Drag Prediction of Two Production Rotor Hub Geometries

This paper presents the results of the application of an unstructured commercial flow solver to the calculation of the hub drag for 1/2 scale models of the S-92A and the UH-60A hubs. The prediction process mimicked the wind tunnel test procedure of the model build-up by component geometry, but in reverse order. The S-92A study used six configurations and the UH-60A used three. A key element of this effort was the demonstration that modern grid generation capabilities remove the grid generation bottleneck for these very complex geometries. Blind calculations were performed for all of the configurations and are shown to agree with the experimental data to within 7 percent error or on any of configurations without any reruns. These results indicate that the use of CFD with modern grid generation tools can be used to provide reasonable absolute drag predictions and potentially be used to discriminate between different component designs to reduce rotor hub drag in a timely manner.