A method for controlling the intake system of a compressor test bench based on boundary layer suction / injection

Abstract

The application provides a control method of a compressor test bench air intake system based on a boundary layer suction / injection, which realizes the diversity of flow control effect by setting a boundary layer suction / injection device in the compressor test bench air intake system. The boundary layer suction / injection device is composed of a porous section, a probe group, an adapter plate, a flow meter, a throttle device group, an air pump, a return air pipe and a control unit. According to the test task requirement, the application reduces the boundary layer thickness of the test piece inlet; the application can change the flow field of the test piece inlet, carry out the compressor air intake stability research, select the specific and arbitrary position suction / injection air hole according to the control purpose and control strategy, and connect the suction / injection air hole with the throttle device and the like, so as to realize the diversity of flow control effect.

Description

Technical Field

[0001] This invention relates to the field of compressor testing technology, and specifically to a control method for the intake system of a compressor test bench based on boundary layer suction / ejection. Background Technology

[0002] The intake system is a crucial component of the compressor test bench. Its function is to provide high-quality air to the compressor test specimen and adjust the inlet air parameters, such as total pressure, density, and temperature, according to test requirements. To achieve these functions, the intake system of the test bench has several components, generally consisting of a flow measurement device, a throttling device, a rectifier, and a guide basin. The flow measurement device measures the airflow through the compressor during the test; the throttling device adjusts macroscopic parameters such as the total pressure and density of the air at the specimen inlet; the rectifier reduces turbulence and improves flow field uniformity; and the guide basin guides the airflow acceleration, accelerating the slower airflow within the intake system to the required airflow velocity for the test specimen. The flow measurement device is positioned at the front of the intake system, measuring the airflow through the compressor during the test; following the flow measurement device is the throttling device, which adjusts macroscopic parameters such as the total pressure and density of the air at the specimen inlet; following the throttling device is the rectifier, which reduces turbulence and improves flow field uniformity; and following the rectifier is the guide basin, which guides the airflow acceleration. The flow guide basin is directly connected to the inlet of the test specimen, such as... Figure 6 As shown.

[0003] The inlet boundary conditions of a real compressor are much simpler, typically consisting of only a short inlet nacelle or passageway without internal rectification measures. Compared to the inlet boundary of a real compressor, the test bench inlet system is longer and more complex, resulting in a significantly greater boundary layer thickness at the inlet of the test specimen, as well as a much larger total pressure loss within the boundary layer. While flow rate, total pressure, and density can be adjusted to match the actual operating conditions of the compressor during testing on a compressor test bench, parameters such as boundary layer thickness lack adjustable means and are difficult to regulate. This can negatively impact the recording of compressor performance parameters, the determination of compressor surge boundaries, and the study of compressor stability margins. In particular, the deviation in boundary layer thickness is more pronounced when small-flow compressors are tested on large test benches. In addition, some studies on compressor intake stability, such as intake distortion studies or flow control of engine intake ducts, require creating distortion at the test specimen inlet or actively controlling the boundary layer at the test specimen inlet. Existing research methods involve adding flow control measures before the test specimen inlet, which means adding extra components to the intake system and increasing the complexity of the test.

[0004] This shows that the existing compressor test bench intake system has the following limitations in terms of test specimen intake control: ① There are few control measures, usually only valve groups are equipped, which can only perform simple control on intake flow and pressure; ② The distribution of inlet air parameters of the test specimen deviates from the actual use environment and cannot be controlled; ③ Additional components are required to carry out research related to compressor intake quality. Summary of the Invention

[0005] To address the shortcomings of existing test benches, this invention provides a control method for the intake system of a compressor test bench based on boundary layer suction / jet. By adding a boundary layer suction / jet device to the intake system of a conventional compressor test bench, a variety of flow control effects can be achieved.

