高超声速边界层转捩特性试验探究

通过在激波风洞中开展转捩试验，选取来流马赫数分别为6和8,单位雷诺数分别为4.1×10 6m -1 、2.6×10 7m -1 和4.4×10 7m -1 的来流条件，研究马赫数、单位雷诺数以及攻角变化对钝锥边界层和平板边界层转捩位置的影响。结果表明，攻角增大使钝锥迎风面和背风面边界层转捩位置均前移，使平板边界层转捩位置也前移；钝锥边界层在低马赫数时更容易转捩，平板边界层转捩受马赫数影响在攻角有差异时有所不同；单位雷诺数的增大促进转捩，但对于钝锥边界层而言，该参数增加到试验选定的上限时，转捩位置的变化并不明显；在转捩过程中平板边界层的脉动压力系数与热流具有相同的变化趋势。试验捕捉到了第二模态扰动。

Experimental Investigation of Hypersonic Boundary Layer Transition

Transition experiments are conducted in shock tunnel. Mach numbers of incoming flow are 6 and 8 respectively, and unit Reynolds numbers are 4.1×10 6〖KG*9〗m -1 , 2.6×10 7〖KG*9〗m -1 , and 4.4×10 7〖KG*9〗m -1 respectively. The influences of Mach number, unit Reynolds number and angle of attack on transition of the boundary layers of blunt cone and flat plate are investigated. Results show that transition locations of windward and leeward side of blunt cone both move forward when the angle of attack increases, and so does the boundary layer of flat plate. As for boundary layer of blunt cone, lower Mach number leads to earlier transition. But the Mach number effect on transition of boundary layer of flat plate varies when angle of attack changes. The increase of unit Reynolds number will lead to obviously early transition, but as for blunt cone, transition location hardly changes when Reynolds number has reached the upper limit of the selected flow conditions. In addition, varying trend of pressure fluctuation coefficient of plate boundary layer is same as heat flux in the transition process. The second mode instability is also observed in the experiment.