Question

Is the effect of turbine and compressor irreversibilities of a turbojet engine to reduce \((a)\) the net work, \((b)\) the thrust, or \((c)\) the fuel consumption rate?

Short answer

Answer: The effects of turbine and compressor irreversibilities in a turbojet engine are: (a) reduced net work, (b) reduced thrust, and (c) increased fuel consumption rate.

Step-by-step solution

Effect on net work

The net work done in a turbojet engine is the difference between the work done by the turbine and the work needed by the compressor for compressing the air. Irreversibilities in a turbine and compressor occur due to losses, such as friction, heat loss, or other inefficiencies. The irreversibilities of the turbine reduce the work output, and the irreversibilities of the compressor increase the work input. Consequently, irreversibilities would decrease the net work.

Effect on thrust

Thrust is the force that propels the engine forward, which is associated with the change in momentum of the exhaust gases. In an ideal case, the maximum possible thrust would be achieved. However, irreversibilities in the turbine and compressor can lead to reduced efficiency and less available energy to be converted into thrust. This means that the effect of turbine and compressor irreversibilities would reduce the thrust of the turbojet engine.

Effect on fuel consumption rate

Fuel consumption rate is the amount of fuel required to produce a certain amount of thrust. Turbojet engines convert thermal energy from combusted fuel into kinetic energy, which creates thrust. If turbine and compressor irreversibilities cause the engine to be less efficient, the engine would need to consume more fuel to generate the same amount of thrust. Therefore, the effect of turbine and compressor irreversibilities would increase the fuel consumption rate. In conclusion, the effect of turbine and compressor irreversibilities in a turbojet engine is to: (a) reduce the net work, (b) reduce the thrust, and (c) increase the fuel consumption rate.