Abstract
This paper proposes a new solution method for the leakage and static characteristics of smooth annular seal under a homogeneous gas-liquid two-phase flow based on a bulk-flow model. In this solution method, the Rayleigh–Plesset equation is introduced into the governing equations to describe the behavior of bubbles considering mixture compressibility. Detailed comparisons between Childs’ experimental leakage rates and predicted ones based on the proposed method are conducted, and the predicted results show good agreement with the experimental results, with a maximum error of 11.2%. Moreover, static characteristics of the seal, including leakage rates, gas volume fraction (GVF) distribution, pressure distribution, mixture density, and viscosity within the seals, are investigated based on the present method. The results show that as the inlet gas volume fraction increases from 0% to 10%, the local gas volume fraction of each axial position will increase, however, the seal leakage, mixture density, and mixture viscosity will decrease. Bubble radius has little effect on the leakage rates and the static characteristics of the seals. Additionally, comparisons between the characteristics of the model seals with different clearances show that the leakages of the seals with bigger clearance behave more sensitively to the inlet GVF changes.
Highlights
Centrifugal pumps are widely used for fluid transportation in marine engineering, aerospace field, and nuclear power plants
Andrés [24] developed a bulk-flow model for rotor-dynamic characteristic predictions of two-phase annular damper seals
Quite different from previous studies, a new solution method based on the bulk-flow model, considering inertia effect, damping effect, and the surface tension effect for static characteristics and leakage predictions of annular seals operating with gas-liquid mixture, is established by introducing the Rayleigh–Plesset (RP) equation to describe the dynamic change of bubbles and is validated by the published experimental results
Summary
Centrifugal pumps are widely used for fluid transportation in marine engineering, aerospace field, and nuclear power plants. When transporting vaporized fluids, centrifugal pumps always work under gas-liquid two-phase operating conditions, which will significantly affect the leakage and rotor-dynamic characteristics of the seals, and affect the overall efficiency and reliability of the pump. San. Andrés [24] developed a bulk-flow model for rotor-dynamic characteristic predictions of two-phase (liquid-gas) annular damper seals. A calculation method for leakage and dynamic characteristics predictions of annular seals under gas-liquid operating conditions is a new research focus and still needs further investigation. Quite different from previous studies, a new solution method based on the bulk-flow model, considering inertia effect, damping effect, and the surface tension effect for static characteristics and leakage predictions of annular seals operating with gas-liquid mixture, is established by introducing the Rayleigh–Plesset (RP) equation to describe the dynamic change of bubbles and is validated by the published experimental results. The effects of bubble radius at the inlet on the leakage rates, pressure distribution, and mixture properties are investigated with the proposed method
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