| A rocket engine is a jet engine that uses only stored propellant mass for forming its high speed propulsive jet. It is the main power plant for the space transportation system and for the spacecraft. And a rocket engine nozzle(usually of the de Laval type) is the most important part for a rocket engine. It makes the gases exit the nozzle at hypersonic velocities. When the charge is limited, the efficiency of the nozzle is directly linked to the performance of the rocket engine. Especially with the shortage of the energy, to increase the efficiency of the nozzle is very meaningful for all the countries in the world.In this paper, the parameters of the Vulcain rocket engine are used. The nozzle design parameters are calculated by gaseq software. With the results of the calculation,the method of changing the nozzle ejection area to increase the efficiency of the nozzle is developed. Then, different methods for designing the rocket engine nozzle are used to design the nozzle based on the design parameters calculated. After the nozzle design,Ansys software is used to simulate the fluid fields of these different nozzles with CFD method. With the result of analyzing, the advantages and disadvantages of different nozzles are obtained. By analyzing the jet field of the conical nozzle, it is found that the choc on the back side of the nozzle decrease the efficiency of the nozzle. To improve the efficiency, inspired by the idea of the variable ejection area of supersonic jet fighter engine, two methods for redesign the conical nozzle are developed experimentally. After the redesign, the jet fields for the two nozzles are simulated and analyzed. A satisfying result indicate the idea of changing the ejection area of the nozzle to decease the influence of the choc, which means to improve the efficiency of the nozzle, is acceptable.The idea and the method for designing a rocket engine nozzle in this paper can be a reference to the similar research. |
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