Compressor over-stall steady-state flow field acquisition method

Abstract

The invention relates to the technical field of aircraft engine design, and particularly provides a method for acquiring an over-stall steady-state flow field of a gas compressor. The gas compressor comprises a rotor and a stator, and the stator is arranged at the downstream of the rotor; the compressor further comprises an auxiliary body, the auxiliary body is arranged on the downstream portion of the stator, the auxiliary body is in a disc shape, and the auxiliary body generates an auxiliary force field to provide aerodynamic damping at a low flow point. The auxiliary body is introduced to the downstream of the air compressor, so that the aerodynamic damping of the compression system can be improved, and the flow instability phenomenon is inhibited.

Description

Technical Field

[0001] This disclosure relates to the field of aircraft engine design technology, and in particular to a method for obtaining the steady-state flow field after compressor stall. Background Technology

[0002] The concept of compressor over-stall characteristics was proposed in the analysis of compressor stability problems to describe the compressor's behavior outside the stability boundary. Although the compressor's operating point is outside the stability boundary, its internal flow field exhibits a circumferentially propagating stall cluster. Therefore, the internal flow of the compressor is typically non-axisymmetric and unsteady when its operating point is outside the stability boundary. This non-axisymmetric, unsteady aerodynamic characteristic is decomposed into a circumferentially uniform stable part and a circumferentially non-uniform dynamic part, which are modeled separately. The compressor's over-stall characteristics are used to describe the former. In the model, it is artificially assumed that the compressor's over-stall characteristics are time-invariant and axisymmetric; therefore, it is also called the Axisymmetric Pressure Rise Characteristic.

[0003] The stability of a compressor is closely related to the spatial distribution of the load, and the critical load in a local region plays a decisive role in the initiation of flow instability. When performing steady-state numerical simulations on compressors with unknown characteristics, the axisymmetry of the compressor cannot be directly obtained. Summary of the Invention

[0004] This disclosure is made in view of the above-mentioned problems. This disclosure provides a method for obtaining the steady-state flow field after compressor stall.

[0005] According to one aspect of this disclosure, a method for obtaining the steady-state flow field after stall of a compressor is provided, comprising: the compressor including a rotor and a stator, the stator being disposed downstream of the rotor;

[0006] The compressor also includes an auxiliary body located downstream of the stator. The auxiliary body is disc-shaped and generates an auxiliary force field to provide aerodynamic damping at low flow points.

[0007] Furthermore, according to one aspect of the compressor over-stall steady-state flow field acquisition method of the present disclosure, the stator includes at least two rows of adjacent blades to reduce the root load of the blades.

[0008] Furthermore, according to one aspect of the compressor over-stall steady-state flow field acquisition method of this disclosure, the distance between the auxiliary body and the stator is 1.2 times the blade height of the second row of blades of the stator.

[0009] Furthermore, according to one aspect of the compressor over-stall steady-state flow field acquisition method of this disclosure, the dimensions of the auxiliary body are: the radius is the same as the blade height of the second row of blades of the stator, and the axial thickness is the same as the axial thickness of the stator.

[0010] Furthermore, according to one aspect of the compressor over-stall steady-state flow field acquisition method of this disclosure, an auxiliary force domain function varying with flow rate is constructed to simulate the aerodynamic damping of the compressor. The auxiliary force domain function is: F=k (M) 失速 -M) A; Where k is the characteristic slope, determined based on the compressor's near-bottom characteristic slope; M 失速 M represents the total flow rate of the compressor after stall; A is the damping coefficient, which is determined based on the aerodynamic damping of the compression system.

[0011] Furthermore, according to one aspect of the compressor over-stall steady-state flow field acquisition method of the present disclosure, when the rotor is at 65% of its maximum speed, the pressure ratio characteristic curve of the compressor after stall exhibits a positive slope.

[0012] Furthermore, according to the compressor over-stall steady-state flow field acquisition method of one aspect of this disclosure, when the rotor is at 65% of its maximum speed, the axial force at the blade tip of the rotor first reaches its peak value, indicating the existence of a local stall zone.

