizer” can be understood as a component, feature or combination of structural measures configured to enhance the stability and performance characteristics of a compressor stage, particularly in terms of operating range, performance curve slope, and possibly addressing issues like surge and efficiency in turbomachinery such as turbochargers.

[0018] In the present disclosure, an “annular stabilizer chamber” can be understood as ring-shaped channel or cavity designed as a structural elementwithin the compressor housing. In particular, the annular stabilizer chamber serves to improve the stability and performance characteristics of the compressor stage, focusing especially on the operating range, performance curve slope, and addressing issues like surge and efficiency in turbomachinery such as turbochargers.

[0019] In the present disclosure, a “main flow channel in the intake region of a compressor wheel” can be understood as a pathway or passage through which the primary airflow enters the compressor wheel of a turbomachine, such as a turbocharger. In particular, the main flow channel is configured to direct the incoming air towards the blades of the compressor wheel for compression.

[0020] In the present disclosure, a “annular web” can be understood as a structural component or partition that separates or delineates different sections within a circular or ring-shaped space, e.g. the space at the intake region of the compressor wheel as described herein. In particular, the annular web is arranged and configured to demarcate and maintain separation between the main flow channel and the surrounding annular stabilizer chamber. In other words, the annular web physically defines the boundary between the main flow channel and the surrounding annular stabilizer chamber. Accordingly, the provision of the annular web ensures that the different flow characteristics can be achieved in the stabilizer chamber than in the main flow channel.

[0021] In the present disclosure, the terms "downstream" and "upstream" refer to the main flow in the main flow channel in the intake region of a compressor wheel. For better understanding, the main flow direction 1 is exemplarily indicated in Figs. 1 and 2. According to an example, the flow inlet 15 into the annular stabilizer chamber 12 can be arranged downstream of an inlet edge 24 of the compressor wheel 21, as shown in Figs. 1 and 2.The flow outlet 16 of the annular stabilizer chamber 12 is typically arranged upstream of the inlet edge 24 of the compressor wheel 21.

[0022] In the present disclosure, “a plurality of first flow guiding elements” can be understood as multiple specific elements or components which are configured to direct or control the flow of a fluid. Typically, the plurality of first flow guiding elements are arranged in a circular manner around the central axis.

[0023] For instance, according to embodiments, which can be combined with other embodiments described herein, the plurality of first flow guiding elements can include one or more recesses. The plurality of first flow guiding elements can, for example, be provided by an angular ring slit in which a plurality of separating walls can be provided. According to another example, the plurality of first flow guiding elements can be provided by a plurality of recesses, i.e. multiple indentations or multiple cavities. The plurality of recesses can be provided in the radial inner surface of the annular web. Alternatively, the plurality of recesses may be provided in a ring element 143 inserted into a reception 144 of the radial inner surface 142, as exemplarily shown in Fig. 2. In a configuration in which the plurality of first flow guiding elements 17 are implemented by a plurality of flow channels, as exemplarily described with reverence to Figs. 8 and 9, the flow channels may be machined, provided by or more insertion elements including the flow channels, or produced by 3D printing.

[0024] Typically, the plurality of first flow guiding elements 17 are circumferentially evenly distributed. However, the plurality of first flow guiding elements 17 may also be circumferentially unevenly distributed Accordingly, the plurality of second flow guiding elements 18, as described herein, can be circumferentially evenly or unevenly distributed. It is to be understood, that in a configuration in which the plurality of first flow guiding elements 17 are provided by a plurality of channels as exemplarily describedwith reference to Figs. 8 and 9, the plurality of channels may be circumferentially evenly or unevenly distributed.

[0025] According to embodiments, which can be combined with other embodiments described herein, two or more recesses, particularly at least 50%, of the plurality of recesses 17 have an identical recess volume. Additionally or alternatively, two or more recesses, particularly at least 50%, of the plurality of recesses 17 have an identical recess shape.

