The cooling of the thermally stressed components of gas turbines becomes more important since still higher turbine inlet temperatures are aspired to increase the engine efficiency. Consequently, higher requirements result to the internal cooling air system. The cooling air is conveyed through very small channels, so it has to be free of impurities in order to prevent the blockage of the small channels. Large filter upstream of the engine are used to protect the gas turbine from impurities. But it is not possible to separate all the dust particles from the air and an additional separation process is required. In modern high efficiency gas turbines so-called pre-swirl system can be used for the separation process. Experimental studies of such a system are very expensive and time-consuming. The application of numerical simulations can reduce the effort significantly. In the present article, a simulation method is presented and explained that was developed for calculations of particle traces in compressible fluids. The self-developed program allows simulations of special effects which were detected within the experimental investigations. These effects are the particle deposition on walls due to the van-der-Waals force, particle cracking caused by collision of particles with walls and the calculation of erosion. Simulation results are presented and compared to the measurement data. The comparison show good agreement between the numerical method and the measurements. With further simulations, the effort of necessary experiments can be reduced significantly. By enhancement of the algorithm, the calculation method could be also used for other numerical studies of particles in fluids.