Open Cycle Gas Turbines

Fresh air from atmosphere is the working fluid used in Open cycle Gas Turbine Plants. The working fluid is compressed in compressor and energy is added by combustion of fuel in the working fluid itself. Combustion products than expands through the turbine and finally exhausted to atmosphere and no recirculation of working fluid takes place.

 

Working Fluid

Air is necessarily required used as working fluid to support combustion in Combustion chamber.

Fuel Used for Combustion

Petroleum derived high quality fuels so that effect of corrosive combustion products is minimum on turbine blades.

 

Starting of Gas Turbines

The gas turbine power plant is started by rotating the compressor – turbine assembly by a starting motor. When the compressor develops enough power to support combustion of fuel in the combustion chamber, the hot gases then themselves drive the gas turbine, and the plant becomes self sustaining.

Coupling of Compressor

Some of the shaft work developed in Turbine is used to run the compressor and hence the compressor is coupled to Turbine.

Operational Speed

Very high operational speed upto 10,000 rpm due to rotary Compressors and Turbines used in Gas Turbines.

 

 Application

Open Gas Turbines when used in aeronautical engines where the gas expands in turbine partially so that power output is just enough to drive compressors and accessories. The rest of gas expansion takes place in nozzle to produce high velocity jet for propulsion of aircraft in opposite direction of jet.

 

Thermal Efficiency

Low thermal efficiency of around 30 % if used without any modifications (Reheating, Regeneration or intercooling) as most of he work developed in turbine is used to run compressors.