Commercial use of hydrogen on-board fuel cell vehicles necessitates the compression of hydrogen gas up to 700 bar, raising unique safety challenges. Potential hazards to be addressed include jet fires from high-pressure hydrogen on-board storage. Previous studies investigated effects of jet fires that occur when pressure relief devices (PRDs) on hydrogen fuel cell vehicles activate. This investigation examines plane jets? axis switching and flame length, accounting for compressibility effects and turbulent combustion near the point of release. Comparison with experimental data and previous plane jet simulation results reveal that combustion process does not affect flow dynamics in compressible region of jet flow. Furthermore, a theoretical design of a variable aperture pressure relief device is examined, which would enable the blow-down time to be minimized while reducing deterministic separation distances is examined using Computational Fluid Dynamics (CFD) techniques. Design recommendations are suggested for a novel PRD design.