Time-Accurate Euler Computations for Rotor Flows

Kurzfassung

Two time accurate schemes for the solution of Euler equations are presented: an explicit residual averaging and an implicit LU-SSOR scheme with inner iterations. The right hand side of the LU-SSOR scheme employs the same spatial discretization as the explicit scheme. Both codes are used to compute the flow around a NACA 0012 airfoil oscillating about its quarter point. The same set of grids is used and the results are compared. A 2D and a 3D version of the explicit Runge-Kutta code are applied to calculate the flow past a rotor in non-lifting and lifting forward flight. The Runge-Kutta and the LU-SSOR scheme produced 2D solutions of the same accuracy, provided the LU-SSOR scheme was run with a sufficient number of inner iterations. In all the cases the LU-SSOR scheme required the shortest CPU-time. The comparison of 2D and 3D computations for rotor flows showed that only 3D methods can accurately predict the quantitative.