Comparative Study on the Operating Characteristics of Fluid Dynamic Pressure Mechanical Seals with Different Groove Type for Turbopumps
Aimed at the problem of sudden increase in leakage in end face seals used in rocket turbopump with low tem-perature medium,based on engineering experience,three types of groove structures,such as laser face(groove depth of 3μm and 5 pm)and spiral groove,were proposed,and their fluid field and sealing performance of the end face were ana-lyzed and compared with the original Rayleigh groove.And a comparative analysis of the sealing dynamic tracking perform-ance for four types of groove structures was conducted.It is found that the hydrodynamic pressure of the fluid of the end face seal with Rayleigh groove is weak under low temperature medium,and hydrostatic effect is the major factor to the seal-ing rings lift-off.Negative dynamic stiffness coefficient and angular instability occur in the Rayleigh grooves with the in-crease of rotational speed and pressure,and there is a risk of leakage.Laser face has lower leakage due to the mixed lubri-cation,which enhance the stability.Laser face with a groove depth of 5 μm has a larger opening force and lower phase tran-sition rate compared to a groove depth of 3 μm,and it has better overall performance.Spiral groove has a greater hydrody-namic effect,and the linear variation of its opening force and with pressure and rotational speed ensures the tracking of sealing ring.The spiral groove structure has a better adaptability to variable working conditions,but the leakage is high.
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