[0026] With exemplary reference to Figs. 5 and 8, according to embodiments, which can be combined with other embodiments described herein, the first flow guiding elements 17 have an aspect ratio L / H within the range 0.25 < L / H < 10, particularly 0.5 < L / H < 5. H is the radial extension of the first flow guiding element 17. L is the axial extension of the first flow guiding element 17.

[0027] According to embodiments, which can be combined with other embodiments described herein, one or more recesses, particularly at least 50% of the plurality of recesses, include a second flow guiding element 18, as exemplarily shown in Figs. 2 to 9. For instance, the second flow guiding element can be a vane 181 as s exemplarily shown in Figs. 5, 6 and 7. Accordingly, it is to be understood that the plurality of second flow guiding elements 18 is different from the plurality of first flow guiding elements 17. Typically, the plurality of second flow guiding elements 18 at least partially overlap with a flow entry portion 2 IE of the compressor wheel 21.

[0028] As exemplary shown in Figs. 5, 6 and 7, the angular orientation of the second flow guiding element 18 may change in the axial direction. In particular, as can be seen from Figs. 6 and 7, the angular orientation of the flow guiding element 18 may change from a clockwise inclination to a counter-clockwise inclination in direction of the main flow direction. In particular, the angular orientation of the flow guiding element 18 may change from an inclination against a pressure side ps of the compressor wheel bladesto an inclination in direction of the pressure side ps of the compressor wheel blades. The pressure side ps and the suction side ss of an exemplary compressor wheel blade 23 is shown in Fig. 7.

[0029] According to embodiments, which can be combined with other embodiments described herein, the second flow guiding element 18 is arranged in a downstream portion 172 of the plurality of recesses. In particular, a main portion of the second flow guiding element 18 is arranged in the downstream portion 172 of the plurality recesses. Typically, the second flow guiding element 18 extends in the axial direction over the inlet edge 24 of the compressor wheel blades 23, as exemplarily shown in Figs. 5 and 8.

[0030] According to embodiments, which can be combined with other embodiments described herein, the plurality of first flow guiding elements 17, particularly in combination with the second flow guiding elements 18, are configured to generate a co-swirl with the rotational direction of the compressor wheel and / or an axial flow against the main flow direction 1 to reduce a flow incidence and / or a relative Mach number at blade tips of the compressor wheel blade 23.

[0031] With exemplary reference to Fig.2, according to embodiments, which can be combined with other embodiments described herein, the plurality of recesses provide a recess inflow angle a and a recess outflow angle P with respect to an axial direction of the main flow channel 13. Typically, the recess inflow angle a is larger than or equal to the recess outflow angle p.

[0032] According to embodiments, which can be combined with other embodiments described herein, the plurality of recesses provide a total recess volume VRwhich is at least ten times smaller, particularly at least 15 times smaller than a volume VSc of the annular stabilizer chamber 12.

[0033] According to embodiments, which can be combined with other embodiments described herein, the stabilizer 10 further includes a plurality of third flow guiding elements 19 provided in the annular stabilizer chamber 12, as exemplarily shown in Fig. 2. The third flow guiding elements 19 are configured such that a flow with a counter-swirl is providable at the upstream flow outlet 16. In particular, the plurality of third flow guiding elements 19 are provided by struts extending from the radial outer surface 141 of the annular web to a radial inner wall 121 of the annular stabilizer chamber 12. Additionally or alternatively, the plurality of third flow guiding elements 19 can be provided by vanes extending into the annular stabilizer chamber 12 from the radial outer surface 141 of the annular web 14 or from the radial inner wall 121 of the annular stabilizer chamber 12.

[0034] With exemplary reference to Fig. 2, according to embodiments, which can be combined with other embodiments described herein, one or more inflow guiding elements 151 can be arranged in the flow inlet 15 of stabilizer 10. Additionally or alternatively, one or more outflow guiding elements 161 can be arranged in the flow outlet 16 of stabilizer 10.

[0035] According to a further aspect of the present disclosure, a compressor 20, in particular of a radial compressor or diagonal compressor, is provided. The compressor 20 includes a compressor wheel 21 and a stabilizer 10 according to any embodiments described herein.

