Research On Dynamic Pressure Lubricationperformance Of Turbine Pump Mechanical Seal And Design Of Magnetic Assistant

Mechanical seal is the main form of shaft end seal for turbopump of liquid rocket engine.Due to the vaporization characteristics of cryogenic liquid fuel,phase transition phenomenon is easy to occur between seal faces.At the same time,the inner and outer sides of the seal ring need to bear a large temperature difference.The deformation of the seal face caused by the temperature difference makes the working condition of liquid film fluid lubrication of the seal face more complex and affects the stability of the seal operation.According to this situation,this paper studies the mechanical seal performance of turbopump shaft end under low temperature conditions.The main contents are as follows:(1)The calculation model of mechanical seal performance considering the change of gasliquid two-phase ratio in low-temperature medium was established.According to the actual operating conditions of the mechanical seal of the turbopump,the change of the rotational speed of the turbopump during the rocket launch was simulated by experiment,and the change of the two-phase ratio of the sealing medium in the low temperature environment was measured,and the quantitative characterization was carried out by mathematical expression.The two-phase lubrication calculation model of mechanical seal based on the measured data was obtained by substituting it into the classical mechanical seal lubrication model with the generalized Reynolds equation as the main control equation.The opening force and leakage of mechanical seal were obtained by numerical solution,and the mechanical seal performance under the two-phase lubrication condition was studied.(2)The mechanical seal performance calculation model and method considering the seal face deformation were established by combining ANSYS Workbench and fluent module.Using the steady-state thermal module in ANSYS Workbench software,the temperature distribution of the mechanical seal end face of the turbine pump was calculated,and then the flow field in the mechanical seal end face area of the turbine pump was calculated using fluent module.In the static calculation module,the seal end face deformation caused by temperature and pressure was calculated,and the deformation was substituted into the mechanical seal lubrication model to analyze the influence of the seal end face deformation on the mechanical seal performance under different working conditions and structural parameters.(3)In view of the fluctuation of liquid film pressure caused by the two-phase working condition and the deformation of the sealing face of the mechanical seal of the turbopump,a mechanical seal structure with magnetic assistance was proposed,and the magnitude of the permanent magnetic force and the liquid film force were obtained through the test.The test results show that the magnetic force of the permanent magnet block can effectively enhance the bearing capacity of the sealing face and increase the opening of the sealing face,which proves that the magnetic assisted mechanical seal scheme proposed in this paper is feasible.