Effects of Inlet-Loss Coefficient on Dynamic Coefficients and Stability of Multistage Pump Annular Seal
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In order to explore the influence of inlet-loss coefficient on dynamic coefficients and stability of finite-length annular seal, and then to provide theoretical basis for multistage pump rotor system vibration and stability, the bulk-flow model is taken into account to model the fluid control equations of clearance flow, and perturbation method is applied to calculate the first-order functions and dynamic coefficients. The calculated results are validated by comparing them with reference results, and the minimum and maximum error percentage are 1.4 and 5.6%, respectively. The dynamic coefficients change rule and stability of annular seal under the multifactor-coupled effects are researched in a detailed manner. The numerical results show that the inlet-loss coefficient plays an important role in dynamic coefficients of finite-length annular seal, especially for direct stiffness. All of the dynamic coefficients increase with the increase in inlet-loss coefficient, and the growth trends are the most distinct for large length–diameter ratio, small clearance or high rotating speed. Moreover, reducing the inlet-loss coefficient can improve the stability of annular seal. The research results and conclusions can provide references for the structure design of multistage pump and optimal design of rotor system.
KeywordsAnnular seal Dynamic coefficients Inlet-loss coefficient Perturbation method Whirl frequency ratio
We acknowledge the financial support from the National Natural Science Foundation of China (No. 51479167) and (No. 51339005).
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