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严重分离流动非定常效应是造成现代飞行器发生抖振的主要因素,因此,准确模拟飞行器分离流动是开展飞行器抖振研究的基础.本文在综合考虑现代计算机资源以及分离流流动模型可信度的基础上,建立了基于MDDES(Modified Delayed Detached Eddy Simulation)的分离流非定常数值模拟方法,通过对典型的战斗机大攻角分离流模拟计算,对计算方法进行了验证.在此基础上,综合利用RBF径向基函数技术与无限插值方法建立高效的、鲁棒性强的动网格技术,结合模态空间下结构动力学方程,建立了飞机气动/结构耦合抖振数值模拟平台,对某战斗机大攻角下边条涡干扰引起的垂尾抖振问题开展研究.数值结果显示:通过对流场中涡破裂位置的压力脉动的时域响应进行的频谱分析表明,不同尺度的涡结构脉动频率覆盖了垂尾的结构固有模态频率,相比较雷诺平均Navier-Stokes方程,MDDES方法能够分辨出更细致的、更高频率的小尺度涡结构;与颤振明显的区别,各阶模态位移加速度响应由自身模态所主导,一阶弯曲与一阶扭转模态存在强烈的耦合,使结构产生加速度,承受较大的惯性力载荷冲击,是引起结构疲劳的主要因素,验证了所采用数值手段和相应方法的有效性.
Severe separation of flow unsteady effects is the main factor causing chattering in modern aircraft, therefore, accurately simulating the separation flow of aircraft is the basis for the study of chattering of aircraft.According to the comprehensive consideration of modern computer resources and the credibility of the separation flow model , An unsteady flow numerical simulation method of separation flow based on Modified Delayed Detached Eddy Simulation (MDDES) was established, and the computational method was verified by a typical fighter attack angle separation flow simulation.On this basis, Radial basis function and infinite interpolation method to establish a highly dynamic and robust dynamic grid technology, combined with the structural dynamic equations under modal space, establish a numerical simulation platform for aircraft aerodynamic / structural coupling chattering, Angle of attack, the numerical results show that the spectral analysis of the time-domain response to pressure pulsations at the vortex rupture in the flow field shows that the fluctuating frequencies of vortex structures at different scales cover the Vertical structure of the natural mode frequency, compared with the Reynolds-average Navier-Stokes equation, MDDES method can And distinguish the finer and higher-frequency small-scale vortex structures. With the obvious difference of flutter, the modal displacement acceleration response of each step is dominated by the self-mode, the first-order bend strongly couples with the first-order torsional mode, The acceleration of the structure and the load impact of larger inertia force are the main factors that cause structural fatigue. The validity of numerical methods and corresponding methods are verified.