Dynamic Mesh Analyses of Helicopter Rotor-Fuselage Flow Interaction in Forward Flight

Unsteady compressible flow analyses of helicopter rotor-fuselage interaction in hover and forward flight conditions are carried out using commercially available computational fluid dynamics (CFD) solver FLUENT. The individual effects of each component on the flow are investigated by simulating the isolated fuselage and the isolated rotor configurations. Then, the rotor-fuselage interaction problem is analyzed. Azimuthal variations of the flap and pitch motions of the blades are prescribed a priori as a first-order Fourier series through a user-defined function feature of the code. The prescribed blade motion may result in meshes with undesirable grid qualities, which may lead to unphysical solutions. A non-overset dynamic mesh motion method that applies volume mesh deformation and cell remeshing within a priori organized block mesh structure is used to accommodate the rigid blade motion. The remeshing is performed when the grid deformation is more than a predefined skewness value of 0.95. The near wall flow region is discretized using triangular base prismatic layers. The remaining part of the computational domain is modeled by tetrahedral volume elements. The results of the present study have been compared with the experiments and other available numerical results found in literature. The present single grid methodology has given similar successful results with much lower number of grid elements, thus resulting in much shorter computing times, using modest computational power. (C) 2016 American Society of Civil Engineers.