Low Frequency Vibration Control Of Wind Tunnel Test Model Based On Dynamic Vibration Absorber

Wind tunnel test is one of the three major means of aerodynamic research,is the most important and effective means of experimental aerodynamic research.The tail support method of the test model is a commonly used support method for wind tunnel testing,which is mainly composed of the test model,the force measurement balance,the model support rod and the tail support mechanism,and its structural form is a typical cantilever beam structure.Due to the low stiffness of the system,it is easy to couple with the low-order pulsation frequency of the wind tunnel and cause vibration,which affects the safety and accuracy of the test.Therefore,it is necessary to carry out vibration control research on wind tunnel test models,reduce the vibration intensity of test models,ensure test safety,and improve the quality and accuracy of wind tunnel tests.Taking the Large Low-speed Wind Tunnel as the research background,the thesis carried out the low-frequency vibration control work of the wind tunnel test model based on the dynamic vibration absorber（DVA for short）,developed a DVA installed inside the head of the test model,and carried out the wind tunnel test application.The main work includes the following aspects:（1）According to the structural characteristics of the 8m low-speed wind tunnel test model and the support system,the vibration control scheme of the test model was analyzed,the vibration control scheme based on the DVA was proposed.（2）Structural modal analysis was carried out on the Large Low-speed Wind Tunnel test models and tail brace systems.The system was analyzed by structure,geometric cleanup and finite element modeling were performed by Hypermesh software,and modal analysis and calculation were performed by Abaqus software.The calculation results show that the frequency of the first-order horizontal swing vibration and the first-order up-and-down oscillation of the experimental model and the tail brace system are close to 2.5～3Hz,the first-order vibration is mainly concentrated in the model support rod,and the maximum amplitude is located in the nose part of the aircraft model.（3）The parameter optimization and structural design of the DVA were carried out.Based on the fixed-point theory,the optimization design of the mass,stiffness and damping parameters of the DVA was carried out,so that the DVA could meet the optimal homophony and optimal damping conditions.The detailed design of the DVA was carried out,and the design and installation and commissioning methods of the DVA were summarized.（4）The wind tunnel test application of the DVA was carried out to evaluate the vibration damping effect of the DVA in the first test of the Large Low-speed Wind Tunnel model test,.The wind tunnel test was carried out with AG600 aircraft stall Angle（Angle of attack 16°）.The vibration displacement signal of the aircraft model was obtained by the Opti Track optical measurement system to evaluate the inhibition effect of the DVA on the maximum amplitude,the fluctuation amplitude of the component signal of the force measurement balance was used to comprehensively determine the vibration control effect of the DVA.The results showed that the maximum displacement amplitude of the aircraft model was reduced by more than 65%,and the maximum amplitude of the balance component reading was reduced by more than 60%.The wind tunnel test proves that the DVA developed meets the expected development requirements and improves the accuracy of the wind tunnel test.The above research work provides ideas and methods for the vibration control of large-scale low-speed wind tunnel test models.