[0013] Furthermore, according to a method for obtaining the compressor over-stall steady-state flow field according to one aspect of this disclosure, when the rotor is at 65% of its maximum speed, the axial force of the stator blades located below 70% of their blade height reaches its peak value.

[0014] Furthermore, according to one aspect of the compressor over-stall steady-state flow field acquisition method of this disclosure, the compressor has a maximum speed of 22,000 rpm, a total pressure ratio of 1.6, and a maximum mass flow rate of 13.5 kg / s.

[0015] Furthermore, according to one aspect of the compressor over-stall steady-state flow field acquisition method of this disclosure, the rotor has 17 blades, a hub / tip ratio of 0.565, and a width-to-height ratio of 0.956. The number of blades in each of the two adjacent rows of the stator is 29.

[0016] The compressor over-stall steady-state flow field acquisition method according to embodiments of this disclosure develops a critical load acquisition strategy that is more convenient to apply in engineering practice. The studied compressor stage and downstream auxiliary force field together form a new compressor assembly, and the introduced auxiliary force field provides significant aerodynamic damping at low flow points. Therefore, although the compressor operates under negative damping conditions and cannot independently maintain the stability of the compression system, the new compressor assembly still provides positive damping for the compression system, which ensures that the system can maintain stable operation despite the inherent instability of the compressor.

[0017] It should be understood that both the foregoing general description and the following detailed description are exemplary and intended to provide further illustration of the claimed technology. Attached Figure Description

[0018] The above and other objects, features, and advantages of this disclosure will become more apparent from the more detailed description of the embodiments thereof in conjunction with the accompanying drawings. The drawings are provided to further illustrate the embodiments of this disclosure and form part of the specification. They are used together with the embodiments of this disclosure to explain the disclosure and do not constitute a limitation thereof. In the drawings, the same reference numerals generally represent the same components or steps.

[0019] Figure 1 This is a schematic diagram of the numerical solution domain of the local critical load acquisition strategy for a compressor according to an embodiment of the present disclosure; Figure 2 This is a schematic diagram of the computational grid of a compressor according to an embodiment of the present disclosure; Figure 3 This is a schematic diagram of the computational grid of the auxiliary body according to an embodiment of the present disclosure; Figure 4 This is a graph showing the total pressure ratio characteristic of a compressor according to an embodiment of the present disclosure at 65% speed. Figure 5 This is an efficiency curve of the compressor according to an embodiment of the present disclosure at 65% speed; Figure 6 A graph showing the total pressure at the blade outlet of a rotor according to an embodiment of this disclosure; Figure 7 A graph showing the axial force at the blade outlet of a rotor according to an embodiment of this disclosure; Figure 8 A graph showing the total pressure at the outlet of the first row of blades of the stator according to an embodiment of the present disclosure; Figure 9 This is a graph showing the axial force at the outlet of the first row of blades of the stator according to an embodiment of the present disclosure. Figure 10 This is a graph showing the total pressure at the outlet of the second row of blades of the stator according to an embodiment of the present disclosure; Figure 11This is a graph showing the axial force at the outlet of the second row of blades of the stator according to an embodiment of the present disclosure; Figure 12 This is a graph showing the variation of axial force in different regions of the rotor blades according to an embodiment of the present disclosure. Figure 13 This is a graph showing the variation of axial force in different regions of the stator blades according to an embodiment of the present disclosure.

[0020] Explanation of reference numerals in the attached figures: Compressor 100, rotor 101, stator 102, first row of blades 121, second row of blades 122, auxiliary body 103, shaft 104. Detailed Implementation

[0021] To make the objectives, technical solutions, and advantages of this disclosure more apparent, exemplary embodiments according to this disclosure will now be described in detail with reference to the accompanying drawings. Obviously, the described embodiments are merely some embodiments of this disclosure, and not all embodiments of this disclosure. It should be understood that this disclosure is not limited to the exemplary embodiments described herein.

