A method for solving the simulated altitude in high-speed wind tunnel tests

Abstract

The present invention belongs to the field of experimental aerodynamics and discloses a method for solving the simulated altitude in a high-speed wind tunnel test. The method for solving the simulated altitude in a high-speed wind tunnel test of the present invention includes conducting a high-speed wind tunnel test; calculating the static pressure of the incoming flow in the wind tunnel; and calculating the simulated altitude of the test. The method for solving the simulated altitude in a high-speed wind tunnel test of the present invention, based on the basic equations of fluid mechanics, through high-speed wind tunnel tests and strict theoretical derivations, establishes a relationship between the simulated altitude in a high-speed wind tunnel test and the static pressure, providing experimental and theoretical support for solving the simulated altitude in a high-speed wind tunnel test and having engineering application value.

Description

Technical Field

[0001] The present invention belongs to the field of experimental aerodynamics, and particularly relates to a method for solving the simulated altitude in a high-speed wind tunnel test. Background Art

[0002] Wind tunnel tests are the most widely used, effective, mature, and perfect research method in experimental aerodynamics. Through various types of wind tunnel tests, flow parameters can be obtained, complex flow phenomena can be understood, and a highly reliable basis can be provided for establishing practical mathematical models in basic research and engineering application research. Especially large high-speed wind tunnels play an important role in the fine design of the aerodynamics / structure / propulsion integration and the aerodynamic characteristics evaluation of advanced large aircraft.

[0003] With the continuous development of aircraft, higher requirements are put forward for the simulated parameters in wind tunnel tests. It is not only required to achieve flight Mach number simulation in wind tunnel tests, but also considering that the change in flight altitude will lead to significant differences in air density, flow field structure, etc., and at the same time, it is also required to achieve flight altitude simulation in the test, in order to accurately measure the key aerodynamic characteristic parameters such as lift, drag, and heat flux of the aircraft in different airspaces such as low altitude, middle altitude, and high altitude, evaluate the stability and reliability of the aircraft in scenarios such as high maneuverability and thermal protection, and reduce the full-airspace flight test risk of the aircraft.

[0004] Currently, the existing main high-speed wind tunnels generally use empirical formulas or chart / table lookup methods to evaluate the test simulated altitude, which have disadvantages such as incomplete unity of empirical formulas and large errors in chart / table lookup methods, and lack strict theoretical support, seriously restricting the accuracy of the evaluation of the test simulated altitude in high-speed wind tunnels and having an adverse impact on the safety of the full-airspace flight test of aircraft.

[0005] Currently, there is an urgent need to develop a method for solving the simulated altitude in a high-speed wind tunnel test. Summary of the Invention

[0006] The technical problem to be solved by the present invention is to provide a method for solving the simulated altitude in a high-speed wind tunnel test.

[0007] The method for solving the simulated altitude in a high-speed wind tunnel test of the present invention includes the following steps:

[0008] S10. Install an axial detection tube;

[0009] Fix the axial detection tube on the middle support, and set N static pressure measuring points on the axial detection tube in the model area of the high-speed wind tunnel, and connect all the static pressure measuring points to the pressure scanning valve through a hose;

[0010] S20. Conduct a high-speed wind tunnel test;

[0011] Start the high-speed wind tunnel, set the incoming flow Mach number, and after the flow field stabilizes, measure the static pressure of the axial detection tube using a pressure scanning valve ;

[0012] S30. Calculate the static pressure of the incoming flow in the wind tunnel p ;

[0013] According to the static pressure of the axial detection tube measurement results, calculate the static pressure of the incoming flow in the wind tunnel p :

[0014] ;

[0015] S40. Calculate the test simulation altitude H ;

[0016] According to the calculated result of the static pressure of the incoming flow in the wind tunnel in step S30 p calculate the test simulation altitude H :

[0017] ;

[0018] In the formula, the static pressure of the incoming flow in the wind tunnel p is in kPa, and the test simulation altitude H is in km.

[0019] Furthermore, the calculation of the test simulation altitude in step S40 H includes the following steps:

[0020] S41. Establish a relationship between the static pressure of the incoming flow in the wind tunnel at the test simulation altitude of 0 - 11 km p and the test simulation altitude H ;

[0021] According to the basic equation of hydrostatics:

[0022] ;

[0023] In the formula, is the gas density, is the acceleration due to gravity, ; is the derivative of the static pressure of the incoming flow in the wind tunnel p , is the derivative of the test simulation altitude H ;

[0024] And, the ideal gas state equation:

[0025] ;

[0026] In the formula, T is the gas temperature,R is the gas constant. For air, ;

[0027] For the test simulation altitude from 0 to 11 km, the gas temperature T varies linearly with the test simulation altitude H as follows:

[0028] ;

[0029] In the formula, is the test simulation altitude H at which = 0, the gas temperature , K is the unit of Kelvin temperature, is the gas temperature T varies linearly with the test simulation altitude H rate, , Combining the above three relationships, the differential relationship between the static pressure of the incoming flow in the wind tunnel p and the test simulation altitude H is obtained as:

