centrifugal compressor

Abstract

A centrifugal compressor is provided. The system includes an overall inlet passage 1, adjustable inlet guide vanes 2, an impeller 3, a variable diffuser 4, a volute casing 5, and an overall outlet passage 6. A tip gap 10 is provided between the impeller and an impeller cover, and a disk cavity is formed between the side of the impeller far from the adjustable inlet guide vanes and the impeller cover. Measurement point densification areas are provided within the impeller, tip gap, and disk cavity, and flow field measurement points are provided at intervals along the fluid flow direction within the impeller, tip gap, and disk cavity, with the spacing between the flow field measurement points located within the measurement point densification area being smaller than the spacing between the flow field measurement points located outside the measurement point densification area. The loss mechanism of the internal leakage flow field between the impeller and the blade tip gap and the external leakage flow field of the disc cavity is studied in detail, and the coupling mechanism of the main flow and leakage flow in the impeller is fully taken into consideration, which improves the granularity, authenticity and reliability of the measurement results and enables the collection of more and more accurate fluid data in the high-density measurement point area.

Description

[Technical Field]

[0001] The present invention relates to the technical field of compressors, and more particularly to centrifugal compressors. [Background technology]

[0002] A centrifugal compressor is a core component of a compressed air energy storage system. The impeller is the core rotating component of the centrifugal compressor. Its rotation increases the pressure of the fluid and changes the direction of the fluid flow, which causes the fluid to be pressurized and accelerated before flowing to the diffuser. Therefore, the performance of the impeller and the degree of internal flow loss have a significant impact on the overall efficiency, pressure ratio, and variable operating condition range of the centrifugal compressor.

[0003] However, in the structure of a conventional centrifugal compressor, it is basically only possible to place measurement points at the inlet and outlet of the entire machine, which makes it difficult for researchers to fully study and analyze the internal flow mechanism of the impeller tip clearance and disc cavity, making it difficult for researchers to further optimize and improve the performance of the impeller. Summary of the Invention [Means for solving the problem]

[0004] In view of the above problems, the present invention provides a centrifugal compressor, including a complete inlet passage, adjustable inlet guide vanes, an impeller, a variable diffuser, a volute casing, and a complete outlet passage, A blade tip gap is provided between the impeller and the impeller cover, a disc cavity is formed between the impeller cover and a side of the impeller remote from the adjustable inlet guide vanes; Measurement point densification areas are provided in the impeller, the blade tip gap, and the disk cavity; Flow field measurement points are provided at intervals along a fluid flow direction within the impeller, the blade tip gap, and the disk cavity; The interval between the flow field measurement points located within the measurement point densification region is smaller than the interval between the flow field measurement points located outside the measurement point densification region.

[0005] In some specific embodiments, the spacing between adjacent flow field measurement points in a region closer to the tongue of the volute casing is smaller than the spacing between adjacent flow field measurement points in a region farther from the tongue of the volute casing.

[0006] In some specific embodiments, the adjustable inlet guide vanes are located within the entire inlet passage; the impeller is located downstream of the adjustable inlet guide vanes; the variable diffuser is located downstream of the impeller; The volute casing is provided downstream of the impeller, the outlet passage is connected to the outlet of the volute casing; The leakage flow inlet of the disk cavity communicates with the main flow outlet of the impeller.

[0007] In some specific embodiments, the impeller is rotatably mounted within the impeller cover, thereby providing the tip clearance between the circumferential direction of the impeller and an inner wall of the impeller cover; The flow field measurement points are: a plurality of first measurement points, the first measurement points being spaced apart along a circumferential direction of the tip gap and a fluid flow direction, and used to detect and acquire flow parameters and environmental parameters of the fluid within the tip gap; The intervals between the first measurement points located within the measurement point densification region are smaller than the intervals between the first measurement points located outside the measurement point densification region.

[0008] In some specific embodiments, the flow field measurement points are: a plurality of second measurement points located on the same plane, the second measurement points being spaced apart along a circumferential direction of the disk cavity and a fluid flow direction, and used to detect and acquire flow parameters and environmental parameters of the fluid within the disk cavity; The intervals between the second measurement points located within the measurement point densification region are smaller than the intervals between the second measurement points located outside the measurement point densification region.

[0009] In some specific embodiments, the disk cavity is an annular gap between the impeller disk and the housing wall, with its outer boundary surface at a large radius connected to the dynamic / static gap and its inner boundary surface at a small radius connected to the seal structure.

[0010] In some specific embodiments, the measurement point densification regions are localized regions where flow field characteristics within the impeller, the tip gap, and the disk cavity exhibit at least one of distortions, transitions, and singularities.

[0011] In some specific embodiments, a detection sensor is also provided at each of the plurality of first measurement points.

[0012] In some specific embodiments, a detection sensor is also provided at each of the plurality of second measurement points.

[0013] In some particular embodiments, the impeller is a semi-open structure.

[0014] Compared with the prior art, the centrifugal compressor of the present invention has at least the following advantages: By providing flow field measurement points at intervals along the fluid flow direction within the impeller, tip gap, and disk cavity, measurements of the flow passing through the internal leakage flow field of the impeller and tip gap and the external leakage flow field of the disk cavity can be performed, obtaining fluid flow parameters and environmental parameters at each flow field measurement point, deeply studying the loss mechanisms of the internal leakage flow field of the impeller and tip gap and the external leakage flow field of the disk cavity, and fully considering the coupling mechanism between the main flow and leakage flow within the impeller, thereby improving the granularity, authenticity, and reliability of the measurement results. Furthermore, the spacing between flow field measurement points within the measurement point densification region is smaller than the spacing between flow field measurement points outside the measurement point densification region, allowing for more and more accurate collection of fluid data within the measurement point densification region.

