Study On The Flow Mechanism And Heat Transfer Characteristics Of The Multiple Turbulent Jet-to-Crossflow

Based on a control–volume numerical procedure utilizing the semi-implicit method for pressure-linked equations-consistent—SIMPLEC pressure-velocity coupling arithmetic, using the Realizable k-εturbulence model and two-layer wall function method, numerical simulation was performed to investigate the flow and heat transfer characteristics of the multiple turbulent jet-to-crossflow. The experiments were conducted by IFA 300 anemometry and the flow fields were measured. The results were contrasted with the numerical simulation and the reliability of numerical simulation was validated.The results show that the standard wall function method results in a larger separation area in the velocity fields, so the two-layer wall function method is suitable for simulating the jet-to-crossflow. In the multiple turbulent jet-to-crossflow, although all the jets have the same initial momentum, but with sheltering from the former jet, the rear jet is more difficult to bend. The wake area are found in the lee of the jet orifice, and the separation of flow appeared in the wake area. In the multiple turbulent jet-to-crossflow, the"hole inhale phenomenon"is more obvious in the lee of the first jet orifice.We got the vortex fields of the multiple turbulent jet-to-crossflow in different conditions. The developing processes of horseshoe vortex and kidney counter-rotating vortex pair are studied. The results suggest that in the multi-hole jet, until the multi-hole jet merging into a new jet, the miniature of horseshoe vortex appears, and the shape of CVP changes regularly.Through comparing and analyzing the efficiency of film cooling of the multiple turbulent jet-to-crossflow in different conditions, we got a conclusion, the film-cooling efficiency of four holes is the highest at lower jet-crossflow velocity ratio R equaling 0.5. And in the same flux of cold gas, the multi-hole jet have the best film-cooling efficiency. Aperture ratio S/D is the important factor which affect the efficiency of film cooling, and we got the best film-cooling efficiency at aperture ratio S/D equaling 2.5.