Assessment of an unstructured mesh approach for CFD predictions of the NH90 fuselage rotor

Abstract

The five year long GOAHEAD project generated a unique and extended experimental database for CFD validation. It is one of the few experimental investigations where a full model helicopter configuration with flexible rotating blades was considered. In this work, an unstructured mesh approach was adopted in order to demonstrate the potential that existing state-of-the-art, general purpose unstructured flow solvers could offer in simulating complex flow phenomena of helicopter aerodynamics. The entire NH90 helicopter model surface and the rotating blades were discretized with triangular elements. A hybrid-type field mesh was generated, where the near wall flow region was represented by triangular base prismatic element layers and the rest of the flow domain was represented by tetrahedral elements. The rotating blades were considered rigid and enclosed in a circular disc which rotated relative to the helicopter fuselage. Time accurate computations were carried out until time periodicity was achieved only then the computed solutions were in reasonable agreement with the measurements.