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.
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