Internal flow resistance measuring device and method based on thrust calibration

Abstract

The invention discloses an internal flow resistance measuring device and method based on thrust calibration, and belongs to the field of internal flow resistance measurement of internal flow aerodynamics. The device comprises an inlet total pressure adjusting device, a flow measuring device, a thrust measuring device, an inlet measuring section, a connecting section, a nacelle model, a backpressure cabin and a backpressure adjusting device, and the flow measuring device, the thrust measuring device, the inlet measuring section, the connecting section and the nacelle model are sequentially installed on the downstream of the inlet total pressure adjusting device. The thrust measuring device, the inlet measuring section, the connecting section and the nacelle model are all arranged in a backpressure cabin, and a backpressure adjusting device is mounted at the downstream of the backpressure cabin. The invention aims to solve the problems that the measurement error caused by pressure integration can be avoided, the bottom of a nacelle model is not interfered, the internal flow resistance measurement accuracy is improved, the internal flow resistance measurement test cost is reduced, the internal flow resistance measurement accuracy is improved, and the internal flow resistance measurement test cost is greatly reduced.

Description

Technical Field

[0001] The invention relates to an internal flow resistance measurement device and method based on thrust calibration, belonging to the field of internal flow resistance measurement of internal flow aerodynamics. Background Art

[0002] In the drag composition of an aircraft, the internal flow drag is not included in the aerodynamic drag of the entire aircraft. This part of the drag should be deducted when analyzing the lift-drag characteristics of the entire aircraft. The existing methods for measuring internal flow drag include direct measurement technology of the flow channel resistance in a ventilation model, DPIV technology, and a ventilation model force measurement test method. Direct measurement technology is difficult to implement on a full aircraft model due to the requirements of the balance layout. DPIV technology has high measurement accuracy and is mostly used to measure the resistance of hypersonic internal flow channels. However, due to its high cost, it is not suitable for early scheme selection from an engineering perspective. At present, the ventilation model force measurement test method is often used in aircraft development, and CFD is used to calculate the resistance of the internal flow channel. However, similarly, the correction of the internal resistance of the ventilation model is still mainly carried out by installing an external pressure measuring rake on the tail strut of the model to measure the total and static pressures at the outlet of the ventilation duct, and then convert them into the internal flow channel resistance. Although this method is currently widely used in wind tunnel tests in my country, it has the following defects: the rake body affects the flow at the bottom of the model, thereby affecting the forebody resistance; the flow at the bottom of the model is complex, which affects the measurement of the rake body and affects the accuracy of the internal resistance.

[0003] Therefore, it is urgent to propose an internal flow resistance measurement device and method based on thrust calibration to solve the above technical problems. Summary of the invention

[0004] The purpose of the research and development of the present invention is to solve the problem of avoiding the measurement error caused by pressure integration, ensuring that there is no interference at the bottom of the nacelle model, improving the accuracy of the internal flow resistance measurement, and reducing the cost of the internal flow resistance measurement test. A brief overview of the present invention is given below to provide a basic understanding of certain aspects of the present invention. It should be understood that this overview is not an exhaustive overview of the present invention. It is not intended to determine the key or important parts of the present invention, nor is it intended to limit the scope of the present invention.

[0005] The technical solution of the present invention: Solution 1: An internal flow resistance measurement device based on thrust calibration, comprising an inlet total pressure regulating device, a flow measuring device, a thrust measuring device, an inlet measuring section, a connecting section, a nacelle model, a back pressure tank and a back pressure regulating device, wherein the flow measuring device, the thrust measuring device, the inlet measuring section, the connecting section and the nacelle model are sequentially installed downstream of the inlet total pressure regulating device, the thrust measuring device, the inlet measuring section, the connecting section and the nacelle model are all arranged in the back pressure tank, and the back pressure regulating device is installed downstream of the back pressure tank; A rectifying orifice plate and a rectifying honeycomb are installed in the inlet measuring section. The rectifying honeycomb is located downstream of the rectifying orifice plate. An inlet total temperature measuring device and an inlet total pressure measuring rake are installed at the outlet of the inlet measuring section downstream of the rectifying orifice plate.

[0006] Preferably, a backpressure cabin temperature measuring point and a backpressure cabin static pressure measuring point are arranged in the backpressure cabin.

