NIFE ENGINES ALL POSSIBLE QUESTIONS AND ANSWERS WITH COMPLETE SOLUTION

NIFE ENGINES ALL POSSIBLE QUESTIONS AND ANSWERS WITH COMPLETE SOLUTION 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? Answer - 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 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 what temperature, altitude, pressure, engine RPM, RAM Effect, and density do to thrust. (TAPERD) Answer - 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. 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 What is the advantage of a centrifugal flow compressor? Answer - Pressure increases at every stage, low cost, rugged, good power output over large RPM ranges What does an impeller do and what does it do to velocity and pressure? Answer - Accelerates air outward toward the diffuser. Velocity and pressure are increased. What does a diffuser do? Answer - Converts high velocity airflow to high pressure What is the disadvantage for Centrifugal flow compressors? Answer - Large frontal area means increased drag. Impractical for multiple stages. What does a manifold do? Answer - Routes air to the combustion chamber What is the biggest advantages for axial flow compressors? Answer - Greatest overall compression ratios, large pressure increase for engine size What is the disadvantage for axial flow compressors? Answer - Not suitable for supersonic airflow. What happens to a rotor driven turbine at high RPM? Answer - Increases velocity, pressure, and total pressure. What is LOHIO and explain it. Answer - Pressure builds as it goes from front to back of an axial flow compressor. The shafts are independent of each other What are Axial-Centrifugal Flow Compressor used for? Answer - Helicopters and small aircraft. Large pressure increase for the small size. What are the parts of a centrifugal flow compressor? Answer - Impeller (accelerates air to the diffuser), diffuser, and manifold. What are the parts of an axial-flow compressor? Answer - Rotor blades and stator vanes What are the parts of an axial-centrifugal flow compressor? Answer - Inlet guide vanes, exit guide vanes, diffuser. What is the difference between the inlet guide vanes and the exit guide vanes of an axial-centrifugal flow compressor? Answer - Inlet guide vanes swirl the air in the direction of the engine rotation for the compressor. Exit guide vanes straighten the air to get ready to exit. What does the diffuser to in an axial-centrifugal flow compressor? Answer - Prepares the air for entry into the burner.