Study on Characteristics of the Stirring Flow and Thermal Effect in High-speed Mechanical Seals

In view of the previous literatures focused only on the viscous friction heat in mechanical seals, an integrated three-dimensional thermohydrodynamic numerical model consisting of the fluid film, fluid in sealed chamber and sealing rings is developed to investigate the stirring flow characteristics, stirred heat generation influencing mechanism and evaluate the influencing level. The comparative analysis and parameterized evaluation of flow, heat generation and heat transfer indicate that the stirring flow generated by high/ultra-high-speed shearing of the rotor impedes the cold fluid of sealed chamber flow into the sealing gap, a flow dead zone is generated at the groove root under the turbulent flow regime, which impedes the cooling of fluid film.

Due to the high/ultra-high-speed shear of rotor, the turbulent fluid in sealed chamber generates a larger effective viscosity, radial velocity gradient, and turbulent dissipation rate, which are the main reasons of stirred heat generation. The temperature difference between the sealing rings and the fluid in sealed chamber is decreased by the stirred heat generation, suppressing the convective heat transfer level. The above phenomenon leads to a significant increase in stirred heat temperature rise and a significant deterioration in sealing performance.

For the high rotational speed and small sealed chamber size, the turbulence and stirred heat are most significant, and the stirred heat temperature rise is up to 36 K, accounting for 54% of the total, the load carrying-capacity deteriorates by 4514 N and the leakage rate increases by 0.022 m3/h. This work could enrich the research on turbulence effect and stirred heat, and provide ideas for controlling the stirred heat temperature rise and guidance for the optimization design in high-speed mechanical seals.