LARGE EDDY SIMULATION OF A FORCED TURBULENT JET IMPACTING ON A SEMI-CYLINDER

摘要

This study is devoted to a forced turbulent plane jet emerging from a slot rectangular nozzle impinging on a semi-cylindrical surface using large eddy simulation. Both forced and unforced cases are considered. The Reynolds number, based on the slot velocity and width, was 5600. The LES simulations were validated using published experimental results and contrasted against RANS models. The study is performed for a slot-to-surface distance equal to twice the nozzle width and considers two forcing frequencies equal to 400 and 800 Hz. The jet was excited using a sinusoidal inlet velocity profile at several harmonics of the preferred mode and the flow and heat transfer characteristics were analyzed. The phase averaged Nusselt number exhibited several peaks along the semi-circular target plane. Increases above the steady unforced jet values of heat transfer rates were obtained in the stagnation region and decreases were observed in the wall jet region. The fluctuations in the phase averaged surface Nusselt number are explained in terms of the interaction of organized shear layer structures with induced target wall structures.