[0036] According to embodiments, which can be combined with other embodiments described herein, the plurality of first flow guiding elements 17 at least partially overlap with a flow entry portion 2 IE of the compressor wheel 21, as exemplary shown in Figs 2, 5 and 8. The entry portion 21E of the compressor wheel 21 may be defined as the axial portion from the nose of the compressor wheel to the downstream flow inlet 15 into the annular stabilizer chamber 12.

[0037] With exemplary reference to Figs. 8 and 9, according to embodiments, which can be combined with other embodiments described herein, the plurality of first flow guiding elements 17 are provided by a plurality of channels 182. Typically, each of the plurality of channels 182 is connected to the main flow channel 13 via a downstream channel inlet 183 and an upstream channel outlet 184. In particular, the downstream channel inlet 183 can be arranged downstream from the inlet edge 24 of the compressor wheel 21 and upstream from the flow inlet 15 into the annular stabilizer chamber 12. The upstream channel outlet 184 is typically arranged upstream from the inlet edge 24 of the compressor wheel 21. The hashed areas in Figs. 8 and 9 indicate that the channels may not necessarily be provided within an axial plane, but can have any three-dimensional configuration.

[0038] In view of the embodiments described herein, it is to be understood compared to the state of the art, an improved stabilizer of a compressor, an improved compressor and an improved turbomachine, particularly an improved turbocharger, are provided. In particular, the stabilizer, the compressor, and the turbomachine described herein are improved in terms of the operating range and the performance curve slope.

[0039] Specifically, the stabilizer includes a combination of a recirculator to induce a counter-swirl at the impeller inlet and a casing treatment. The casing treatment includes a plurality of first flow guiding elements arranged and configured to act locally in the blade tip region near the leading edge, thereby alleviating blade tip loading. The casing treatment has the effect that the relative Mach number and the incidence angle deviation at the blade tip section can be reduced, both with and without co-swirl. Particularly, by implementing a casing treatment having flow guiding elements as described herein, direct leakage flows from the tips and associated losses are minimized. The compact axial extension and local effectiveness of the casing treatment can beneficially minimize mixing with the counter-swirl-affected, radially inner main flow. It is to be noted that synergic effects can be achieved by thecombination of the first flow guiding elements, the second flow guiding elements and the third flow guiding elements, particularly together with inflow guiding elements and / or outflow guiding elements, as described in the present disclosure, in order to reduce a flow incidence and / or a relative Mach number at blade tips of the compressor wheel blade. Consequently, embodiments of the present disclosure provide for an enhanced surge margin and efficiency.

[0040] While the foregoing is directed to embodiments, other and further embodiments may be devised without departing from the basic scope, and the scope is determined by the claims that follow.REFERENCE NUMBERSI main flow direction5 compressor housing10 stabilizerI I central axis / axis of rotation of the compressor wheel12 annular stabilizer chamber121 radial inner wall of the annular stabilizer chamber13 main flow channel14 annular web141 a radial outer surface of annular web142 radial inner surface of annular web143 ring element144 reception for ring element15 flow inlet of stabilizer151 inflow guiding element16 flow outlet of stabilizer161 outflow guiding element17 plurality of first flow guiding elements171 upstream portion of recess172 downstream portion of recess18 plurality of second flow guiding elements181 vane182 channel183 channel inlet184 channel outlet19 plurality of third flow guiding elements20 compressor21 compressor wheel2 IE flow entry portion of compressor wheel23 compressor wheel blade231 blade tip24 inlet edge r radial direction x axial direction a recess inflow angleP recess outflow angle