[0015] Additional features and advantages of the invention will be set forth in the description that follows, and in part these advantages will be obvious from the description or may be learned by the practice of the invention. The objectives and other advantages of the invention will be realized and obtained through the structure particularly pointed out in the description and drawings. [Brief explanation of the drawings]

[0016] In order to more clearly describe the embodiments of the present invention or the technical solutions in the prior art, the drawings that need to be used in the description of the embodiments or the prior art are briefly described below. Obviously, the drawings in the following description are some embodiments of the present invention. Those skilled in the art can obtain other drawings based on these drawings without any creative efforts.

[0017] [Figure 1] FIG. 1 is a schematic diagram showing the overall structure of a centrifugal compressor according to an embodiment of the present invention. [Figure 2] FIG. 2 shows a schematic diagram of the arrangement of the first and second measurement points in an embodiment of the present invention. [Figure 3]FIG. 3 shows a flowchart of the main steps of the method for analyzing impeller leakage flow in a centrifugal compressor according to an embodiment of the present invention. [Figure 4] FIG. 4 is a flowchart showing some steps of a method for analyzing impeller leakage flow in a centrifugal compressor according to an embodiment of the present invention. [Figure 5] FIG. 5 shows a partial simulation model of the adjustable inlet guide vanes in an embodiment of the present invention. [Figure 6] FIG. 6 shows a partial simulation model of an impeller in an embodiment of the present invention. [Figure 7] FIG. 7 shows a partial simulation model of the disc cavity of the impeller in the embodiment of the present invention. [Figure 8] FIG. 8 shows a partial simulation model of a variable diffuser according to an embodiment of the present invention. [Figure 9] FIG. 9 shows a simulation model of the volute casing in the embodiment of the present invention. [Figure 10] FIG. 10 shows a schematic diagram of a first part of the simulation of an impeller in an embodiment of the present invention. [Figure 11] FIG. 11 shows a schematic diagram of a second part of the impeller according to an embodiment of the present invention. [Figure 12] FIG. 12 shows a schematic diagram of a third part of the impeller according to the embodiment of the present invention. [Figure 13] FIG. 13 shows a schematic diagram of a fourth part of the impeller according to the embodiment of the present invention. [Figure 14] FIG. 14 shows a schematic diagram of a first partial simulation of the disk cavity of the impeller in an embodiment of the present invention. [Figure 15] FIG. 15 shows a schematic diagram of a second partial simulation of the disk cavity of the impeller in the embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0018] In order to make the objectives, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, but not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative efforts fall within the scope of protection of the present invention.

[0019] 1 and 2, an embodiment of the present invention provides a centrifugal compressor including an overall inlet passage 1, adjustable inlet guide vanes 2, an impeller 3, a variable diffuser 4, a volute casing 5, and an overall outlet passage 6. A tip gap 10 is provided between the impeller 3 and an impeller cover. A disk cavity 20 is formed between the impeller 3 on the side remote from the adjustable inlet guide vanes 2 and the impeller cover. Measurement point densification regions are provided in the impeller 3, the tip gap 10, and the disk cavity 20. Flow field measurement points are spaced apart in the impeller 3, the tip gap 10, and the disk cavity 20 along the fluid flow direction, and the intervals between the flow field measurement points located within the measurement point densification region are smaller than the intervals between the flow field measurement points located outside the measurement point densification region.

[0020] Flow field measurement points are spaced apart along the fluid flow direction within the impeller 3, the tip gap 10, and the disk cavity 20. This allows measurements of the flow passing through the internal leakage flow field of the impeller 3 and the tip gap 10 and the external leakage flow field of the disk cavity 20 to obtain fluid flow parameters and environmental parameters at each flow field measurement point. This allows for in-depth research into the loss mechanisms of the internal leakage flow field of the impeller 3 and the tip gap 10 and the external leakage flow field of the disk cavity 20, and fully considers the coupling mechanism between the mainstream and leakage flow within the impeller 3, thereby improving the granularity, authenticity, and reliability of the measurement results. Furthermore, by making the spacing between flow field measurement points within the measurement point densification region smaller than the spacing between flow field measurement points outside the measurement point densification region, more fluid data can be collected within the measurement point densification region with greater accuracy.

[0021] In some specific embodiments, as shown in Figure 1, adjustable inlet guide vanes 2 are provided in the entire machine inlet passage 1. An impeller 3 is provided downstream of the adjustable guide vanes 2. A variable diffuser 4 is provided downstream of the impeller 3. A volute casing 5 is provided downstream of the impeller 3. An outlet passage is connected to the outlet of the volute casing 5. The leakage flow inlet of the disk cavity 20 is connected to the mainstream outlet of the impeller 3.

[0022] In some specific embodiments, as shown in Fig. 2, the impeller 3 is rotatably mounted inside the impeller cover, thereby forming a tip gap 10 between the circumferential direction of the impeller 3 and the inner wall of the impeller cover. The flow field measurement points include a plurality of first measurement points 100, which are spaced apart along the circumferential direction of the tip gap 10 and the fluid flow direction, and are used to detect and acquire flow parameters and environmental parameters of the fluid within the tip gap 10. The spacing between the plurality of first measurement points 100 located within the measurement point densification region is smaller than the spacing between the plurality of first measurement points 100 located outside the measurement point densification region.

[0023] Specifically, as the impeller 3 rotates, the fluid flows through the impeller 3 and into the variable diffuser 4. The flow parameters and environmental parameters of the fluid in the tip gap 10 can be detected and acquired via the multiple first measurement points 100. Furthermore, because the spacing between the multiple first measurement points 100 within the high-density measurement area is smaller than the spacing between the multiple first measurement points 100 outside the high-density measurement area, more fluid data can be acquired and captured via the denser first measurement points 100 within the high-density measurement area. This facilitates analysis of the fluid performance in the tip gap 10 and the leakage mechanism of the impeller 3.

