TEHD Analysis Of Hydrodynamic Mechanical Seal In Reactor Coolant Pump

With the rapid expansion of nuclear power industry in China,yet little progress was made at the hydrodynamic seal of reactor coolant pump,as long as the theoretical analysis to it.A mass-energy-conserving TEHD finite element method model is presented in this study,aimed at solving the thermos-hydro-mechanical coupled problem in engineering design,which has a great impact on the property of mechanical seal.With the TEHD model proposed in this study,the property of hydrodynamic mechanical seal can be accurately predicted,which will low the cost of blue print a lot.This study mainly focused on the hydrodynamic seal of reactor coolant pump in service.Mechanism of the notch on the seal face,deformation law with the effects of thermos-hydromechanical coupling of the seal face as well as operation status under different conditions were analyzed.This study proposed a mass-energy conserving TEHD model to analyze the hydrodynamic mechanical seal of reactor coolant pump.Fischer-Burmeister function was utilized to deal with the non-liner relation between pressure and density in the cavitation problem.Newton-Raphson method was used to solve the EHD loop which concludes Reynolds equation,cavitation equation and force balancing equation.Relaxation iteration method was used to solve the temperature distribution loop concludes heat transfer equation of seal ring,and energy equation of lubrication film.A TEHD analysis was conducted to investigate the U type notched seal property.Results show that the cooling provided by the groove hasn’t lead to a significant thermal waves on the surface,while the circumferential mechanical deformation of the notched soft ring appears to contribute more to the circumferential wave.Parameter study to the notch shows that the hydrodynamic lift significantly improved with more notch number and long notch length.The operation status and seal property under normal condition are almost the same of the three stages of hydrodynamic seal.While under full pressure condition,the seal leakage rapidly raised,about 30 times larger than normal condition.With the steady model this study proposed,considering the hydrodynamic lift,a conclusion can be got that more notch number and long notch length like products of Flowserve is the optimal direction of seal structure.Yet this steady model is not able to explain the hot pot problem which will lead to seal failure.Further research like a transient model need to be conducted to analyze the cooling effect of the notch on the seal face.