Questions 13 to 18 refer to the following

A gas turbine engine is modeled using the Brayton Cycle as an Air Standard Cycle approximation.

The turbine and the compressor are assumed to be adiabatic, with isentropic efficiencies of 80%.

The engine is used to drive an electric generator, so the design uses the maximum possible size of

turbine to maximize the shaft work output. The cycle has a pressure ratio of 14, and the

temperature reaches a maximum of 1,350 °C at the combustion chamber outlet.

The surrounding air entering the gas turbine engine is at 100 kPa and 29 °C.

Assume that air is an ideal gas with constant specific heats Cv=718 J/kgK and C₂ = 1005 J/kgK,

and specific gas constant R=287 J/kgK and the ratio of specific heats k = 1.4.

QUESTION 13

Sketch both a schematic diagram of the engine and a T-S state diagram of the air standard cycle,

using corresponding numbers to indicate the initial and final states of each thermodynamic process.

QUESTION 14

Calculate the amount of heat transferred to the air (per kg) in the heating process.

QUESTION 15

Calculate the amount of work done on the air (per kg) in the compression process.

QUESTION 16

Calculate the temperature of the air at the turbine outlet and the work output of the turbine.

QUESTION 17

Calculate the back-work ratio for the engine and the overall thermal efficiency of the cycle.

QUESTION 18

Explain how this engine could be modified for use as a turbojet engine in aircraft propulsion.