楔-前掠圆柱构型第Ⅱ类激波干扰气动热特性研究
TYPE Ⅱ HYPERSONIC SHOCK WAVE INTERACTION ON A SWEPT-FORWARD FIN
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摘要: 针对楔-前掠圆柱构型激波干扰, 采用数值模拟和理论分析方法, 研究了第Ⅱ类干扰下游流场结构和气动热特性随几何参数的变化规律. 数值结果表明, 在不同楔角和前掠角组合下, 第Ⅱ类干扰下游形成了3种射流结构, 分别是超声速、亚声速和跨声速射流. 其中超声速射流会导致壁面热流大幅上升, 亚声速和跨声速射流对壁面冲击较弱, 壁面热流维持在较低水平. 楔角是决定射流速度的重要因素, 小楔角下产生对热流影响较大的超声速射流, 大楔角下产生对热流影响较小的亚声速和跨声速射流. 因此在一定参数范围内, 增大楔角不仅不会造成热流上升, 反而会因为射流变为亚声速造成热流减小. 利用干扰区内局部均匀流动假设, 对亚/超声速射流的产生条件进行了理论分析与数值验证. 理论分析结果表明, 亚声速和跨声速射流这两种产生热流较小的干扰类型在一定参数范围内普遍存在, 在给定来流马赫数时, 楔角越大时越容易产生亚声速或跨声速射流. 由于采用了均匀流动假设, 给定来流马赫数下理论分析得到的亚/超声速射流临界楔角略高于CFD结果, 误差在1°左右.Abstract: An investigation of swept-forward fin shock interactions is conducted theoretically and numerically, focusing on the effects of wedge angle and swept-forward angle on the flow pattern and heat flux distribution of type II interaction. Numerical results indicate that three types of jets are observed in the downstream flow pattern of the type II interaction on the symmetry plane: supersonic, subsonic, and transonic jets. Notably, an extremely high heat flux which is caused by a supersonic jet is observed in the case where the wedge angle is 20°. In contrast, for cases with transonic and subsonic jets, the peak heat flux is significantly lower than that of the supersonic jet, due to the weakening of the wall strike effect. The study demonstrates that within a specific range of geometric parameters, increasing the wedge angle does not necessarily result in a corresponding increase in heat flux. Instead, a larger wedge angle can promote the transition of the jet from supersonic to subsonic speeds, thus leading to a reduction in heat flux. This finding challenges conventional assumptions and offers potential pathways for controlling aerodynamic heating in high-speed flows. The conditions for the generation of subsonic and supersonic jets are theoretically analyzed under the assumption of local uniform flow in the interference region and numerically verified with a freestream Mach number of 6.36. Theoretical analysis indicates that subsonic and transonic jets, which result in lower heat flux peaks, are generally present within a wide range of parameters. For a given freestream Mach number, larger wedge angles are more likely to produce subsonic or transonic jets. Due to the simplifications inherent in the uniform flow assumption, the critical wedge angles predicted for the formation of subsonic and supersonic jets were found to be slightly higher than those obtained from CFD simulations, with a discrepancy of approximately 1°.