What is the purpose of stationary blades in a reaction turbine?
In a reaction turbine both the nozzles and blades act as expanding nozzles. Therefore, the static pressure decreases in both the fixed and moving blades. The fixed blades act as nozzles and direct the flow to the moving blades at a velocity slightly higher than the moving blade velocity.
Why the blade passage in an impulse turbine is of uniform cross section?
In Impulse Turbine, Blades Passage is of constant cross section area, as there is no expansion of steam. In Reaction Turbine, Because of small pressure drop in each stage, the number of stages are more for the same pressure drop. Hence the size of the reaction turbine for the same power output is large.
What is the type of blades present in reaction and impulse turbines?
In a reaction turbine, the nozzles and blades both work as expanding nozzles. Therefore, the static pressure reduces across both the fixed and moving blades. The fixed blades perform as nozzles and guide the flow to the moving blades at a velocity somewhat higher than the moving blade velocity.
How does an impulse turbine work?
Working Principle of Impulse Turbine A jet nozzle or a series of nozzles directs the high-speed flow to the blades, which are usually in the shape of buckets or cups. The potential energy of the water inside the nozzle is converted into kinetic energy and injected into the blades or buckets; thus, the runner spins.
What is pure reaction turbine?
In pure reaction turbines with a degree of reaction of one, the entire pressure energy in the rotor is converted to kinetic energy. This compressed-air driven experimental unit can be used to understand turbines powered by steam or water. HM 272 is a single-stage, pure reaction turbine with a horizontal shaft.
How are turbine blades cooled?
Cooling is achieved by passing the air through these passages from hub towards the blade tip. This cooling air comes from an air compressor. In case of gas turbine the fluid outside is relatively hot which passes through the cooling passage and mixes with the main stream at the blade tip.
What is the hottest part of a turbine engine?
The hottest section of a gas turbine is the combustion chamber, where the atomized fuel and air are ignited. These parts are exposed to the highest temperature, but the walls of the combustion chamber are comparatively cool because of heat conduction.
How much does a turbine blade cost?
For a 1.5-MW turbine, typical blades should measure 110 ft to 124 ft (34m to 38m) in length, weigh 11,500 lb/5,216 kg and cost roughly $100,000 to $125,000 each. Rated at 3.0 MW, a turbine’s blades are about 155 ft/47m in length, weigh about 27,000 lb/12,474 kg and are valued at roughly $250,000 to $300,000 each.