[0006] To achieve the above objectives, the technical solution adopted by the present invention is as follows: A control method for the intake system of a compressor test rig based on boundary layer suction / ejection is proposed. A boundary layer suction / ejection device is installed in the intake system of the compressor test rig. This device comprises a multi-hole section, a probe assembly, an adapter plate, a flow meter and throttling device assembly, an air pump, a return air pipe, and a control unit. The multi-hole section is a cylindrical section of equal diameter installed after the outlet guide basin and before the test piece inlet, with numerous suction / ejection orifices arranged along the flow direction. The suction / ejection of the boundary layer is controlled through these orifices, which are connected to the adapter plate via flexible hoses. The probe group is positioned after the last row of suction / jet air holes and before the test piece inlet; the suction / jet air holes and the flow meter and throttling device group are connected via the adapter plate; the flow meter and throttling device group is equipped with multiple sets of flow meters and throttling devices according to test requirements; air is drawn from the multi-hole section or from the air intake system via the air pump; the air drawn from the multi-hole section by the air pump is returned to the air intake system via the return air pipe, or air is drawn from the air intake system and injected into the multi-hole section; the probe group, the electrically controlled throttling device, the flow meter, and the air pump are connected via the control unit.

[0007] Furthermore, the suction / jet air holes are uniformly spaced and regularly distributed circular holes of equal diameter.

[0008] Furthermore, the probe group includes a boundary layer probe and a total pressure probe, used to evaluate the flow field parameters after boundary layer suction / ejection.

[0009] Furthermore, the adapter plate, flow meter, and throttling device are in one-to-one correspondence; one end of the adapter plate has a large number of connectors, which are connected to a number of suction / jet air holes through hoses.

[0010] Furthermore, the flow meter and the throttling device are in one-to-one correspondence; the throttling device includes a valve; the throttling device is electrically controlled or manually controlled.

[0011] Furthermore, the number of air pumps corresponds one-to-one with the flow meter and the throttling device, or multiple air pumps are connected to a flow meter and throttling device group, or multiple flow meters are connected to a single air pump.

[0012] Furthermore, the return air pipe is a single pipe that connects all the air pumps; or the return air pipe is multiple pipes, each of which connects to one or more sets of air pumps or flow meters as needed, and finally merges into the intake system; or, when some air pumps draw air from the multi-hole section and some air pumps draw air from the intake system, the air pumps with different airflow directions are connected separately to different return air pipes; the connection point between the return air pipe and the intake system is any position after the intake system flow control device and before the rectifier device.

[0013] Furthermore, the control unit consists of a pressure acquisition module and a control PLC. The control unit acquires the flow field data collected by the probes of the probe group and the flow data collected by the flow meter through the pressure acquisition module, and adjusts the suction / ejection air volume of the throttling device or air pump through the control PLC to change the inlet flow field of the test piece so that it meets the test requirements.

[0014] Furthermore, it also includes a pneumatic parameter control method, comprising the following steps: Step 1: Based on the experimental objective and control strategy, group the suction / jet vents on the porous section; when controlling the boundary layer thickness, group the suction / jet vents located in the same circular cross section; when conducting the intake distortion test, group the suction / jet vents with the same flow rate based on theoretical analysis or computational fluid dynamics simulation results. Step 2: Connect each set of suction / jet air holes to the adapter plate, and the corresponding flow meter and throttling device set through hoses of equal length; Step 3: Connect the flow meter and throttling device to the air pump, and connect the air pump to the intake system through the return air pipe; Step 4: Connect the probe assembly and control unit of the boundary layer suction / jet device to the air intake system; Step 5: Without starting the test bench, start the boundary layer suction / jet device and check whether the boundary layer suction / jet device is operating normally and whether there is any air leakage. Step 6: Turn off the boundary layer suction / ejection device, start the compressor test bench normally, and adjust the operating parameters of the compressor test bench to achieve the target working conditions; Step 7: Start the boundary layer suction / jet device, and adjust the flow rate of each throttling device or the suction / jet volume of each air pump based on the data from the flow meter and probe group. Step 8: After starting the boundary layer suction / jet device, if the operating parameters of the compressor test bench change, fine-tune the operating parameters of the compressor test bench to make the inlet airflow field of the test piece meet the test requirements. Beneficial effects

[0015] 1) The technical solution provided by the present invention can reduce or increase the thickness of the boundary layer at the entrance of the test piece according to the needs of the test task; 2) The technical solution provided by this invention can change the flow field at the inlet of the test piece and carry out research on the inlet stability of the compressor; 3) The number of suction / jet air holes, throttling devices, flow meters, air pumps, etc. in the boundary layer suction / jet device of the present invention can be freely configured. Specific suction / jet air holes at arbitrary positions can be selected according to the control purpose and control strategy, and connected with throttling devices, etc., to achieve a variety of flow control effects. Attached Figure Description

