在Ma=6低噪声风洞中开展了半锥角7?的直圆锥边界层转捩相关实验研究.利用响应频率达到MHz量级的高频压力传感器对圆锥壁面脉动压力进行了测量,研究了高超声速圆锥边界层中扰动波的发展过程.结果表明:高超声速圆锥边界层中第二模态扰动...在Ma=6低噪声风洞中开展了半锥角7?的直圆锥边界层转捩相关实验研究.利用响应频率达到MHz量级的高频压力传感器对圆锥壁面脉动压力进行了测量,研究了高超声速圆锥边界层中扰动波的发展过程.结果表明:高超声速圆锥边界层中第二模态扰动波产生的位置以及扰动波特征频率和波长等参数受雷诺数影响较大,当单位雷诺数从2×106m^(-1)增加到8×106m^(-1)时,第二模态波的特征频率从55 k Hz增加到226 k Hz;随着单位雷诺数增加,边界层中扰动增长速度加快,第二模态波出现在圆锥表面更靠近上游的位置;相同单位雷诺数条件下,随着第二模态波的向下游传播,其特征频率逐渐减小.通过对比发现自由来流湍流度对边界层中扰动波的发展同样有较大影响,自由来流湍流度降低,边界层中的第二模态波的特征频率明显减小.利用互相关分析得出第二模态扰动波在边界层中的传播速度大约为当地主流速度的0.8—0.9倍.在1?小攻角条件下,圆锥迎风面和背风面边界层发展呈现出明显的差异,背风面边界层中扰动发展提前,第二模态波出现在更靠近上游的位置,而迎风面中扰动发展受到抑制,第二模态波特征频率更大.展开更多
The high-frequency instability on a cone at 6°angle of attack is measured in a hypersonic quiet wind tunnel with Reynolds number of 6.90×10^(6)m^(−1),and Mach number is 6.Fast-response pressure sensors are u...The high-frequency instability on a cone at 6°angle of attack is measured in a hypersonic quiet wind tunnel with Reynolds number of 6.90×10^(6)m^(−1),and Mach number is 6.Fast-response pressure sensors are used to measure the disturbance waves on the surface of the cone.The nano-tracer-based planar laser scattering(NPLS)technique is used to visualize the coherent structures of the three-dimensional boundary layer.At the plane of azimuthal angle ofθ=30°from the leeward ray,low-and high-frequency disturbance waves with the characteristic frequency of f=10–20 kHz and f=120–140 kHz are detected.From the NPLS image,the regular large-scale traveling crossflow waves structures are observed,which are related to the low-frequency instability.On the top of the traveling crossflow waves,there are a series of small-scale structures,which suggests there is strong shear on the top of the traveling crossflow waves.These small vortices likely are the secondary instability of the traveling crossflow waves,which are associated with the high-frequency instability.The disturbance waves characteristics in different planes are measured using PCB transducers.The result shows that the high-frequency instability occurs in the planes ofθ=15°-60°,and the characteristic frequency is between f=106.97-181.08 kHz.With the increase of azimuthal angle,the characteristic frequency increases obviously,which is related to the thinner boundary layer near the windward side.With the increase of the x-coordinate,the circumferential range of the high-frequency instability gradually widens.展开更多
文摘在Ma=6低噪声风洞中开展了半锥角7?的直圆锥边界层转捩相关实验研究.利用响应频率达到MHz量级的高频压力传感器对圆锥壁面脉动压力进行了测量,研究了高超声速圆锥边界层中扰动波的发展过程.结果表明:高超声速圆锥边界层中第二模态扰动波产生的位置以及扰动波特征频率和波长等参数受雷诺数影响较大,当单位雷诺数从2×106m^(-1)增加到8×106m^(-1)时,第二模态波的特征频率从55 k Hz增加到226 k Hz;随着单位雷诺数增加,边界层中扰动增长速度加快,第二模态波出现在圆锥表面更靠近上游的位置;相同单位雷诺数条件下,随着第二模态波的向下游传播,其特征频率逐渐减小.通过对比发现自由来流湍流度对边界层中扰动波的发展同样有较大影响,自由来流湍流度降低,边界层中的第二模态波的特征频率明显减小.利用互相关分析得出第二模态扰动波在边界层中的传播速度大约为当地主流速度的0.8—0.9倍.在1?小攻角条件下,圆锥迎风面和背风面边界层发展呈现出明显的差异,背风面边界层中扰动发展提前,第二模态波出现在更靠近上游的位置,而迎风面中扰动发展受到抑制,第二模态波特征频率更大.
文摘The high-frequency instability on a cone at 6°angle of attack is measured in a hypersonic quiet wind tunnel with Reynolds number of 6.90×10^(6)m^(−1),and Mach number is 6.Fast-response pressure sensors are used to measure the disturbance waves on the surface of the cone.The nano-tracer-based planar laser scattering(NPLS)technique is used to visualize the coherent structures of the three-dimensional boundary layer.At the plane of azimuthal angle ofθ=30°from the leeward ray,low-and high-frequency disturbance waves with the characteristic frequency of f=10–20 kHz and f=120–140 kHz are detected.From the NPLS image,the regular large-scale traveling crossflow waves structures are observed,which are related to the low-frequency instability.On the top of the traveling crossflow waves,there are a series of small-scale structures,which suggests there is strong shear on the top of the traveling crossflow waves.These small vortices likely are the secondary instability of the traveling crossflow waves,which are associated with the high-frequency instability.The disturbance waves characteristics in different planes are measured using PCB transducers.The result shows that the high-frequency instability occurs in the planes ofθ=15°-60°,and the characteristic frequency is between f=106.97-181.08 kHz.With the increase of azimuthal angle,the characteristic frequency increases obviously,which is related to the thinner boundary layer near the windward side.With the increase of the x-coordinate,the circumferential range of the high-frequency instability gradually widens.
