基于Euler方程的B型和C型嗡鸣特性数值研究

Numerical analysis for B-type buzz and C-type buzz basing on Euler codes

运用非定常Eu ler方程求解气动力,耦合结构运动方程,采用改进的四步龙格-库塔推进方法,在时间域内研究了音速附近发生的单自由颤振问题。其中气动力模块采用非结构网格技术进行空间离散,运用线性弹簧方法实现非结构网格的运动。空间上采用Jam son中心格式的有限体积法,时间上采用双时间推进方法。从无量纲化的结构方程出发,把M数、音速、密度、舵面刚度、转动惯量、弦长等一系列气动、结构参数对嗡鸣特性的影响归结为三个无量纲参数的影响。通过研究发现,运用非定常Eu ler方程可以模拟B型和C型嗡鸣,但不能模拟因激波附面层干扰而产生的A型嗡鸣。C型嗡鸣比B型嗡鸣发展缓慢,提高系统阻尼对于排除C型嗡鸣更有效。

Using unsteady Euler codes to solve aerodynamic loads, coupled with structural equations, using improved RungeKutta time marching method, the flutter of one-degree of freedom-buzz that often occurs in transonic flows is studied in timedomain. The unstructured meshes are used and deformed by an improved spring analogy for unsteady flow field. Finite-volume method is used for spatial discretization and the implicit scheme with dual time-stepping is used for time discretization. Based on the dimensionless structural equations, the influences of all the aerodynamic and structural parameters such as the Mach numbers, speed of sound, air density, rudder stiffness, moment of inertia and chord on the buzz characteristics are reduced to the influences of three dimensionless parameters. It is found that unsteady Euler codes can be used to simulate Btype buzz and C-type buzz, but can not be used to simulate A-type buzz driven by shock-layer interaction. C-type buzz grows slower than B-type buzz, so it is more efficient for solving C-type buzz by increasing the structural damping.