Large eddy simulation of flow characteristics in an unconfined slot impinging jet with various nozzle-to-plate distances

To study the detailed flow structure of the unconfined plane impinging jet, a 3-dimensional flow analysis is carried out focused on the flow mechanism with the non-dimensional distance, Lid, as flow parameter by using the LES turbulent technique. The symbols d and L represent the nozzle width and the nozzle-to-plate distance, respectively. Then, the flow structures along both the stream-wise and spanwise direction are investigated. For these purposes, the plane impinging jet with Reynolds number of 11,000 is analyzed. The nozzle width was fixed at 1.3mm, but the nozzle-to-plate distance was varied between 4mm and 24mm. As a result, the plane impinging jet shows different flow patterns with Lid. In conclusion, the plane impinging jet is classified into three types with the non-dimensional variable, Lid. L/d < 4: Stable impinging jet, 4<L/d <= 11: periodically-stable impinging jet and L/d >= 11: Unstable impinging jet.