细长锥边界层绊线转捩风洞自由飞试验

通过在半锥角θ_c=10°细长锥面上布置一定数量的人工绊线,促使细长锥表面边界层在相应轴向位置上发生层流向湍流转变的固定转捩,采用运动自由度不受约束的风洞自由飞试验技术研究边界层转捩对高超声速细长锥再入体无控自由飞行下的运动特性和气动特性影响规律,并与以往无人工绊线的细长锥风洞自由飞试验结果作对比.试验马赫数Ma=5.0,通过改变风洞前室总压P_0实现两个雷诺数的模拟,以模型长为特征尺寸自由流雷诺数分别为0.84×10~6和1.68×10~6.结果表明:当自由流雷诺数Re=0.84×10~6时,人工绊线尚不足以促使边界层发生转捩,有绊线的细长锥气动特性与无绊线基本一致,动稳定导数大于零;当自由流雷诺数Re=1.68×10~6时,人工绊线促使边界层发生固定转捩,细长锥的动稳定导数小于零,细长锥自由飞行动稳定.

WIND-TUNNEL FREE-FLIGHT TEST OF BOUNDARY LAYER TRANSITION INDUCED BY TRIPPED THREAD FOR SLENDER CONE 1)

This paper stduy the motion and aerodynamic characteristics affected by boundary layer transition for the hypersonic slender cone re-entry vehicle with the wind-tunnel free-flight testing which the motion freedom is not limited by artificially fixing definite number tripped thread that can produce the change of laminar to turbulent on the 10° halfangle cone surface. The experiment Mach number is Ma=5.0 and we achieve the two Reynolds number's simulation by changing the wind tunnel total pressure P₀. The free flow Reynolds number based on the model length L are 0.84×10⁶ and 1.68×10⁶, respectively. The experimental result shows that artificial tripped thread can not induce the boundary layer transition which have a similar motion and aerodynamic characteristics to the slender cone without tripped thread when the Reynolds number is Re=0.84×10⁶. When the Reynolds number Re=1.68×10⁶,artificial tripped thread can induce boundary layer transition which have a different motion and aerodynamic characteristics to the slender cone without tripped thread and the dynamic stability derivative of the slender cone is below zero which the hypersonic slender cone's motion is steady.