Experimental investigation on the influence of second throat throttling on transonic wind tunnel flow quality

The research and development of a new generation of advanced aeronautical and aerospace vehicles put forward higher requirements for the use of the large transonic wind tunnels. As one of the important sections of a large transonic wind tunnel, second throat can effectively control and regulate Mach number, reduce airflow instability and improve the quality of dynamic flow field in the test section. China Aerodynamics Research and Development Center (CARDC) has implemented the precise control on Mach number in 0.6m×0.6m continuous transonic wind tunnel by using the second throat with adjusting flap and center strut. The running experience of the wind tunnel has proved that second throat has a significant effect on the quality of the wind tunnel flow field. To fully understand the influence of choked second throat on transonic wind tunnel, researchers compared transonic wind tunnel flow field quality changes with analysising influence on flow stability and Ma uniformity before and after the second throat choked. The researchers even put forward some specific technical measures to improve the performance of wind tunnel, which is of great significance for the transonic wind tunnel device design and debugging operation.