TURBO MACHINES UNITIII Reaction Water Turbines Dr Pramod

TURBO MACHINES UNIT-III Reaction Water Turbines Dr. Pramod B. Salunkhe

Overview • • Classification Franis turbine Kaplan turbine Velocity diagrams Draft tube Degree of Reaction Cavitation Performance characteristics

Principle of Operation • Water enters the turbine and glides over the blades • Both kinetic and pressure energies are used to transfer momentum • Pressure reduces from inlet to exit of turbine, hence air-tight casing is required

Classification of Reaction Turbines 1. Radial Flow Reaction Turbine i. Inward radial flow turbine -Water flows from outward to inward ii. Outward radial flow turbine -Water flows from inward to outward 2. Axial Flow Reaction Turbine -Water flows parallel to the axis of shaft 3. Mixed Flow Reaction Turbine -water enters axially and leaves radially or vice-versa

Francis Turbine • Developed by James Francis • Works under medium head (50 m – 150 m) and medium discharge condition

Components of Francis Turbine • Runner – to absorb momentum from the flow of water • Inlet Guide Vanes – to guide water at correct angle and control the flow rate of water • Casing- to convert kinetic energy of water into pressure energy • Draft Tube- to increase the pressure energy at the exit so as to allow turbine to locate above the tail race

Velocity Triangle