China
Africa
Explore chapters and articles related to this topic
Hydropower
Published in Robert Ehrlich, Harold A. Geller, John R. Cressman, Renewable Energy, 2023
Robert Ehrlich, Harold A. Geller, John R. Cressman
As we have noted, the Pelton turbine and the more primitive water wheel are two types of impulse turbines. The other category of turbines is known as reaction turbines. The defining characteristic of a reaction turbine is that it is completely submerged in the water, and it spins in reaction to the changing pressure of the water as it flows over its surface. Most commonly, reaction turbines have a vertical axis unlike impulse turbines, which more often have horizontal axes. Reaction turbines are more difficult to mathematically analyze than impulse turbines, and their optimization relies on sophisticated fluid dynamics software in order to find the fluid flow over their surface. The most common turbine in use today, the Francis turbine (Figure 8.5), is one example of a reaction turbine, and it is very efficient. In the Francis turbine, static vanes placed around the runner direct the flowing water tangentially to the turbine wheel, so that as the water encounters the vanes on the runner, it causes it to spin. The static guide vanes also known as a wicket gate is adjustable in angle and spacing so as to allow for changing amounts of incoming flow. The Francis turbine is an inward flow turbine where the water gives up its energy to the turbine and exits out the bottom at low velocity and pressure.
Hydro Power
Published in Sergio C. Capareda, Introduction to Renewable Energy Conversions, 2019
A monograph is usually used to plan a project and select a turbine. An example is shown in Figure 5.7. This figure shows the combination of head (in meters) and flow (in m3/s). Each enclosed gray colored region displays the type of turbine recommended. As shown in the figure, Francis turbines are used for up to 1,000 MW [0.03 Quad/yr] of power, with heads ranging from 10 to 1,000 meters [32.8 to 3,280 ft]. Kaplan turbines can have as much as close to 100 MW [0.003 Quad/yr] of power, with flows ranging from 1 to 1,000 m3/s [15,837 to 15,837,053 gpm]. Pelton turbines have heads of 1,000 meters [3,280 ft] and flows up to 60 m3/s [950,223 gpm].
Prediction and analysis of the cavitating performance of a Francis turbine under different loads
Published in Energy Sources, Part A: Recovery, Utilization, and Environmental Effects, 2021
Mustafa Kamal, Gaurav Saini, Ali Abbas, Vishnu Prasad
Hydropower played a crucial role in the economic development of many countries (Saini and Saini 2019). This promising technology ensures the least environmental impact among other renewable resources (Kamal 2017). In order to tap the hydropower energy with conventional manner, mainly two types of turbine have been employed like impulse (Pelton, Turgo-impulse) and Reaction (Francis and Kaplan turbine) (Jain 2002). Francis turbine gained more popularity among other conventional turbines due to its maximum efficiency among available conventional hydro turbines (IHA 2020). Therefore, this turbine is always designed to operate at best efficiency point (BEP) condition (Celebioglu et al. 2017),(Celebioglu et al., 2018). In reality, it is quite impossible to run a turbine at rated condition due to load variations caused by variations in input parameters (head and discharge) and output parameters (power and RPM). It leads to various unsteady phenomenon such as pressure pulsation in draft tube, vortex rope formation at the outlet of runner, and cavitation occurrence on the surface of runner blade. (Trivedi, Gandhi, and Michel 2013). The hydraulic efficiency of turbine is greatly affected by these unsteady phenomena. The hydraulic efficiency of a hydraulic turbine can mathematically be expressed as;