Flow measurement method for engine body air inlet duct fan coupling test

Abstract

The invention belongs to the technical field of integrated test of airplanes and engines, and discloses a flow measurement method for coupling test of an airframe air inlet duct fan. The flow measuring method for the engine body air inlet duct fan coupling test comprises the steps that the pressure value of a pressure measuring point is calculated through CFD; calculating slope screening pressure measuring points; carrying out an air inlet channel wind tunnel test; training a neural network; carrying out an engine body air inlet duct fan integrated wind tunnel test; calculating a pressure correction coefficient; calculating a predicted flow coefficient; and correcting the flow coefficient. According to the flow measurement method for the engine body air inlet duct fan coupling test, the flow coefficient-surface pressure distribution matching characteristic of an air inlet duct is obtained through a wind tunnel test, and then the flow coefficient is obtained through the matching characteristic and the engine body surface and air inlet duct inner surface pressure distribution in an engine body air inlet duct fan integrated model; the method can accurately predict the air inlet flow and has engineering practical value.

Description

Technical Field

[0001] The invention belongs to the technical field of aircraft and engine integration testing, and in particular relates to a flow measurement method for a body air inlet fan coupling test. Background Art

[0002] As a key component connecting the engine and the aircraft, the aircraft engine inlet not only affects the engine's efficiency and safe operating boundary, but also affects the external flow and aerodynamics of the aircraft through coupling with the fuselage, fan and other components. The inlet flow is a key factor affecting engine performance. In the inlet wind tunnel test, the inlet flow needs to be accurately measured to provide support for the inlet configuration design and optimization.

[0003] In a separate inlet wind tunnel test, the total pressure and static pressure are usually measured in the uniform flow field at the inlet outlet, and then the inlet flow rate is calculated. However, for the integrated inlet fan configuration of the fuselage, due to the influence of flow field distortion, the inlet flow rate obtained by measuring the total pressure and static pressure at the inlet of the turbofan engine simulator has a large error.

[0004] The China Patent Literature Library has published a flow matching evaluation method for the joint operation of the intake duct and the engine (CN109460628A). The flow matching evaluation method first obtains the flow coefficient-total pressure recovery coefficient characteristic data of the intake duct through a wind tunnel test, and then obtains the engine component characteristic data through an engine component test. The flow coefficient-total pressure recovery coefficient characteristic data of the intake duct is then coupled to the engine model, and the engine performance is estimated. However, the problem of accurate measurement of the intake duct flow is not solved.

[0005] Currently, there is an urgent need to develop a flow measurement method for airframe inlet fan coupling testing. Summary of the invention

[0006] The technical problem to be solved by the present invention is to provide a flow measurement method for a fuselage air intake duct fan coupling test, so as to provide support for flow monitoring in a fuselage air intake duct fan integrated wind tunnel test.

[0007] The flow measurement method for a body air intake duct fan coupling test of the present invention comprises the following steps: S10.CFD calculates the pressure value at the pressure measuring point; Set the same total pressure as the wind tunnel test , static pressure of incoming flow , Inflow temperature , the flow coefficient of the integrated model of the air intake duct and fan is obtained through CFD calculation , arranged on the fuselage surface and the inner surface of the air inlet Static pressure measuring points, record the horizontal coordinates of the pressure measuring points , Indicates the number of the pressure measuring point. The corresponding static pressure value of each pressure measuring point is ; S20. Calculate the slope to select the pressure measuring points; For Pressure measuring points, calculate the flow coefficient With static pressure value The slope of change ; The slope calculation formula is: , where: Indicates the change in static pressure value, Indicates the change in flow rate; if The slope of any pressure measuring point All less than , is the set upper limit of the slope, then the number of the pressure measuring point is recorded as ; S30. Conduct air inlet wind tunnel tests; The air intake model in the air intake fan integrated model is processed into an air intake physical model separately. The location of the pressure measuring points Arrange static pressure measuring points in the physical model of the air intake duct; measure the static pressure through the wind tunnel test of the physical model of the air intake duct. Static pressure value at each pressure measuring point , and record the corresponding total intake pressure ; Use a flow meter to measure the inlet outlet flow and obtain the flow coefficient ; S40. Training the neural network; First The location of the pressure measuring points and static pressure values ​​measured in wind tunnel tests As the training input of the neural network, the flow coefficient As the output of neural network training; using the fully connected deep neural network to train the traffic prediction model; the fully connected deep neural network contains hidden layers, the network structure is , iterative training Second, we get the traffic prediction network ; S50. Conduct wind tunnel tests on the integration of air intake and fan; Processing the integrated model of the air intake duct and fan, according to the The location of the pressure measuring points Static pressure measuring points are arranged in the physical model of the air intake duct in the air intake duct fan integration model; the air intake duct fan integration wind tunnel test is carried out using the air intake duct fan integration model to measure the static pressure measuring points. Static pressure value at each pressure measuring point , and record the corresponding total pressure of the whole model ; S60. Calculate the pressure correction coefficient; The pressure correction factor is calculated using the following formula: ; in, represents the pressure correction coefficient, and the corrected static pressure is ; S70. Calculate the predicted flow coefficient; The first The location of the pressure measuring point is and the corrected static pressure Enter the traffic prediction network The predicted flow coefficient is obtained ; S80. Correction flow coefficient; The flow coefficient is corrected using the following formula: ; in, Represents the corrected predicted flow coefficient.

