The Effects of Ground Clearance and Boundary Layer Blockage Factor on the Aerodynamics Performance of the Hyperloop Pod and Transonic Ground-Effect Aircraft

View Video Presentation: https://doi.org/10.2514/6.2021-2586.vid The theoretical discovery of the boundarly layer blockage (BLB) persuaded Sanal flow choking and shock-wave/boundary-layer interaction is a critical physical situation that underpins the design optimization of transonic ground-effect vehicles (V.R.S.Kumar et al., Physics of Fluids, Vol. 33, No.3, 2021, DOI: 10.1063/5.0040440). The application of the BLB persuaded flow choking phenomenon is more significant in high-speed ground-effect vehicles, viz., hyperloop pod in non-vacuum medium and transonic ground-effect aircraft. The occurrence of Sanal flow choking and streamtube flow choking in such ground-effect vehicles causes wave drag and structural failures due to the generation of undesirable shock waves. Herein, in the first phase of this study, the proof of the concept of BLB persuaded external-flow-choking (EFC) at hyperloop pod (HLP), operating with low density fluid medium, in ground-effect is presented. When the ground clearance of the HLP is relatively low the evolving BLB factor from both planes (the bottom surface of the HLP and the ground) create a transient fluid-throat, leading to the Sanal flow choking in the duct flow region. At this physical situation the pressure ratio (Ptotal/Pstatic) at the region of the external flow choking is an exclusive function of the specific heat ratio of the fluid. The EFC is more prone for the high-speed magnetic levitation HLP, at near-vacuum condition, with low ground clearance. The accurate estimation of the BLB factor at the location of the EFC of the HLP at the ground-effect is presented in this manuscript as a universal yardstick for two-dimensional (2D) in silico simulation. In this paper in silico studies have been carried out for the geometry optimization of HLP and also for fixing its minimum ground clearance for prohibiting the external flow choking. We could establish herein that in addition to the tunnel-blockage-factor, the BLB factor at the ground-effect is also important for the design optimization of high-speed HLP systems for its safe-operation in any non-vacuum environment. In the second phase, comprehensive in silico studies have been carried out on transonic aircraft at ground-effect and demonstrated the possibilities of the occurrence of Sanal flow choking and shock wave generation in underneath of the aircraft. In silico studies reveal that injecting a secondary subsonic jet into the region of the Sanal flow choking negate the transonic shock waves without affecting the desirable aerodynamic performance. This is a remarkable finding for the design optimization and safe operation of transonic ground-effect vehicles. This paper is a pointer towards for the design optimization of wing-in-ground effect aircraft and hyperloop pod operating in any non-vacuum environment.