Numerical study of rarefied gas flows in micro propulsion nozzles using the stochastic DSMC method

Abstract

Micro propulsion systems are a very important part of modern technology. They can be nuclear powered ones, laser-thermal, solar thermal propelled, or electric ones and all make use of a chamber along with a nozzle. Micro-propulsion systems can be used in medicine micro-bots, underwater vehicles, microsatellites or in the space industry. Under the conditions met in the micro propulsion systems, the flow through the nozzle covers the whole range of the gas collisionality and the gas behaviour cannot be captured by the usual Navier-Stokes formulation (compressible or not). Instead, the gas flow behaviour in these systems should be studied at the molecular level based on the kinetic theory of gases. In this thesis, non-equilibrium transport phenomena appearing in the flows through micro-nozzles will be studied at the microscopic level via the kinetic theory of gases. The stochastic method Direct simulation Monet Carlo (DSMC) will be applied and the validity of the provided results will be demonstrated by performing comparisons with available theoretical/experimental data. Overall, the thesis will provide an analysis of the micro propulsion nozzle performance paying special attention on the study of the influence of the implicit boundary conditions. Some conclusions useful in the numerical simulation of the micro propulsion nozzles will be drawn.