[0024] Furthermore, eight first measurement points 100 are provided spaced apart along the fluid flow direction, but this is not limited to this, and the number of first measurement points 100 can be designed as needed.

[0025] In some specific embodiments, as shown in Fig. 2, the flow field measurement points further include a plurality of second measurement points 200 located on the same plane, the second measurement points 200 being spaced apart along the circumferential direction of the disk cavity 20 and the fluid flow direction, for detecting and acquiring flow parameters and environmental parameters of the fluid within the disk cavity 20. The spacing between the second measurement points 200 located within the measurement point densification region is smaller than the spacing between the second measurement points 200 located outside the measurement point densification region.

[0026] The multiple second measurement points 200 are spaced apart along the circumferential direction of the disk cavity 20 and the fluid flow direction, and the spacing between the second measurement points 200 located within the measurement point densification area is smaller than the spacing between the second measurement points 200 located outside the measurement point densification area. Therefore, more fluid data can be obtained and captured through the denser second measurement points 200 located within the measurement point densification area, and the performance of the fluid in the disk cavity 20 can be analyzed to further analyze the leakage mechanism of the impeller 3.

[0027] Furthermore, the number of second measurement points 200 can be set as needed, but is not particularly limited.

[0028] The flow field measurement points, including the first measurement point 100 and the second measurement point 200, are provided inside the impeller 3. Specifically, the flow field measurement points may be disposed on the impeller 3, or may be disposed in the gaps between the blades of the impeller 3 in a plasma-like manner, but are not particularly limited thereto.

[0029] Furthermore, the first measurement point 100 and the second measurement point 200 are each provided with a detection sensor, which can detect the flowing fluid. The detection sensor includes at least one of a contact sensor and a non-contact sensor. The contact sensor may be at least one of a piezoresistive pressure sensor, a strain gauge pressure gauge, a thermocouple, a thermistor, a turbine flowmeter, an electromagnetic flowmeter, a differential pressure flowmeter, a target flowmeter, an accelerometer, a strain gauge, a conductivity sensor, a capacitance sensor, a rotational viscometer, a capillary viscometer, a multi-parameter composite sensor, a du Nouy method sensor, a plate method sensor, a contact microphone, a capacitance hygrometer, a stylus contour measuring instrument, and a displacement sensor. The non-contact sensor may be at least one of a piezoelectric pressure sensor, a capacitive pressure sensor, an infrared thermometer, an ultrasonic flow meter, a laser Doppler velocimeter (LDV), a non-contact electromagnetic flow meter, an ultrasonic flow meter, a laser vibrometer, a near-infrared spectrum sensor, a microwave sensor, a microwave / radio frequency sensor, a non-contact flow meter + viscosity sensor, a laser surface roughness sensor, a laser microphone, an infrared humidity sensor, a microwave humidity sensor, a laser interferometer, a white light interferometer, an ultrasonic thickness gauge, and an optical 3D scanner.

[0030] In some specific embodiments, the measurement point densification regions are localized regions where the flow field characteristics within the impeller 3, tip gap 10 and disk cavity 20 are distorted and exhibit at least one of transitions and singularities.

[0031] According to the above centrifugal compressor, as shown in FIG. 3, a leakage flow analysis method for the impeller 3 of the centrifugal compressor is specifically proposed, which includes the following steps:

[0032] A simulation model of the entire circumferential passage of the centrifugal compressor is constructed.

[0033] Based on the complete all-passage simulation model of the centrifugal compressor, preset fluid parameters, and preset boundary conditions, a simulation of all operating conditions of the entire pass-through region is performed.

[0034] Based on the numerical results of the simulation of all operating conditions, the external performance and internal flow characteristics of the entire centrifugal compressor are obtained, and the measurement point densification areas set up for measuring the flow field in the impeller 3, the blade tip gap 10, and the disk cavity 20 are analyzed, selected, and determined. Among them, the focus is on detecting and analyzing the internal leakage flow in the blade tip gap 10 and the external leakage flow in the disk cavity 20.

[0035] Flow field measurement points are provided at intervals within the impeller 3, the blade tip gap 10, and the disk cavity 20 along the fluid flow direction, and the intervals between flow field measurement points located within the measurement point densification region are made smaller than the intervals between flow field measurement points located outside the measurement point densification region.

[0036] Based on the measurement system for the entire machine and internal flow field of the centrifugal compressor, measurements are carried out on the flow passing through the internal leakage flow field of the impeller 3 and the blade tip gap 10, and the external leakage flow field of the disk cavity 20, and the flow parameters and environmental parameters of the fluid at each flow field measurement point in the impeller 3, the blade tip gap 10, and the disk cavity 20 are obtained, and the numerical results of the simulation are compared and verified with the measurement results.

[0037] In addition, when performing a simulation of all operating conditions of the entire passing flow area of ​​the entire circumferential passage simulation model of the entire aircraft and performing measurements of the passing flows for the impeller 3, the internal leakage flow field of the blade tip gap 10, and the external leakage flow field of the disk cavity 20, it is necessary to take into account the effect of the circumferential asymmetry caused by the tongue of the volute casing 5 (the spacing between adjacent flow field measurement points in the area close to the tongue of the volute casing is smaller than the spacing between adjacent flow field measurement points in the area far from the tongue of the volute casing).

