前体非对称涡Re效应初探及其风洞模拟技术

对不同长细比(11和6.15)的细长旋成体模型在低速风洞中完成了亚临界和 临界雷诺数(Re)的测压实验研究.结果表明,只要后体尾部截断至离二涡区足够远,就不会影响由前体二涡主控的多涡系结构,并且头部扰动与非对称涡响应之间的相关关系也保持不变,这为在常规低速风洞中通过增大旋成体直径、减小长细比来扩大Re实验范围提供了实验依据.基于此技术,临界Re下低速实验结果表明细长旋成体在层流和转捩分离区的截面压力分布有明显的区别,导致在临界Re内的侧向力较亚临界显著减小,而且头部扰动对背涡流动的主控作用明显减弱,单孔位微吹气扰动主动控制技术不再适用.

Simulation experimental technique and primary study of Reynolds number effect on vortex asymmetry at forebody

An experimental study with pressure measurement at low speed subcritical and critical Reynolds number range has been carried out for both slender body models with fineness ratios of 6.15 and 11. The results show that if the end of afterbody is far enough from the twin asymmetric vortices region, the muti-vortices system controlled by twin asymmetric vortices at forebody should be not influenced, and the correlations between manual mini-perturbation on the model nose and asymmetric vortex response are also consistent for experimental results of both models. It provides a high Reynolds simulation experimental technique in low speed wind tunnel with increasing the model diameter and decreasing the fineness ratio of test slender model. Based on this simulation technique, the results in critical Reynolds show that the sectional pressure distributions are much different at subcritical and critical Reynolds number ranges. At critical Reynolds number, the side force on the slender body is much lower, and the two-cyclebehavior of the curve C_y vs. γ is no longer existed, therefore the active control technique of asymmetric vortices with a single hole bleed perturbation is useless at critical Reynolds number range.