DESIGN OF SMALL BULB TURBINES WITH UNEQUAL SPECIFIC WORK DISTRIBUTION OF THE RUNNER’S ELEMENTARY STAGES

Abstract Regarding the present state of knowledge in the field of the turbomachinery design, the method for designing small bulb turbines with unequal specific work distribution of the turbine runner’s elementary stages near the hub is presented in the paper. The distribution function of specific work of all the elementary stages is obtained, according to which the averaged axisymmetric flow surfaces of the turbine runner have a negligibly small deviation from the cylindrical flow surfaces. The specific work of the near-the-hub elementary stages, in the given distribution function, can be reduced up to 60% of the required (design) specific work, still achieving nearly cylindrical flow surfaces. References Babić, M., Stojković, S., 1990, Basics of Turbomachinery: operating principles and mathematical modeling, University of Kragujevac, Naučna knjiga, Beograd, Serbia (in Serbian). Benišek, M., 1998, Hydraulic Turbines, Faculty of Mechanical Engineering, Belgrade (in Serbian). Bogdanović, B., Bogdanović-Jovanović, J., Spasić, Ž., 2010, Designing of low pressure axial flow fans with different specific work of elementary stages, The International Conference Proceedings: Mechanical Engineering in XXI Century, pp. 99-102, Niš. Bogdanović, B., Bogdanović-Jovanović, J., Todorović, N., 2011, Program for determination of unequal specific work distribution of elementary stages in the low-pressure axial flow fan design procedure, Facta Universitatis, Series Mechanical Engineering, 9(2) pp.149-160. Obradović, N., 1974, Turbocompressors, Tehnička knjiga, Beograd (in Serbian). Bogdanović, B., Bogdanović-Jovanović, J., Spasić, Ž., Milanović, S., 2009, Reversible axial fan with blades created of slightly distorted panel profiles, , Facta Universitatis Series Mechanical Engineering, 7(1) pp.23-36 Ristić B., Milenković, 1996, Small hydropower plants, Naučna knjiga, Beograd (in Serbian). Bogdanović-Jovanović, J., Bogdanović, B., Milenković, D., 2012, Determination of averaged axisymmetric flow surfaces according to results obtained by numerical simulation of flow in turbomachinery, Thermal Science, 16(2) pp. 647-662. Jovičić, N., Babić, M., Jovičić, G., Gordić, D., 2005, Performance Prediction of Hydraulic Turbomachinery, Facta Universitatis, series Mechanical Engineering, 3(1) pp. 41-57. Albuquerque, R.B.F., Manzanares-Filho, N., Oliveira, W., 2007, Conceptual optimization of axial-flow hydraulic turbines with non-free vortex design, IMechE 221, Part A: J. Power and Energy, pp.713-725. Hofler, E., Gale, J., Bergant, A., 2011, Hydraulic design and analysis of the saxo-type vertical axial turbine, Transactions of the Canadian Society for Mechanical Engineering, 35(1), pp.119-143. Da Cruz, A.G.B., Luiz, A. Mesquita, A.L.A., Blanco, C.J.C, 2008, Minimum Pressure Coefficient Criterion Applied in Axial-Flow Hydraulic Turbines, J.of the Braz.Soc. of Mech. Sci. & Eng., 30(1), pp.30-38. Ferro, L.M.C., Gato, L.M.C., Falcão A.F.O., 2011, Design of the rotor blades of a mini hydraulic bulb-turbine, Renewable Energy 36, pp.2395-2403.