Through the groundbreaking work of Ernst Mach and Peter Salcher, [1, 2], the experimental proof was provided that projectiles flying faster than the speed of sound create shock waves. The same is true for supersonic jet flows in ambient air [3]. Since these findings, a lot of investigations of supersonic and hypersonic flows around real configurations like aircraft and spacecraft as well as flow through propulsion systems, inlets and diffusors etc. have revealed that in such flow fields, very complex structures of discontinuities exist. These discontinuities are not only shock waves, but also vortex sheets and contact discontinuities and their interactions.