What is it about?
When a hypersonic vehicle (rocket, re-entry vehicle etc.) moves at speeds exceeding five times the speed of sound, its surface is exposed to enormous heat loads caused by friction. Injecting gas out of the surface can help to reduce this heat load. However, this gas injection also has an influence on the boundary layer. This layer, is the layer of fluid closest to a body that moves in a fluid and it can either be laminar (orderly) or turbulent. A turbulent boundary layer causes much more heating and should hence be avoided. It could thus occur that with said cooling technique turbulent is caused and hence even more heating occurs. In this study, we outline the effect of different gases on a characteristic mechanism (the second mode) that causes turbulence. A normalization could be found to draw conclusion in between the type of gas and amount of injection with respect to their influence on the instability.
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Why is it important?
Surface heating is one of the major challenges in hypersonics. Solving this issue could enable the great potential of hypersonic flight, travelling the globe much faster than ever before.
Perspectives
As an author of this article it is great to see how all the preparation work finally pays off. More than a year of designing and building the model as well as testing it in the tunnel yielded interesting results. Those will hopefully be useful in the field of hypersonic research!
Philipp Kerth
University of Oxford
Read the Original
This page is a summary of: Gas Injection into Second Mode Instability on a 7 degree Cone at Mach 7, June 2022, American Institute of Aeronautics and Astronautics (AIAA),
DOI: 10.2514/6.2022-3856.
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