Short Answer:
Losses occurring in turbines are the energy losses that prevent the turbine from converting all the water or steam energy into useful mechanical power. These losses reduce the efficiency and overall performance of the turbine.
Common losses in turbines include hydraulic losses, mechanical losses, leakage losses, and frictional losses. These can happen due to water flow resistance, moving parts rubbing against each other, or steam or water escaping through gaps. Reducing these losses is important for improving turbine output and ensuring smooth operation.
Detailed Explanation:
Losses occurring in turbines
Turbines are designed to convert the energy of flowing water or steam into mechanical energy. However, in practical operation, not all of the input energy gets converted into useful output. A part of it is lost in various forms. These energy losses affect the efficiency, performance, and durability of the turbine.
Understanding the different types of losses in turbines helps in designing better systems and improving overall performance. The major losses can be grouped into the following categories:
Hydraulic losses
Hydraulic losses happen due to the behavior of the water or steam as it flows through the turbine. These include:
- Frictional losses: When water or steam moves through pipes, nozzles, and passages, it rubs against the walls, creating resistance and losing energy.
- Turbulence losses: If the flow is not smooth or hits sharp edges, it creates swirls and disturbances, causing energy waste.
- Sudden expansion or contraction: Changes in flow area lead to sudden pressure and velocity changes, causing energy loss.
- Improper blade angle: If the flow direction does not match the blade design, energy is lost during impact or gliding over the blade surface.
Hydraulic losses reduce the amount of energy that reaches the turbine runner, directly lowering hydraulic efficiency.
Mechanical losses
Mechanical losses occur in the moving parts of the turbine due to:
- Friction between rotating parts: Bearings, shafts, and seals experience rubbing, which produces heat and wastes energy.
- Vibration and misalignment: Poor installation or wear can lead to small unwanted movements, consuming energy.
- Gear and coupling losses: In some turbines, mechanical transmission devices like gears also lose some energy.
These losses reduce the amount of power actually delivered at the shaft, affecting mechanical efficiency.
Leakage losses
Leakage losses happen when some amount of water or steam escapes through unwanted paths:
- Seal gaps: Small spaces between moving and stationary parts allow water or steam to leak.
- Joint leakage: Poor sealing at pipe connections or turbine casings leads to energy loss.
- Bypass flow: Water or steam bypassing the turbine blades without doing useful work.
Leakage losses are especially significant in high-pressure turbines and need proper sealing to minimize their effect.
Other minor losses
- Windage losses: These occur due to air resistance acting on the rotating parts.
- Cooling system losses: Energy used for cooling the turbine components is also a form of loss.
- Noise and vibration energy: Sound and vibrations also carry away a small part of energy, although very minor.
All these small losses add up and reduce the overall performance of the turbine.
Conclusion:
Several types of losses occur in turbines, such as hydraulic, mechanical, and leakage losses. These losses reduce the effective energy conversion and impact the turbine’s efficiency. Identifying and minimizing these losses is essential for better turbine design, improved efficiency, and long-term reliable operation.