Computational investigation of nonstationary processes at launch of the rocket engine

Nonstationary processes in the nozzle and the development of a nonstationary jet at launch of the rocket engine are considered, nonstationary gas-dynamic loads acting on the bottom part of the space rocket at launch are determined. Nonstationary Navier-Stokes equations completed with algebraic models of turbulence are solved numerically. Separated flows in the nozzle which, as is shown by the authors, essentially influence on the load values are taken into consideration. Two variants of build-up time are studied: for a short build-up time and for the build-up time that is typical of modern engines used in the space rockets. The computational results for the gas temperature field, static pressure, the Mach numbers, as well as graphs of pressure on the rocket bottom are presented. It is shown that for the both versions of the launch due to the transition from the air outflow from the nozzle to the combustion products outflow and due to separated flows in the nozzle, the mass flow through the nozzle section first reaches its maximum and then decreases sharply...