[0007] Preferably, the upstream and downstream sides of the nacelle model are respectively arranged as a nacelle inlet and a nacelle outlet, and a nacelle outlet total pressure measuring rake and a nacelle outlet static pressure measuring point are arranged on the nacelle outlet.

[0008] Preferably, the rectifying orifice plate is provided with circular holes with equal triangular distribution, and the opening ratio of the circular holes is in the range of 0.55 to 0.65.

[0009] Preferably, the rectifying honeycomb is provided with regular hexagonal holes, and the aspect ratio of the regular hexagonal holes is in the range of 5-10.

[0010] Solution 2: A method for measuring internal flow resistance based on thrust calibration is implemented based on the internal flow resistance measurement device based on thrust calibration described in Solution 1, and includes the following steps: Step 1, controlling and adjusting the total pressure of the incoming air by the inlet total pressure regulating device, measuring the mass flow by the flow measuring device, ensuring the circulation of the airflow and measuring the load on the test piece by the thrust measuring device, measuring the ambient temperature and ambient pressure by the backpressure cabin temperature measuring point and the backpressure cabin static pressure measuring point, measuring the total inlet temperature and the total pressure of the nacelle inlet by the inlet total temperature measuring device and the inlet total pressure measuring rake respectively, measuring the total pressure of the nacelle outlet airflow by the nacelle outlet total pressure measuring rake, and measuring the static pressure of the nacelle outlet airflow by the nacelle outlet static pressure measuring point; Step 2, equivalent Mach number Ma eq Simulation: Taking the inlet total pressure measurement rake as the feedback point, the inlet total pressure regulating device is used to control the nacelle inlet total pressure to be the same as the total pressure corresponding to the wind tunnel test Mach number. At the same time, taking the static pressure measurement point of the back pressure tank as the feedback point, the back pressure regulating device is used to control the ambient pressure of the back pressure tank to be the same as the back pressure corresponding to the wind tunnel test Mach number. When the nacelle inlet total pressure and ambient pressure simultaneously meet the accuracy requirements, the equivalent Mach number Mach is determined. eq Simulation success; Step 3, parameter measurement: Equivalent Mach number Ma based on step 2 eq The internal flow aerodynamic parameters measured by the flow measurement device include: the nacelle mass flow rate m 测 , the thrust measuring device measures the nacelle thrust F g , the inlet total temperature measurement device measures the inlet total temperature T t , the inlet total pressure measurement rake measures the inlet total pressureP 0 , the nacelle outlet total pressure measurement rake measures the outlet total pressure P 0e , the outlet static pressure is measured at the nacelle outlet static pressure measuring point P e , the back pressure tank static pressure measurement point measures the ambient pressure P a ; Step 4, calculate the velocity coefficient and flow coefficient: Calculate the actual nacelle exit speed The following formula: ; In the formula, A e is the nacelle exit area; Calculate the ideal isentropic speed at the nacelle exit , as follows: ; In the formula, is the gas constant, k is the specific heat ratio; Calculate speed factor , as follows: ; In the formula, Ve is the actual nacelle exit speed, Vi is the ideal isentropic speed at the nacelle exit; The ideal isentropic mass flow rate through the nacelle is calculated as follows: ; Calculate the flow coefficient , as follows: ; In the formula, m i is the ideal isentropic mass flow rate of the nacelle; Step 5: Establish the speed factor , Flow coefficient Equivalent Mach number Ma eq Relationship: After steps 1 to 4, an equivalent Mach number Ma can be obtained eq The speed coefficient and flow coefficient Repeat steps 1 to 4 until all speed coefficients within the equivalent Mach number envelope of the wind tunnel test are obtained. and flow coefficient , and establish the equivalent Mach number-speed coefficient and equivalent Mach number-flow coefficient relationship; Step 6, calculate the internal flow resistance: According to the equivalent Mach number-speed coefficient and equivalent Mach number-flow coefficient relationship obtained in step 5, calculate the speed coefficient under the wind tunnel test Mach number and flow coefficient , the absolute value of the internal resistance is obtained, that is, the internal flow resistance , as follows: ; In the formula, V ∞ is the free flow speed.

