Direct Comparison of Hover Prediction Workshop Results

摘要

Comparing many different CFD cases of the same problem is complicated by the use of differing meshes, solver codes, etc. The Helicopter Hover Prediction Workshop 2016 provides an opportunity to apply a standardized, automated post-processing workflow that eases dataset comparison, report generation and knowledge extraction for a diverse set of CFD results. This paper presents direct comparisons of the CFD simulation results submitted by the participants of the workshop. A standardized post-processing scheme based upon FieldView was developed that tracks a helicopter rotor tip vortex core to determine its first passage and lift distance for quantitative comparisons. For qualitative comparisons, iso-surfaces and coordinate cut planes of Q-criterion were created and saved as FieldView XDB files. These surface extracts allow interactive viewing and direct comparisons of the predicted wakes using multi window graphical displays. By comparing the rotor blade boundary surfaces against one consistent boundary surface, geometry differences were identified that may affect the comparisons. Proper comparisons require that all the datasets have similar normalizations. All appropriate normalizations were made to be consistent with PLOT3D normalization conventions. Several participants use wake filaments. These participants used FieldView particle file formats (.fvp ) that enabled the creation of images and XDB's that directly compare the filaments between the various filament based solvers and the tip vortex paths predicted by the grid based solvers. The paper herein presents select participant submissions that utilized Reynolds-averaged Navier-Stokes solvers with overset structured, overset unstructured, and hybrid Navier-Stokes/wake filaments.