An aerodynamic analysis of Hyperloop breach using a scaled physical test setup and background oriented schlieren

Abstract

This master thesis investigates the aerodynamic response of the Hyperloop breach failure scenario. Using a scaled physical test setup, the air pressure inside a Hyperloop tube is lowered to 10 mbar, emulating Hyperloop conditions. By opening a breach hole inside the tube, air will flow into the tube due to the pressure difference with the outside ambient. A transparent PMMA tube is used to allow for background oriented schlieren(BOS) measurements. BOS is used to investigate shockwaves and pressure differences through the tube and to determine the feasibility of BOS for Hyperloop breach research. A ray tracing model based on Snell's law is created to relate physical test results to local pressure values inside the tube. Three tests are performed using two different sizes of breach holes. The first test is a low camera capture frequency test in which the entire pressure range from its initial 10 mbar to ambient 1000 mbar is captured. The second test is a shockwave detection test in which a high camera capture frequency is used in an attempt to capture shockwave effects on BOS images. The third test is a Hyperloop pod test, in which the effects of Hyperloop breach on a Hyperloop pod placed inside the test tube are measured. By comparing the results from BOS with measurements from pressure meters installed in the test setup, the feasibility of BOS is investigated. The results from the first test showed pixel displacement from BOS correlation images overestimate the pressure levels inside the tube while also showing pressure jumps compared to pressure values from the pressure meters. While data smoothing and correction operations could mitigate parts of the pressure overestimation and pressure jumps, error sources causing this remained. From the second test the presence of shockwaves could not be confirmed. While for the third test the pixel displacements around the pod could be visualized using a masking function over the Hyperloop pod, shockwave effects on the Hyperloop pod could not be visualized. From the experiment performed the use of background oriented schlieren for Hyperloop breach research is deemed feasible, however the results are sensitive to error sources.