[0016] To more clearly illustrate the technical solutions in the specific embodiments of the present invention, the drawings used in the description of the specific embodiments will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0017] Figure 1 This is a schematic diagram of a specific example of the boundary layer suction / jet device in an embodiment of the present invention. Since the actual pipe wiring is relatively complex and the specific pipe wiring forms are different in different embodiments, solid lines are used in the figure to represent the air pipe connection topology between components, including the return air pipe, and dashed lines are used to represent the control line topology connecting the components, without giving the specific pipe wiring. Figure 2 This is a schematic diagram of an isometric view of a specific example of a porous segment in an embodiment of the present invention. Figure 3 This is a front view schematic diagram of a specific example of the probe group in an embodiment of the present invention; Figure 4 This is a schematic diagram of an isometric view of a specific example of a multi-hole section and probe group installed on an intake system in an embodiment of the present invention. Figure 5 This is a schematic diagram of the orthogonal isometric view of a specific example of the adapter plate in an embodiment of the present invention; Figure 6 This is a schematic diagram of the intake system of a conventional compressor test bench.

[0018] Figure label: 1-Multi-hole section, 2-Probe group, 3-Adapter plate, 4-Flow meter and throttling device group, 5-Air pump, 6-Return air pipe; 7-Control unit. Detailed Implementation

[0019] like Figure 1As shown, the present invention provides a control method for the intake system of a compressor test bench based on boundary layer suction / ejection, by means of... Figure 6 The conventional compressor test bench shown is achieved by adding a boundary layer suction / ejection device to the intake system. The porous section 1 of the boundary layer suction / ejection device is installed after the intake system guide basin and before the test piece, and the return air pipe 6 is installed after the intake system throttling device and before the rectifier device.

[0020] Specifically, the boundary layer suction / jet device consists of a porous section 1, a probe group 2, an adapter plate 3, a flow meter and throttling device group 4, an air pump 5, a return air pipe 6, and a control unit 7.

[0021] The porous section 1 is a cylindrical section of equal diameter installed after the outlet guide basin and before the test specimen inlet. It has numerous suction / jet air holes arranged along the flow direction to control the boundary layer through suction / jet air. These holes are connected to the adapter plate 3 via flexible hoses. Unused suction / jet air holes are sealed with plugs to prevent leakage. The diameter of the suction / jet air holes, the number of holes in each row, and the total number of suction / jet air holes must be calculated to ensure that the suction / jet air volume meets the test requirements. There are no specific requirements for the opening type, size, or distribution of the suction / jet air holes, but for ease of manufacturing and simplified control strategies, it is recommended to use uniformly spaced, regularly distributed cylindrical holes of equal diameter.

[0022] The probe group 2 is located after the last row of suction / jet vents and before the test specimen inlet. It includes boundary layer probes and total pressure probes, and is used to evaluate the flow field parameters after boundary layer suction / jet.

[0023] The adapter plate 3 is used to connect the suction / jet air orifice and the flow meter and throttling device assembly 4. The adapter plate 3 and the flow meter and throttling device assembly 4 are in one-to-one correspondence. One end of the adapter plate 3 has numerous connectors, which can be connected to a number of suction / jet air orifices via flexible hoses. Unused connectors are sealed with plugs.

[0024] The flow meter and throttling device group 4 is equipped with multiple sets of flow meters and throttling devices according to the test requirements, with a one-to-one correspondence between the flow meters and throttling devices. The throttling device can be a valve or other equipment capable of flow control; it can be electrically or manually controlled. In some cases, such as when the suction / jet control strategy is relatively simple, or when the air pump 5 has flow control capabilities, a throttling device may not be required. Before the test, the flow range of the flow meters and throttling devices must be calculated to ensure that they meet the test requirements.

[0025] The air pumps 5 are used to draw air from the multi-hole section (suction) or from the air intake system (ejection), and their number corresponds one-to-one with the flow meters and throttling devices. Under certain test conditions, the number of air pumps can be reduced, for example, multiple air pumps can be connected to a flow meter and throttling device group, or multiple flow meters can be connected to a single air pump. Before the test, the air pump's pumping capacity must be calculated to ensure it meets the test requirements.