[0038] The above-described leakage flow analysis method for the impeller 3 of a centrifugal compressor can be used to perform simulations of the entire pass-through region under all operating conditions using the constructed full-circumferential passage simulation model of the entire centrifugal compressor. Based on the numerical results of the simulation, the external performance and internal flow characteristics of the entire centrifugal compressor can be obtained, and high-density measurement points for measuring the flow field within the impeller 3, the tip gap 10, and the disk cavity 20 can be analyzed and selected. During the measurement experiment, flow field measurement points are spaced along the fluid flow direction in the high-density measurement points in the high-density measurement points in the impeller 3, the tip gap 10, and the disk cavity 20. The spacing between flow field measurement points within the high-density measurement points is made smaller than the spacing between flow field measurement points outside the high-density measurement points. In other words, by increasing the density of flow field measurement points within the high-density measurement points, more fluid data can be collected within the high-density measurement points, with greater accuracy. Finally, measurements are carried out on the flow passing through the impeller 3, the internal leakage flow field of the blade tip gap 10, and the external leakage flow field of the disk cavity 20, and the flow parameters and environmental parameters of the fluid at each flow field measurement point are obtained, and the measurement results are used to compare and verify the numerical results of the simulation.

[0039] The above method combines simulation and experimental measurement, and in conjunction with theoretical analysis, carries out overall performance evaluation and local steady-state analysis of the centrifugal compressor, studies in detail the loss mechanisms of the impeller 3, the internal leakage flow field of the blade tip gap 10, and the external leakage flow field of the disk cavity 20, and fully considers the coupling mechanism of the main flow and leakage flow in the impeller 3, thereby improving the granularity, authenticity, and reliability of the measurement results.

[0040] Specifically, the impeller 3 is the central rotating component of a centrifugal compressor, accelerating, pressurizing, and heating the gas by performing work on the fluid. As a result, due to the influence of centrifugal and Coriolis forces generated by the rotation, a more complex and robust three-dimensional flow structure is formed inside the impeller 3 than in stationary components. On the rotation surface of the impeller 3, there are axial vortices in the opposite direction to the rotation direction of the impeller 3, and radial flows along the large radius direction. Furthermore, at the blade outlet of the impeller 3, there is a jet-wake flow field structure with uneven height, which can directly affect the aerodynamic performance of stationary components located downstream.

[0041] The external structure of the impeller 3 is classified into four types: closed type, semi-open type, mixed flow type, and double-sided intake type. According to the blade outlet angle of the impeller 3, it is classified into three types: swept type, radial type, and forward curved type. The blade structure of the impeller 3 is classified into tandem type and split type.

[0042] Loss analysis is divided into internal loss analysis and external loss analysis. Internal loss analysis includes leading edge shock loss, inlet diffusion loss, skin friction loss, blade loading loss, tip clearance loss or undercurrent loss, flow path blockage loss, suction surface shock wave loss, wake mixing loss, transonic or supersonic shock wave loss. External loss analysis includes disk drag loss, disk leakage loss, and reverse pressure reflux loss.

[0043] The leakage flow in the tip clearance 10 caused by the inherent clearance of the semi-open impeller 3 exhibits obvious unsteady fluctuation phenomena, which have a significant impact on the flow field distribution of the impeller 3 and the aerodynamic performance of the entire aircraft. Among them, the trajectory of the tip leakage vortex is often used to predict the stall onset point of a centrifugal compressor.

[0044] By analyzing the flow characteristics of the tip clearance 10 under the flow rate and rotation speed, the angle of the adjustable inlet guide vane 2 and the variable diffuser 4, and the influence of the tip leakage vortex on the internal flow field of the impeller 3, it is possible to effectively control and improve the flow characteristics of the tip clearance 10, reduce the flow field loss in the tip clearance 10, and prevent potential instability, which provides an important reference for optimizing the gap ratio design of the impeller 3.

[0045] The disk cavity 20 of the impeller 3 is a through-flow section that is often overlooked and simplified in centrifugal compressors. However, in reality, it has a significant impact on the local flow field details, pressure ratio, efficiency, torque, axial power, and axial thrust of a centrifugal compressor. This study focuses primarily on the internal flow structure and heat transfer characteristics of the disk cavity 20. From a geometric perspective, the disk cavity 20 is an annular gap between the disk of the impeller 3 and the housing wall. The outer boundary surface at the large radius is connected to the dynamic and static gaps, and the inner boundary surface at the small radius is connected to the seal structure. From a flow characteristic perspective, the airflow entering the disk cavity 20 from the trailing edge of the impeller 3 has a unique flow field structure and flow characteristics that are different from those of the mainstream. Its interior exhibits fundamental characteristics of temperature rise and pressure loss, resulting in friction loss and leakage flow loss of the impeller. By measuring the fluid flow parameters and environmental parameters at different radii of the stationary wall of the disk cavity 20 in detail, the changes in the flow parameter distribution within the disk cavity 20 under different mainstream flow rates and the impact of the disk cavity 20 on the performance of the centrifugal compressor can be analyzed, and the flow field change law and cavity coupling characteristics within the disk cavity 20 under the rotation speed of the upstream impeller 3 and the angle of the downstream variable diffuser 4 can be studied, which is very important for understanding the unique flow field structure within the disk cavity 20, leading to a better lightweight design of the impeller 3, and reducing disk friction loss and leakage flow loss. The centrifugal compressor has a semi-open impeller 3.

[0046] In some embodiments, as shown in FIG. 4, constructing a full passage simulation model of the entire centrifugal compressor includes the following steps:

[0047] A simulation model of the entire entrance aisle 1 is constructed.

[0048] An all-round passage simulation model of the adjustable inlet guide vane 2 is constructed, and the all-round passage simulation model of the adjustable inlet guide vane 2 is placed inside the all-round passage simulation model of the all-machine inlet passage 1.

[0049] A full-circle passage simulation model of the impeller 3 is constructed, and the full-circle passage simulation model of the impeller 3 is arranged downstream of the full-circle passage simulation model of the adjustable inlet guide vane 2.

[0050] A full-circumferential passage simulation model of the variable diffuser 4 is constructed, and the full-circumferential passage simulation model of the variable diffuser 4 is disposed downstream of the full-circumferential passage simulation model of the impeller 3.

