整流罩母线形状对脉动压力环境的影响研究

使用隐式大涡模拟方法，研究传统球锥外形、幂次率外形以及冯·卡门外形3种母线形状对整流罩外壁面脉动压力环境的影响。研究结果表明：在跨声速条件下，3种外形都在折角区域产生激波/分离泡干扰现象，从而产生脉动压力的峰值，且峰值位置与时均激波位置基本一致；幂次率外形与冯·卡门外形能够显著减缓该区域的脉动压力环境，均方根脉动压力的极值比传统球锥外形低17%；由于分离点位置前后移动，使得母线折点与分离点之间的流动速度变化剧烈，同样会引起脉动压力的峰值，而冯·卡门母线在折点处过渡均匀，膨胀加速效应较弱，峰值并不显著。通过瞬时流场涡结构以及声压级频谱分析可知：传统球锥外形在折角之前的锥面区域湍流发展较慢，声压级要低于幂次率与冯卡门外形；分离再附后，传统球锥外形涡结构发展迅速，声压级比其他两种外形高出10 dB左右。

An Investigation of Fluctuating Pressure Environment around Rocket Fairing with Different Curvetypes

The surface fluctuating pressure environments of the rocket fairings with different curve types,namely normal spherically blunted cone,power series cone and yon Karman cone,are systematically investigated by large-eddy simulations (LES).For all the three curve types,the peak of fluctuating pressure is found at a region where shock/separation bubble interacts at a transonic Mach number.The location of the maximum value is consistent with the time-averaged station of shocks.Compared with the fluctuating pressure environment of normal spherically blunted cone,the range and peak of root-mean square pressure coefficient Cp are diminished,with the peak value being decreased by 17％ for both power series cone and von Karman cone.In particular,serious fluctuating environment could also be induced by the expansion fan,where significant flow acceleration and deceleration occur.The reattached turbulent boundary-layer develops more quickly for normal spherically blunted cone,with its noise magnitude being 10 dB larger than others.