Advantages exploration and flowfields of waveriders with variable Mach numbers in hypersonic regime

Variable-Mach-number waveriders (VMWs) were believed to perform well over a wide range of hypersonic velocities. However, comparisons with traditional fixed-Mach-number waveriders (FMWs) have not considered identical planforms and equal volumes. Accordingly, the alleged advantages of VMWs over a wide-speed range are not persuasive. In this study, the VMW configurations given leading-edge profiles were generated using the planform-customized waverider design method. Meanwhile, the FMW configurations featuring identical leading edges and equal volumes as the VMWs were also built to be compared. Computational fluid dynamics techniques are used to analyze the flowfields and calculate the aerodynamic forces of the equivalent configurations to explore whether wide-speed advantages truly exist for VMWs in the hypersonic regime. The results show that, compared with FMWs with identical planforms and equal volumes, VMWs offer no advantages in terms of the lift-to-drag ratio at hypersonic velocities. Moreover, the basis variable-Mach-number flowfields and therefore the caused change in waveriding surface merely influenced the longitudinal stability when the planform was fixed. Two preliminary explanations for this phenomenon are provided, and we hypothesize that traditional waveriders designed using a fixed-Mach-number flowfield achieve satisfactory wide-speed performance in the hypersonic regime. Consequently, improving the wide-speed performance for a waverider ought to focus on the sub-, trans-, and supersonic states, which dramatically deviate from the on-design state, instead of the hypersonic regime.