[0051] Taking into account the influence of the circumferential asymmetry caused by the tongue, a full-circumferential passage simulation model of the volute casing 5 is constructed, and the full-circumferential passage simulation model of the volute casing 5 is installed downstream of the full-circumferential passage simulation model of the variable diffuser 4.

[0052] An all-around passage simulation model of the all-machine outlet passage 6 is constructed, and the all-around passage simulation model of the outlet passage and the all-around passage simulation model of the volute casing 5 are connected.

[0053] A full-circumferential passage simulation model of the disk cavity 20 of the impeller 3 is constructed, and taking into account the influence of the leakage flow of the disk cavity 20 of the impeller 3, the leakage flow inlet of the full-circumferential passage simulation model of the disk cavity 20 is connected to the main flow outlet of the full-circumferential passage simulation model of the impeller 3.

[0054] Specifically, during the actual operation of the centrifugal compressor, a portion of the main flow will leak from the disk cavity 20 of the impeller 3. Therefore, in the simulation stage, the influence of the leakage flow from the disk cavity 20 of the impeller 3 is taken into consideration, and a full-circle passage simulation model of the entire inlet passage 1, a full-circle passage simulation model of the adjustable inlet guide vane 2, a full-circle passage simulation model of the impeller 3, a full-circle passage simulation model of the disk cavity 20 of the impeller 3, a full-circle passage simulation model of the variable diffuser 4, a full-circle passage simulation model of the volute casing 5, and a full-circle passage simulation model of the entire outlet passage 6 are established, that is, a full-circle passage simulation model of the entire centrifugal compressor is established, and the simulation is carried out based on the full-circle passage simulation model of the entire centrifugal compressor, which improves the accuracy and reliability of the simulation results.

[0055] In some embodiments, the step of performing a simulation of all operating conditions of the entire pass-through region based on the entire pass-through simulation model of the centrifugal compressor, the preset fluid parameters, and the preset boundary conditions includes: A calculation model of the entire throughflow basin of the centrifugal compressor combined with the disk cavity 20 is constructed, and simulations of all operating conditions with different main flow rate and / or different impeller 3 rotation speed and / or different adjustable inlet guide vane 2 angle and / or different variable diffuser 4 angle are performed.

[0056] By constructing a full-circumferential flow basin calculation model of the entire centrifugal compressor coupled with the disk cavity 20, and performing simulations under all operating conditions with different main flow rates and / or different impeller 3 rotational speeds and / or different adjustable inlet guide vane 2 angles and / or different variable diffuser 4 angles, simulation data under different operating conditions of the entire centrifugal compressor coupled with the disk cavity 20 can be obtained, and the comprehensiveness of the simulation data can be improved.

[0057] In some embodiments, the step of constructing a full-circumferential passage simulation model of the disk cavity 20 of the impeller 3 includes the steps of: The disk cavity 20 is divided into a periodic, fully orthogonal hexahedral structure mesh using mesh preprocessing software, and the mesh nodes of the leakage flow inlet of the disk cavity 20's full-circumferential passage simulation model are matched with the mesh nodes of the mainstream outlet of the impeller 3's full-circumferential passage simulation model. The leakage flow outlet of the disk cavity's full-circumferential passage simulation model is closed, and the meshes of the communication surface between the leakage flow inlet and the mainstream outlet, the moving and stationary walls of the disk cavity 20, and the seal structure of the leakage flow outlet are all densified. The interior and moving walls of the disk cavity 20 are set as rotating regions, and the stationary walls of the disk cavity 20 are set as stationary regions. A mixing plane is selected as the mesh calculation method for the communication surface between the leakage flow inlet and the mainstream outlet.

[0058] According to the above method, the constructed full-circumferential passage simulation model of the disk cavity 20 is more compatible with the full-circumferential passage simulation model of the impeller 3, and the leakage flow inlet / outlet, moving wall surface and stationary wall surface of the disk cavity 20 of the full-circumferential passage simulation model are processed accordingly, so that the constructed full-circumferential passage simulation model of the disk cavity 20 is more suitable for practical use.

[0059] FIG. 7 shows a partial full-circumferential passage simulation model of the disc cavity 20 of the impeller 3, and all the dark areas in the figure are mesh-densified areas of the disc cavity 20.

[0060] In some embodiments, the step of constructing a full-circumferential passage simulation model of the volute casing 5 includes: Using mesh pre-processing software, tetrahedral unstructured mesh division is performed on the solid wall and boundary layer of the volute casing 5, the boundary layer mesh is densified, and the tongue mesh is partially densified.

[0061] By using the above method, a simulation model of the entire circumferential passage of the volute casing 5 is constructed, and the mesh at a specific position of the volute casing 5 is made denser to improve the accuracy of the simulation.

[0062] As shown in FIG. 9, a simulation model diagram of the entire circumferential passage of the volute casing 5 is shown, and the dark areas in FIG. 9 are all mesh densification areas of the volute casing 5.

[0063] It should be noted that the construction of the full-circle passage simulation model of the adjustable inlet guide vane 2, impeller 3 and variable diffuser 4 of the centrifugal compressor can be done with reference to the method of the disk cavity 20 and the volute casing 5.

[0064] Figure 5 shows a partial full-circle passage simulation model of the adjustable inlet guide vane 2. Figure 6 shows a partial full-circle passage simulation model of the impeller 36. Figure 8 shows a partial full-circle passage simulation model of the variable diffuser 4. The dark areas in the above figure are all mesh densification areas. Specifically, the adjustable inlet guide vane 2, impeller 3, and variable diffuser 4 were all divided into a full hexahedral structure mesh using mesh pre-processing software. A body-fit H-type mesh was used on the wall surface, and densification was performed on the boundary between the leading and trailing edges of the blade and the wall surface and the blade tip gap 10 using an O-type mesh. When constructing a full-circle passage simulation model of a centrifugal compressor, the same mesh topology structure and coarse mesh densification configuration were combined to verify the independence of the mesh number for the full-circle passage mesh in the throughflow region of the entire machine, constructed 1:1 based on the original structural parameters of the object of study.

