Analysing the Possible Ways for Short-Term Forcing Gas Turbine Engines in Auxiliary Power Unit
# 05, May 2016
1 Bauman Moscow State Technical University, Moscow, Russia
Using a gas turbine energy unit as an example, the article discusses possible ways for forcing the short-term gas turbine engines (GTE). The introduction explains the need for forcing the air transport and marine GTE in specific driving conditions and offers the main methods. Then it analyzes the three main short-term forcing methods according to GTE power, namely: pre-compressor water injection, a short-term rise in temperature after the combustion chamber, and feeding an additional compressed air into combustion chamber from the reserve cylinders.References
The analysis of the water injection method to force a GTE presents the main provisions and calculation results of the cycle, as a function of engine power on the amount of water injected into compressor inlet. It is shown that with water injection into compressor inlet in an amount of 1% of the total airflow there is a 17% power increase in the compressor. It also lists the main implementation problems of this method and makes a comparison with the results of other studies on the water injection into compressor.
Next, the article concerns the GTE short-term forcing method through the pre-turbine short-term increase in the gas temperature. The article presents the calculation results of the cycle as a function of the power and the fuel-flow rate on the gas temperature at the turbine inlet. It is shown that with increasing temperature by 80 degrees the engine power increases by 11.2% and requires 11% more fuel. In the analysis of this method arises an issue of thermal barrier coating on the blade surface. The article discusses the most common types of coatings and their main shortcomings. It lists the main challenges and some ways of their solving when using this method to implement the short-term forcing.
The last method under consideration is GTE short-term forcing by feeding the compressed air into the combustion chamber from the additional reserve cylinders. It should be noted that this method is applied only to small-sized and auxiliary gas turbines, operating as part of gas turbine power plants in vehicles, which comprise additional compressed air cylinders. Here are calculation results as a function of the engine power and forcing time on the amount of additional compressed air fed into the combustion chamber. The article shows that in feeding the additional compressed air in the amount of 15% of the airflow the engine power in the compressor is increased by 27%. It also describes the main implementation difficulties of this method.
In conclusion, the article presents data on the considered methods for short-term forcing the GTE and shows the main difficulties in their implementation. It also comes to conclusion that the electro-generator design strength and characteristics restrict the limits of these short-term forcing methods.
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