Investigation of the gas flow features in the path of a rocket engine with a swinging nozzle

A technique is presented for modeling the gas flow in the path of a solid-fuel rocket engine with a swinging nozzle. Currently, it is believed that the use of swinging nozzles is one of the most effective methods for controlling the thrust vector of a rocket engine. Such nozzles provide relatively small thrust losses and create significant control forces. The swinging nozzles have a small swivel joint, high performance and a small steering body weight. However, in this case, the hinge joint is located in the zone of maximum heat flows. When the engine is running, the gas flow disturbances occur at the junction of the fixed and moving parts of the nozzle, which contributes to the erosion of the critical section. A system of defining equations is given describing a three-dimensional compressed gas flow. The system of equations was discretized over space using the finite volume method. A computational algorithm based on the explicit Steger-Warming scheme (flow vector splitting scheme) was proposed. A calculation program was developed based on the proposed algorithm. An unstructured computational grid consisting of polyhedra was used for the calculations. Using the developed program, the studies of the gas flow in the gas turbine engine at various inclination angles of the swinging nozzle were carried out. The results showed that due to a change in the geometry of the gas flow path, the distribution of the parameters in the nozzle ceased to be symmetrical. When the nozzle was tilted, the gas temperature along the perimeter of the critical section changed, in contrast to the neutral position of the nozzle. The dependence of the maximum gas temperature in the critical section zone on the nozzle inclination angle was obtained.