[0022] The stability of a compressor is closely related to the spatial distribution of the load, and the critical load in a local region plays a decisive role in the initiation of flow instability. This embodiment selects the axial component of the blade force as a quantitative parameter of the local load. By comparing the flow field load distribution during the flow instability process with the local critical load value, the initiation location of compressor instability and its corresponding overall flow rate are determined. When performing steady-state numerical simulations on compressors with unknown characteristics, the axisymmetry of the compressor cannot be directly obtained. This embodiment introduces auxiliary aerodynamic components downstream of the compressor to increase the aerodynamic damping of the compression system, thereby suppressing flow instability.

[0023] The embodiments of this disclosure will now be described in detail with reference to the accompanying drawings.

[0024] like Figure 1 , Figure 2 , Figure 3 As shown, this disclosure provides a method for obtaining the compressor over-stall steady-state flow field, including: a compressor 100; The compressor 100 includes a rotor 101 and a stator 102, the stator 102 being located downstream of the rotor 101, and both the rotor 101 and the stator 102 being mounted on a shaft 104. The compressor 100 also includes an auxiliary body 103, which is located downstream of the stator 102 and also on the shaft 104. The auxiliary body 103 is disc-shaped and generates an auxiliary force field to provide aerodynamic damping at low flow points.

[0025] In some possible implementations, such as Figure 1 , Figure 2 As shown, the stator 102 includes at least two rows of adjacent blades to reduce the root load on the blades. (As...) Figure 2 As shown, the stator 102 includes a first row of blades 121 and a second row of blades 122.

[0026] In some possible implementations, such as Figure 1 As shown, the distance between the auxiliary body 103 and the stator 102 is 1.2 times the leaf height of the second row of blades 122 of the stator 102.

[0027] In some possible implementations, such as Figure 1 As shown, the dimensions of the auxiliary body 103 are: the radius is the same as the blade height of the second row of blades 122 of the stator 102, and the axial thickness is the same as the axial thickness of the stator 102. The overall dimensions of the auxiliary domain should be kept close to those of the stator domain; slight deviations in dimensions have no significant impact on this method.

[0028] Taking a single-stage transonic compressor as an example, the design parameters of this compressor are detailed in Table 1. Detailed parameters of the rotor and stator blades, as well as the absolute flow angle and consistency, are listed in Table 2. Given that the diffusion factor in the rotor hub region is close to 0.5 at the design point, a tandem stator design is adopted to reduce the stator blade root load. This design aims to improve the compressor's aerodynamic performance and stability by more effectively distributing the load distribution among the stator blades.

[0029]

[0030] As shown in Table 1, the compressor has a maximum speed of 22,000 rpm, a total pressure ratio of 1.6, and a maximum mass flow rate of 13.5 kg / s.

[0031] As shown in Table 1, the rotor has 17 blades, a hub / tip ratio of 0.565, and a width-to-height ratio of 0.956; the stator has 29 blades in each of its two adjacent rows.

[0032]

[0033] For transonic rotors, this embodiment employs a critical load acquisition strategy for calculation. The compressor stage mesh generation was performed using the commercial software NUMECA, such as... Figure 2 , Figure 3 As shown. The calculation process was performed using the commercial numerical simulation software CFX. At the inlet boundary, the total temperature and total pressure of the incoming flow were specified, while a static pressure outlet condition was applied at the outlet. When analyzing the compressor characteristics at stall velocity, an auxiliary force domain function varying with flow rate was constructed to simulate the compressor's aerodynamic damping. The auxiliary force domain function is: F = k (M) 失速 -M) A; where k is the characteristic slope, determined based on the compressor near-bottom characteristic slope; M 失速 The total flow rate after compressor stall is represented by M, where M represents the total flow rate of the compressor; A is the damping coefficient, determined based on the aerodynamic damping of the compression system. This method allows for detailed monitoring of the impact of the auxiliary force field on compressor stability and performance during throttling. The resulting data provides profound insights into the critical load distribution, helping to ensure accurate predictions of stall occurrence and its behavior.