[0008] The flow measurement method for the fuselage inlet duct fan coupling test of the present invention obtains the flow coefficient-surface pressure distribution matching characteristics of the inlet duct through a wind tunnel test, and then obtains the flow coefficient by utilizing the matching characteristics and the pressure distribution on the fuselage surface and the inlet duct inner surface in the fuselage inlet duct fan integrated model. This method can accurately predict the inlet duct flow and has practical engineering value. BRIEF DESCRIPTION OF THE DRAWINGS

[0009] Figure 1 Schematic diagram of the inlet wind tunnel test principle of comparative example 1; Figure 2 This is a schematic diagram of the principle of the airframe air intake fan integrated wind tunnel test of Comparative Example 2; Figure 3 The flow chart of the flow measurement method for the airframe inlet fan coupling test of the present invention is as follows; Figure 4 This is a diagram of the test flow prediction results obtained in the embodiment. DETAILED DESCRIPTION

[0010] The present invention is described in detail below with reference to the accompanying drawings and embodiments.

[0011] Comparative Example 1: Figure 1As shown, this comparative example is a separate inlet wind tunnel test. The inlet outlet flow field is first rectified by a rectifier to achieve uniform total pressure at the inlet outlet. The total pressure at the inlet outlet is then measured by a pressure rake, and the static pressure at the inlet outlet is measured by a pressure gauge. Finally, the test flow rate is calculated using the total pressure and static pressure.

[0012] Comparative Example 2: Figure 2 As shown in the figure, this comparative example is a wind tunnel test of the integrated air intake duct and fan of the airframe. The air intake duct is directly connected to the turbofan engine simulator, and a separate high-pressure air source is used to drive the turbine to drive the fan to rotate. The driving air source is discharged downstream through the turbine and mixed with the airflow from the air intake duct and the fan. Due to the influence of flow field distortion, the test flow rate obtained by installing a pressure rake at the inlet of the turbofan engine simulator has a large error, and it is impossible to continue to use the air intake outlet rectification method shown in comparative example 1 to measure the air intake duct flow.

[0013] Example: Figure 3 As shown, the flow measurement method for the air intake fan coupling test of the embodiment includes the following steps: S10.CFD calculates the pressure value at the pressure measuring point; Set the same total pressure as the wind tunnel test , static pressure of incoming flow , Inflow temperature , the flow coefficient of the integrated model of the air intake duct and fan is obtained through CFD calculation , arranged on the fuselage surface and the inner surface of the air inlet Static pressure measuring points, record the horizontal coordinates of the pressure measuring points , Indicates the number of the pressure measuring point. The corresponding static pressure value of each pressure measuring point is ; In this embodiment, the total pressure of the incoming flow is , the static pressure of the incoming flow is , Inflow temperature , ; S20. Calculate the slope to select the pressure measuring points; For Pressure measuring points, calculate the flow coefficient With static pressure value The slope of change ; The slope calculation formula is: , where: Indicates the change in static pressure value, Indicates the change in flow rate; if The slope of any pressure measuring point All less than , The upper limit of the slope is set. , then the number of the pressure measuring point is recorded as ; In this embodiment, ; S30. Conduct air inlet wind tunnel tests; The air intake model in the air intake fan integrated model is processed into an air intake physical model separately. The location of the pressure measuring points Arrange static pressure measuring points in the physical model of the air intake duct; measure the static pressure through the wind tunnel test of the physical model of the air intake duct. Static pressure value at each pressure measuring point , and record the corresponding total intake pressure ; Use a flow meter to measure the inlet outlet flow and obtain the flow coefficient ; S40. Training the neural network; First The location of the pressure measuring points and static pressure values ​​measured in wind tunnel tests As the training input of the neural network, the flow coefficient As the output of neural network training; using the fully connected deep neural network to train the traffic prediction model; the fully connected deep neural network contains hidden layers, the network structure is , iterative training Second, we get the traffic prediction network ; This embodiment takes , the network structure is ; S50. Conduct wind tunnel tests on the integration of air intake and fan; Processing the integrated model of the air intake duct and fan, according to the The location of the pressure measuring points Static pressure measuring points are arranged in the physical model of the air intake duct in the air intake duct fan integration model; the air intake duct fan integration wind tunnel test is carried out using the air intake duct fan integration model to measure the static pressure measuring points. Static pressure value at each pressure measuring point , and record the corresponding total pressure of the whole model ; S60. Calculate the pressure correction coefficient; The pressure correction factor is calculated using the following formula: ; in, represents the pressure correction coefficient, and the corrected static pressure is ; This embodiment takes , ; S70. Calculate the predicted flow coefficient; The first The location of the pressure measuring point is and the corrected static pressure Enter the traffic prediction network The predicted flow coefficient is obtained ; S80. Correction flow coefficient; The flow coefficient is corrected using the following formula: ; in, Represents the corrected predicted flow coefficient.

