典型激波针减阻降热特性及流动机理

为研究激波针对超/高超声速钝头飞行器进行减阻降热的相关特性，采用数值模拟方法对6种典型激波针构型的流动特征开展系统研究。给出了激波针长度、来流马赫数对流动特征的影响规律，并对其形成机理进行了探讨。结果显示:马赫数较低时，头部有扰流物的5种激波针在回流区即将分裂时减阻率最大；马赫数较高时，减阻率在回流区分裂前后出现局部峰值，但最大减阻率将出现在回流区分裂后更长的激波针长度下。马赫数为3时，6种构型减阻率达最大时的相对长度在0.8~1.2之间，相比而言，球型、半球型和双锥型的减阻效果最好，最大减阻率为45%~50%；圆锥型最差，为20%~25%，明显低于头部有扰流物的构型。相同的激波针长度下，头部有扰流物构型的减阻率随马赫数增大而增大，圆锥型则相反。流场回流区、分离激波、弓形激波、局部膨胀流动等导致的压力分布变化是构型整体阻力变化的主要成因。 

Drag and heat reduction characteristics and flow mechanism of typical aero-spikes

In order to study the relevant characteristics of drag and heat reduction for the supersonic/hypersonic blunt aircraft with an aero-spike，numerical simulation was used to study the flow characteristics of six kinds of typical configurations of spike systematically.The influence laws of length of spike and Mach number of inlet flow on flow characteristics were given，and the mechanisms of its formation were also discussed.The results showed that when the Mach number was low，five kinds of the spikes with a flow interferent at the head reached the maximum drag reduction rates when the recirculation region was about to split； when the Mach number was high，local peaks of drag reduction rates appeared before and after the recirculation region splitting，but the maximum drag reduction rates occurred at longer lengths of the spikes after the recirculation region splitting.When the Mach number was 3，the relative lengths of the six kinds of spikes were between 0.8 and 1.2 when the drag reduction rates were maximum，in comparison，the drag reduction effects of sphere-spike，hemisphere-spike and bicone-spike were the best，the maximum drag reduction rates were between 45% and 50%；the cone-spike was the worst，which was between 20% and 25% and was obviously lower than the configurations with a flow interferent at the head.When the lengths of the aero-spikes were the same，the drag reduction rates of the aerospikes with a flow interferent at the head increased with the increase of Mach number，while that of the cone-spike was opposite.The change of pressure distribution caused by recirculation region，separation shock，bow shock and local expansion flow of the flow fields was the main reason for the change of the overall resistance of the configurations.