Abstract
Annular seals have significant effects on the hydraulic and rotordynamic performances of turbomachinery. In this paper, an analysis method for calculating the leakage flow rates and dynamic characteristics of liquid annular seals with herringbone grooves on the rotor is proposed and verified. Leakage flow rates and dynamic characteristics of the model seals under different operating conditions are theoretically analysed and compared with those of plain and spiral-grooved seals of the same size. In addition, the influence of geometric parameters such as spiral angle and the lengths of the constituent parts on the sealing and rotordynamic coefficients of seals with herringbone grooves are also discussed. The results show that seals with herringbone grooves have better sealing performance, while providing better support actions and damping characteristics than the other two seal types under the same operating conditions. The seal geometric parameters including spiral angle, the lengths of the constituent parts and the clearance value have a significant influence on the dynamic characteristics of seals with herringbone grooves.
Highlights
Annular liquid seals are primarily used to control leakage in turbomachinery, especially in multi-stage centrifugal pumps such as boiler feed pumps and other heavy-duty pumps
Zhai et al [25] developed a theoretical analysis method for the leakage rate and dynamic characteristics of herringbone-grooved liquid seals based on the method of Iwatsubo and Childs
According to the calculation results shown in figure 6 and table 4, the sealing performance of seals with herringbone grooves on the rotor is significantly better than that of spiral-grooved seals and plain seals, which will have a positive effect on the improvement of the single-stage head for centrifugal pumps
Summary
Annular liquid seals are primarily used to control leakage in turbomachinery, especially in multi-stage centrifugal pumps such as boiler feed pumps and other heavy-duty pumps. Childs [2] performed a finite-length analysis for annular plain seals based on Hirs’ lubrication equations and the bulk-flow model proposed 3 by Black. This analysis method has been the most widely used in engineering. Zhai et al [25] developed a theoretical analysis method for the leakage rate and dynamic characteristics of herringbone-grooved liquid seals based on the method of Iwatsubo and Childs. CFDbased methods are mainly used only in the research field, while theoretical prediction procedures based on the bulk-flow theory are still the main methods for calculating leakage rates and dynamic characteristics in engineering. Uptream spiral part w high pressure side z middle plain part stator downstream spiral part low pressure side rotor
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