Method for optically measuring shear stress of boundary layers of flow fields

A technology of shear stress and optical measurement, which is applied in the field of wind tunnel testing, can solve problems such as severe temperature influence, limited measurement sensitivity and precision, theoretical basis of measurement, and complicated mathematical derivation process, so as to improve color recognition and test accuracy degree, the effect of improving the accuracy

Active Publication Date: 2017-05-31
CHINA ACAD OF AEROSPACE AERODYNAMICS
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Problems solved by technology

Frictional balance technology uses strain electrical measurement technology to directly measure the shear stress acting on the balance sensing surface, and can directly obtain the absolute value of shear stress, but due to factors such as gap effects and temperature effects, its measurement sensitivity and a

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  • Method for optically measuring shear stress of boundary layers of flow fields
  • Method for optically measuring shear stress of boundary layers of flow fields

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Embodiment Construction

[0029] Below in conjunction with accompanying drawing and specific embodiment the present invention is described in further detail:

[0030] Such as figure 1 Shown is the flow chart of the optical measurement method. It can be seen from the figure that an optical measurement method of the boundary layer shear stress in the flow field is characterized in that it includes the following steps:

[0031] Step (1), the wind tunnel test model is made of aluminum and the surface is polished, then the surface of the model is anodized to form an oxidation protective film, and then the model is blackened to ensure that the color of the liquid crystal coating base is uniform And increase the contrast with the color of the liquid crystal coating to improve the color rendering effect of the liquid crystal coating;

[0032] Step (2), spray the mixed solution of liquid crystal and acetone on the surface of the wind tunnel test model, the ratio of liquid crystal and acetone is 1:8-1:6; form a...

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Abstract

The invention discloses a method for optically measuring shear stress of boundary layers of flow fields, and relates to the technical field of wind tunnel tests. The method includes main steps of (1), anodizing and blackening wind tunnel test models; (2), smearing liquid crystal coatings; (3), acquiring relation curves of colors of the liquid crystal coatings and shear force; (4), mounting 6 test cameras; (5), simultaneously photographing the liquid crystal coatings by the 6 test cameras to obtain images of the liquid crystal coatings; (6), removing position difference of the images photographed by the different test cameras; (7), carrying out distortion removal processing; (8), correcting identical colors of the images photographed by the various cameras; (9), acquiring model surface shear stress vector distribution results. The method has the advantages that the obtained images are clear and visual, and the method is high in measurement accuracy and sensitivity and can be used for displaying the flow fields of wind tunnels, diagnosing transition and quantitatively measuring model surface friction drag.

Description

technical field [0001] The invention relates to the technical field of wind tunnel tests, in particular to an optical measurement method for flow field boundary layer shear stress. Background technique [0002] The shear stress in the boundary layer generated by the relative motion of the flow field and the object is one of the important aerodynamic parameters in the process of aircraft development. It has a great influence on the aerodynamic / thermal performance and is the basic work in fluid mechanics. However, due to the existence of complex flow phenomena such as boundary layer transition, the prediction of shear stress is difficult for numerical simulation. And because of its small absolute value, it is also a challenge for wind tunnel test measurement. [0003] Research on surface shear stress measurement technology mainly focuses on three areas: friction balance technology and oil film technology. Frictional balance technology uses strain electrical measurement techn...

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Application Information

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IPC IPC(8): G01M9/06G01L11/02
CPCG01L11/02G01M9/06
Inventor 陈星文帅宫建姚大鹏潘俊杰
Owner CHINA ACAD OF AEROSPACE AERODYNAMICS
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