The Numerical Study of Improving the Performance of the Overexpanded SERN by Using SJA

Based on the unsteady CFD method and combined with periodic User Defined Function (UDF), the numerical study of improving the performance of the overexpanded Single Expansion Ramp Nozzle (SERN) by using Synthetic Jet Actuator (SJA) was conducted in this paper. The changes of the separation zone, thrust and lift of the SERN were studied according to the variation of the oscillatory amplitude of the SJA. It was shown that when the amplitude value of the SJA was about 20m/s under present condition, which corresponding to the mass flow ratio of the SJA to the main stream as about 3.35%, the thrust and lift of the SERN during a whole period was improved by 1.8% and 3%, separately by using the SJA. It was also shown that if the exit momentum of the SJA was strong enough to make the separation area near the expansion ramp change from “closed style” to the “open style”, the thrust and lift of the SERN could be greatly improved by 16% and 21%, separately.