This paper presents an experimental study of the influence of viscous flows on the aerodynamic behaviour of waveriders. This investigation was carried out in the MARHy facility, under supersonic and rarefied flow conditions. Three supersonic and low density flow conditions were tested operating at Mach 2 and 4 with free stream pressures of 8 Pa and 2.67 Pa giving slip regime flows. Knudsen numbers associated with these flow conditions and this test model are between 2.79 $\times$ 10^-3 and 7.33 $\times$ 10^-4. In terms of pressure, these conditions are similar at altitudes between 50 km and 80 km. The studied waverider has a geometry proposed in the literature and optimised for a Mach 10 flow and an altitude of 50 km. The purpose of this work is to experimentally analyse how viscous effects will affect the aerodynamic performances of the waverider in off-design conditions. This work is based on the analysis of the upper and lower shock wave angles obtained from glow discharge imaging technique for different angles of attack and the three operating conditions. Results showed that the evolution of shock wave angles are Mach number dependent, as predicted by the inviscid shock relations, but also strongly depends on the flow pressure. From these experimental results, fitting equations have been established to predict the variation of upper and lower shock angles with the flow density, Mach number as a function of the angle of attack in continuum and especially in slip regime. Shock wave angles behaviour are compared to measured Lift-to-Drag ratio. Comparison presents a similar behaviour with flows conditions and shows that viscous layers appearing at low densities have a great influence on aerodynamic forces.

本文介绍了粘性流对乘波器气动性能影响的实验研究。这项调查是在 MARHy 设施中，在超音速和稀薄流动条件下进行的。测试了三种超音速和低密度流动条件，以 2 和 4 马赫运行，自由流压力为 8 Pa 和 2.67 Pa，产生滑流状态。与这些流动条件和该测试模型相关的 Knudsen 数在 2.79 之间$\times$10 ^-3和 7.33$\times$10 ^-4. 就压力而言，这些条件在 50 公里到 80 公里之间的高度是相似的。所研究的乘波器具有文献中提出的几何形状，并针对 10 马赫的气流和 50 公里的高度进行了优化。这项工作的目的是通过实验分析粘性效应将如何影响非设计条件下乘波器的空气动力学性能。这项工作基于对辉光放电成像技术在不同攻角和三种操作条件下获得的上下冲击波角的分析。结果表明，冲击波角度的演变与马赫数有关，正如无粘性冲击关系所预测的那样，但也强烈依赖于流动压力。从这些实验结果来看，已经建立了拟合方程来预测上下激波角随流动密度、马赫数作为连续介质攻角的函数，特别是在滑动状态下的变化。冲击波角度行为与测量的升阻比进行比较。比较显示了与流动条件类似的行为，并表明以低密度出现的粘性层对空气动力有很大的影响。