壁温对钝三角翼边界层稳定性及转捩影响

Effect of wall temperature on stability and transition of hypersonic boundary layer on a blunt delta wing

选择典型的高超声速流动条件,基于线性稳定性理论研究了不同壁温条件对典型大后掠角平板钝三角翼外形高超声速三维边界层流动稳定性及转捩的影响。研究表明,壁温比的增加促进横流和第一模态波的增长,第二模态波受到抑制,钝三角翼表面N值分布的变化呈现随壁温比增加先减小后增大的特点,预示在高壁温比下(绝热壁附近,约0.8)将出现转捩反转;转捩反转的内在机理在于壁温比对不同模态彼此相反的影响规律以及在不同位置不同的影响量值,导致在低壁温比区壁温比的增加主要影响第二模态,引起转捩延迟,而在高壁温比区壁温比的增加对第一模态的影响超过了对第二模态的影响,转而造成转捩前移。

Effects of different wall temperature conditions on stabilities and transition of three-dimensional hypersonic boundary layer over a flat plate blunt delta wing with large sweep angle are studied by using linear stability theory(LST)analysis.An adiabatic wall case and three isothermal wall cases with wall-to-total temperature ratios of 0.357,0.714,which are lower than adiabatic case ratio,and 0.952,which is higher than adiabatic case ratio,are considered.The results indicate that the increase of wall-to-total temperature ratio promotes the growth of cross mode and T-S mode disturbances,while suppressing second mode disturbances,which leads to a transition reversal,the N-factor decreases first and then increases at high temperature ratio(about 0.8 near adiabatic wall condition).The mechanism of the transition reversal is the opposite influence tendency of temperature ratio on different disturbance modes,and the different influence degrees at different locations of delta wing.When there is a low temperature ratio,the increase of ratio mainly affects the second mode near center line of delta wing,resulting in the delay of transition;however,when the ratio is high,it affects cross mode and T-S mode along leading edge more than the second mode near center,which in turn causes the transition to move forward.