Plume flow and plume impingement in space technology

Rocket thrusters of various types are the common means of propulsion in space technology. In the space vacuum the exhaust gases form a large free jet, called a plume, which can impinge on neighbouring surfaces. The impingement effects, often unavoidable due to the unrestricted spreading of the gas, are disturbing forces and unwanted heat load. They can reduce the lifetime of the spacecraft or lead to damages. The solution of the problem includes the determination of the non-uniform plume flow field (hypersonic continuum and free molecule flow together with the non-equilibrium transition), the treatment of the nozzle flow with the characteristic viscosity influence, the assessment of the impinging plume flow and finally the determination of forces and heat transfer. Various theoretical and experimental investigations in the past and the present state are presented.