Transient stability of air film floating ring seal under pressure disturbance

SHI Ren-jie, ZHEN Rao, LI Shuang-xi, CHEN Xiao-zhu, MA Yu-hu, CHENG Tian-fu
(School of Mechanical and Electrical Engineering, Beijing University of Chemical Technology, Beijing 100029, China)

Abstract: Aiming at the problem that the performance of floating ring seal was unstable due to the disturbance of seal gas pressure, the transient sealing stability and floating stability of floating ring under pressure disturbance were studied. The transient research model of floating ring seal gas film was established by UDF programming and Fluent software. The initial value of the disturbed transient simulation was set by the results of steady-state operation, the method of adjusting the time step was adopted to make the iterative results converge, and the grid simulation results with different accuracy were compared and analyzed to verify its independence. The variation law of transient sealing performance and transient floating performance of floating ring under sinusoidal pressure disturbance was researched, and the internal relationships of the floating ring clearance, throttle length and transient stability were explored. The results indicate that under the sinusoidal pressure disturbance, the larger the gap of the floating ring is, the worse the stability of the transient seal of the floating ring is. When the clearance is 0.013 mm, the sealing transient stability under disturbance is the best. When the flow length of the floating link increases, the fluctuation of transient leakage under pressure disturbance can decrease, while the fluctuation of transient upper buoyancy can increase. However, when the throttling length exceeds 5 mm, the stability can not basically deteriorate. Therefore, the gap can be reduced and the throttling length can be increased to enhance the transient stability of the floating ring.
Key words: pressure disturbance; UDF programming; transient studies; sealing performance stability