Study On Dynamic Adaptability Of Gas Control Pipeline Of Liquid Rocket Engine

In order to improve the capability of deep space exploration,all countries need launch vehicles capable of launching large loads,and more importantly liquid rocket engines with large thrust.However,with the increase of thrust,the vibration environment is even worse.The gas control pipeline(used to actualize controlling valve through transferring gas)designed according to the original vibration conditions has been exposed to the problem of insufficient strength.Especially when considering reducing launch cost,reusable liquid rocket engine is adopted,higher requirements are placed on the strength margin and reliability of the gas control pipeline.Based on the above reasons,combined with the engineering practice,this paper studies the dynamic adaptability of the engine pipeline under multi-vibration-source environment through theoretical analysis and test verification for a certain liquid rocket,aiming to provide a theoretical basis for improving work reliability of the engine pipeline.Firstly,the vibration data of turbine pump and combustion chamber collected in engine thermal test is analyzed in time domain and frequency domain by signal processing software DASP.The time-domain and frequency-domain characteristics of vibration loads generated in axial,tangential,and radial directions are given respectively.Then the mode analysis of a single gas-controlled pipeline is carried out,and the modal modes and natural frequencies of the pipeline are obtained.On this basis,the random vibration response analysis is applied,and taking the acceleration power spectrum density of the measured points of the turbine pump and combustion chamber as input excitation,the vibration response of the gas control pipeline with single point excitation and multi-point excitation is studied respectively.The sensitivity of the response stress to the structure,size and spatial direction of the gas control pipeline is analyzed.The results show that when the two ends of the pipeline are subjected to different excitations at the same time,the response stress is greatly affected by the position of the vibration source.Finally,the influence of the installation direction of the three-way on the stress response of the pipeline is studied,and the random vibration test is carried out.The results show that the theoretical analysis is in good agreement with the test verification results.In addition,the influence of various joints,constraint forms,and assembly deviations on the stress response of the pipeline is also studied.