| Wind tunnel test is a key technical means for the research of basic science of hypersonic aerodynamics and the development of hypersonic aircraft.Compared with other wind tunnels,pulse combustion wind tunnel has the advantages of high energy efficiency,high enthalpy,high dynamic pressure and engine working time in hypersonic propulsion test at the same time.It is the key ground experimental equipment for hypersonic aerodynamics research in China.Because the high-speed incoming flow during the start-up of the pulse combustion wind tunnel will have a huge transient impact on the experimental model,and the effective experimental time of the wind tunnel is short,only 300 ms,in such a short period of time,it is a very challenging scientific problem to measure the aerodynamic force of an aircraft model.Compared with the traditional testing technology,the suspended force measurement technology has unique advantages in model support stiffness,inter-channel interference and channel sensitivity.In addition,the suspension force measurement technology places the force measurement unit outside the model and does not occupy the internal space of the model,which can successfully carry out the body-propulsion integration experiment.Therefore,it has good development prospects and research value.Although the suspension force measurement technology has many advantages and has a very wide application prospect in the pulse combustion wind tunnel test,the suspension force measurement technology is still in the early stage of research and application,and the current theoretical research on the suspension force measurement technology is not perfect.It includes the optimization of machine stiffness,the improvement of channel sensitivity,the reduction of inter-channel interference and the method of dynamic calibration.For this reason,a distributed suspension aerodynamic testing system(referred to as force measurement system)is designed and developed in this paper,which provides experimental platform support for the theoretical research of suspension force measurement technology.Based on this force measurement system,the dynamic characteristic theory and dynamic calibration method of suspension force measurement technology are studied.Based on the test principle of suspension force measurement technology and many factors that affect the test performance of suspension force measurement technology,this paper completes the principle design of the force measurement system.The overall design scheme of the force measuring system is determined,including design purpose and design requirements.According to the overall design scheme,the subsystems of the force measuring system are designed.The simulation analysis of the force measuring system is completed.The whole machine and key parts of the force measuring system are simulated and analyzed by using Ansys Workbench,including static analysis and modal analysis.The static analysis results show that the key parts of the force measuring system: strip plate,force measuring rod and experimental model meet the strength requirements,and the deformation in the work is within the allowable range,which meets the design requirements.The modal analysis results show that the natural frequency of the first six modes of the force measuring system is 65 Hz,which is higher than the external excitation frequency,which can avoid the deformation caused by resonance,and then improve the force measurement accuracy of the force measuring system.The simulation results show that the strength and dynamic performance of the force measuring system meet the operational requirements.The drawing of the machining drawing of the force measuring system and the design of the machining process of the force measuring system are completed.After the completion of the processing,the force measuring system is assembled,and the assembly effect is good and meets the operational requirements.Based on the force measuring system,the static calibration under specific working conditions is carried out.This paper introduces the purpose,method and equipment of the static calibration of the force measuring system,designs the static calibration experiment scheme,and completes the experiment.Through the arrangement and analysis of the experimental data,the static calibration formula of the force measuring system is obtained.It is verified that the force measurement system is feasible in the study of force transmission characteristics of suspension force measurement technology.Based on the force measuring system,the dynamic calibration experiments under specific working conditions are carried out.The dynamic calibration experimental scheme is designed,and the force / torque frequency response functions of nine sensors to six components of the force measurement system are obtained by using the force hammer percussion method,which puts forward a feasible method for the dynamic calibration of suspension force measurement technology.the results show that the frequency response function calculated by this method meets the operational requirements,thus demonstrating the feasibility of the force measurement system in the dynamic calibration of suspension force measurement technology. |
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