Thrust engine - Essay Example

Increase system reliability. It Is especially promising In the tiny thrust engine. Compared with hydrogen, methane has better suitability characteristics and higher density specific impulse. It can be used in a variety of space missions and planetary vehicles. In this paper, a preliminary design of NON gas oxygen / methane vortex cooling thrust chamber is performed. The influence of the fuel injection methods and the configurations of the thrust chamber on improving heat distribution of head- panel are mainly investigated. Adopting RING k-E turbulence model and PDF non- premixed combustion model, Fluent 6. Immemorial software was used to simulate the flow field of thrust chamber for sphere-head thrust chamber, cylindrical thrust chamber, variety of fuel Injection methods (axial, Impinging and tangential) and their combinations. Thrust chamber performance and the cooling wall effect of these designs were compared, and the Influence of thrust chamber aspect ratio, contraction ratio and gas oxygen swirl velocity on specific performance, thermal load of the head and side wall temperature rise was analyzed in order to increase specific impulse performance and improve the heat transfer behavior of thrust chamber.

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The results showed that the combustion in the thrust chamber was stable. The sidewall temperature rise can be effectively reduced under a small mixing ratio (oxygen fuel ratio 2. 5-4). The heat load of head-panel is significantly affected by the fuel injection method and head structure. The spherical head is helpful to avoid high head temperature. Axial and tangential fuel injection would help to improve propellant mixing and Increase combustion efficiency. Combustion efficiency is increased dramatically with the swirl velocity increase of gaseous oxygen.

It appears that optimum aspect ratio and contraction ratio exists when considering both specific Impulse performance and head, sidewall temperature rise. RFC SO p NSP -rave NOMENCLATURE chamber pressure oxidized-to-fuel mass mixture ratio fuel distribution radius chamber radius chamber length nozzle inlet radius pressure drop diffusion coefficient user-defined source item kinetic energy turbulence eddy fuel injection angle oxygen injection angle density velocity vector coordinate system specific efficiency average temperature l.

INTRODUCTION As a new type research of liquid rocket engine, vortex injection techniques 1 have gained widespread attention at home and abroad. Unlike traditional thrust chamber, injection of vortex cooling thrust chamber is usually arranged at both ends of the thrust chamber, as shown in figure 1. Gas oxygen is tangentially injected at the end of the thrust chamber, and forms a vortex flow field of inner and outer vortex layer, which are coaxial and reverse.

Due to this special structure of flow field, the propellant flow mixing and combustion is limited in the core inner vortex, while outer vortex prevents the contact of high temperature gas with the wall surface, and then reduce the surface heat load caused by chemical combustion and heat convection. At the same time, high-speed rotating vortex effectively improved the side wall temperature rise. The technology was first proposed by the Orbital Technology Corporation. It focused on test research and technology validation-3 of a hydrogen / oxygen vortex cooling thrust chamber, and obtained rich test data.

The main factors affecting the thrust chamber specific IAC-13- CO, P, 25. Pixie 64th International Astronautically Congress, Beijing, China. Copyright 02013 by the impulse performance and the key structure of heat load were analyses and summarized. Research showed that, the vortex injection techniques could eliminate cooling structure, so as to effectively simplify thrust chamber structure design, reduce development cost, increase chamber life and improve safety and reliability. The characteristics of the side wall of low temperature, has great potential applications-5 in the upper stage small thrust engine.

And the engine has the characteristics of fast ignition, steady-state operation under low temperature, high performance etc. Fig. L Vortex cooling thrust chamber structure and flow schematic In China, Jeanine Lie and others of Beijing University f Aeronautics and Astronautics focused on different thrust level test and combustion visualization. Their results confirmed research of Martina, 3, 4 et al. Experimental results showed that, good cooling effect of thrust chamber side wall was obtained, but ablation existed near the head and fuel injection panel, and specific impulse efficiency needs to be improved.

The conclusion was also proved in the simulation of the flow field characteristics of the thrust chamber, as shown in figure 2. Fig. 2 Simulation results of the characteristics of thrust chamber flow field The simulation shows the existence of a low elicits recirculation zone in the thrust chamber head, where the high temperature gas cannot be took away, resulting in high temperature head panel. At the same time, ineffective mixing of part of the axially injected fuel leads to loss of specific impulse thrust.

Taking into account many excellent features of methane when adopted in upper stage small thrust engine applications, this paper adopts gas oxygen / methane propellant combination. After standard design of the thrust chamber, thrust chamber performance special thrust chamber configuration, thrust chamber structure parameters and gas oxygen flow parameters ere conducted. Changing rule of vortex cooling thrust chamber performance with parameters, and influence of thrust chamber parameters on the thermal load of key structure (head, side wall) are studied to provide basis for the design of engine.