CN-122021389-A - Aerodynamic coefficient quality ejection correction method and system based on wall friction data

CN122021389ACN 122021389 ACN122021389 ACN 122021389ACN-122021389-A

Abstract

The invention relates to the technical field of aerodynamic characteristic prediction of aircrafts, in particular to a aerodynamic coefficient quality ejection correction method and system based on wall friction data, comprising the steps of obtaining hydrodynamic data of a target aircraft under the condition of no quality ejection, and calculating the local streamline length s at each grid unit i of the wall based on wall shear stress data; the method comprises the steps of calculating boundary layer outer edge parameters at each grid unit i based on wall pressure data, shear stress data and incoming flow parameters, calculating wall friction data of each grid unit i under the condition of mass ejection by referring to a friction calculation model subjected to mass ejection correction based on the boundary layer outer edge parameters and local streamline length s at each grid unit i, and obtaining the total friction of a target aircraft through integration by utilizing the wall friction data of all grid units under the condition of mass ejection, wherein the total friction is not dimensionalized, and aerodynamic coefficients are obtained. The invention improves the prediction accuracy of the reference temperature method considering the mass injection correction in the high-altitude and high-speed state.

Inventors

WANG LI
LI PENGFEI
LI GUOLIANG
LIU XIAOWEN
WU FAN
CHEN GUANGQIANG

Assignees

中国航天空气动力技术研究院

Dates

Publication Date: 20260512
Application Date: 20251219

Claims (10)

1. The aerodynamic coefficient quality ejection correction method based on wall friction data is characterized by comprising the following steps of: S1, obtaining hydrodynamic data of a target aircraft under the condition of no mass injection, wherein the hydrodynamic data comprise wall grid data, wall shear stress data and wall pressure data; s2, calculating the local streamline length S at each grid unit i of the wall surface based on the wall surface shear stress data; s3, calculating boundary layer outer edge parameters at each grid unit i based on wall pressure data, shear stress data and incoming flow parameters, wherein the boundary layer outer edge parameters comprise boundary layer outer edge pressure Density of boundary layer outer edge And boundary layer outer edge mach number Ma e ; S4, calculating wall friction data of each grid unit i under the condition of mass injection by referring to a friction calculation model subjected to mass injection correction based on boundary layer outer edge parameters and local streamline length S of each grid unit i; s5, using wall friction data of all grid cells under the condition of mass injection, and integrating to obtain the total friction of the target aircraft without dimensionalization, thereby obtaining aerodynamic coefficients.
2. The aerodynamic coefficient mass ejection correction method based on wall friction data according to claim 1, wherein in step S2, the method for calculating the local streamline length S at each grid unit i of the wall comprises: Calculating a limit flow line based on the wall shear stress data, wherein the limit flow line satisfies the following equation: In the formula, Tangential stress data of wall grid points in the x direction, the y direction and the z direction respectively; Solving the equation by adopting a 4-order range-Kutta method to obtain a streamline from the current unit i to the head stagnation point of the aircraft, and calculating to obtain the local streamline length s at each grid unit i of the wall surface.
3. The aerodynamic coefficient mass ejection correction method based on wall friction data as claimed in claim 1, wherein in step S3, boundary layer outer edge pressure at each grid cell i With corresponding wall pressure Equal.
4. The aerodynamic coefficient quality ejection correction method based on wall friction data according to claim 1, wherein in step S3, the post-shock pressure is calculated according to the total pressure relation before and after the shock Wherein, the relation of the front and back pressure of shock wave is as follows: In the formula, In order to be the pressure of the free flowing stream, In order to achieve the mach number of the incoming stream, Is the ratio of specific heat of gas.
5. The aerodynamic coefficient quality ejection correction method based on wall friction data according to claim 1, wherein in step S3, the boundary layer outer edge density at each grid unit i is calculated according to the along-streamline entropy invariance Wherein, the isentropic relation is as follows: In the formula, Is the density of the gas after shock.
6. The aerodynamic coefficient mass ejection correction method based on wall friction data according to claim 1, wherein in step S3, the method for determining the boundary layer outer edge mach number Ma e at each grid cell i is as follows: setting an initial assumption value of the boundary layer outer edge Mach number Ma e ; at the boundary layer outer edge parameters of Under the condition of adopting a reference temperature method without mass injection, calculating to obtain the wall friction coefficient ; Calculating friction coefficient of current grid cell i by wall shear stress data Wherein ρ ∞ is the incoming flow density, and u ∞ is the incoming flow speed; continuously adjusting the Mach number Ma e at the outer edge of the boundary layer until And (3) with The error is smaller than a preset threshold value, and the Mach number adopted at the moment is the final boundary layer outer edge Mach number Ma e ; Preferably, the value of the boundary layer outer edge Mach number Ma e is continuously adjusted until And (3) with The mach numbers used at this time are equal to each other, i.e., the final boundary layer outer edge mach number Ma e .
7. The aerodynamic coefficient mass ejection correction method based on wall friction data according to claim 1, wherein step S4 comprises: based on boundary layer peripheral parameters The reference temperature T * is calculated using the following formula: wherein T w is the wall temperature; Based on p e and T * , the density of the reference states is calculated using the following formula : Wherein R is a gas constant; Density based on reference state Boundary layer peripheral velocity And the local streamline length s at grid cell i, the local reynolds number Re s is calculated using the following formula: Wherein μ is a gas viscosity coefficient; according to the friction calculation model corrected by mass ejection, calculating to obtain the friction coefficient under the condition of mass ejection ; According to The dimensional friction at the grid cell i is obtained.
8. The aerodynamic coefficient mass ejection correction method based on wall friction data according to claim 1, wherein in step S4, a friction calculation model subjected to mass ejection correction is as follows: In the formula, , Re s is the local Raney number and a n is the polynomial coefficient.
9. The aerodynamic coefficient mass ejection correction method based on wall friction data according to claim 1, wherein in step S5, friction is dimensionless by actual incoming flow pressure.
10. Aerodynamic coefficient quality ejection correction system based on wall friction data, which is characterized by comprising: The data acquisition and processing module is used for acquiring wall grid data, wall shear stress data and wall pressure data of the target aircraft under the condition of no mass injection; The local streamline length calculation module is used for calculating the local streamline length s at each grid unit i of the wall surface based on the wall surface shear stress data; the boundary layer outer edge parameter calculation module is used for calculating boundary layer outer edge parameters at each grid unit i based on wall pressure data, shear stress data and incoming flow parameters; the mass ejection friction calculation module is used for calculating wall friction data of each grid unit i under the condition of mass ejection based on boundary layer outer edge parameters and local streamline length s at each grid unit i by referring to the friction calculation model subjected to mass ejection correction; And the aerodynamic coefficient generation module is used for carrying out integral and dimensionless processing on wall friction data of all grid cells under the condition of mass injection to generate an aerodynamic coefficient of the aircraft considering the mass injection effect.

