Comprehensive guide to hydraulic turbines detailing various types including Pelton Wheel, Francis, Kaplan, and more for hydroelectric power generation.
Introduction to Hydraulic Turbines
Hydraulic turbines are prime movers that convert the energy of flowing water into mechanical work, a fundamental transformation exploited in the generation of hydroelectric power. These turbines harness the kinetic and potential energy of water, which is then converted into electricity through generators. Varying in design and application, each type of hydraulic turbine serves a specific purpose depending on water flow, hydraulic head, and power needs. Here, we explore 10 common types of hydraulic turbines used in hydroelectric power stations.
Pelton Wheel
The Pelton wheel is an impulse turbine, primarily utilized in high-head, low-flow water conditions. It consists of spoon-shaped buckets mounted on the wheel’s edge, designed to capture water jets shot from a nozzle. The impact of the water creates a force that turns the wheel, making it highly efficient in settings with substantial height differences.
Francis Turbine
Developed by James B. Francis, the Francis turbine is a reaction turbine suitable for a wide range of head and flow conditions. It features a radial inflow design where water enters the turbine radially and exits axially through the runner. This flexibility makes it the most commonly used turbine in the world for hydroelectric power generation.
Kaplan Turbine
The Kaplan turbine is an axial flow reaction turbine, perfect for locations with low head and high flow. Its main characteristic is the adjustable blades, which can be optimized according to varying water conditions, thereby maintaining efficiency. It is particularly useful in river and run-of-river hydropower developments.
Turgo Turbine
A modification of the Pelton wheel, the Turgo turbine is another type of impulse turbine. It directs water jet at an angle on the runner, allowing it to handle more flow at a lower head compared to the Pelton wheel. This turbine is more compact and often preferred in medium head hydro sites.
Crossflow (Banki-Michell) Turbine
The Crossflow turbine, also known as a Banki-Michell turbine, features a simple design where water flows through a rectangular section runner twice. This unique design offers good efficiency across a range of head and flow conditions, and its simplicity makes it suitable for small scale and community-based hydro projects.
Bulb Turbine
The Bulb turbine integrates the generator into a waterproof casing in the water stream, often seen in tidal and low-head river applications. The placement allows direct drive without extensive gearing, thereby minimizing energy losses associated with mechanical transmissions.
Straflo Turbine
The Straflo turbine incorporates the generator around the periphery of the turbine’s runner. This arrangement facilitates a direct connection between the generator and the turbine, enhancing the unit’s overall compactness and efficiency, ideal for low-head hydroelectric plants.
Tubular Turbine
Designed for very low head hydroelectric projects, the Tubular turbine features a straight flow-through design, which enables the water to pass linearly through the turbine. These turbines are often used in tidal and wave power plants.
Pit Turbine
Characterized by its vertical design, the Pit turbine saves a significant amount of space, making it suitable for small locations. It is typically used in low to medium head applications and integrates well within existing dam structures without requiring extensive modifications.
Diagonal Turbine
Also known as an inclined flow turbine, the Diagonal turbine works under a variety of head conditions but is especially efficient in low to medium head and high flow situations. Its design allows water to flow diagonally to the axis of rotation, providing a compact solution with fewer cavitation issues.
Conclusion
Hydraulic turbines are a cornerstone of hydroelectric power generation, showcasing a variety of designs tailored to different environmental and operational requirements. Understanding the specific characteristics and suitable applications of each turbine type helps engineers and energy developers select the most appropriate technology for maximizing energy generation while considering environmental and geographical constraints.