基于局部偏转吻切方法的多级压缩乘波体设计

乘波体因优异的气动特性, 被认为是突破现有“升阻比屏障”的有效途径之一, 已成为高超声速飞行器气动设计的研究热点. 针对常规单级压缩乘波前体压缩量不足的问题, 基于局部偏转吻切方法提出一种多级压缩乘波体设计方法, 实现了多道非轴对称激波的逆向乘波设计. 通过引入多道非轴对称激波, 可充分发挥乘波前体的预压缩效果, 并为复杂外形条件下的高超声速飞行器设计提供新的思路. 以基于非轴对称椭圆锥激波的两级压缩乘波体为例阐述了该多级设计方法, 并在相同条件下设计了3种不同长短轴比的两级椭圆锥压缩乘波体. 设计状态下的数值模拟结果表明, 无黏条件下, 该设计方法得到的壁面压力分布与CFD结果基本一致, 且对应气动力参数的最大误差仅为0.3%左右, 证明了该方法的可靠性. 相较于两级圆锥压缩乘波体, 长短轴比大于1的两级压缩乘波体拥有更好的压缩性能和升阻特性, 但总压恢复系数和容积特性有所下降, 而长短轴比小于1的两级压缩乘波体性能恰好与之相反. 黏性条件下, 此类乘波体的激波系结构变化不大, 两道椭圆锥激波在底部截面基本相交, 仍具备较佳的乘波特性. 

DESIGN OF MULTISTAGE COMPRESSION WAVERIDER BASED ON THE LOCAL-TURNING OSCULATING CONES METHOD

Due to its outstanding aerodynamic performance, the waverider is considered as one of the effective ways to break through the current “lift-to-drag barrier”. It has become the research hotspot for hypersonic vehicle design. However, the traditional waverider is widely generated by a single shock wave, which cause the lack of compression efficiency. To solve the aforementioned problem, a multistage compression waverider design method for non-axisymmetric shock waves, has been proposed in this paper based the local-turning osculating cones method. With the help of multiple non-axisymmetric shock waves, the pre-compression effect of the waverider forebody is able to be fully exerted, and new design ideas for the design of hypersonic vehicles under complicated geometric conditions can be provided as well. The double compression waverider with two elliptic cone shock waves was specified as an example to introduce the new proposed method in detail. Three types of double elliptic cone compression waveriders with different eccentricities were designed under the same conditions. The numerical results demonstrate that under the inviscid conditions, the wall pressure obtained by the proposed design method is basically consistent with the CFD result. The maximum error of the corresponding aerodynamic parameters is about 0.3%, which proves the reliability of this new proposed design method. Compared with the double conical compression waverider, the waverider with eccentricity larger than one has better compression performance and lift-drag characteristics, but lower total pressure recovery coefficient and volumetric efficiency. In contrast, the double compression waverider with eccentricity less than one has larger total pressure recovery coefficient and volumetric efficiency, but lower compression performance and lift-to-drag characteristics. Additionally, the shock structure of the waverider under the viscous conditions remain essentially the same, and the corresponding two elliptic cone shock waves basically intersect at the bottom section. It reveals that this kind of waverider still owns wonderful “wave-ride” characteristics when the viscosity is taken into consideration.