Study On Vaporization Phase Change Microfluidic Analysis And Sealing Performance Of Liquid Film Between Dynamic Pressure Seal Faces

Liquid fuel propellants and oxidants have the advantages of large reserves,low density,high energy,and clean combustion products.They are used as rocket engine fuels to power rocket launches.However,the liquid fuel is unstable in nature and is prone to vaporization phase change at low temperatures,which may cause instability or even failure of the seal operation,which may lead to engineering accidents.Therefore,this paper will analyze and discuss the vaporization phase change microfluidic mechanism and sealing performance of the liquid-pressure non-contact end face seal between liquid-phase applications in low temperature environment.The viscous shear heat value of the sealing end face and the convective heat transfer coefficient of the sealing surface were solved.The temperature field distribution of the vaporized microfluidic field of the dynamic pressure sealing liquid film was analyzed.The results show that the static ring temperature distribution is uniform,but there is a large temperature difference on the moving ring.Considering the combined action of heat and force,the micro-flow field force and the thermal coupling deformation field of the vapor-phase phase change of the dynamic pressure sealing liquid film are analyzed,and the end face deformation of the sealing dynamic and static ring end faces is obtained.It is found that the deformation of the sealing end face has a significant influence on the micro-flow field.Analysis of the deformation field of the end face shows that the deformation of the end face caused by temperature is the dominant factor,and the dynamic pressure of the fluid generated by the micro flow has little effect on the deformation of the end face.Considering the interaction between the end face deformation and the micro-flow field,the flow-solid-thermal coupling iteration is finally obtained to obtain the micro-flow field distribution.The sealing performance of dynamic pressure seal under different operating conditions was analyzed.It is known that the micro-flow field pressure increases with the sealing operation pressure,the speed,the viscosity of the fluid medium,and decreases with the increase of the outlet temperature.The degree of vaporization phase transition of the liquid film between the end faces of the microfluidic field decreases with the increase of the operation pressure and the operating speed,and increases with the rise of the outlet temperature.The key parameters of the sealing performance,namely leakage,opening force,fluid film stiffness and frictional power consumption,increase linearly with increasing operating pressure and operating speed.The influence of the microfluidic structure of the moving end face,the groove angle,the number of spiral grooves,the depth of the spiral groove,the ratio of the groove width and the ratio of the groove to the dam on the dynamic pressure sealing performance are investigated.The results show that when the helix angle is 15°,the number of slots is 12 The groove depth is 6?m,the groove width ratio is 0.5?0.6,and the groove ratio is 0.7,the sealing performance corresponding to the structural parameters is the best.The orthogonal optimization method is used to analyze the comprehensive performance of multi-structural parameters.When the degree of vaporization of the liquid film between the end faces is low,the end face structure adopts a helix angle of 14°,a groove number of 12,a groove depth of 3 ?m,a groove ratio of 0.7,and a groove-to-dam ratio of 0.4.The sealing performance is better.On the contrary case,the end face structure adopts a helix angle of 14°,a groove number of 8,a groove depth of 6?m,a groove ratio of 0.7 and a groove-to-dam ratio of 0.5.The liquid film vapor phase change pressure sealing test device and test seal were developed.The operation tests under different medium,pressure and speed conditions were carried out,and the test results and numerical analysis results were compared and analyzed.The seal was successfully opened and operated,and the correctness of the seal structure design was verified.The test results were consistent with the numerical analysis results,which verified the correctness of the numerical analysis model.Through the research of this subject,the characteristics and mechanism of vaporization and micro-flow of liquid film phase change between the end faces of dynamic pressure seals are obtained.The influence of operating parameters and structural parameters on the sealing performance is obtained,which provides the design,optimization and operation of such seals.A certain theoretical basis and technical support.