Assessment of Urans approach for predicting twin impinging jets in a cross-flow

Abstract

Paper presented at the 9th International Conference on Heat Transfer, Fluid Mechanics and Thermodynamics, Malta, 16-18 July, 2012.A very complex flow field is present when a vertical/short take-off and landing (VSTOL) aircraft is operating in ground effect. One major concern for this kind of aircraft in ground effect is the possibility of ingestion of hot gases from the jet engine exhausts back into the engine, known as hot gas ingestion (HGI), which can increase the intake air temperature and also reduce the oxygen content in the intake air, potentially leading to compressor stall, low combustion efficiency and causing a dramatic loss of lift. It is therefore important for these flow features to be identified and modelled accurately through numerical simulations. This flow field can be represented by the configuration of twin impinging jets in a cross-flow. Accurate prediction of this complicated flow field under the Reynolds Averaged Navier-Stokes (RANS) approach (current practise in industry) is a great challenge as previous studies suggest that some important flow features cannot be captured by the Steady-RANS (SRANS) approach even with a second order Reynolds Stress Model (RSM). This paper presents a numerical study of this flow using the UnsteadyRANS approach (URANS) with a RSM and assess the capability of the URANS approach by comparing the results against the experimental data and the SRANS predictions.