Abstract
An analytical method is presented, which enables the non-uniform velocity and pressure distributions at the impeller inlet of a pump to be accurately computed. The analyses are based on the potential flow theory and the geometrical similarity of the streamline distribution along the leading edge of the impeller blades. The method is thus called streamline similarity method (SSM). The obtained geometrical form of the flow distribution is then simply described by the geometrical variable G(s) and the first structural constant G I . As clearly demonstrated and also validated by experiments, both the flow velocity and the pressure distributions at the impeller inlet are usually highly non-uniform. This knowledge is indispensible for impeller blade designs to fulfill the shockless inlet flow condition. By introducing the second structural constant G II , the paper also presents the simple and accurate computation of the shock loss, which occurs at the impeller inlet. The introduction of two structural constants contributes immensely to the enhancement of the computational accuracies. As further indicated, all computations presented in this paper can also be well applied to the non-uniform exit flow out of an impeller of the Francis turbine for accurately computing the related mean values.
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References
Shi F., Tsukamoto H. Numerical study of pressure fluctuations caused by impeller-diffuser interaction in a diffuser pump stage [J]. Journal of Fluids Engineering, 2001, 123(3): 466–474.
Muggli F., Eisele K., Zhang Zh. et al. Numerical investigations of the flow in a pump turbine in pump mode [C]. ImechE: 3rd European Conference on Turbomachinery, London, UK, 1999.
Feng J., Benra F., Dohmen H. Unsteady flow visualization at part-load conditions of a radial diffuser pump: By PIV and CFD [J]. Journal of Visualization, 2009, 12(1): 65–72.
Guleren K., Pinarbasi A. Numerical simulation of the stalled flow within a vaned centrifugal pump [J]. Proceedings of the Institution of Mechanical Engineers, Part C: Journal of Mechanical Engineering Science, 2004, 218: 1–10.
Zhang Zh. Rotating stall mechanism and stability control in the pump flows [J]. Proceedings of the Institution of Mechanical Engineers Part A: Journal of Power and Energy, 2011, 225: 779–788.
Hong S., Kim D., Kim J. et al. Study on inducer and impeller of a centrifugal pump for a rocket engine turbopump [J]. Proceedings of the Institution of Mechanical Engineers, Part C: Journal of Mechanical Engineering Science, 2013, 227: 311–319.
Pfleiderer K. Die kreiselpumpen für flüssigkeiten und gase [M]. Berlin, Germany: Springer-Verlag, 1955, 126.
Casey M., Roth P. A streamline curvature throughflow method for radial turbocompressors [C]. International Mechanical Engineering Conference, Solihull, UK, 1984.
Casey M., Robinson C. A new streamline curvature throughflow method for radial turbomachinery [J]. Journal of Turbomachinery, 2008, 132(3): 2119–2130.
Gong W. Q., Wu R. K., Zhang B. A new finite difference method to solve the velocity gradient equation in streamline curvature method [J]. Advances in Mechanical Engineering, 2016, 8(9): 1–13.
Wu C. H. A general theory of three-dimensional flow in subsonic and supersonic turbomachines of axial-, radial-, and mixed-flow types [R]. Washington DC, USA: NACA, 1952, NACA-TN-2604.
Stoffel B., Weiss K. Different types and locations of part-load recirculations in centrifugal pumps found from LDA measurements [C]. XVIII IAHR Symposium on Hydraulic Machinery and Caviatation, Valencia, Spain, 1996, II: 1034–1044.
Eisele K. Global und LDA messungen am radialpumpenlaufrad la 033.112 mit unbeschaufeltem und beschaufeltem diffusor [R]. Sulzer Innotec Report, 1992, IT 1773.
Zhang Zh., Titzschkau M. Self-validated calculation of characteristics of a Francis turbine and the mechanism of the S-shape operational instability [J]. IOP Conference Series: Earth and Environmental Science, 2012, 15(3): 032036.
Gülich J. Centrifugal pumps [M]. 2nd Edition, Berlin, Germany: Springer-Verlag, 2010, (Fig. 7.4).
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Zhang, Z. Streamline similarity method for flow distributions and shock losses at the impeller inlet of the centrifugal pump. J Hydrodyn 30, 140–152 (2018). https://doi.org/10.1007/s42241-018-0015-8
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DOI: https://doi.org/10.1007/s42241-018-0015-8