[0011] The present invention has the following beneficial effects: 1. The present invention proposes an internal flow resistance measurement device and method based on thrust calibration, which simulates the nacelle through ground thrust measurement equipment but is not limited to the equivalent Mach number of the nacelle inlet, and measures its thrust and flow rate at the same time, thereby obtaining the speed coefficient and flow rate coefficient, and establishing the relationship between the speed coefficient, flow rate coefficient and the equivalent Mach number. Finally, the internal flow resistance data under the corresponding test state can be obtained by combining the wind tunnel test data. Starting from the definition of internal flow resistance, the consistency of the definition of the sum of the outlet momentum and the pressure difference force with the thrust of the internal flow channel is used, and the speed coefficient and flow rate coefficient are obtained by calibrating the nacelle thrust, thereby realizing the accurate measurement of the internal flow resistance of the nacelle. 2. The present invention uses a method of accurately measuring thrust and flow to obtain internal resistance, avoiding the error caused by pressure integration and greatly improving the accuracy of internal resistance measurement; 3. The bottom of the nacelle model of the present invention has no interference, will not affect the forebody resistance, will not affect the pressure measurement and affect the internal resistance measurement accuracy, the internal resistance data obtained is more accurate and the law is more reasonable; 4. The present invention can complete the measurement of the internal flow resistance by relying on the thrust measurement equipment, which greatly reduces the test cost. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] Figure 1 It is a schematic diagram of the structure of an internal flow resistance measurement device based on thrust calibration; Figure 2 This is the installation diagram of the inlet measurement section and the nacelle model.

[0013] In the figure: 1-inlet total pressure regulating device, 2-flow measuring device, 3-thrust measuring device, 4-inlet measuring section, 5-connecting section, 6-nacelle model, 7-back pressure cabin, 8-back pressure regulating device, 41-rectifying orifice plate, 42-rectifying honeycomb, 43-inlet total temperature measuring device, 44-inlet total pressure measuring rake, 61-nacelle inlet, 62-nacelle outlet, 63-nacelle outlet total pressure measuring rake, 64-nacelle outlet static pressure measuring point, 71-back pressure cabin temperature measuring point, 72-back pressure cabin static pressure measuring point. DETAILED DESCRIPTION

[0014] In order to make the purpose, technical scheme and advantages of the present invention clearer, the present invention is described below by the specific embodiments shown in the accompanying drawings. However, it should be understood that these descriptions are only exemplary and are not intended to limit the scope of the present invention. In addition, in the following description, the description of well-known structures and technologies is omitted to avoid unnecessary confusion of the concept of the present invention.

[0015] The connection mentioned in the present invention is divided into fixed connection and detachable connection. The fixed connection is a non-detachable connection including but not limited to conventional fixed connection methods such as folding connection, rivet connection, bonding connection and welding connection. The detachable connection includes but not limited to conventional detachable methods such as threaded connection, snap connection, pin connection and hinge connection. When the specific connection method is not clearly defined, it is assumed that at least one connection method can always be found in the existing connection methods to achieve the function. Those skilled in the art can choose according to their needs. For example: a fixed connection is selected as a welding connection, and a detachable connection is selected as a hinge connection.

[0016] Specific implementation method 1: Combination Figure 1-Figure 2 The present embodiment is described. The present embodiment is an internal flow resistance measurement device based on thrust calibration, comprising an inlet total pressure regulating device 1, a flow measuring device 2, a thrust measuring device 3, an inlet measuring section 4, a connecting section 5, a nacelle model 6, a back pressure tank 7 and a back pressure regulating device 8. The flow measuring device 2, the thrust measuring device 3, the inlet measuring section 4, the connecting section 5 and the nacelle model 6 are sequentially installed downstream of the inlet total pressure regulating device 1. The thrust measuring device 3, the inlet measuring section 4, the connecting section 5 and the nacelle model 6 are all arranged in the back pressure tank 7. The back pressure regulating device 8 is installed downstream of the back pressure tank 7. The inlet total pressure regulating device 1 has the function of adjusting the airflow pressure in real time with high precision, the flow measuring device 2 has the function of measuring the gas mass flow in real time with high precision, the thrust measuring device 3 has ventilation, airtightness and high-precision thrust measurement functions, which can ensure the circulation of airflow and accurately measure the load on the test piece. The vacuum tank or vacuum pump connected to the rear end of the back pressure regulating device 8 can realize the static pressure simulation in the back pressure cabin, and the connecting section 5 realizes a smooth transition between the inlet measuring section 4 and the nacelle model 6 to improve the uniformity of the inlet airflow of the test piece.