Claims

CLAIMS1. A compressor (20), in particular a radial compressor or diagonal compressor, comprising a compressor wheel (21) and a stabilizer (10), the stabilizer (10) comprising:- an annular stabilizer chamber (12), which surrounds a main flow channel (13) in the intake region of a compressor wheel (21) and is delimited with respect to the main flow channel by an annular web (14), wherein the annular web (14) has a radial outer surface (141) that provides a wall of the annular stabilizer chamber (12), and wherein the annular web (14) has a radial inner surface (142) that provides a wall of the main flow channel (13), wherein the annular stabilizer chamber (12) is connected to the main flow channel (13) via a downstream flow inlet (15) and an upstream flow outlet (16); and- a plurality of first flow guiding elements (17) circumferentially provided at the radial inner surface (142) of the annular web (14), wherein the plurality of first flow guiding elements (17) are provided closer to the downstream flow inlet (15) than to the upstream flow outlet (16), and wherein the plurality of first flow guiding elements (17) at least partially overlap with the compressor wheel (21) in the axial direction, and- a plurality of second flow guiding elements (18) different from the plurality of first flow guiding elements (17), wherein the plurality of second flow guiding elements (18) at least partially overlap with a flow entry portion (21E) of the compressor wheel (21).

2. The compressor (20) of claim 1, wherein the plurality of first flow guiding elements (17) comprise one or more recess, particularly wherein the plurality of first flow guiding elements (17) are provided by a plurality of recesses.

3. The compressor (20) of claim 2, wherein the plurality of recesses are provided in the radial inner surface (142) of the annular web (14), or wherein the plurality of recesses are provided in a ring element inserted into a reception (144) of the radial inner surface (142).

4. The compressor (20) of claim 2 or 3, wherein two or more recesses, particularly at least 50% of the recesses, have an identical recess volume and / or an identical recess shape.

5. The compressor (20) of any of claims 2 to 4, wherein the plurality of recesses provide a recess inflow angle a and a recess outflow angle P with respect to an axial direction of the main flow channel (13), wherein the recess inflow angle a is larger than or equal to the recess outflow angle p.

6. The compressor (20) of any of claims 2 to 5, wherein the plurality of recesses provide a total recess volume VRwhich is at least ten times smaller, particularly at least 15 times smaller than a volume VSc of the annular stabilizer chamber (12).

7. The compressor (20) of any of claims 1 to 6, wherein the plurality of first flow guiding elements (17), particularly in combination with the second flow guiding elements (18) of claim 7, are configured to generate a co-swirl with the rotational direction of the compressor wheel and / or an axial flow against the main flow direction (1) to reduce a flow incidence and / or a relative Mach number at blade tips of the compressor wheel blade (23).

8. The compressor (20) of any of claims 2 and 6, wherein the plurality of second flow guiding elements (18) are arranged in a downstream portion (172) of the plurality of recesses , particularly wherein the plurality of second flow guiding element (18) are vanes (181).

9. The compressor (20) of claim 1, wherein the plurality of first flow guiding elements (17) are provided by a plurality of channels (182), wherein each of the plurality of channels (182) is connected to the main flow channel (13) via a downstream channel inlet (183) and an upstream channel outlet (184)10. The compressor (20) of any of claims 1 to 9, wherein an aspect ratio L / H of the first flow guiding elements (17) is 0.25 < L / H < 10, particularly is 0.5 < L / H < 5, wherein H is the radial extension of the first flow guiding elements (17), and wherein the L is the axial extension of the first flow guiding elements (17).

11. The compressor (20) of any of claims 1 to 10, further comprising a plurality of third flow guiding elements (19) provided in the annular stabilizer chamber (12), wherein the third flow guiding elements (19) are configured such that a flow with a counter-swirl is providable at the upstream flow outlet (16), particularly wherein the plurality of third flow guiding elements (19) are provided by struts extending from the radial outer surface (141) of the annular web to a radial inner wall (121) of the annular stabilizer chamber (12), and / or particularly wherein the plurality of third flow guiding elements (19) are provided by vanes extending into the annular stabilizer chamber (12) from the radial outer surface (141) of the annular web (14) or from the radial inner wall (121) of the annular stabilizer chamber (12).

12. The stabilizer (10) of any of claims 1 to 11, further comprising one or more inflow guiding elements (151) arranged in the flow inlet (15) of stabilizer (10), and / or further comprising one or more outflow guiding elements (161) arranged in the flow outlet (16) of stabilizer (10).

13. A turbomachine, in particular a turbocharger, comprising a compressor according to any of claims 1 to 12.

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