In order to investigate the low Mach number starting characteristics of hypersonic inward turning inlets

four kinds of inlets with rectangular

square

elliptical and round entry shapes were designed. Simulation method was used to investigate their unstarting/restarting flow-field structures. Results show that

the inlets with rectangular and elliptical entry shape have similar restarting Mach number while the inlet with square and round entry shape have the similar and higher restarting Mach number. Further analysis shows that the difference of restarting capability may be caused by the different aspect ratios of the entry shape

therefore

a series of inward turning inlets with different aspect ratios were designed

and their unstarting/restarting flow-field structures were investigated. Results show that the aspect ratio of the entry plays an important role in inlet starting characteristics of inward turning inlet. The larger aspect ratio means the easier inlet restarts.