Research On Aerodynamic Multi-point Suspension Measurement Of Large-scale Model

High-speed aircraft such as supersonic weapons and new fighter jets are high-end equipment in the aerospace field.In order to ensure operational performance,the aerodynamic characteristics of the aircraft in various speed ranges and attitudes must be accurately evaluated.Wind tunnel test is an important means to obtain aerodynamic data of high-speed aircraft.However,with the continuous increase of wind tunnel test aircraft models,the limitations of traditional test methods are increasingly revealed.Therefore,an aerodynamic six-dimensional force test method for large-scale aircraft models is urgently needed.For large-scale aircraft models,the test space is limited,and it is difficult to meet the size and dynamic characteristics requirements of wind tunnel tests based on conventional support devices and measurement methods.Therefore,this paper uses piezoelectric sensors as the core test element,proposes a support method based on multi-point suspension,and develops an aerodynamic six-dimensional force test system that integrates support devices,aircraft models,and test elements.To improve the accuracy of the aerodynamic six-dimensional force test of the aircraft model in the wind tunnel test.Aiming at the problems of large-size aircraft models in traditional wind tunnel tests,such as large support interference and insufficient test space,a solution for aerodynamic sixdimensional force measurement of aircraft models based on multi-point suspension and parallel cable support is proposed.Based on the principle of six-point positioning and statics balance,the principle of measuring the six-dimensional force of the aircraft model in this support mode is deduced,the mathematical model for solving the six-dimensional force is established,and the key factors affecting the test accuracy are analyzed.Combining the above measurement principles and test system design requirements,the support device is designed and optimized,which lays the foundation for the subsequent performance research of the test system.Aiming at the support angle of the tension line in the six-dimensional force solution model,which is a key parameter that affects the measurement accuracy,a support angle image recognition program based on the Python-Open CV module is written.By comparing a variety of image preprocessing schemes,the HSV color detection algorithm is selected to extract the overall outline of the supporting line in a complex environment.Morphological operations are performed on the preliminarily extracted contours of the line,which eliminates interference such as noise while preserving the complete contours.Based on the least square method to solve the best fitting straight line of the profile of the tension line and then to solve the straight line angle.The establishment of the support angle recognition algorithm not only improves the accuracy of the six-dimensional force solution of the test system,but also provides convenience for the subsequent calibration experiments.Build and test the performance of the multi-point suspension test system.First of all,in order to ensure the test accuracy and the dynamic characteristics of the system,two unidirectional force piezoelectric sensors directly connected to the support wire are designed.The calibration results show that the above sensors have good linearity,repeatability and test accuracy.The overall test system is statically calibrated through the weight force source loading device.The experimental data is processed by the decoupling algorithm for the coupling phenomenon between the various dimensions in the experimental results;the test system is dynamically pulsed by the hammer method.Obtain the first-order natural frequencies of the system in X,Y,and Z directions.Finally,in view of the phenomenon of large inter-directional interference in some dimensions in the calibration experiment,the test system was statically simulated and analyzed by ANSYS simulation software,and the cause of inter-directional interference was explored through the simulation loading method,which provided direction for the follow-up work.The research content of this paper has further enriched the multi-dimensional force test method of wind tunnel test,and its research results can provide experimental technology reference for the rapid development of my country's aerospace industry.