The influence of the flat-plate leading-edge shape on laminar–turbulent transition is investigated. Experiments were carried out at a Mach number of $M_{\infty }=5$; a unit Reynolds number ${\mathit{Re}}_{1\infty }$ from $1.5\times {10}^7$ to $9\times {10}^7{\mathrm{m}}^{-1}$; and a Reynolds number ${\mathit{Re}}_{b\infty }$, based on the leading-edge thickness $b$, up to $7\times {10}^5$. Four leading-edge shapes were investigated: cylindrical, elliptical, flat face, and “smoothed” cylindrical. It has been shown that for ${\mathit{Re}}_{b\infty }<0.4\times {10}^5$, these shapes practically do not affect transition; whereas at large ${\mathit{Re}}_{b\infty }$, the laminar run can be lengthened or shortened by the leading-edge shaping. The influence of bluntness thickness on the flow parameters at transition onset is analyzed by solving the Navier–Stokes and boundary-layer equations.

研究了平板前缘形状对层流-湍流转变的影响。实验是在马赫数为${米}_{\infty }=5$; 单位雷诺数${\mathit{关于}}_{1\infty }$ 从 $1.5\times {10}^7$ 到 $9\times {10}^7{\mathrm{米}}^{-1}$; 和雷诺数${\mathit{关于}}_{乙\infty }$, 基于前沿厚度 $乙$， 取决于 $7\times {10}^5$. 研究了四种前缘形状：圆柱形、椭圆形、平面和“平滑”圆柱形。已经表明，对于${\mathit{关于}}_{乙\infty }<0.4\times {10}^5$，这些形状实际上不影响过渡；而在大${\mathit{关于}}_{乙\infty }$，层流运行可以通过前缘成形来延长或缩短。通过求解 Navier-Stokes 方程和边界层方程，分析了钝化厚度对过渡开始时流动参数的影响。