Abstract:To solve the liquid dynamic coefficients of small coneshaped annular seal and exciting force that rotor sustained, a full threedimensional model of small coneshaped annular seal was built. By applying CFD Fluent software to cavitation model, the surface pressure distribution of rotor and location of cavitation were obtained. The rotor surface pressure variation under the condition of pressure drop, ω/Ω and different rotor speed were studied, and the distribution of the gas phase was obtained. Finally, as per rotor dynamic model and excitation force formulas, seal dynamic coefficients and whirlfrequency ratio were analyzed under conditions of pressure drop 1.38, 2.41 and 3.45 MPa; rotor speed 1.02×104, 1.74×104 and 2.46×104 r/min respectively. Calculated values were then compared with theoretical values of Childs and experimental values of Lindsey. The results show that, by increasing the pressure drop, the ω/Ω or speeding up the rotor, small coneshaped annular seal gap pressure can be increased, cavitation range can be reduced effectively and the sealing performance of annular seal can be improved. The simulation results correspond closely to experimental values and theoretical values, wholly approaching the experimental values. The research can provide theoretical basis for engineering study of small coneshaped liquid annular seal.
[1]Iwatsubo T,Sheng B C. Evaluation of seal effects on the stability of rotating fluid machinery[J]. International Journal of Rotating Machinery,1995,2(2):85-92.[2]Hirs G G. A bulkflow theory for turbulence in lubricant films[J]. Journal of Lubrication Technology,1973,95(2):137-146.[3]Childs D W. Dynamic analysis of turbulent annular seals based on Hirs′ lubrication equation[J]. Journal of Lubrication Technology,1983,105(3):429-436.[4]Childs D W. Finitelength solutions for rotordynamic coefficients of turbulent annular seals[J]. Journal of Lubrication Technology,1983,105(7):437-445.[5]Lucas V,Bonneau O,Frene J. Roughness influence on turbulent flow through annular seals including inertia effects[J]. Journal of Tribology,1996,118(1):175-182.[6]Kim C H,Childs D W. Analysis for rotordynamic coefficients of helicallygrooved turbulent annular seals[J]. Journal of Tribology,1987,109(1):136-143.[7]鲁周勋. 环状密封转子动力系数的数值计算[J]. 应用力学学报,1995,12(1):81-85.Lu Zhouxun. Numerical calculations for rotordynamic properties of annular seals[J]. Chinese Journal of Applied Mechanics,1995,12(1):81-85. (in Chinese)[8]孙启国,狄杰建. 有限长大间隙环流中偏心转子动特性系数的简化分析方法[J]. 润滑与密封,2010,35(12):13-16.Sun Qiguo,Di Jiejian. A simplified method for analyzing the dynamic coefficients of eccentric rotor in finitelength annular flow of large gap annuli[J]. Lubrication Engineering,2010,35(12):13-16. (in Chinese)[9]丁雪兴,富影杰,张静,等. 基于CFD的螺旋槽干气密封端面流场流态分析[J]. 排灌机械工程学报,2010,28(4):330-334.Ding Xuexing,Fu Yingjie,Zhang Jing,et al. Fluid state analysis on flow field of gas seal with spiral groove based on CFD[J]. Journal of Drainage and Irrigation Machinery Engineering,2010,28(4):330-334. (in Chinese)[10]Lindsey W T,Childs D W. The effects of converging and diverging axial taper on the rotordynamic coefficients of liquid annular pressure seals: Theory versus experiment[J]. Journal of Vibration and Acoustics,2000,122(4):126-131.