[0017] A rectifying orifice plate 41 and a rectifying honeycomb 42 are installed in the inlet measuring section 4. The rectifying honeycomb 42 is located downstream of the rectifying orifice plate 41. An inlet total temperature measuring device 43 and an inlet total pressure measuring rake 44 are installed at the outlet of the inlet measuring section 4 downstream of the rectifying orifice plate 41.

[0018] The backpressure chamber 7 can ensure the stability of the environmental pressure of the test piece, and a backpressure chamber temperature measuring point 71 and a backpressure chamber static pressure measuring point 72 are arranged in the backpressure chamber 7 .

[0019] The upstream and downstream sides of the nacelle model 6 are respectively provided with a nacelle inlet 61 and a nacelle outlet 62 , and the nacelle outlet 62 is provided with a nacelle outlet total pressure measuring rake 63 and a nacelle outlet static pressure measuring point 64 .

[0020] The rectifying orifice plate 41 is provided with circular holes distributed in equal triangles, and the opening ratio of the circular holes is in the range of 0.55 to 0.65.

[0021] The rectifying honeycomb 42 is provided with regular hexagonal holes, and the aspect ratio of the regular hexagonal holes is in the range of 5-10.

[0022] Specific implementation method 2: Combination Figure 1-Figure 2 This embodiment is described. A method for measuring internal flow resistance based on thrust calibration in this embodiment is implemented based on an internal flow resistance measuring device based on thrust calibration described in the first embodiment, and includes the following steps: Step 1, the inlet total pressure regulating device 1 controls the total pressure of the incoming air, the flow measuring device 2 measures the mass flow, the thrust measuring device 3 ensures the circulation of the airflow and measures the load on the test piece, the back pressure cabin temperature measuring point 71 and the back pressure cabin static pressure measuring point 72 measure the ambient temperature and ambient pressure, the inlet total temperature measuring device 43 and the inlet total pressure measuring rake 44 measure the inlet total temperature and the nacelle inlet total pressure respectively, the nacelle outlet total pressure measuring rake 63 measures the nacelle outlet airflow total pressure, and the nacelle outlet static pressure measuring point 64 measures the nacelle outlet airflow static pressure; Step 2, equivalent Mach number Ma eq Simulation: Taking the inlet total pressure measurement rake 44 as the feedback point, the inlet total pressure regulating device 1 is used to control the nacelle inlet total pressure to be the same as the total pressure corresponding to the wind tunnel test Mach number. At the same time, taking the back pressure tank static pressure measurement point 72 as the feedback point, the back pressure regulating device 8 is used to control the ambient pressure of the back pressure tank 7 to be the same as the back pressure corresponding to the wind tunnel test Mach number. When the nacelle inlet total pressure and the ambient pressure simultaneously meet the accuracy requirements, the equivalent Mach number Mach is determined. eq Simulation success; Step 3, parameter measurement: Equivalent Mach number Ma based on step 2 eq The internal flow aerodynamic parameters measured by the flow measurement device 2 include: the nacelle mass flow rate m 测 , the thrust measuring device 3 measures the nacelle thrust F g , the inlet total temperature measuring device 43 measures the inlet total temperature T t , the inlet total pressure measurement rake 44 measures the inlet total pressure P 0 , Nacelle outlet total pressure measurement rake 63 measures the outlet total pressure P 0e , the outlet static pressure is measured at the nacelle outlet static pressure measuring point 64P e , the ambient pressure is measured at the static pressure measuring point 72 of the back pressure tank P a ; Step 4, calculate the velocity coefficient and flow coefficient: Calculate the actual nacelle exit speed , as follows: ; In the formula, A e is the nacelle exit area; Calculate the ideal isentropic speed at the nacelle exit , as follows: ; In the formula, is the gas constant, k is the specific heat ratio; Calculate speed factor , as follows: ; In the formula, Ve is the actual nacelle exit speed, Vi is the ideal isentropic speed at the nacelle exit; The ideal isentropic mass flow rate through the nacelle is calculated as follows: ; Calculate the flow coefficient , as follows: ;