[0026] The return air pipe 6 is used to return air drawn from the porous section 1 by the air pump 5 to the intake system, or to draw air from the intake system and inject it into the porous section 1. The return air pipe 6 can be a single pipe connecting all the air pumps 5; or it can be multiple pipes, each connecting one or more sets of air pumps 5 or flow meters as needed, ultimately converging into the intake system. Under certain experimental requirements, some air pumps 5 may draw air from the porous section 1 while others draw air from the intake system. In this case, air pumps with different airflow directions should be connected separately to different return air pipes 6. The connection point between the return air pipe 6 and the intake system can be anywhere after the flow control device and before the rectifier. The control unit 7 consists of a pressure acquisition module and a control PLC. The control unit 7 is connected to the probe group 2, an electrically controlled throttling device, a flow meter, and an air pump 5. The control unit 7 can acquire flow field data collected by the probes of the probe group 2 via the pressure acquisition module and flow rate data collected by the flow meter. By controlling the PLC, it can adjust the suction / ejection volume of the throttling device or the air pump 5 to change the inlet flow field of the test piece, making it meet the test requirements. Figure 1 The diagram only shows the possible connection methods between components such as adapter plate 3, flow meter and throttling device group 4, probe group 2, air pump 5 and return air pipe 6. Except for the one-to-one correspondence between adapter plate 3 and flow meter and throttling device group 4, there is no limit to the number of each component. Related equipment can be added or removed as needed.

[0027] The compressor test bench intake system based on boundary layer suction / ejection of the present invention also includes a pneumatic parameter control method, comprising the following steps: Step 1: Based on the experimental objective and control strategy, group the suction / jet orifices. For example, when controlling the boundary layer thickness, suction / jet orifices located in the same circular cross-section can be grouped together. For inlet distortion experiments, suction / jet orifices with the same flow rate can be grouped together based on theoretical analysis or CFD (Computational Fluid Dynamics) simulation results.

[0028] Step 2: Connect each set of suction / jet air holes to adapter plate 3, i.e., the corresponding flow meter and throttling device, through hoses of equal length. Note that since some models of flow meters and throttling devices are directional, the flow meter and throttling device must be connected according to the airflow direction within the suction / jet device.

[0029] Step 3: Connect the flow meter and throttling device to the air pump 5. Again, pay attention to the air pump 5's suction direction. Connect the air pump 5 to the intake system via the return air pipe 6.

[0030] Step 4: Connect the other components of the boundary layer suction / jet device to the system.

[0031] Step 5: Without starting the test bench, start the boundary layer suction / jet device and check whether the air intake system is operating normally and whether there is any air leakage.

[0032] Step 6: Turn off the boundary layer suction / ejection device, start the compressor test bench normally, and adjust the operating parameters of the compressor test bench to achieve the target working conditions; Step 7: Start the boundary layer suction / ejection device. Based on the data from the flow meter and probe group, adjust the flow rate of each throttling device or the suction / ejection volume of each air pump 5 one by one. To improve efficiency, the flow rate of each throttling device or the suction / ejection volume of each air pump 5 can be preliminarily determined before the test through CFD simulation, theoretical analysis, etc., and then adjusted according to the actual situation during the test. Step 8: After starting the boundary layer suction / ejection device, if the operating parameters of the compressor test bench change, the operating parameters of the compressor test bench can be finely adjusted to make the inlet airflow field of the test piece meet the test requirements.

[0033] To more clearly illustrate the technical solution of the present invention, this embodiment uses a compressor test bench as an example to introduce the specific implementation process of the technical solution of the present invention. It should be understood that the embodiments described herein are merely for explaining the present invention and are not intended to limit the present invention; the present invention can also be applied in other embodiments.

