Impulsively starting flow problem: from incompressible tohypersonic flow

Impulsively starting flow has important applications in aero-elastics, flapping flight and flight maneuvering. In this paper we provide a state-of-art overview of the related flow characteristics, lift evolution mechanisms and analytical methods for starting flow and point out new issues for future studies. It is shown that starting flow problems have been treated separately to have independent methods and conclusions and the present survey gives a link between these two apparently unrelated problems. We point out that it lacks theoretical method and analysis for compressible starting flow at large angle of attack. As a supplementary study, we perform numerical computation of a hypersonic starting flow at high angle of attack and find a phenomenon never reported before: the lift increases from a small value to a high peak in a very short time and then drops to the steady state value also in a very short time. The methods provided in this review may be useful for studying the lift evolution of starting flow.