[0023] In the formula, m i is the ideal isentropic mass flow rate of the nacelle; Step 5: Establish the speed factor , Flow coefficient Equivalent Mach number Ma eq Relationship: After steps 1 to 4, an equivalent Mach number Ma can be obtained eq The speed coefficient and flow coefficient Repeat steps 1 to 4 until all speed coefficients within the equivalent Mach number envelope of the wind tunnel test are obtained. and flow coefficient And establish the equivalent Mach number-speed coefficient and equivalent Mach number-flow coefficient relationship through appropriate data processing methods such as data difference, data fitting, least square method, etc.; For example, the equivalent Mach number-speed coefficient and equivalent Mach number-flow coefficient relationship are established by the least squares method: Assume that the mathematical model of the time-invariant dynamic process is: (5-1) In the formula and is the input and output of the system; It is noise; and is a polynomial defined as: (5-2) Where: ) is a polynomial The remainder of ) is a polynomial The remainder of n For polynomial The order of m For polynomial The order of k is the number of data points.

[0024] The question now is how to exploit the system Sequence, Estimated Polynomial and The unknown coefficients in , defined as: (5-3) Then equation (5-1) can be transformed into a standard least squares format: (5-4) The above formula (5-4) can be written as a linear equation system in the following form: (5-5) in: ; ; The least squares criterion It can be: (5-6) Minimization , the system coefficient can be obtained Estimated value of The general valuation formula for least squares estimation is given below: (5-7) The corresponding method is called the least squares method. By using this method, the equivalent Mach number-speed coefficient and the equivalent Mach number-flow coefficient relationship can be obtained accordingly.

[0025] Step 6, calculate the internal flow resistance: According to the equivalent Mach number-speed coefficient and equivalent Mach number-flow coefficient relationship obtained in step 5, calculate the speed coefficient under the wind tunnel test Mach number and flow coefficient , the absolute value of the internal resistance is obtained, that is, the internal flow resistance , as follows: ; In the formula, V ∞ is the free flow speed.

[0026] It should be noted that in the above embodiments, as long as the technical solutions are not contradictory, they can be arranged and combined, and those skilled in the art can exhaust all possibilities based on the mathematical knowledge of arrangement and combination. Therefore, the present invention will no longer describe the technical solutions after arrangement and combination one by one, but it should be understood that the technical solutions after arrangement and combination have been disclosed by the present invention.

[0027] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. An internal flow resistance measurement device based on thrust calibration, characterized in that: The invention comprises an inlet total pressure regulating device (1), a flow measuring device (2), a thrust measuring device (3), an inlet measuring section (4), a connecting section (5), a nacelle model (6), a back pressure tank (7) and a back pressure regulating device (8); the flow measuring device (2), the thrust measuring device (3), the inlet measuring section (4), the connecting section (5) and the nacelle model (6) are sequentially installed downstream of the inlet total pressure regulating device (1); the thrust measuring device (3), the inlet measuring section (4), the connecting section (5) and the nacelle model (6) are all arranged in the back pressure tank (7); and the back pressure regulating device (8) is installed downstream of the back pressure tank (7); A rectifying orifice plate (41) and a rectifying honeycomb (42) are installed in the inlet measurement section (4); the rectifying honeycomb (42) is located downstream of the rectifying orifice plate (41); and an inlet total temperature measuring device (43) and an inlet total pressure measuring rake (44) are installed at the outlet of the inlet measurement section (4) downstream of the rectifying orifice plate (41).

2. The internal flow resistance measurement device based on thrust calibration according to claim 1, characterized in that: A backpressure chamber temperature measuring point (71) and a backpressure chamber static pressure measuring point (72) are arranged in the backpressure chamber (7).

3. The internal flow resistance measurement device based on thrust calibration according to claim 2, characterized in that: The upstream and downstream sides of the nacelle model (6) are respectively provided with a nacelle inlet (61) and a nacelle outlet (62), and the nacelle outlet (62) is provided with a nacelle outlet total pressure measuring rake (63) and a nacelle outlet static pressure measuring point (64).