[0034] The parameters of this embodiment are based on a compressor test bench, whose inlet system is approximately 60m long, with a guide basin outlet diameter of 980mm, and a porous section 1 of the same diameter connected to the test specimen. The length of porous section 1 is 980mm. Under a certain operating condition, the inlet flow rate of the test specimen is approximately 70 kg / s, the local flow velocity at the guide basin outlet is 78 m / s, and the density is 1.19 kg / m³. 3 According to the turbulent boundary layer formula, the inlet boundary layer thickness of the test specimen under this condition is calculated to be 59 mm, and the displacement thickness is 5.74 mm. To control the boundary layer thickness according to actual operating conditions, the calculated boundary layer thickness under this condition is 16.5 mm, and the displacement thickness is 1.60 mm. This means that approximately 4.14 mm of air needs to be extracted using a boundary layer suction / jet device at a flow rate of 1.18 kg / s.

[0035] In this embodiment, as Figure 2As shown, 30 vent holes are opened on the porous section 1, with 150 vent holes evenly distributed in each row. The first vent hole is 100mm away from the outlet of the guide basin, the spacing between each vent hole is 20mm, and each vent hole has a diameter of 3mm and a depth of 10mm. Connect every 2 rows of 300 vent holes to... Figure 5 The pneumatic connector shown is used to connect to a 6mm inner diameter, 5m long hose, and then to a flow meter and a throttling device.

[0036] This embodiment is equipped with 15 sets of flow meters and throttling devices, each with a flow rate of 0.0787 kg / s. The flow meters are venturi tubes, and the throttling devices are ball valves. The venturi tube inlet diameter is DN40 mm, and the ball valve has a maximum CV value of 100. The adapter plate is equipped with 303 6 mm connectors, with some adapter slack to accommodate other test requirements.

[0037] Based on the orifice flow rate formula and considering the pressure loss along the airflow path, to meet the suction flow rate requirement of 1.18 kg / s, the pressure difference between air pump 5 and the orifice section 1 needs to be approximately 5 kPa, and the suction capacity of each air pump 5 is approximately 0.0787 kg / s. In actual operation, the suction capacity of each air pump 5 can be adjusted based on probe data. In this embodiment, the suction capacity of a single air pump is very small; a single high-flow-rate air pump can meet the requirements, and a throttling device controls the flow rate. To reduce control complexity, multiple flow meters can be combined into one air pump 5. The air pump is connected to the intake system through a return air pipe 6, which can be a single pipe or multiple pipes with a total flow area of ​​0.1 m². 2 about.

[0038] In this embodiment, as Figure 4 As shown, four boundary layer probe rakes are installed 200 mm after the last exhaust port. The structure of the boundary layer probe rakes is as follows: Figure 3 As shown, the rake is 100mm high, and each rake has 10 total pressure measurement points arranged at equal intervals along the height direction.

[0039] Before the experiment, according to Figure 1 After connecting all components in the embodiment and verifying their accuracy, conduct the experiment step by step. Monitor the boundary layer suction by monitoring the data from the boundary layer probe rake, and monitor the suction flow rate by monitoring the flow meter to determine whether the suction control target has been achieved. In this embodiment, if the time-average difference of the total pressure at measuring points at a distance of 16.5 mm or more from the object surface is <1%, and the total flow rate of the flow meter reaches 1.18 kg / s, the boundary layer suction control can be considered to have reached the target operating condition. Other tests can select appropriate criteria according to the needs of the task.

[0040] Other components in this invention, including flow meters and throttling devices, air pumps, control units, etc., are all mature products. The return air pipe is a common rigid pipe. In this invention, all these components are selected from existing physical objects. As long as the parameters and accuracy range meet the requirements of the test task, no example diagrams are given here.

[0041] It should be noted that, without departing from the technical solution of this invention, those skilled in the art can make equivalent substitutions or modifications to the relevant technical features, and the embodiments after such substitutions or modifications still fall within the protection scope of this invention.

