Influence of filling processes for mixing head of gas generators on dynamics of liquid rocket engine without starter device

One of the most difficult tasks in the development of a liquid rocket engine is to ensure its reliable and stable igni- tion. During this period of engine operation, in the process of its development, abnormal and emergency situations very often appear. It typically happens due to a large range of the mass flow of components entering the gas generator and combustion chamber. For these moments of entering and the mass flow value, the processes of filling of free volumes and mixing heads of the gas generator and the combustion chamber have a significant effect. The mix ratio of the com- ponents coming into them depends on the evolution of the working processes and, in particular, the temperature of the generator gas. Its efficiency depends on the working opportunity of the nozzle apparatus and turbine blades. It is very important, in the process of starting the engine, not to allow large temperature to spike in the gas generator, especially for engines with an oxidative scheme of gas generation, as in an oxidizing environment, the ignition of elements of the gas path is possible at relatively low gas temperatures. The article shows the problem of filling the mixing heads of the gas generator and the effect of this process on the dynamics of the launch of a liquid rocket engine which does not use special starter devices. The analysis of the designs of gas generators and their mixing heads is carried out; the features of the organization of the working process in the volumes of the gas generator are considered. For a theoretical analysis of the problem a nonlinear mathematical model of a liquid rocket engine is used. With its help, the study of the launch of a liquid rocket engine with and without taking into account the injection of gas into the mixing head of the gas generator was made. The injection of gas is one of the methods for metering the mass flow of the fuel component, which essentially enhances the spray of the component entering the combustion zone. When examining the start-up process of a gas generator without injection of gas, various forms of the functions of the outflow of fuel from the mixing head have been studied. It is shown that the shape of the functions of the outflow has a significant effect on the presence and amplitude of the temperature burst in the gas generator. In order for the results of mathematical simulation of the launch of a liquid rocket engine to be adequate for full- scale testing of engines, it is necessary to conduct special experiments to fill the mixing heads on normal-boiling and cryogenic components of the fuel.