| Rocket engine nozzle jet noise is very harmful,the noise when the rocket engine test running and launching around the field produced is sharp,and it will cause huge harm to the launch site staff and the equipment.By CFD method,the three types of nozzle(round nozzle,round to square nozzle and double nozzles)of jet flow field and the noise field distribution are simulated,meanwhile,analyzing the differences between the comparison.Then this paper researches simulates the affect caused by the water injected to the gas jet shear layer of three kinds of nozzle,and studies the three kinds of nozzle on jet noise reduction effect.Based on the analysis of three kinds of nozzle calculation results,we can know that the flow field formed by the high speed gas sprayed from the rocket motor nozzle is filled with complicated expansion wave and compression wave;unlike round nozzle,the round to square nozzle appears the division of core flow and smaller core flow migrates to both width sides in the potential flow;for double nozzle,due to the interaction of two jet makes two jet gradually close,and changes the core flow shape,because the jet pressure of both sides,it produces a series of complicated expansion wave and compression wave.By monitoring the changing rule of the pressure,temperature,velocity and Mach number on axis,founding potential flow core is between D ~ 12 D after the export of three types of nozzle,where it is the main source area of the jet noise.Through the analysis of results of three types of nozzle sound field,founding the round nozzle noise values between 147.49 ~ 164.02 db,45 ° direction appears the maximum noise;the noise of round to square nozzle is less than round nozzle,the overall sound pressure level of each measuring point is distributed from 135.76 to 155.90 db and the maximum noise direction from 45 ° turn to 60 °;for double nozzle,the noise is higher than single nozzle,OASPL is distributed from 144 to 166 db,and it directivity is same as the round to square nozzle;three types of nozzle noise peak are concentrated between2000 ~ 4000 Hz,proves that the rocket jet noise is mainly distributed in the high frequency noise.Under the scheme of spraying water with water spraying angle of 60 °and gas water mass ratio of 3,the OASOL of round nozzle is reduced by 15 db,the noise reduction effect of the round to square nozzle is poor,and it’s noise reduced by 5db,themaximum noise direction of the double nozzle from 45 ° turn to 60 °,because the two water adding devices are respectively used to spray the nozzle,the noise reduction effect is obvious,and the total sound pressure is reduced by 18 db. |