[0030] ;

[0031] For the convenience of integration, using the substitution method, the above formula is transformed into:

[0032] ;

[0033] Integrating the above formula, we get:

[0034] ;

[0035] In the formula, is the integration constant. The boundary condition of the above equation is H when = 0, , Solving the integration constant , and substituting it into the above formula, we get:

[0036] ;

[0037] Substituting the known constants into the above formula, we get:

[0038] ;

[0039] In the formula, p is in the unit of kPa, H is in the unit of km. The static pressure of the incoming flow in the wind tunnel corresponding to the test simulation altitude from 0 to 11 km p ranges from , Interchanging the independent variable and the dependent variable of the above formula, we get:

[0040] ;

[0041] S42. Establish the static pressure of the wind tunnel incoming flow at the test simulation altitudes of 11 km to 25 km p and the test simulation altitude H relation;

[0042] For the test simulation altitudes of 11 km to 25 km, the gas temperature T does not vary with the test simulation altitude H According to the linear variation relation of the gas temperature T with the test simulation altitude H in step S41, the gas temperature at the test simulation altitude is obtained. The differential relation between the static pressure p in step S41 and the test simulation altitude H degenerates to:

[0043] ;

[0044] Integrating the above equation gives:

[0045] ;

[0046] In the formula, is the integration constant. The boundary condition of the above equation is when , Solve for the integration constant

[0047] ;

[0048] Substitute the known constant into the above formula to get:

[0049] ;

[0050] In the formula, p is in kPa, H is in km. The static pressure p of the wind tunnel incoming flow corresponding to the test simulation altitudes of 11 km to 25 km is in the range of

[0051] .

[0052] The method for solving the simulation altitude in high-speed wind tunnel tests of the present invention, based on the basic equations of fluid mechanics, establishes the relationship between the simulation altitude and static pressure in high-speed wind tunnel tests through high-speed wind tunnel tests and strict theoretical derivations, providing experimental and theoretical support for solving the simulation altitude in high-speed wind tunnel tests and having engineering application value. Brief Description of the Drawings

[0053] Figure 1 It is a flowchart of the method for solving the simulation altitude in high-speed wind tunnel tests of the present invention. Detailed Description of the Preferred Embodiments

[0054] The present invention will be described in detail below with reference to the drawings and embodiments.

[0055] Embodiment: As Figure 1 shown, the method for solving the simulation altitude in high-speed wind tunnel tests of this embodiment includes the following steps:

[0056] S10. Install the axial detection tube;

[0057] Fix the axial detection tube on the middle bracket, and set N static pressure measurement points on the axial detection tube in the high-speed wind tunnel model area, and connect all the static pressure measurement points to the pressure scanning valve through hoses;

[0058] S20. Conduct high-speed wind tunnel tests;

[0059] Start the high-speed wind tunnel, set the incoming flow Mach number, and after the flow field is stable, measure the static pressure of the axial detection tube using the pressure scanning valve ;

[0060] S30. Calculate the static pressure of the wind tunnel incoming flow p ;

[0061] According to the measurement result of the static pressure of the axial detection tube , calculate the static pressure of the wind tunnel incoming flow p :

[0062] ;

[0063] S40. Calculate the test simulation altitude H ;

[0064] According to the calculation result of the static pressure of the wind tunnel incoming flow p in step S30, calculate the test simulation altitude H :

[0065] ;

[0066] In the formula, the unit of the static pressure of the wind tunnel incoming flow p is kPa, and the unit of the test simulation altitude H is km.

[0067] Furthermore, the calculation test simulation height of step S40 is H The following steps are involved:

[0068] S41. Establish a wind tunnel static pressure test to simulate the static pressure at an altitude of 0~11km p Test simulation height H The relationship between

[0069] According to the basic equation of fluid statics:

[0070] ;

[0071] In the formula, is the gas density, is the acceleration due to gravity, ; The static pressure of the wind tunnel flow p The derivative of is the test simulation height H The derivative of

[0072] And, the ideal gas state equation:

[0073] ;

[0074] In the formula, T is the gas temperature, R is the gas constant, for air, ;

[0075] For the test simulation altitude of 0~11km, the gas temperature T Simulated height of the test H Linear change:

[0076] ;

[0077] In the formula, Simulate the height for the test H = 0 gas temperature, , K Kelvin is the unit of temperature. is the gas temperature T Simulated height of the test H The linear rate of change, , combining the above three relationships, we can get the static pressure of the wind tunnel flow p Test simulation height H The differential relationship of:

[0078] ;

[0079] To facilitate integration, use the substitution method to change the above formula into:

[0080] ;

[0081] Integrating the above equation gives:

[0082] ;

[0083] In the formula, is the integration constant, and the boundary condition of the above equation H = 0, Solving for the integration constant and substituting it into the above equation gives:

[0084] ;

