Semiempirisches Modell zur Strömungsablösung in überexpandierenden Raketendüsen

Abstract

The commercial potential of space flight systems can be described as the quotient of system performance and system weight. The system costs are primarily dependent on this quotient. In the nearest past most efforts to increase this quotient have been focused on reducing the system weight. At present the rocket nozzle has been rediscovered as the parameter with most potential in increasing system performance. After exploiting numerous ways of reducing the system weight and finally reaching the limits of mechanical load capacities the current aim is to increase the specific momentum of the nozzle. In the case of rocket nozzles the enlargement of specific momentum is achieved by increasing the expansion ratio. This causes the nozzle to be driven overexpanded at sea level and provokes the nozzle flow to separate from the wall. The unsteadiness of flow separation leads to side loads on the nozzle wall due to different pressure distributions. These side loads can be of dimensioning size for the nozzle and rocket structure and at least for the payload.