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Hydropower
Published in Robert Ehrlich, Harold A. Geller, John R. Cressman, Renewable Energy, 2023
Robert Ehrlich, Harold A. Geller, John R. Cressman
Of course, Equation 8.11 directly follows from Equation 8.10 with just the conversion of a unit. Thus, by Equation 8.10, a 1 hp turbine having a head of 1 ft has a specific speed ωS equal to the actual speed ω in revolutions per minute, and a 1 kW turbine operating with a head of 1 m would have a specific speed that is 26.26% of its actual speed. For any given turbine, ωS refers to the point of maximum efficiency for that type of turbine, and this number can be obtained from the turbine manufacturer. The specific speed allows a useful comparison to be made between different types of turbines and can be a guide as to which is best suited to particular applications. Finally, it can be used to scale an existing design of known performance to a new size and predict its performance. Here are typical ranges of specific speeds for various turbines, some of which are the impulse (I) and some the reaction (R) type: Pelton (I) 10–30, Turgo (I) 20–70, Crossflow 20–200 (I), Francis (R) 30–400, Propeller (R) 200–1,000, and Kaplan (R) 200–1,000.
Scaling Laws and Dimension Analysis
Published in Getu Hailu, Michal Varchola, Peter Hlbocan, Design of Hydrodynamic Machines, 2022
Getu Hailu, Michal Varchola, Peter Hlbocan
Specific speed is very important and used as a guide to the selection of type of pump or turbine required for a particular role. The physical meaning of specific speed is the rotational speed needed to discharge 1 unit of flow against 1 unit of head. Figure 2.2 illustrates the relationship and type of pump. The figure shows that axial-flow pumps have higher specific speeds compared to, for example, radial-flow pumps.
Operating Efficiency Improvement Considerations
Published in Heinz P. Bloch, Allan R. Budris, Pump User’s Handbook, 2021
Heinz P. Bloch, Allan R. Budris
Specific Speed is a dimensionless factor that dictates the impeller geometry and best attainable efficiency for the head, flow rate and speed, as shown by the chart in Figure 4-31. Not to be confused with suction specific speed, specific speed is defined as: SpecificSpeed(NS)=rpm×(capacityingpm)1/2(totalheadinfeet)3/4
Micro-hydropower in drinking water gravity pipelines: a case study in Uttarakhand, India
Published in ISH Journal of Hydraulic Engineering, 2020
Epari Ritesh Patro, Thomas J. Voltz, Arun Kumar, Thomas Grischek
The hydropower plant operation must not impact the primary function of the water supply scheme. Thus, the turbine has to be as flexible as possible regarding the available pressures and discharges. Suitable turbines for such schemes are Pelton or cross-flow, primarily because of their operation at varied discharge and other solid particles in water. A PAT can also be suitable for such projects due to its low cost and relatively low maintenance requirement. The turbine selection and design is based on the site flow duration curve and specific speed calculations. The turbine must be connected in a bypass pipe to the main supply pipeline to ensure the primary function of supplying water at all times. If no appropriate pressure-reducing device exists at the site, one must be fitted to the main pipeline to regulate the flow of water across the turbine. The advantages of hydropower schemes at sites with gravity-based schemes could be generally summarized as follows: Many civil works already exist, which reduces the necessary investment.They typically have a guaranteed base discharge through the year to maintain water supply and generate electricity.The schemes have practically no mentionable environmental impacts (see Section 5).The generated electricity can be used in the water supply system or by local people.There is no additional land acquisition required.
Energy-saving oriented optimization design of the impeller and volute of a multi-stage double-suction centrifugal pump using artificial neural network
Published in Engineering Applications of Computational Fluid Mechanics, 2022
Jiantao Zhao, Ji Pei, Jianping Yuan, Wenjie Wang
The reference model under investigation is an industrial multi-stage double-suction centrifugal pump designed and manufactured by Shangdong Shuanglun Co., Ltd., China. The design flow rate, head, and power are 0.15 m3/s, 132 m, and 269 kW, respectively, and the rotating speed is 1490 rpm. At the design flow rate, the specific speed of the pump is calculated to be 17.62 using the following expression (Fang et al., 2020). Where n represents the rotating speed, Qd represents the design flow rate, and H represents the head.