The flow around delta wings is dominated by a system of vortices. Within the present work, a double delta wing is investigated with regard to the development of these vortex systems at different Mach numbers. Data from Reynolds averaged Navier-Stokes (RANS) simulations are evaluated to describe features and mechanisms of the vortical flow. To analyze different effects within the vortex flow, the accelerating contribution of vorticity source terms on the core velocity is discussed under different conditions leading to the conclusion that depending on the wing planform compressibility effects can stabilize or destabilize the vortex. Finally, the observation of swirl numbers and their development along the vortex indicates a relation to the breakdown behavior. This relation is used as an indication of shock-vortex interaction.