Numerical Investigation of Nozzle Jet Flow in a Pelton Microturbine

Abstract

The characterization of flow through Pelton hydro turbines allows the optimization of their operation and maximization of energy performance. The flow in the injector of Pelton turbines and in the free jet area (the area from the injector outlet surface to the runner bucket inlet surface) is influenced by several parameters: the geometry of injector components (nozzle and injector spear), the injector opening, and the turbine head. The parameters of the free jet flow (velocity distribution, pressure distribution, and jet spread) are reflected in the turbine efficiency. The research presented in this paper focuses on the numerical characterization of flow in the injector and the free jet of a Pelton microturbine. Three injector geometries were considered, with different nozzle diameters: 13.3 mm, 14.4 mm, and 16.3 mm. For each of these geometries, the flow was analyzed for five values of turbine head (H = 15 m, H = 20 m, H = 25 m, H = 30 m, H = 35 m) and six values of injector opening (S = 3 mm, S = 6 mm, S = 9 mm, S = 12 mm, S = 15 mm, S = 18 mm). The results of numerical simulations were used to plot injector flow-rate characteristics and injector force characteristics (the resultant force on the injector spear and the resultant force on the injector nozzle). The highest influence on the flow rate variation is given by the variation of turbine head, followed by the variation of the injector opening and the variation of the nozzle diameter. Increasing the nozzle diameter accentuates the variation of the flow rate versus the turbine head. The variation of axial velocity and pressure in the free jet is presented for four sections parallel to the outlet section of the injector. The injector openings that generate the highest values of velocity/pressure on the runner inlet surface are highlighted. The results allow optimization of functional parameters for increasing turbine efficiency and optimizing the design process of Pelton microturbines.

Inovasi Kincir Hidro Energi untuk Peningkatan Pariwisata Air Terjun Blemantung di Desa Pujungan Pupuan Tabanan-Bali

“…Aplikasi kincir air adalah dengan meningkatkan kecepatan aliran air melalui nozzle, sehingga dapat meningkatkan effisiensi ekstraksi energi air (Du et al, 2020) (Haidar et al, 2012). Berbeda dengan model turbin aksial dan hydrokinetic, kecepatan aliran air disebabkan oleh draft tube pada konstruksi instalasinya (Nedelcu et al, 2021)(Niebuhr et al, 2019. Walaupun demikian konstruksi desain kincir air ini dapat mengurangi gesekan pada putaran turbin yang disebabkan oleh viskositas air.…”

Study on Internal Flow Characteristics and Abrasive Wear of Pelton Turbine in Sand Laden Water

“…Jung et al [17] found that pressure deviation caused by jet eccentricity and jet velocity imbalance are the main causes of jet diffusion. Nedelcu et al [18] found that the largest effect on flow variation is the head, followed by the opening and the nozzle diameter. Alimirzazadeh et al [19] simulated the interaction between two adjacent jets under eight operating conditions based on the finite volume particle method and found that jet perturbations produce load fluctuations and may exacerbate fatigue at speeds below and above the optimum efficiency point.…”

Design and Optimization of High-Pressure Water Jet for Coal Breaking and Punching Nozzle Considering Structural Parameter Interaction

“…As the executing element of a high-pressure water jet system, the nozzle converts the pressure energy of the water into the kinetic energy of the water jet, and shoots out in the form of a high-speed water jet to break and punch the coal; therefore, the nozzle is one of the core components of the entire system. In recent years, local and international scholars have conducted substantial research on the structural parameters and working conditions of coal breaking and punching nozzle that affect water jet performance [7][8][9][10]. Wen et al [11] conducted a theoretical analysis and numerical simulation of computational fluid dynamics (CFD) to study the water jet performance of nozzles, particularly conestraight nozzles, with different flow channel shapes.…”