[0065] In some embodiments, the steps of obtaining the external performance and internal flow characteristics of the entire centrifugal compressor based on the numerical results of the simulation of all operating conditions, and analyzing, selecting, and determining the measurement point densification areas provided for flow field measurement in the impeller 3, the tip gap 10, and the disk cavity 20 include: Based on the numerical results of the simulation, the loss mechanism of the centrifugal compressor as a whole and the internal flow characteristics of each component under different operating conditions are analyzed, and the external overall performance and internal flow characteristics of the centrifugal compressor are obtained.

[0066] Then, local area positions where the flow field characteristics of the impeller 3, the blade tip gap 10 and the disk cavity 20 are distorted and show at least one of a transition and a singularity are intentionally captured as measurement point densification areas.

[0067] Through the numerical results of the simulation, the loss mechanism of the entire centrifugal compressor and the internal flow characteristics of each part are analyzed under different operating conditions, and the loss mechanism of the entire compressor and the internal flow characteristics of each part under variable operating conditions are evaluated. The areas where the flow field characteristics of the impeller 3, the tip gap 10 and the disk cavity 20 show obvious changes, including but not limited to distortion, transition and singularity conditions, are intentionally captured, and the areas where the local characteristics change obviously are used as measurement point densification areas to analyze the coupling characteristics and internal flow structure of each through-flow part under variable operating conditions, where emphasis should be placed on the analysis of the flow field characteristics of the impeller 3, the tip gap 10 and the disk cavity 20.

[0068] As shown in FIGS. 10 to 15, (a) of FIG. 10 shows a simulation data diagram of static pressure changes as the fluid flows through the impeller 3, and (b) of FIG. 10 shows a simulation data diagram of total pressure changes as the fluid flows through the impeller 3. (c) of FIG. 11 shows a simulation data diagram of static temperature changes as the fluid flows through the impeller 3, and (d) of FIG. 11 shows a simulation data diagram of total temperature changes as the fluid flows through the impeller 3. (e) of FIG. 12 shows a simulation data diagram of density changes as the fluid flows through the impeller 3, and (f) of FIG. 12 shows a simulation data diagram of Mach number changes as the fluid flows through the impeller 3. (g) of FIG. 13 shows a simulation data diagram of viscosity changes as the fluid flows through the impeller 3, and (h) of FIG. 13 shows a simulation data diagram of turbulent kinetic energy changes as the fluid flows through the impeller 3. 14(a) shows a simulation data diagram of static pressure change as the fluid flows through the disk cavity 20, FIG. 14(b) shows a simulation data diagram of static temperature change as the fluid flows through the disk cavity 20, FIG. 14(c) shows a simulation data diagram of total pressure change as the fluid flows through the disk cavity 20, and FIG. 14(d) shows a simulation data diagram of total temperature change as the fluid flows through the disk cavity 20. FIG. 15(e) shows a simulation data diagram of density change as the fluid flows through the disk cavity 20, FIG. 15(f) shows a simulation data diagram of Mach number change as the fluid flows through the disk cavity 20, FIG. 15(g) shows a simulation data diagram of viscosity change as the fluid flows through the disk cavity 20, and FIG. 15(h) shows a simulation data diagram of turbulent kinetic energy change as the fluid flows through the disk cavity 20. In Figures 10 to 15, the positions surrounded by each dotted circle or the regions where the gradient changes significantly are local region positions where the fluid shows at least one of distortion, transition, and singularity, that is, measurement point densification regions.

[0069] As can be seen from Figures 10 to 15, except for viscosity and turbulent kinetic energy, significant local gradient changes are observed only in the passage near the impeller 3 exit and near the impeller cover. This indicates undercurrent losses due to leakage flow from the tip clearance 10 and the influence of low-energy, high-entropy flow in the wake. All other flow parameters show a clear increasing trend along the fluid flow direction under the action of the impeller 3, but the magnitude of the increasing gradients is different. The circumferential gradient changes of static pressure, total pressure, and density near the impeller cover and trailing edge are more pronounced than the circumferential gradient changes of static temperature and total temperature. This is due to the generation, development, instability, and fragmentation of leakage vortices in the tip clearance 10 driven by the lateral pressure difference on the pressure or suction surface, as well as the mixing effect of shock waves at the trailing edge and exit of the impeller 3 with the mainstream boundary layer of the impeller 3 blade. There is essentially no circumferential gradient change in the Mach number. The radial gradients of static pressure, static temperature, density, and Mach number on the impeller surface are more pronounced than the radial gradients of total pressure and total temperature, and are more pronounced at the front and middle of the impeller 3 than at the rear. Three-dimensional twisting and compression are observed along the impeller 3 flow path and along its height. Near the rear of the impeller 3, a rapidly increasing linear velocity prevails overall, compared to the influence of the impeller's radius. Generally speaking, each flow parameter within the disk cavity 20 is uniformly distributed in the circumferential direction due to its annular axisymmetric structure. Except for the static pressure and density distributions near the junction of the impeller 3 outlet and the disk cavity 20, other flow parameters show essentially no circumferential gradients. This is due to the presence of a circumferentially non-uniform "jet-wake" at the upstream impeller 3 outlet. The airflow entering the disk cavity 20 is driven by the circumferential rotation and gradually flows into the disk cavity 20 along the axial direction. This allows microclusters of airflow to move, develop, and aggregate instantaneously in specific regions, forming areas of relatively high or low pressure and density that are distinct from most other regions in the circumferential direction, and this is the primary pathway for the airflow at the outer boundary surface to exchange energy and mass.

