Numerical studies of twin‐jet impingement for STOVL flow application

Abstract

The behaviour of turbulent jet impingement is of considerable importance to the performance of STOVL (Short Take-Off and Vertical Landing) aircraft. Theoretical analyses of the flow field produced by jet impingement on a ground surface are formulated in terms of solving the full Reynolds-Averaged Navier-Stokes (RANS) equations. This paper presents predictions of a twin-jet impingement on ground plane flow using the standard two-equation k-ε turbulence model. Predictions were performed for two impingement heights and two jet spacings. An examination of the effect of switching from first-order (Hybrid) to second-order (Quick) convection discretization was also studied. The results presented are sensibly independent of numerical influence and represent a true assessment of the performance of the turbulence model. The predictions were compared with LDV (Laser Doppler Velocimetry) experimental results. The main features of the flow field were correctly predicted. The fountain formation region was qualitatively predicted but quantitative under-prediction of fountain development characteristics was observed to be around 50%. This is probably due to fountain unsteadiness, which is not included in the steady state CFD predictions presented here.