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A Fast Search Method for Eigenvalues ​​of Entropy Layer

An eigenvalue and fast technology, which is applied in the field of fast search of entropy layer eigenvalues, can solve the problems of increasing the amount of calculation, being unable to judge the entropy layer eigenvalue solution, and not easy to find the eigenvalue solution, so as to reduce time cost and facilitate entropy The effect of layer stability analysis, calculation and search speed

Active Publication Date: 2022-04-19
CALCULATION AERODYNAMICS INST CHINA AERODYNAMICS RES & DEV CENT
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  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

[0004] The disturbance in the entropy layer can be obtained by solving the modal eigenvalues ​​of the linear stability equation, but its inflection point instability characteristics are not obvious, and its eigenvalue solutions are not easy to find, which has always been a headache for scholars.
The traditional method is to "get" the correct physical understanding by "spreading points widely", but it is often time-consuming and labor-intensive and not necessarily obtained. The main reasons are: 1) Blindly setting the frequency range increases unnecessary calculations ; 2) Blindly setting the disturbance wavelength interval, it is easy to miss the correct physical understanding; 3) It is impossible to judge whether the entropy layer eigenvalue solution is a real physical understanding

Method used

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  • A Fast Search Method for Eigenvalues ​​of Entropy Layer
  • A Fast Search Method for Eigenvalues ​​of Entropy Layer
  • A Fast Search Method for Eigenvalues ​​of Entropy Layer

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Effect test

Embodiment 1

[0039] Embodiment 1: a kind of quick search method of entropy layer characteristic value, comprises steps:

[0040] S1, to obtain the laminar flow field;

[0041] S2, extract the laminar flow calculation section: transform the laminar flow field obtained in step S1 into the body-fitted coordinate system through coordinate transformation, and then use the interpolation method to interpolate the flow field to the orthogonal grid to obtain the flow field on the vertical surface Calculate the profile;

[0042] S3, find the entropy layer eigenvalue: given the initial eigenvalue to iteratively solve;

[0043] S4, physical understanding of identifying entropy layer stability: judging whether the following conditions are met: the growth rate in the preset condition is greater than 0, and the phase velocity is in the set interval; and it must be satisfied that the eigenvalues ​​in the frequency interval do not exist in isolation. The characteristic solution can be found near the eigenv...

Embodiment 2

[0045] Embodiment 2: On the basis of Embodiment 1, in step S1, the acquisition of the laminar flow field includes a sub-step: using a CFD computing system to calculate and obtain laminar flow field data, and the laminar flow field data includes a two-dimensional blunt cone shape.

Embodiment 3

[0046] Embodiment 3: On the basis of Embodiment 1, in step S3, the given initial eigenvalue includes sub-steps: the dimensionless frequency range of the entropy layer eigensolution is limited to the interval [0, 0.3], and the phase velocity It is limited to the interval [0.8, 0.9], and the interval between the phase velocities is 0.01, and the growth rate is limited to the order of 0.0001.

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Abstract

The invention discloses a fast search method for entropy layer eigenvalues, belonging to the field of aerodynamic flow stability, comprising the steps of: S1, obtaining a laminar flow field; S2, extracting a laminar flow calculation profile; S3, searching for entropy layer eigenvalues; S4, identification of physical understanding of entropy layer stability; S5, verification. The invention can find the effective eigenvalues ​​of the entropy layer, avoid the problem of not being able to find the eigenvalues, can identify the real physical understanding of the eigenvalues ​​of the entropy layer, facilitate the analysis of the stability of the entropy layer, and has the advantage of fast calculation and search speed of the eigenvalues ​​of the entropy layer , reducing the time cost.

Description

technical field [0001] The invention relates to the field of aerodynamic flow stability, and more specifically, relates to a method for quickly searching for characteristic values ​​of entropy layers. Background technique [0002] When the aircraft flies at high speed, it will be strongly compressed to form a shock wave. In the head region, the shock wave is strongly bent causing its shape to become a kind of bow, this shock wave is called a bow shock. The gas behind the bow shock is stratified due to different flow characteristics. From the surface of the aircraft to the shock, the gas is divided into a boundary layer, an entropy layer, and an outer layer in sequence. The boundary layer is a thin layer formed by the adhesion of the gas to the surface due to the viscosity of the gas; the entropy layer is the area where high entropy gradient, high temperature, and low density gas are formed after the shock wave due to the bending of the shock wave; the outer layer is the bas...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): G06F30/28G06F113/08G06F119/14
CPCG06F30/28G06F2113/08G06F2119/14
Inventor 万兵兵李晓虎陈坚强涂国华袁先旭段茂昌孙培成
Owner CALCULATION AERODYNAMICS INST CHINA AERODYNAMICS RES & DEV CENT