[0070] In some embodiments, the preset fluid parameters include fluid flow parameters and environmental parameters, where the fluid flow parameters include at least one of pressure, temperature, velocity, flow rate, vibration displacement, phase concentration, viscosity, Reynolds number, and surface tension of the fluid, and the fluid environmental parameters include at least one of sound pressure decibels, humidity, surface roughness, and wear of an environment in which the fluid is located.

[0071] The fluid flow parameters reflect the flow characteristics of the fluid, and the fluid environment parameters reflect the characteristics of the environment in which the fluid is located, and since fluid detection includes both the fluid flow parameters and the fluid environment parameters, the obtained fluid data is more accurate and comprehensive.

[0072] Specifically, pressure includes static pressure, total pressure, and differential pressure; temperature includes static temperature and total temperature; velocity includes average velocity, instantaneous velocity, absolute velocity, relative velocity, and peripheral velocity; flow rate includes volumetric flow rate and mass flow rate; vibration displacement includes low frequency, medium frequency, and high frequency; phase concentration includes gas-liquid and liquid-solid; viscosity includes Newtonian and non-Newtonian; Reynolds number includes laminar flow, transitional flow, and turbulent flow; surface tension includes static and dynamic; sound pressure decibels includes fluid noise, mechanical noise, and electromagnetic noise; humidity includes absolute humidity and relative humidity; surface roughness includes average roughness and maximum height; and wear volume includes abrasive particles, adhesion, and fatigue.

[0073] The fluid may be a medium in a gas phase, a liquid phase, or a gas-liquid two-phase flow, such as air, carbon dioxide gas, nitrogen gas, or helium gas.

[0074] In some embodiments, the predefined boundary conditions include an inlet boundary condition, an outlet boundary condition, an all-contact wall boundary condition, a periodic boundary condition, a rotating-stationary interferometric boundary condition, and a turbulence model boundary condition.

[0075] In the analysis stage of the simulation, the accuracy of the simulation results can be improved by restricting the parameters related to the preset boundary conditions.

[0076] Specifically, the inlet boundary conditions are set to the designed total temperature and total pressure boundaries, with turbulence intensity along the axial airflow direction at 5%. The outlet boundary conditions are set to the mean static pressure at the start of the calculation, and the back pressure is gradually increased. As the total pressure ratio gradually increases, the designed mass flow rate is applied. When the total pressure ratio begins to decrease, it is considered that the centrifugal compressor is approaching its numerical stall point. All contact wall boundary conditions are set to adiabatic and no-slip boundary conditions on the blade surface and casing wall. The periodic boundary conditions are as follows: For single-passage calculations, the adjustable inlet guide vanes 2, impeller 3, disk cavity 20, and variable diffuser 4 all select single-blade passages, and rotating periodic surfaces are used along the circumferential boundaries on both sides of the passage. The full-passage simulation model is obtained by rotating and copying the single-blade model. The rotating-stationary interaction treatment boundary conditions are as follows: Commonly used boundary surfaces include the mixing plane, frozen rotor, and transient rotor stator. A mixing plane is selected for a single passage to average the upstream boundary physical quantities circumferentially and transfer them to the downstream boundary, ignoring the effects of circumferential asymmetry. In a full-passage simulation model, a frozen rotor is selected to analyze the rotor in a rotating coordinate system and the stator in a stationary coordinate system. Information between the rotor and stator is transferred by interpolation, reflecting the effects of circumferential asymmetry on the upstream and downstream flow fields. The turbulence model boundary conditions are as follows: The SST turbulence model is used, and the mass, momentum, and energy equations are discretized using second-order upwind finite difference. At least 10 mesh points are placed in the laminar sublayer region, and the wall function y+ is set to approach 1.

[0077] In some embodiments, the step of acquiring fluid flow parameters and environmental parameters at each flow field measurement point in the impeller 3, the blade tip gap 10, and the disk cavity 20, and comparing and verifying the numerical results of the simulation with the measurement results, includes the following steps:

[0078] The fluid flow parameters and environmental parameters are acquired at flow field measurement points installed in the impeller 3, a first measurement point 100 in the tip gap 10, and a second measurement point 200 in the disk cavity 20. The processing results of the acquired fluid flow parameters and environmental parameters are then compared and analyzed with the numerical simulation results to evaluate the overall external performance of the entire machine and the internal loss distribution of the impeller 3 under variable operating conditions, clarify the combined loss mechanism of the main flow and leakage flow in the impeller 3, determine the impact of the leakage flow in the impeller 3 and the magnitude of the loss, and further provide design directions for optimizing the impeller 3 blades, the size of the tip gap 10, and the configuration of the disk cavity 20.

[0079] The fluid flow parameters and environmental parameters are obtained at the flow field measurement points installed in the impeller 3, the first measurement point 100 in the tip gap 10, and the second measurement point 200 in the disk cavity 20, and the processing results of the obtained fluid flow parameters and environmental parameters are compared and analyzed with the numerical results of the simulation. This makes it possible to evaluate and analyze the overall external performance of the entire machine under variable operating conditions and the flow field loss distribution within the impeller 3, the tip gap 10, and the disk cavity 20. This reveals the coupling loss mechanism of the disk cavity 20 and provides design directions for optimizing the blade shape of the impeller 3, the size of the tip gap 10, and the configuration of the disk cavity 20.

[0080] In some embodiments, as shown in Figures 1 to 15, based on the overall and internal flow field measurement system of the centrifugal compressor, the steps of performing flow passing measurements on the internal leakage flow field of the impeller 3 and the blade tip gap 10 and the external leakage flow field of the disk cavity 20 include the following steps:

[0081] Design and construct a measurement system for the overall and internal flow field of a centrifugal compressor.

