摘要:
要解决先进飞行器的气动/运动非线性耦合问题,就需要建立气动/飞行力学一体化的虚拟飞行试验平台,用于获取飞行器机动飞行过程中的非定常气动力特性,弄清气动/运动非线性耦合机理。2.4m×2.4m 跨声速风洞(以下简称2.4m风洞)虚拟飞行试验天平研制技术是虚拟飞行试验机理性研究的关键技术之一。由于试验模型为两段的细长结构,天平设计空间受到限制,并且载荷极不匹配。风洞试验研究要求天平不仅要实现分段模型气动力的测量,还要实现两段模型的同步小摩擦滚转运动,传统天平无法满足试验要求。新设计的天平采用一种带有轴承和心轴的环式“双天平”新结构,较好解决了载荷匹配问题以及测量与运动之间的矛盾。天平设计利用有限元软件ANSYS进行应变和应力分析与优化,并设计了耦合式电桥。天平静校和风洞试验数据表明,该天平满足风洞虚拟飞行试验机理性研究的要求。
Abstract:
The virtual flight test(VFT)is an effective test mothed for getting characteristics of unsteady aerodynamics when aircrafts maneuver and understanding the aerodynamics-move-ment nonlinear coupling mechanism.The virtual flight test balance development is a key tech-nique in 2.4m×2.4m transonic wind tunnel virtual flight test.We developed a special dedicated VFT strain-gauged balance to measure aerodynamic parameters for closed-loop control.The test model is long and thin because of being devided into two parts so that the balance design space is limited,and the design loads do not match extremely.The aerodynamic forces on the model’s two parts get worse due to this division.Computational Fluid Dynamics (CFD)results show that the maximum normal force on the aft half of the model reaches 12000N,and the pitch moment reaches 6000N·m.One challenging thing is that the wind tunnel test requires both measurement of forces on two separated model parts and the movement of those parts rolling around the axial shaft with low-friction together,so the normal balances don′t meet the requirements.Movement and measurement must be fully considered together.Through theoretical analysis and numerical simulation we optimized the structure of the new balance.A new assembly configuration with bearings and mandril is used for the balance,which is inside the balance and could rotate with the model together with low friction.A kind of serial twin-balance with the same earth end in the middle of the balance was measure forces on the two parts of the model.Eight components are set on four groups of sixteen beams which are located in four different sections.Different dimen-sions of these beams are optimized to solve the loads match problem and conflict of measurement and movement of model parts.During the course of design,the balance stress and strain analysis optimization was generated by finite element simulation method using software ANSYS,and then combined bridges are schemed.Both calibration and wind tunnel test results show that the balance meets all requirements of VFT research.
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