[0085] Substituting the known constant into the above equation gives:

[0086] ;

[0087] In the formula, p is in kPa, H is in km, and the static pressure of the wind tunnel inflow corresponding to the test simulation height of 0 - 11 km p ranges from Interchanging the independent variable and the dependent variable of the above equation gives:

[0088] ;

[0089] S42. Establish the relationship between the static pressure p of the wind tunnel inflow and the test simulation height H at the test simulation height of 11 km - 25 km;

[0090] For the test simulation height of 11 km - 25 km, the gas temperature T does not change with the test simulation height H According to the linear variation relationship of the gas temperature T with the test simulation height H in step S41, the gas temperature at the test simulation height is obtained. The differential relationship between the static pressure p in step S41 and the test simulation height H degenerates to:

[0091] ;

[0092] Integrating the above equation gives:

[0093] ;

[0094] In the formula, is the integration constant, and the boundary conditions of the above equation are when , solve the integration constant , and substitute it into the above formula to obtain:

[0095] ;

[0096] Substitute the known constant into the above formula to obtain:

[0097] ;

[0098] In the formula, p has the unit of kPa, H has the unit of km, and the static pressure of the oncoming flow in the wind tunnel corresponding to the test simulation height of 11 km to 25 km p ranges from . Interchange the independent variable and the dependent variable of the above formula to obtain:

[0099] .

[0100] Although the embodiments of the present invention have been disclosed as above, they are not limited to the applications listed in the specification and the embodiments. For those skilled in the art, without departing from the principle of the present invention, all the features disclosed in the present invention, or all the steps in the disclosed methods or processes, except for mutually exclusive features and / or steps, can be combined in any way. The present invention is not limited to the specific details and the illustrated examples described herein.

Claims

1. A method for solving the simulation height of a high-speed wind tunnel test, characterized in that: The following steps are involved: S10. Install the axial detection tube; The axial detection tube is fixed on the middle bracket and set in the high-speed wind tunnel model area. N Static pressure measuring points, connect all static pressure measuring points to the pressure scanning valve through hoses; S20. Conduct high-speed wind tunnel tests; Open the high-speed wind tunnel, set the incoming flow Mach number, and after the flow field stabilizes, use the pressure scanning valve to measure the static pressure of the axial detection tube. ; S30. Calculation of static pressure of wind tunnel inflow p ; According to the static pressure of the axial detection tube Measurement results, calculation of wind tunnel inflow static pressure p : ； S40. Calculate the test simulation height H ; According to the wind tunnel static pressure in step S30 p The calculation results of the test simulation height are calculated H : ； Where, the static pressure of wind tunnel inflow is p The unit is kPa, the test simulation height H The unit is km.

2. The high-speed wind tunnel test simulation height solution method according to claim 1, characterized in that: The S40 calculation test simulation height H The following steps are involved: S41. Establish a wind tunnel static pressure test to simulate the static pressure at an altitude of 0~11km p Test simulation height H The relationship between According to the basic equation of fluid statics: ； In the formula, is the gas density, is the acceleration due to gravity, ; The static pressure of the wind tunnel flow p The derivative of is the test simulation height H The derivative of And, the ideal gas state equation: ； In the formula, T is the gas temperature, R is the gas constant, for air, ; For the test simulation altitude of 0~11km, the gas temperature T Simulated height of the test H Linear change: ； In the formula, Simulate height for test H = 0 gas temperature, , K Kelvin is the unit of temperature. is the gas temperature T Simulated height of the test H The linear rate of change, , combining the above three relationships, we can get the static pressure of the wind tunnel flow p Test simulation height H The differential relationship of: ； To facilitate integration, use the substitution method to change the above formula into: ； Integrating the above formula, we get: ； In the formula, is the integration constant, and the boundary conditions of the above equation are H =0, , solve for the integral constant , and substitute it into the above formula, we get: ； The known constant Substituting into the above formula, we get: ； In the formula, p The unit is kPa, H The unit is km. The static pressure of the wind tunnel flow corresponding to the test simulation height of 0~11km p The range is , swap the independent variable and the dependent variable in the above formula to get: ； S42. Establish a wind tunnel static pressure test to simulate the static pressure at an altitude of 11km~25km p Test simulation height H The relationship between For the test simulation altitude of 11km~25km, the gas temperature T Not with test simulation height H changes, according to the gas temperature in step S41 T Simulated height of the test H Linear change relationship, get the test simulation height Gas temperature , the static pressure of step S41 p Test simulation height H The differential relationship degenerates into: ； Integrating the above formula, we get: ； In the formula, is the integration constant, and the boundary conditions of the above equation are hour, , solve for the integral constant , and substitute it into the above formula, we get: ； The known constant Substituting into the above formula, we get: ； In the formula, p The unit is kPa, H The unit is km. The static pressure of the wind tunnel flow corresponding to the test simulation height of 11km~25km p The range is , swap the independent variable and the dependent variable in the above formula to get: 。

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