[0082] Measurements are performed under all operating conditions and all internal flow fields for the inlet of the entire inlet passage 1 and the outlet of the entire outlet passage 6, the inlet / outlet and interior of the adjustable inlet guide vane 2, the inlet / outlet and interior of the impeller 3, the disk cavity 20 of the impeller 3, the tip clearance 10 of the impeller 3, the booster passage 42 and upstream and downstream of the variable diffuser 4, and the booster passage 42 and upstream and downstream of the volute casing 5 under different main flow rates, different angles of the adjustable inlet guide vane 2, different rotational speeds of the impeller 3, and different angles of the variable diffuser 4.

[0083] During the actual operation of the centrifugal compressor, a part of the main flow will leak from the disk cavity 20 and the blade tip gap 10 of the impeller 3. Therefore, in the measurement experiment stage of the passing flow, taking into account the influence of the leakage flow from the disk cavity 20 and the blade tip gap 10 of the impeller 3, measurements are carried out under all operating conditions and all internal flow fields under different main flow rate conditions, different angles of the adjustable inlet guide vanes 2, different rotation speeds of the impeller 3, and different angles of the variable diffuser 4, so as to improve the accuracy of the measurement experiment results.

[0084] In some embodiments, targets affected by the circumferential asymmetry due to the tongue include at least one of the volute casing 5 itself, the upstream and downstream internal flow fields, and overall machine performance. The extent of the impact of the circumferential asymmetry due to the tongue includes at least one of a part, an area, and a degree.

[0085] By limiting the objects affected by the circumferential asymmetry caused by the tongue to include at least one of the volute casing 5 itself, the internal flow fields on the upstream and downstream sides, and the overall machine performance, it is possible to more comprehensively analyze the effect of the circumferential asymmetry caused by the tongue on the internal flow field of the centrifugal compressor.

[0086] The above are merely preferred specific embodiments of the present application, and the scope of protection of the present application is not limited thereto. Any modifications or alternatives that can be easily conceived by a person skilled in the art within the technical scope disclosed in the present application shall be included in the scope of protection of the present application.

[0087] Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art should understand that it is still possible to modify the technical solutions described in the above embodiments or replace some of the technical features with equivalents, and such modifications or replacements will not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions in the embodiments of the present invention. [Explanation of symbols]

[0088] 1 All aircraft entrance passage 2 adjustable inlet guide vanes 3 impeller 4 Variable Diffuser 5. Spiral casing 6 All aircraft exit passage 10 Tip clearance 20 disc cavity 41 Booster blade 42 Pressure booster passage 100 1st measurement point 200 2nd measurement point

Claims

1. A centrifugal compressor, The invention includes an overall inlet passage (1), adjustable inlet guide vanes (2), an impeller (3), a variable diffuser (4), a volute casing (5), and an overall outlet passage (6), A blade tip gap (10) is provided between the impeller (3) and the impeller cover, A disc cavity (20) is formed between the impeller (3) on the side remote from the adjustable inlet guide vanes (2) and the impeller cover; The impeller (3), the tip gap (10), and the disk cavity (20) are provided with measurement point densification areas; Flow field measurement points are provided at intervals along the fluid flow direction within the impeller (3), the blade tip gap (10), and the disk cavity (20); A centrifugal compressor, characterized in that the intervals between the flow field measurement points located within the measurement point densification region are smaller than the intervals between the flow field measurement points located outside the measurement point densification region.

2. 2. The centrifugal compressor according to claim 1, characterized in that the spacing between adjacent flow field measurement points located closer to the tongue region of the volute casing (5) is smaller than the spacing between adjacent flow field measurement points located further from the tongue region of the volute casing (5).

3. The adjustable inlet guide vanes (2) are provided in the entire inlet passage (1), The impeller (3) is located downstream of the adjustable inlet guide vanes (2), The variable diffuser (4) is provided downstream of the impeller (3), The volute casing (5) is provided downstream of the impeller (3), The outlet passage is connected to the outlet of the volute casing (5), 2. A centrifugal compressor according to claim 1, characterized in that the leakage flow inlet of the disk cavity (20) communicates with the main flow outlet of the impeller (3).

4. The impeller (3) is rotatably provided inside the impeller cover, whereby the blade tip gap (10) is formed between the circumferential direction of the impeller (3) and the inner wall of the impeller cover; The flow field measurement points are: a plurality of first measurement points (100) spaced apart along a circumferential direction of the tip gap (10) and a fluid flow direction, for detecting and acquiring flow parameters and environmental parameters of the fluid within the tip gap (10); 2. The centrifugal compressor according to claim 1, wherein the intervals between the first measurement points (100) located within the measurement point densification region are smaller than the intervals between the first measurement points (100) located outside the measurement point densification region.

5. The flow field measurement points are: The disk cavity (20) further includes a plurality of coplanar second measurement points (200) spaced apart along the circumferential direction of the disk cavity (20) and along the fluid flow direction, the second measurement points (200) being used to detect and acquire flow parameters and environmental parameters of the fluid within the disk cavity (20); 2. The centrifugal compressor according to claim 1, wherein the intervals between the second measurement points (200) located within the measurement point densification region are smaller than the intervals between the second measurement points (200) located outside the measurement point densification region.

6. 2. The centrifugal compressor according to claim 1, wherein the disk cavity (20) is an annular gap between the disk of the impeller (3) and the wall surface of the casing, and an outer boundary surface of the disk cavity at a large radius position is connected to the dynamic and static gaps, and an inner boundary surface of the disk cavity at a small radius position is connected to the seal structure.

7. 2. The centrifugal compressor according to claim 1, wherein the measurement point densification region is a local region position where there is at least one of distortion, transition, and singularity in the flow field characteristics of the impeller (3), the blade tip gap (10), and the disk cavity (20).

8. The centrifugal compressor according to claim 4, wherein a detection sensor is also provided at each of the plurality of first measurement points (100).

9. The centrifugal compressor according to claim 5, wherein a detection sensor is also provided at each of the plurality of second measurement points (200).

10. 2. A centrifugal compressor according to claim 1, characterized in that the impeller (3) is of semi-open design.

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