Shock wave generated due to fast moving vehicle inside Hyperloop tube is studied, especially for its interaction with structures such as tube end wall and vehicle. The generation of corresponding reflection waves and its properties are estimated using analytical modeling based on the nozzle analogy and piston analogy. The interaction of reflection wave with vehicle and its corresponding impact on vehicle drag and flow properties around the vehicle is estimated using unsteady Reynolds-averaged Navier Stokes (URANS) equations. The parametric study of vehicle drag and reflection wave properties is obtained for varying blockage ratio ( BR ), vehicle speed ( U v ), tube pressure ( p t ), and vehicle geometry. The supersonic conditions developed in the vehicle tail are found to be modified due to interaction of vehicle with reflection wave, and multiple oblique shocks are observed behind the vehicle with increased blockage ratio and vehicle speed. In addition, secondary reflection wave propagating ahead of vehicle due to interaction with shock waves leads to pressure rise ahead of vehicle. As a consequence, an instantaneous rise in drag is observed. The mitigating measure to deal with the corresponding decrease in vehicle speed is estimated based on Proportional-Integral-Derivative (PID) control theory. The PID parameters are calculated, and the timescale for vehicle speed control is studied for varying control parameters. Special features on the tube wall of type pseudo-perforated wall are simulated to obtain reduced shock strength and shock speed for incident and reflecting waves. It is observed that such features of the tube wall allow for a substantial decrease in vehicle drag by modifying the shock properties.
Rajdeep Deb (Thu,) studied this question.