Research On Altitude Simulation Test Technology Of Large Area Ratio Nozzle

On the basis of YF-75 D engine,YF-75 E engine increases the area ratio of nozzle to improve its performance.In order to ensure the normal operation of rocket engine under vacuum environment,the high altitude environment simulation test of rocket engine is one of the key tasks in the development of rocket engine.In this paper,CFD numerical simulation software is used for numerical simulation.Firstly,the selected model is verified.Based on existing YF-75 D engine simulation simulated altitude test data,simulation of annular ejector without secondary flow,flow observation of flow field,confirm before starting the engine vacuum tank pressure whether conform to the requirements of the task,to determine the numerical simulation method,and based on YF-75 engine high altitude simulation simulation test validation to determine the correctness of the model.According to the requirements of the simulation simulation test of YF-75 E engine before ignition,a two-stage annular ejector simulation was established to calculate the flow field of the zero secondary flow annular ejector.In order to obtain better ejecting capacity,the steam volume of the first and second ring ejectors was changed,and the two working states of the ejector,namely not started and normal operation,were determined by comparing different flow field structures.The optimal steam distribution scheme was obtained by analyzing the three states.The working condition of the main stage engine is further studied.Firstly,the simulation of "engine + diffuser + ring ejector" of YF-75 D engine high altitude simulated test test system,the flow field and vacuum chamber pressure in main engine section are determined.Then the accuracy of the strategy was verified by the simulation of "engine + diffuser" of YF-75 D engine high altitude simulated test test system with the strategy of "segmented calculation".Finally,the "segment calculation" strategy is applied to the simulation calculation of the large-area ratio nozzle high altitude simulated test simulation test.The models of the high-altitude simulation simulation test of YF-75 E engine were calculated in sections.By comparing the two simulation results,it was found that the flow fields of the two were highly consistent and met the requirements of the task book,the results meet the requirement of experimental task.