| In order to be able to devastate the target effectively,hypersonic aircrafts with a sophisticated guidance system are required to maintain a high flight speed and accurate measurement of the target,which triggers the optical window facing severe thermal environment.The introduction of the film cooling can be a good solution to this problem.However,structures of the shear layer formed by the flow and cooling jet lead to a complex flow field above the optical window,which has a bad influence on the accuracy of the missile guidance system.Therefore,the meaning of study of aero-optical effect of shear layer in hypersonic flow field is to ensure the cooling efficiency and improve the imaging quality at the same time.In this paper,the experimental study on the cooling efficiency and wavefront distortion is carried out using a hypersonic optical dome with supersonic cooling jet.First,the thin film platinum resistance temperature sensor is used to measure the cooling efficiency of the optical window surface in a hypersonic and low noise wind tunnel.Moreover,there is no evident influence caused by the total pressure of the main flow and the height of the cooling jet along the direction of the cooling jet,but the increase the thickness of the initial cooling jet is,the better the cooling efficiency is.Finally,the BOS-WS system was used to study the wavefront distortion of the shear layer with different main-jet flow pressure condition,total pressure and the thickness of the initial cooling jet.It is found that the wavefront distortion is the lowest without the cooling jet.In under-pressure condition,along with the increases of the pressure ration,the wavefront distortion will increase at first and decreases in the end;In over-pressure condition,the wavefront distortion increases concomitant with increase of the pressure ratio,but on the contrary,the slope of the increase of the wavefront distortion will decrease concomitant with increase of the pressure ratio. |
PDF Full Text Request