[0034] like Figure 4 , Figure 5 The diagram shows the total pressure ratio characteristic curve and efficiency curve of the transonic compressor at 65% of its maximum speed. The calculation result without the auxiliary force domain is labeled IB, while the post-stall state result obtained after adding the auxiliary force domain is labeled MB. Point A represents the last stable operating point that can be calculated using conventional numerical methods without employing the critical load acquisition strategy. The critical load acquisition strategy enables the calculation of stable operating conditions at lower flow rates, characterized by a positive slope in the pressure ratio characteristic curve. This indicates that the compressor can still achieve stable operation even beyond the conventional stall boundary, fully demonstrating the effectiveness of the auxiliary force domain in extending the stable operating range of the compressor.

[0035] like Figures 6-11 As shown, to further investigate the impact of the auxiliary force domain on load distribution, operating point A was selected, and the radial distribution of total pressure and axial velocity at different blade interfaces before and after the addition of the auxiliary force domain was compared. The results show that, due to the sufficient distance between the auxiliary force domain and the study stage, it mainly provides aerodynamic damping for the system without significantly altering the radial load distribution of the compressor in the study stage. This finding underscores the reliability of the stable operating conditions obtained through the critical load acquisition strategy, confirming that the addition of the auxiliary force domain did not significantly change the load distribution of the compressor in the study stage.

[0036] like Figure 12 , Figure 13 As shown, based on the flow field calculated above, the rotor blades and stator blades are divided into 10 regions in the radial direction on an average basis, and the axial force in each region is integrated. Figure 12 and Figure 10This diagram illustrates the variation of integral axial forces at various radial positions of the rotor and stator blades during throttling. At 65% of maximum rotor speed, the rotor blade tips (region 9) first reach their peak value, indicating a local stall region. However, at this mass flow rate, the compressor does not lose stability. As throttling continues, the axial force at the rotor tips begins to weaken, making it increasingly difficult to balance the pressure and axial momentum differences between the upstream and downstream sections. For the stator, the axial force below 70% of the blade height reaches its peak at condition A flow rate. However, the axial force in the blade tip region still shows a slight increase with further throttling.

[0037] Based on the above processing and analysis, this embodiment obtained the peak axial force of the transonic compressor at different blade heights and determined the critical load in this embodiment. Subsequent work will use this critical load, combined with a volume force model, to determine the stability boundary of the compressor under different operating conditions. The method of this embodiment will help to more accurately predict the stable operating boundary of the compressor.

[0038] The above description, with reference to the accompanying drawings, illustrates a method for obtaining the compressor over-stall steady-state flow field according to an embodiment of the present disclosure, which has the following advantages: A more practical critical load acquisition strategy was developed. The studied compressor stage and downstream auxiliary force field together form a novel compressor assembly. The introduced auxiliary force field provides significant aerodynamic damping at low flow points. Therefore, although the compressor operates under negative damping conditions and cannot independently maintain the stability of the compression system, the novel compressor assembly still provides positive damping for the compression system. This ensures that the system can maintain stable operation despite the inherent instability of the compressor.

[0039] The basic principles of this disclosure have been described above with reference to specific embodiments. However, it should be noted that the advantages, benefits, and effects mentioned in this disclosure are merely examples and not limitations, and should not be considered as essential features of each embodiment of this disclosure. Furthermore, the specific details disclosed above are for illustrative and facilitative purposes only, and are not limitations. These details do not limit the scope of this disclosure to the necessity of employing the aforementioned specific details for implementation.

[0040] The block diagrams of devices, apparatuses, devices, and systems disclosed herein are merely illustrative examples and are not intended to require or imply that they must be connected, arranged, or configured in the manner shown in the block diagrams. As those skilled in the art will recognize, these devices, apparatuses, devices, and systems can be connected, arranged, and configured in any manner. Words such as “comprising,” “including,” “having,” etc., are open-ended terms meaning “including but not limited to,” and are used interchangeably with them. The terms “or” and “and” as used herein refer to the terms “and / or,” and are used interchangeably with them unless the context clearly indicates otherwise. The term “such as” as used herein refers to the phrase “such as but not limited to,” and is used interchangeably with it.

[0041] Additionally, as used herein, the "or" used in a list of items beginning with "at least one" indicates a separate list, such that a list of, for example, "at least one of A, B, or C" means A or B or C, or AB or AC or BC, or ABC (i.e., A and B and C). Furthermore, the word "exemplary" does not imply that the described example is preferred or better than other examples.