Description

Aerodynamic coefficient quality ejection correction method and system based on wall friction data Technical Field The invention relates to the technical field of air-driven characteristic prediction of aircrafts, in particular to a aerodynamic coefficient quality ejection correction method and system based on wall friction data. Background In aircraft design, it is one of the primary works to obtain aerodynamic force data quickly and accurately, and these data are the basis for developing aerodynamic layout optimization, and for performing control system design and flight simulation. At present, the main means for acquiring relatively accurate aerodynamic data are wind tunnel test and Computational Fluid Dynamics (CFD) simulation, but the two means generally have the problems of long time consumption and high economic cost, and are difficult to meet the urgent requirements of large amount of data calculation and iterative analysis in the preliminary design and the optimal design stages of the aircraft. In contrast, the aerodynamic engineering prediction method has the advantages of high calculation speed and certain accuracy in results, and is widely applied to the preliminary design and the optimal design of the aircraft. For aircraft flying in high altitude, high speed environments, friction occupies a significant proportion of the total drag and the duty cycle increases rapidly with increasing altitude, having a decisive effect on the lift-drag ratio of the aircraft. In order to effectively reduce friction and aerodynamic heat, a common technical measure is "mass injection", i.e. active injection of gas through the aircraft wall facing the external flow field. The mass injection can obviously change the state of the boundary layer of the aircraft, thereby achieving the effects of drag reduction and heat reduction. In addition, under the condition of extremely high-speed flight, severe pneumatic heating causes pyrolysis of the thermal protection material, and passive mass ejection can be generated. Notably, during the initial design phase of the aircraft, aerodynamic predictions are typically calculated based on "clean" profiles without mass ejection, and the effects of mass ejection are not considered. If the quality injection effect needs to be evaluated in the later design period, the design period is greatly prolonged by re-developing large-scale aerodynamic force calculation, and the research and development cost is obviously increased. In the existing engineering prediction method, a reference temperature method is a main stream method for calculating the friction resistance of a high-altitude high-speed aircraft, the method adopts a friction resistance calculation formula of an incompressible boundary layer to calculate the friction resistance of the compressible boundary layer, and parameters in the formula are calculated by using a boundary layer reference temperature constructed manually. For plate flow, the reference temperature method can give more satisfactory results in a low-altitude and hypersonic speed state. However, the traditional reference temperature method has obvious limitations, and cannot meet the requirements of the modern high-speed aircraft on the fine design, and is characterized in that firstly, shock waves are generated by the supersonic flight of the blunt-end aircraft, the boundary layer outer edge parameters and the incoming flow parameters have large differences, the reference temperature method brings great errors if the incoming flow parameters are directly adopted for calculation, secondly, the reference temperature method friction calculation formula needs the local Reynolds number of the current calculation point, how the length during the Reynolds number calculation is selected and influences the calculation accuracy, thirdly, the high-altitude high-speed flight brings strong viscous interference effects, wall friction and pressure distribution are influenced, and the reference temperature method does not consider the influence of the effects. Therefore, there is an urgent need to develop a new method that can quickly and accurately correct and evaluate the quality ejection effect based on the existing quality-free ejection pneumatic data, so as to overcome the defects of the prior art, shorten the design period, and reduce the development cost. In view of this, the present invention has been made. Disclosure of Invention The invention aims to provide a aerodynamic coefficient quality ejection correction method and system based on wall friction data, which solve the problem that a reference temperature method cannot be applied to wall quality ejection, and improve the prediction accuracy of the reference temperature method in a high-altitude and high-speed state. In a first aspect, the invention provides a aerodynamic coefficient quality ejection correction method based on wall friction data, which comprises the following steps: S1, obtaining hydrodynamic data of