Numerical Simulation On Thrust Vector Control Of Submerged Nozzle With Gas Secondary Lateral Injection

As the significant rise in rocket charge weight in China, key technical problems in improving the performance of rocket engine arise in the respects of reducing resistance and rocket weight as well as enhancing the mobility and safety. Secondary gas injection thrust vector control is an ideal technical scheme used on the submersible large size nozzle to get a smaller thrust loss and larger lateral force. Based on the case of a secondary gas injection used in submersible nozzle, an investigation is made on the issues of characteristics of injection parameters, process of flow field with valve close to open and flow field with two-phase flow problems in this paper. Main contents are as follows:(1) Contents of this paper is determined via a survey of the study situations on both experiments and numerical simulations of secondary gas injection thrust vector control at home and abroad. The researches abroad on this problem have started much earlier than domestic ones, and they are undergoing a transition to practical use. On the other side,although the domestic researches have tracked the abroad ones in an early time, the substantial results turned out rather late. Besides, little work has been done in the systematic analysis of impact parameters. The present paper, therefore, investigated the thrust vector control from the aspect of the injection parameters. gas parameters, valve and two-phase flow based on a secondary gas injection in large scale submerged nozzle.(2) High quality pretreatment of the nozzle shape is obtained by appropriate modeling and meshing. A submerged nozzle shape with two secondary injections is designed by reference to the engineering data, and the grid independence, computation scheme and boundary condition adaptability are verified.(3) By comparing the flow fields with and without secondary injection, the wall pressure distribution is analyzed and the generation mechanism of the lateral control force is interpreted. The performance of thrust vector control is analyzed with respect to the factors of jet orifice number, diameter, obliquity, position, outflanking angle, and the angle between two jet orifices by means of linear regression. A relevancy ranking is obtained, and investigations on the influence laws, high temperature distributions and shock wave influence patterns are made in detail according to the factors in the analysis.(4) Valve opening process is realized in the simulation using surface domain control method, and the thrust vector performance variation is analyzed in this process. The law of flow field formation in the valve moving process is found and the generation process of lateral control force is revealed. It is expected to be a valuable reference for engineering practice.(5) Preliminary research on the influence of two phase flow is conducted using DPM model in discrete phase computations based on the frozen flow calculation results. A phenomenon is found that, the thrust loss increases simultaneously with the increase of lateral control force under a two phase flow condition. Investigations are also made on the distributions of particle deposition and mechanical erosion on the combustion chamber wall.It is expected to present a useful reference for the nozzle material design in practice.