[0014] This embodiment obtains Figure 4 The experimental flow prediction results shown are from Figure 4 It can be seen that the prediction result of the flow measurement method for the airframe inlet fan coupling test of the present invention is consistent with the actual value, has high accuracy, and can accurately predict the inlet flow coefficient.

[0015] Although the embodiments of the present invention have been disclosed as above, they are not limited to the applications listed in the specification and implementation modes. For those familiar with the art, all features disclosed in the present invention, or steps in all methods or processes disclosed, except for mutually exclusive features and / or steps, can be combined in any way without departing from the principles of the present invention. The present invention is not limited to the specific details and illustrations shown and described herein.

Claims

1. A flow measurement method for a body air intake fan coupling test, characterized in that: The following steps are involved: S10.CFD calculates the pressure value at the pressure measuring point; S20. Calculate the slope to select the pressure measuring points; S30. Conduct air inlet wind tunnel tests; S40. Training the neural network; S50. Conduct wind tunnel tests on the integration of airframe air intake and fan; S60. Calculate the pressure correction coefficient; S70. Calculate the predicted flow coefficient; S80. Correction of flow coefficient.

2. The flow measurement method for airframe intake duct fan coupling test according to claim 1, characterized in that: The CFD calculation of the pressure value at the pressure measuring point of S10 includes the following steps: Set the same total pressure as the wind tunnel test , static pressure of incoming flow , Inflow temperature , the flow coefficient of the integrated model of the air intake duct and fan is obtained through CFD calculation , arranged on the fuselage surface and the inner surface of the air inlet Static pressure measuring points, record the horizontal coordinates of the pressure measuring points , Indicates the number of the pressure measuring point. The corresponding static pressure value of each pressure measuring point is .

3. The flow measurement method for airframe intake duct fan coupling test according to claim 2, characterized in that: The calculation slope of S20 screens the pressure measuring points, including the following steps: For Pressure measuring points, calculate the flow coefficient With static pressure value The slope of change ; The slope calculation formula is: , where: Indicates the change in static pressure value, Indicates the change in flow rate; if The slope of any pressure measuring point All less than , is the upper limit of the slope, then the number of the pressure measuring point is recorded as .

4. The flow measurement method for airframe intake duct fan coupling test according to claim 3, characterized in that: The S30 air intake wind tunnel test includes the following steps: The air intake model in the air intake fan integrated model is processed into an air intake physical model separately. The location of the pressure measuring points Arrange static pressure measuring points in the physical model of the air intake duct; measure the static pressure through the wind tunnel test of the physical model of the air intake duct. Static pressure value at each pressure measuring point , and record the corresponding total intake pressure ; Use a flow meter to measure the inlet outlet flow and obtain the flow coefficient .

5. The flow measurement method for airframe intake duct fan coupling test according to claim 4, characterized in that: The training neural network of S40 includes the following steps: First The location of the pressure measuring points and static pressure values ​​measured in wind tunnel tests As the training input of the neural network, the flow coefficient As the output of neural network training; using the fully connected deep neural network to train the traffic prediction model; the fully connected deep neural network contains hidden layers, the network structure is , iterative training Second, we get the traffic prediction network .

6. The flow measurement method for airframe intake duct fan coupling test according to claim 5, characterized in that: The S50 airframe inlet fan integrated wind tunnel test includes the following steps: Processing the integrated model of the air intake duct and fan, according to the The location of the pressure measuring points Static pressure measuring points are arranged in the physical model of the air intake duct in the air intake duct fan integration model; the air intake duct fan integration wind tunnel test is carried out using the air intake duct fan integration model to measure the static pressure measuring points. Static pressure value at each pressure measuring point , and record the corresponding total pressure of the whole model .

7. The flow measurement method for airframe intake duct fan coupling test according to claim 6, characterized in that: The calculation of the pressure correction coefficient of S60 includes the following steps: The pressure correction factor is calculated using the following formula: ； in, represents the pressure correction coefficient. The corrected static pressure is .

8. The flow measurement method for airframe intake duct fan coupling test according to claim 7, characterized in that: The calculation of the predicted flow coefficient of S70 includes the following steps: The first The location of the pressure measuring point is and the corrected static pressure Enter the traffic prediction network The predicted flow coefficient is obtained .

9. The flow measurement method for airframe intake duct fan coupling test according to claim 8, characterized in that: The correction flow coefficient of S80 includes the following steps: The flow coefficient is corrected using the following formula: ； in, Represents the corrected predicted flow coefficient.

Images