EXTENSION OF THE NON-LINEAR HARMONIC METHOD TO FLOW COMPUTATIONS AROUND MOVING AND DEFORMING STRUCTURES

摘要

Extensions to the existing Non-Linear Harmonic (NLH) method in presence of moving bodies are presented. The deformations of the structures are imposed through their natural mode shapes and complex generalized displacements. A harmonic mesh deformation is performed with a Radial Basis Function (RBF) interpolation. The harmonic flow equations are modified to incorporate the harmonic evolution of the mesh cells. The method is applied to pitching airfoils. Comparisons with full unsteady time-marching computations show a good agreement between bom approaches for subsonic flows. For transonic flows, to accurately follow the high non-linear effects due to the motion of shock position, the first order linearization of the harmonic equations has to be relaxed by taking into account the crossing terms into the harmonic equations. The NLH method has also been applied to turbomachinery aero-elastic effects, such as the STCF 11 axial turbine cascade. The results are in accordance with the experimental measurements.