Characteristics of Supersonic Sweeping Jet with Geometry Variation of Actuator Exits.

Supersonic sweeping jets (SWJs) have demonstrated their effectiveness across a variety of scenarios, particularly in aeronautic applications (e.g., lift enhancement). An experimental study is conducted to investigate the characteristics of SWJs emitted from actuators with different spreading angle θ and exit length θ. Schlieren visualization is used to capture the near- and far-field SWJs at nozzle pressure ratios (NPRs) ranging from 1.6 to 6.9. The results show that as NPR increases the SWJs become underexpanded when θ≠0. Different θ have an impact on the shock structure and the law of the spreading angle of jet control area θ changing with NPR. When θ is approximately 100 deg, θ increases at first and then decreases with increasing NPR, reaching up to 90 deg at high NPRs. When θ is about 50 deg, θ remains roughly constant and equal to θ. Internal flow measurements reveal that flow attachment caused by the Coanda effect plays a significant role in the mechanism that leads to a change in θ. Proper orthogonal decomposition is applied to analyze the spatial and temporal patterns. Far-field measurements show multiple sound waves propagating upstream and downstream, which generated by the supersonic SWJs. [ABSTRACT FROM AUTHOR]