喷流对飞机尾流涡影响的试验研究

飞机产生的尾流涡,特别是大尺度的翼尖涡,对尾随其后的飞行器是非常有害的,本文旨在探索利用飞机发动机产生的喷流加速尾流涡消亡的方法。试验采用简化的飞机模型(有尾翼),建立了包含一对翼尖涡及一对反向旋转的尾翼涡(通过以负迎角安装尾翼得到)的4涡尾流系统。在无外来扰动的情况下,不同的尾翼设置下得到的尾翼涡对翼尖涡的作用效果不同,有的能导致翼尖涡提前消亡,有的则不能。考察了不同强度的喷流对不同4涡尾流系统的影响,且作为对比,对无尾翼(2涡系统)及无喷流下的各种情况也分别作了观测。试验在拖曳水槽中进行,运用体视粒子图像测速(SPIV)技术,观测了与模型拖曳方向垂直的、从机翼后缘到下游约45翼展间均布的一系列切面。结果表明:当喷流直接作用于涡时,其效果主要取决于两者之间的初始距离及相对强度;而当喷流作用于整个4涡尾流系统时,其引入的扰动对不同的系统均能起到一定程度的改善作用,这种作用的关键在于利用喷流优化对翼尖涡进行扰动的机制,而不仅仅取决于喷流的强度。

Experimental Investigation of Influence of Jets on Aircraft Wake Vortices

Wake vortices, especially large-scale tip vortices generated by airplanes, are hazardous for following aircraft. This article tries to explore a way to accelerate wake vortex decay through the jets spouted out of the aeroengine. In the experiment, a simplified aircraft model (with tail wing) is employed to construct a 4-vortex wake system consisting of a pair of tip vortices and a pair of counter rotating tail plane vortices. Without external disturbance, effects of vortices generated by the tail plane with different configurations acting on tip vortices differ: some tail plane vortices can lead to the acceleration of tip vortex disintegration, while others cannot. The influence of jets with different intensities on different 4-vortex systems is studied. As a contrast, a 2-vortex systems (without tail wing) with and without jets are also observed. The experiment is carried out in a water towing tank. A stereo particle image velocimetry (SPIV) system is employed to observe and measure a series of sections which are perpendicular to the towing direction and distributed uniformly between the tailing edge of the main wing and the position of 45 spans downstream. The result indicates that, when the jet is acting on the vortex directly, the effect depends on the original distance and relative strength between them; when the jet is acting on the overall 4-vortex wake system, the interruption caused by the jet can accelerate the destruction of various 4-vortex systems to a certain degree. The key is how to use jets to optimize the interaction mechanism of disturbance to the tip vortex, rather than merely the intensity of jets.