Design And Implementation Of The Model Elastic Deformation Measurement System In Wind Tunnel

With the development of increasing accuracy and complexity of modern large-scale civil aircraft and transport aircraft,the disturbance from the viscosity of aircraft surface has become more complex,and the Reynolds Number effect is more prominent,which urgently requires high Reynolds number wind tunnel test data with good quality.In wind tunnel tests,the model deformation under large aerodynamic load has become a sensitive parameter with the same importance as the Reynolds number.It could cause a large error of the aerodynamic test data,and therefore the aerodynamic deformation correction is necessary.In order to improve the data quality,a model deformation measurement system with high accuracy will be built in FL-9 wind tunnel,which,as an important basic test facility,has the property of low-speed,high-pressure and high Reynolds number,to provide the technical support for the development of the advanced large-scale civil aircraft and transport aircraft.In this dissertation a model deformation video measurement system has been designed and implemented based on the mark point feature and binocular stereo vision measurement method.The key techniques of the model deformation measurement have been deeply studied.The main research contents is as follows:Firstly,the general scheme of the model deformation video measurement system is designed based on the domestic and foreign literature and the detailed analysis of the characteristics of the FL-9 low-pressure pressurized wind tunnel.The influence factors of two kinds of measurement accuracy are summarized from the influence scope.Secondly,according to the practical problem of accurately reconstructing the spatial coordinates of the marker points in the actual experimental conditions,this paper analyzes the influence of the imaging device selection,the mark point structure and the feature extraction method,the calibration of the measurement system,the layout of the camera,the influence of the air density change on the measurement The main reason for the reconstruction error of the coordinates of the space is analyzed and studied,and the solution is put forward from the angle of engineering application.Furthermore,the elastic deformation of the model support mechanism under the wind load is the main source of the model deformation measurement error.According to the ideal situation,the difference between the model position and the model position without wind at the same angle can not get accurate results.In this paper,virtual point measurement technology is proposed to eliminate the deformation error of model support mechanism.The method is based on the hypothesis of deformation of the model body in the reasonable hair test,and the fuselage rigid body is constructed with the fuselage surface marking point,and the virtual rigid wing of the current model position is obtained by the rigid body transformation.The difference between the current model wing position and the virtual rigid wing position is an accurate model deformation that successfully addresses this critical problem.Finally,The actual test results in FL-9 wind tunnel are in good agreement with the results in F1 wind tunnel test,which shows the test results are correct.The measurement accuracy of better than 0.3mm reaches the leading level in the country and can be used for practical application.