Research On The Flow Field Of Convergent Cone-type Mechanical Seal

Hydrostatic convergent cone-type mechanical seal is mainly used in pump of nuclear power plant; seal performance will directly determine the performance of pump of nuclear power plant. The research of sealing performance is of great significance.Flow field of hydrostatic convergent cone-type mechanical seal is analyzed in this paper. Building the mathematical model of the flow field, a detailed analysis is provided by using Matlab. Meanwhile, a numerical simulation is provided for flow field of seal by using Fluent. Compared to theoretical values, the effect of structure parameters (convergent angle, film thickness, ratio of convergent length) of seal on sealing performance (opening force, leakage, stiffness) is analyzed. The main conclusions are as follows:(1) While film thickness and the ratio of convergent length keep unchanging, convergent angle has a great impact on the pressure distribution of end face. With the increase of convergent angle, the pressure distribution of end face was similar to the distribution of the logarithmic form. Hydrostatic effect of convergent conical section is revealed. When convergent angle is greater than10points, the pressure distribution of convergent conical section is approximately a horizontal line; Hydrostatic effect of convergent conical section gradually weakened.(2) When film thickness and the ratio of convergent length are unchanged, opening force and leakage increase with the increase of the convergent angle, and increase rapidly in the beginning. The tendency of increase slows down when convergent angle is greater than10points, then becomes smooth. But stiffness increases rapidly in the beginning, reaches a maximum at about one minute, and then gradually decreases. It achieves better sealing performance when convergent angle is1-2(3) When ratio of convergent length and the convergent angle are unchanged, with the increase of film thickness, opening force is gradually decreased, leakage increases approximately as index, stiffness increases rapidly in the beginning, reaches a maximum at about0.4micron. Considering the impact of leakage, it achieves better sealing performance when film thickness is between ten micron and twenty micron.(4) When film thickness and the convergent angle are unchanged, with the increase of ratio of convergent length, opening force and leakage and stiffness all increase, and increase rapidly in the beginning. When ratio of convergent length is greater than10, the tendency of increase slows down, then becomes smooth. It achieves better sealing performance when ratio of convergent length is2-3.(5) The results of numerical simulation are substantially the same to results of theoretical calculation. Because theoretical calculation ignores the effect of speed, the results of numerical simulations generally are smaller than result of theoretical calculation.