`基于轴对称流场的定前缘型线乘波体设计
WAVERIDER DESIGN WITH GIVEN LEADING-EDGE SHAPE FROM AXISYMMETRIC FLOW
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摘要: 借鉴锥导乘波体设计思路, 给定激波出口型线为圆弧, 以乘波体前缘型线作为输入获得旋成体的预设激波面, 通过逆特征线法计算轴对称流场, 并使用四叉树加快流线追踪效率, 实现了基于轴对称流场的定前缘型线乘波体设计. 以带上反外翼的双后掠外形作为基准前缘型线设计定前缘型线乘波体, 分析不同旋转轴距离对定前缘型线乘波体性能的影响. 结果表明, 基于轴对称流场乘波体设计方法所获得的乘波体外形在高超声速时均具有较高的升阻比, 且升阻比大小与容积率密切相关; 下表面激波位置与设计曲线吻合较好, 表现出良好的“乘波”特性; 随着旋转轴的距离增大, 乘波体外形的纵向稳定性逐渐降低; 偏离设计状态时, 乘波体升阻比及纵向稳定性在高超声速阶段随马赫数变化差异较小, 且在马赫数大于设计状态时仍能够呈现良好的“乘波”特性. 总体而言, 基于轴对称流场的定前缘型线乘波体设计扩大了乘波体设计空间, 但受限于逆特征线法及轴对称流场特性, 限制了适用的前缘形状, 当前方法无法准确生成头部尖锐或大后掠角外形, 针对此类局限性未来还需要进行深入研究.Abstract: Drawing on the cone-derived waverider design method, this study established an axisymmetric flow-based given leading-edge waverider design method. By taking the leading-edge of the waverider as input with an arc-shape inlet capture curve (ICC), a predetermined shock surface was generated for axisymmetric body. Employing the inverse method of characteristics (iMoC) for axisymmetric flow computation while enhancing streamline tracing efficiency through quadtree spatial partitioning, the customized leading-edge waveriders using the axisymmetric flows with different rotational axes are designed. Taking a double-swept waverider with wing anhedral as baseline leading-edge shape, the effect of the rotational axes offset distance on the waverider performance was analyzed. Results shows that customized leading-edge waveriders generated from the axisymmetric flows with different rotational axes featured high lift-to-drag ratio, showing strong correlation between lift-to-drag ratio and volume ratio. The shock wave positions in their flow fields were nearly identical, indicating promising wave-riding performance. When the rotational axes offset distance increased, the longitudinal stability of the corresponding waveriders decreased. Under off-design conditions, the lift-to-drag ratio and longitudinal stability of the waverider vary slightly with Mach number in the hypersonic regime, and maintain promising wave-riding performance when the Mach number is greater than the design Mach number. While the waverider design given leading-edge shape from axisymmetric flow expands the waverider design space, it is limited by the inherent constraints of the iMoC and axisymmetric flow properties, which restricts the applicable leading-edge shapes. The present method cannot accurately generate sharp-nosed or large-sweep-angle configurations, thus necessitating further research to improve this approach.
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