基于结合部优化的脉冲燃烧风洞测力系统动态特性优化

Joint Part Based Dynamic Property Optimum of Force Measuring System in Impulse Combustion Wind Tunnel

关键词:  脉冲燃烧风洞  测力系统  结合部  应变能密度  动态特性优化

Key words:  Impulse combustion wind tunnel  Force measuring system  Joint part  Strain energy density  Dynamic property optimization

摘要:

对脉冲燃烧风洞测力系统动态特性进行优化有助于改善风洞测力实验数据的准确性。提出了一种基于结合部动态特性优化来改善测力系统整机动态特性的方法。首先在Ansys中准确建立了风洞测力系统整机有限元模型，其中采用弹簧-阻尼模型来模拟结合部的接触特性，通过Yoshimura法计算出弹簧-阻尼单元的刚度系数和阻尼系数。其次，进行模态分析，并计算各阶模态下的测力系统应变能密度分布，基于应变能密度分布分析发现结合部为测力系统刚度最为薄弱的地方。最后，以结合部接触面压为优化变量对测力系统进行动态特性优化，对比了优化前后测力系统的前五阶固有频率和天平应变片粘贴处的频响函数，发现优化后的整机固有频率较优化前有明显的提高，最高提高了16.7%，所有应变片粘贴处的频响函数幅值较优化前有明显的降低，测力系统的动态特性有了较明显的改善，验证了该优化方法的可行性。

Abstract:

Optimizing dynamic?performance of force measuring system in impulse combustion wind tunnel can be helpful?in?improving?the?accuracy of the wind tunnel force measurement experimental data. A novel method is proposed， which is based on joint part dynamic property optimum， to improve the dynamic property of force measuring system in impulse combustion wind tunnel. To the beginning， the Ansys finite element model of force measuring system is established precisely. The spring-damper model， whose stiffness coefficient and damping coefficient can be calculated by Yoshimura method， are used to describe contact characteristic of joint part. Next， the?modal?analysis?and the calculation of strain energy density distribution for force measuring system?is carried out. On the basis of strain energy density distribution， joint part is the weakest part of stiffness in force measuring system. Finally， surface pressure of contact area working as optimization variable is conducted to optimize the dynamic?performance of force measuring system. The top 5 inherent frequencies and the frequency response function of strain gauge in wind load balance of the optimal?force measuring system are compared with original?force measuring system. Comparing with the original condition， results?show that?the inherent frequencies of force measuring system are improved efficiently， the maximum one is up to 16.7%. And the amplitude for frequency response functions of strain gauge is evidently reduced. It also shows that the dynamic characteristics of force measuring system are improved obviously. The feasibility of the proposed optimization method is validated.