1 | P a g e NIFE ENGINES EXAM 2024/ 205 POSSIBLE EXAM QUESTIONS AND CORRECT ANSWERS /LATEST UPDATE 2024 -2025 /ALREADY GRADED A+ What is Bernoulli's theorem ANSWER Any incompressible fluid that passes through a convergent opening, velocity increase, pressure decreases What is Bernoulli's Equation ANSWER Pt=Ps+Pk Which type of air is compressible? ANSWE R Supersonic air What happens to Velocity and Pressure in a nozzle ANSWER Pressure decreases, velocity increases What happens to Velocity and Pressure in a diffuser? ANSWER Pressure increases, velocity decreases Draw the tootsie roll method ANSWER Left side are diffusers, right side are nozzles What does an increase in pressure at the inlet do for the engine? ANSWER It packs more oxygen tighter together so the engine runs more efficiently What is the shape of the inlet? ANSWER Convergent -divergent What is the shape of an incompressible air diffuser ? ANSWER Divergent What are the events/components of the Otto and the Brayton Cycle? ANSWER Intake, Compression, Combustion, Exhaust Explain what happens at each of the events in the Otto cycle ANSWER Intake: Air is entering the valve while the piston is at the bottom 2 | P a g e Compression: The pressure is increased as the piston moves up Combustion: Spark ignites the air and sends the piston down Exhaust: the valve opens to release the air and start the cycle over What is the difference between the Otto and Brayton cycle? ANSWER All events happen simultaneously in the Brayton cycle, while they happen in order in the Otto cycle What three parts does a gas turbine engine have at a minimum? What else can also be included? ANSWER Compressor, Combustion Chamber/Burner, Turbine Inlet, Compressor, Diffuser, Combustion chamber/burner, Turbine, exhaust (I cant do complex turbine equations) What happens to temperature, pressure, and velocity at all 6 different parts of the gas turbine engine? Answer - What is gross thrust? ANSWER Thrust solely from the velocity of the exhaust gases (ignores inlet) at standard day conditions (29.92 in/Hg and 15C) What is net thrust and its equation? ANSWER Thrust that corrects for the inlet air. Net Thrust=m*(Vf -Vi)/t What is the thrust equation ? ANSWER T=m*a Explain the RAM effect in a gas turbine engine ANSWER As the aircraft goes faster, more and more air is being rammed into the inlet. This increases the mass and pressure of the inlet air causing better engine performance. 3 | P a g e What are the cockpit thrust measuring devices? ANSWER EPR (Engine Pressure Ratio) gauge, Torquemeter, and Tachometer What is a EPR? ANSWER Engine pressure ratio. It measures the pressure ratio between the inlet and exhaust airflow What is a torquemeter and what type of aircraft use it? ANSWER Indicated shaft horsepower available to drive the rotor or prop. Aircrafts that have rotors or props. What is a Tachometer? What is it measured in? ANSWER Gauge used to measure engine performance/ speed. Measured in percent RPM What is the purpose of an inlet duct? What is it designed to act like (nozzle or diffuser)? ANSWER Provides the proper amount of high pressure, turbulence free air that is steady and uniform to the first stage of the compressor. Diffuser . What shape is the inlet of a subsonic aircraft? ANSWER Diverging shape What shape is the inlet of a supersonic aircraft? ANSWER Converging -diverging What is a variable geometry inlet duct and how does it work? ANSWER An inlet duct that uses mechanical devices such as ramps, wedges, or cones that change the shape of the inlet duct as speed goes between subsonic and supersonic. What is the purpose of a compressor? ANSWER To supply enough air to satisfy the requirements of the combustion section. What makes up one stage of a compressor? ANSWER Stator blades and rotor blades What are the three types of compressors? ANSWER Centrifugal, axial, axial -
centrifugal
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