[0042] It should also be noted that in the systems and methods of this disclosure, the components or steps can be decomposed and / or recombined. These decompositions and / or recombinations should be considered as equivalent solutions to this disclosure.

[0043] Various changes, substitutions, and modifications can be made to the technology described herein without departing from the teachings defined by the appended claims. Furthermore, the scope of the claims of this disclosure is not limited to the specific aspects of the processes, machines, manufactures, events, means, methods, and actions described above. Currently existing or later-developed processes, machines, manufactures, events, means, methods, or actions that perform substantially the same function or achieve substantially the same result as the corresponding aspects described herein can be utilized. Therefore, the appended claims include such processes, machines, manufactures, events, means, methods, or actions within their scope.

[0044] The above description of the disclosed aspects is provided to enable any person skilled in the art to make or use this disclosure. Various modifications to these aspects will be readily apparent to those skilled in the art, and the general principles defined herein may be applied to other aspects without departing from the scope of this disclosure. Therefore, this disclosure is not intended to be limited to the aspects shown herein, but rather to be carried out within the widest scope consistent with the principles and novel features disclosed herein.

[0045] The above description has been given for purposes of illustration and description. Furthermore, this description is not intended to limit the embodiments of this disclosure to the forms disclosed herein. Although numerous exemplary aspects and embodiments have been discussed above, those skilled in the art will recognize certain variations, modifications, alterations, additions, and sub-combinations thereof.

Claims

1. A method for obtaining the steady-state flow field after compressor stall, characterized in that, include: air compressor; The compressor includes a rotor and a stator, the stator being disposed downstream of the rotor; The compressor also includes an auxiliary body located downstream of the stator. The auxiliary body is disc-shaped and generates an auxiliary force field to provide aerodynamic damping at low flow points.

2. The method for obtaining the compressor over-stall steady-state flow field according to claim 1, characterized in that, The stator comprises at least two rows of adjacent blades to reduce the root load on the blades.

3. The method for obtaining the compressor over-stall steady-state flow field according to claim 2, characterized in that, The distance between the auxiliary body and the stator is 1.2 times the leaf height of the second row of blades of the stator.

4. The method for obtaining the compressor over-stall steady-state flow field according to claim 1, characterized in that, The dimensions of the auxiliary body are: the radius is the same as the blade height of the second row of blades of the stator, and the axial thickness is the same as the axial thickness of the stator.

5. The method for obtaining the compressor over-stall steady-state flow field according to claim 1, characterized in that, An auxiliary force domain function varying with flow rate is constructed to simulate the aerodynamic damping of the compressor. The auxiliary force domain function is: F=k (M) 失速 -M) A; Where k is the characteristic slope, determined based on the compressor's near-bottom characteristic slope; M 失速 M represents the total flow rate after the compressor stalls; A is the damping coefficient, which is determined based on the aerodynamic damping of the compression system.

6. The method for obtaining the compressor over-stall steady-state flow field according to claim 1, characterized in that, When the rotor is at 65% of its maximum speed, the pressure ratio characteristic curve of the compressor after stall exhibits a positive slope.

7. The method for obtaining the compressor over-stall steady-state flow field according to claim 6, characterized in that, When the rotor is at 65% of its maximum speed, the axial force at the blade tip of the rotor first reaches its peak, indicating the existence of a local stall zone.

8. The method for obtaining the compressor over-stall steady-state flow field according to claim 6, characterized in that, When the rotor is at 65% of its maximum speed, the axial force of the stator blades located below 70% of their blade height reaches its peak.

9. The method for obtaining the compressor over-stall steady-state flow field according to claim 1, characterized in that, The compressor has a maximum speed of 22,000 rpm, a total pressure ratio of 1.6, and a maximum mass flow rate of 13.5 kg / s.

10. The method for obtaining the compressor over-stall steady-state flow field according to claim 1, characterized in that, The rotor has 17 blades, a hub / tip ratio of 0.565, and a width-to-height ratio of 0.

956. The number of blades in each of the two adjacent rows of the stator is 29.

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