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

Using unsteady Euler codes to solve aerodynamic loads, coupled with structural equations, using improved Runge-Kutta time marching method, the flutter of one-degree of freedom-buzz that often occurs in transonic flows is studied in time-domain. 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 B-type 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.