| Mechanical seal is an important part of reactor coolant pump.Its performance directly affects the operation and maintenance of reactor coolant pump.At present,all mechanical seals for reactor coolant pump in China rely on imports,but China does not have the ability to develop related products and is subject to long-term technical blockade by foreign countries.In order to realize the overall development of nuclear power and promote the independent process of reactor coolant pump seal technology in China,this paper studies the mechanical seal for reactor coolant pump.Firstly,a new streamline groove is proposed,and then the streamline groove mechanical seal is analyzed.This paper first gives the control equation of streamline groove,establishes the three-dimensional model of streamline groove,and establishes the fluid film lubrication model of streamline groove mechanical seal end face through the analysis and derivation of mechanical seal theory.The opening force,leakage,stiffness and stiffness to leakage ratio are obtained by using MATLAB software.The main conclusions are as follows:(1)With the increase of the number of grooves,the opening force first increases,then tends to be stable,and then increases,and the leakage increases.The change trend of stiffness is the same as that of opening force,while the stiffness-to-leakage ratio decreases.When the number of grooves increases after 14,the change trend of opening force and stiffness is very small.(2)With the increase of groove depth,the opening force presents a trend of first rising and then falling,and other parameters have the same trend as the opening force.The opening force and leakage reach the maximum value when the groove depth is 2μm.(3)With the increase of seal end face gap,the opening force,stiffness and the stiffness-to-leakage ratio decrease,while the leakage increases.When the seal end face gap is between 0～5μm,the opening force decreases rapidly.When the seal end face gap is after 5μm,the opening force decreases slowly,and finally tends to be stable.(4)With the increase of groove-to-dam ratio,the opening force and the stiffness-to-leakage ratio first increase and then decrease,while the leakage and stiffness increase.The opening force reaches the maximum when the groove-to-dam ratio is 0.7,and the stiffness-to-leakage ratio reaches the maximum when the groove-to-dam ratio is 0.4.(5)With the increase of weir width ratio,the opening force first increases and then decreases,and the variation trend of leakage,stiffness and the stiffness-to-leakage ratio are the same as that of opening force.The maximum values of opening force,leakage,stiffness and the stiffness-to-leakage ratio are obtained when the weir width ratio is 0.6,0.7,0.6 and 0.5,respectively.Through the analysis of the sealing performance,it is found that the performance parameters of streamline groove mechanical seal change with the structure parameters and working conditions parameters.The orthogonal experiment was designed to analyze the influence of each model parameter on the sealing performance.The structural parameters were optimized by single variable method and orthogonal test method.The optimized structural parameters range is:Groove number N=10～12,Groove depth h_g=2～5μm,Gap h_o=1～2μm,Groove-to-dam ratioδ=0.6～0.8,and Groove-to-weir ratioη=0.5～0.7. |
