Gas Film Lubrication Mechanism And Sealing Performance Of High-speed Turbine Pump Hydrostatic Isolation Seal

The turbopump isolation seal system in the liquid rocket power system operates under severe conditions such as high speed,low temperature,and high vibration,which poses a big challenge to its design and performance to ensure its long life and high stability operation.In order to meet the demand for lowtemperature and high-speed turbine pump isolation,this paper designs a noncontact hydrostatic isolation seal,which has the advantages of long life,strong anti-vibration capability and stable performance,and has strong applicability for turbine pump isolation demand.This paper presents a systematic and indepth study of the hydrostatic isolation seal through numerical analysis and experimental verification.Based on the multi-physical field coupling analysis method,ANSYS and Fluent software are used to establish the analysis model of hydrostatic isolation seal film flow and sealing performance for the heat balance and force balance analysis of the seal assembly and the gas film flow characteristics between the seal end faces.Calculate the gas film pressure distribution and obtain the gas flow state and law.Analyze the viscous shear heat of gas film and convective heat transfer between low-temperature medium and seal ring,and discuss the influence of temperature and fluid pressure on seal ring.And the accuracy of the model is verified by comparing the test results.Based on the analytical model of gas film flow field of hydrostatic isolation seal,the mechanism of gas film lubrication is revealed and the gas film lubrication is realized by the formation of stable pressure distribution between the seal end faces.The influences of inlet pressure and dynamic ring speed on gas film bearing capacity,gas film stiffness and friction power consumption and other gas film lubrication characteristics are analyzed,and a rapid estimation method of gas film pressure distribution is obtained.The air film lubrication test was carried out to compare the friction coefficients of the two states of open and unopened end surfaces,and it can be seen that the friction coefficient in the air film lubrication state is only 0.6% of that in the dry friction state,which has good lubrication performance.The trend and characteristics of seal face deformation under the working conditions are analyzed.In the low-temperature environment,the seal face shows a "dispersion" trend,and the low-temperature environment provided by the isolated medium dominates the seal face deformation.The influence of single parameters such as inlet pressure,thickness of gas film,width of pressure stabilizing groove and number of throttle holes on the leakage and opening characteristics of the seal is analyzed,and a multi-parameter optimization of the hydrostatic isolation seal is carried out based on the orthogonal optimization method.The principle test platform of hydrostatic isolation seal was designed and built,and the seal gas film thickness test,hydrostatic test and operation test with variable pressure and speed were conducted.The variation law of film opening thickness with inlet pressure and the variation law of air consumption and leakage with inlet pressure and rotational speed were obtained,which verified the accuracy of the analysis model of the operating characteristics of the hydrostatic isolation seal and the feasibility and correct design of the hydrostatic isolation seal.In this paper,through the study of gas film lubrication mechanism and sealing performance of hydrostatic isolation seal,we obtained the gas film lubrication characteristics,analyzed the influence law of working condition parameters and structural parameters on sealing performance,formed a specific design method,verified the feasibility and structural rationality of hydrostatic isolation seal,and provided a theoretical basis and guidance for the design and optimization of hydrostatic isolation seal.