Engine efficiency and performance analysis MCQs – Aerospace

1. Engine efficiency is generally defined as:
(A) The ratio of useful work output to the total energy input
(B) The ratio of fuel consumption to engine power
(C) The ratio of exhaust temperature to ambient temperature
(D) The ratio of engine weight to thrust

2. The thermal efficiency of a jet engine is typically:
(A) Higher at lower altitudes
(B) Lower at higher altitudes
(C) Constant across all altitudes
(D) Higher at higher altitudes

3. The specific fuel consumption (SFC) of an engine is:
(A) The amount of fuel required to produce a specific amount of thrust or power
(B) The ratio of fuel flow rate to engine thrust
(C) The fuel efficiency ratio of different engine types
(D) The total fuel burned in a given time

4. In turbofan engines, bypass ratio refers to:
(A) The ratio of the mass of air bypassing the core to the mass of air passing through the core
(B) The ratio of fuel consumption to thrust produced
(C) The ratio of the jet velocity to the inlet velocity
(D) The ratio of engine thrust to the total engine weight

5. Engine thrust can be calculated using:
(A) The difference between the jet velocity and the ambient air velocity, multiplied by the mass flow rate
(B) The pressure difference across the engine
(C) The temperature difference between the exhaust and intake
(D) The weight of the engine divided by the fuel consumption rate

6. The power output of an aircraft engine is defined as:
(A) The product of thrust and velocity
(B) The product of fuel consumption and engine efficiency
(C) The difference between the exhaust temperature and ambient temperature
(D) The weight of the aircraft divided by the fuel consumption rate

7. The efficiency of a turboprop engine is generally higher at:
(A) High speeds
(B) Low speeds
(C) Medium speeds
(D) All speeds equally

8. The overall efficiency of an aircraft engine can be improved by:
(A) Increasing the bypass ratio and optimizing the combustion process
(B) Decreasing the engine weight and increasing the fuel flow
(C) Increasing the exhaust temperature and decreasing the inlet temperature
(D) Reducing the engine speed and fuel consumption

9. The thrust specific fuel consumption (TSFC) is defined as:
(A) The amount of fuel needed to produce one unit of thrust per unit of time
(B) The ratio of thrust to the weight of the engine
(C) The amount of thrust produced per unit of fuel burned
(D) The efficiency of the engine in converting fuel into power

10. The Brayton cycle’s efficiency in a jet engine increases with:
(A) Higher pressure ratios and higher turbine inlet temperatures
(B) Lower pressure ratios and lower turbine inlet temperatures
(C) Higher ambient temperatures
(D) Lower ambient temperatures