Renewable energies-LEC6

Combustion and Dilution:
Combustors will not generate smoke when the equivalence ratio in the primary zone is below 1.5. Visible smoke is considered an air pollution problem. Following combustion, the rich burning mixture leaves the combustion zone and mixes with the air jets entering the liner, resulting in intensive turbulence throughout the combustor. Dilution air enters through holes in the liner and mixes with the combustion products to lower the temperature of the products. The mixture enters the turbine at a suitable temperature for the blade materials
Film Cooling of the Liner:
The liner is exposed to the highest temperature in the gas turbine due to combustion and heat radiated by the flame. The life of the liner is extended by using material having a high resistance to thermal stress and fatigue and by cooling the liner using an air film. This cooling is accomplished by admitting air through rows of small holes in the liner. Fuel Atomization and Ignition:
The liquid fuel used in gas turbines should be atomized in the form of a
fine spray when it is injected into the combustors. Figure (7) illustrates a typical low-pressure fuel atomization nozzle