Claims

1. A control method for the intake system of a compressor test bench based on boundary layer suction / ejection, characterized in that, A boundary layer suction / ejection device is installed in the air intake system of the compressor test bench. This device consists of a multi-hole section, a probe assembly, an adapter plate, a flow meter and throttling device assembly, an air pump, a return air pipe, and a control unit. The multi-hole section is a cylindrical section of equal diameter installed after the outlet guide basin and before the test piece inlet, with numerous suction / ejection holes arranged along the flow direction. These holes control the suction / ejection of the boundary layer. The suction / ejection holes are connected to the adapter plate via flexible hoses. The probe assembly is positioned after the last row of suction / ejection holes and before the test piece inlet. The adapter plate connects the suction / jet air inlet and the flow meter and throttling device assembly; the flow meter and throttling device assembly is equipped with multiple sets of flow meters and throttling devices according to the test requirements; air is drawn from the porous section by the air pump or from the air intake system; the air drawn from the porous section by the air pump is returned to the air intake system through the return air pipe, or air is drawn from the air intake system and then injected into the porous section; the control unit connects the probe assembly, the electrically controlled throttling device, the flow meter, and the air pump; according to the test requirements, the boundary layer thickness at the inlet of the test piece is reduced or increased, changing the flow field in the mainstream region outside the boundary layer; It also includes aerodynamic parameter control methods, comprising the following steps: Step 1: Based on the experimental objective and control strategy, group the suction / jet vents on the porous section; when controlling the boundary layer thickness, group the suction / jet vents located in the same circular cross section; when conducting the inlet distortion test, group the suction / jet vents with the same flow rate based on theoretical analysis or computational fluid dynamics simulation results. Step 2: Connect each set of suction / jet air holes to the adapter plate, and the corresponding flow meter and throttling device set through hoses of equal length; Step 3: Connect the flow meter and throttling device to the air pump, and connect the air pump to the intake system through the return air pipe; Step 4: Connect the probe assembly and control unit of the boundary layer suction / jet device to the air intake system; Step 5: Without starting the test bench, start the boundary layer suction / jet device and check whether the boundary layer suction / jet device is operating normally and whether there is any air leakage. Step 6: Turn off the boundary layer suction / ejection device, start the compressor test bench normally, and adjust the operating parameters of the compressor test bench to achieve the target working conditions; Step 7: Start the boundary layer suction / jet device, and adjust the flow rate of each throttling device or the suction / jet volume of each air pump based on the data from the flow meter and probe group. Step 8: After starting the boundary layer suction / jet device, if the operating parameters of the compressor test bench change, fine-tune the operating parameters of the compressor test bench to make the inlet airflow field of the test piece meet the test requirements.

2. The control method for the intake system of a compressor test bench based on boundary layer suction / ejection according to claim 1, characterized in that, The suction / jet air holes are uniformly spaced and regularly distributed circular holes of equal diameter.

3. The control method for the intake system of a compressor test bench based on boundary layer suction / ejection according to claim 1, characterized in that, The probe group includes boundary layer probes and total pressure probes, which are used to evaluate the flow field parameters after boundary layer suction / ejection.

4. The control method for the intake system of a compressor test bench based on boundary layer suction / ejection according to claim 1, characterized in that, The adapter plate, flow meter, and throttling device are in one-to-one correspondence; one end of the adapter plate has a large number of connectors, which are connected to a number of suction / jet air holes through hoses.

5. The control method for the intake system of a compressor test bench based on boundary layer suction / jet according to claim 1, characterized in that, The flow meter and the throttling device are in one-to-one correspondence; the throttling device includes a valve; the throttling device is electrically controlled or manually controlled.

6. The control method for the intake system of a compressor test bench based on boundary layer suction / ejection according to claim 1, characterized in that, The number of air pumps corresponds one-to-one with the flow meter and the throttling device, or multiple air pumps are connected to a flow meter and throttling device group, or multiple flow meters are connected to a single air pump.

7. The control method for the intake system of a compressor test bench based on boundary layer suction / jet according to claim 1, characterized in that, The return air pipe is a single pipe that connects all the air pumps; or the return air pipe is multiple pipes, each of which connects to one or more sets of air pumps or flow meters as needed, and finally merges into the intake system; or, when some air pumps draw air from the multi-hole section and some air pumps draw air from the intake system, the air pumps with different airflow directions are connected to different return air pipes separately; the connection point between the return air pipe and the intake system is any position after the intake system flow control device and before the rectifier device.

8. The control method for the intake system of a compressor test bench based on boundary layer suction / jet according to claim 1, characterized in that, The control unit consists of a pressure acquisition module and a control PLC. The control unit acquires the flow field data collected by the probes of the probe group and the flow data collected by the flow meter through the pressure acquisition module. It then adjusts the suction / ejection air volume of the throttling device or air pump through the control PLC to change the inlet flow field of the test piece so that it meets the test requirements.

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