4. The internal flow resistance measurement device based on thrust calibration according to claim 3, characterized in that: The rectifying orifice plate (41) is provided with circular holes distributed in an equitriangular pattern, and the opening ratio of the circular holes is in the range of 0.55 to 0.

65.

5. The internal flow resistance measurement device based on thrust calibration according to claim 4, characterized in that: The rectifying honeycomb (42) is provided with regular hexagonal small holes, and the aspect ratio of the regular hexagonal small holes is in the range of 5 to 10.

6. A method for measuring internal flow resistance based on thrust calibration, which is implemented by relying on the device for measuring internal flow resistance based on thrust calibration as claimed in claim 5, characterized in that: The following steps are involved: Step 1, controlling and adjusting the total pressure of the incoming air by the inlet total pressure regulating device (1), measuring the mass flow by the flow measuring device (2), ensuring the circulation of the airflow and measuring the load on the test piece by the thrust measuring device (3), measuring the ambient temperature and the ambient pressure by the backpressure cabin temperature measuring point (71) and the backpressure cabin static pressure measuring point (72), measuring the inlet total temperature measuring device (43) and the inlet total pressure measuring rake (44) respectively measuring the inlet total temperature and the nacelle inlet total pressure, measuring the nacelle outlet total pressure measuring rake (63) measuring the nacelle outlet airflow total pressure, and measuring the nacelle outlet static pressure measuring point (64) measuring the nacelle outlet airflow static pressure; Step 2, equivalent Mach number Ma eq Simulation: With the inlet total pressure measurement rake (44) as the feedback point, the inlet total pressure regulating device (1) is used to control the nacelle inlet total pressure to be the same as the total pressure corresponding to the wind tunnel test Mach number. At the same time, with the back pressure tank static pressure measurement point (72) as the feedback point, the back pressure regulating device (8) is used to control the ambient pressure of the back pressure tank (7) to be the same as the back pressure corresponding to the wind tunnel test Mach number. When the nacelle inlet total pressure and the ambient pressure simultaneously meet the accuracy requirements, the equivalent Mach number Mach is determined. eq Simulation success; Step 3, parameter measurement: Equivalent Mach number Ma based on step 2 eq The internal flow aerodynamic parameters measured below include: the mass flow rate of the nacelle measured by the flow measurement device (2) m 测 , the thrust measuring device (3) measures the nacelle thrust F g , the inlet total temperature measuring device (43) measures the inlet total temperature T t , the inlet total pressure measuring rake (44) measures the inlet total pressure P 0 , the nacelle outlet total pressure measuring rake (63) measures the outlet total pressure P 0e , the outlet static pressure is measured at the nacelle outlet static pressure measuring point (64) P e , the ambient pressure is measured at the static pressure measuring point (72) of the back pressure tank P a ; Step 4, calculate the velocity coefficient and flow coefficient: Calculate the actual nacelle exit speed , as follows: ； In the formula, A e is the nacelle exit area; Calculate the ideal isentropic speed at the nacelle exit , as follows: ； In the formula, is the gas constant, k is the specific heat ratio; Calculate speed factor , as follows: ； In the formula, Ve is the actual nacelle exit speed, Vi is the ideal isentropic speed at the nacelle exit; The ideal isentropic mass flow rate through the nacelle is calculated as follows: ； Calculate the flow coefficient , as follows: ； In the formula, m i is the ideal isentropic mass flow rate of the nacelle; Step 5: Establish the speed factor , Flow coefficient Equivalent Mach number Ma eq Relationship: After steps 1 to 4, an equivalent Mach number Ma can be obtained eq The speed coefficient and flow coefficient Repeat steps 1 to 4 until all speed coefficients within the equivalent Mach number envelope of the wind tunnel test are obtained. and flow coefficient , and establish the equivalent Mach number-speed coefficient and equivalent Mach number-flow coefficient relationship; Step 6, calculate the internal flow resistance: According to the equivalent Mach number-speed coefficient and equivalent Mach number-flow coefficient relationship obtained in step 5, calculate the speed coefficient under the wind tunnel test Mach number and flow coefficient , the absolute value of the internal resistance is obtained, that is, the internal flow resistance , as follows: ； In the formula, V ∞ is the free flow speed.

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