Which statement is correct for a gas turbine engine with a constant speed propeller and free power turbine when the power setting is decreased I The HP spool speed decreases II The EGT decreases ? Students > orientation
I correct ii correct. Hp spool speed egt gas generator speed all decrease a gas turbine engine with a constant speed propeller free power turbine when power setting decreased.
The FADEC of a gas turbine engine consists of ?
The fadec of a gas turbine engine consists of An electronic engine control unit its peripherals (fuel metering actuators electrical wiring sensors). Hp spool speed egt gas generator speed all decrease a gas turbine engine with a constant speed propeller free power turbine when power setting decreased.
The bypass ratio I is the ratio of inlet air mass flow to exhaust air mass flow II can be determined from the bypass air mass flow and the HP compressor mass flow ?
The bypass ratio i the ratio of inlet air mass flow to exhaust air mass flow ii can be determined from bypass air mass flow and hp compressor mass flow I incorrect ii correct.
bypass ratio = bypass mass flow / hp compressor mass flow
the bypass ratio can be determined from inlet air mass flow the bypass mass flow. The fadec of a gas turbine engine normally includes An engine overspeed and/or an egt protection function.
bypass ratio = bypass mass flow / hp compressor mass flow
the bypass ratio can be determined from inlet air mass flow the bypass mass flow. In a gas turbine engine propelling jet generated Expansion of hot gases resulting in a conversion of potential energy (pressure) into kinetic energy (velocity). The process of energy conversion in a multistage turbine consists of a number of successive processes in individual stages
compressed heated gas at an initial velocity passes through blade to blade channels of nozzle assembly where in course of expansion part of available heat drop converted into kinetic energy of exhaust flow further gas expansion conversion of heat drop into useful work take place in blade to blade channels of rotor
the gas flow acting on rotor blades develops torque on turbine's shaft as a result absolute velocity of gas reduced the lower this velocity larger part of available gas energy that converted into mechanical work on shaft
the rotor blades receive forces produced a change in direction of gas velocity flowing around them (impulse flow effect) by acceleration of gas flow relative to movement in blade to blade channels (reaction flow effect). The internal geometry of a turbofan intake a subsonic commercial aeroplane Divergent in order to reduce airflow velocity increase static pressure in front of fan.
in a divergent intake flow speed decreases the static pressure increases
dynamic pressure decreases total pressure remains unchanged. The turbine in a gas turbine engine generates shaft power using Expansion of hot gas followed conversion of kinetic energy (velocity) into (mechanical) work. The expansion the drop of pressure like a venturi tube velocity must increase to keep same mass flow this kinetic energy of hot gases converted into useful rotational mechanical energy the turbine this increased velocity (kinetic energy) what drives shaft. 8 The principle of aeroplane propulsion to generate a propelling force Accelerating air or gas in order to obtain a reaction force. The expansion the drop of pressure like a venturi tube velocity must increase to keep same mass flow this kinetic energy of hot gases converted into useful rotational mechanical energy the turbine this increased velocity (kinetic energy) what drives shaft. 9 Which statement correct a gas turbine engine with a constant speed propeller and free power turbine when power setting increased i the gas generator speed decreases ii the egt remains constant I incorrect ii incorrect. Hp spool speed egt gas generator speed all increase a gas turbine engine with a constant speed propeller free power turbine when power setting increased. 10 Which statement correct a gas turbine engine with a constant speed propeller and free power turbine when power setting increased i the gas generator speed decreases ii the egt decreases I incorrect ii incorrect. Hp spool speed egt gas generator speed all increase a gas turbine engine with a constant speed propeller free power turbine when power setting increased. 11 The primary performance indicator cockpit instrument the thrust of a turbofan engine I incorrect ii incorrect. Primary engine indications
n1 epr egt are primary engine indications on a turbofan engine
secondary engine indications
n2 fuel flow oil pressure oil temperature oil quantity engine vibration are secondary engine indications
a turbofan engine a dual rotor axial flow turbofan the n1 rotor consists of a fan a low pressure compressor a low?pressure turbine the n2 rotor consists of a high pressure compressor a high pressure turbine the n1 n2 rotors are mechanically independent
epr engine pressure ratio it compares pressure in engine inlet with pressure in exhaust nozzle
n1 the speed of first stage engine compressor this used as a power setting in most jet engines. 12 If air tapped from a gas turbine hp compressor effect on engine pressure ratio epr and exhaust gas temperature egt that Epr decreases egt increases. If you bleed air from compressor you are reducing pressure inside compressor therefore turbine outlet pressure will be reduced if inlet pressure remains same outlet pressure reduced then epr decreases
since hot air tapped directly from a compressor stage temperature will rise in turbine egt increases. 13 An abortive hung start the term used to describe an attempt to start in which engine Lights up but fails to accelerate sufficiently. After normal light up sequence (until starter 'cut out') a hung start identified light off followed abnormally slow acceleration rpm stabilization below idle a hung start may be result of fuel scheduling being either too lean or too rich a lean hung start associated with low fuel flow proportionally low egt a rich condition can be recognized a high fuel flow an egt rise which may tend to develop into an over temperature condition possible compressor stall
hung starts may be caused
starter air pressure too low to accelerate engine to self sustaining speed
premature starter deactivation
fod (foreign object debris) to compressor
faulty pressurizing valves not opening at scheduled fuel pressure setting
incorrect scheduling of hp compressor igv variable stators
turbine section damage. 14 On a fadec jet engine meaning of f a d e c on a gas turbine engine Full authority digital engine control. After normal light up sequence (until starter 'cut out') a hung start identified light off followed abnormally slow acceleration rpm stabilization below idle a hung start may be result of fuel scheduling being either too lean or too rich a lean hung start associated with low fuel flow proportionally low egt a rich condition can be recognized a high fuel flow an egt rise which may tend to develop into an over temperature condition possible compressor stall
hung starts may be caused
starter air pressure too low to accelerate engine to self sustaining speed
premature starter deactivation
fod (foreign object debris) to compressor
faulty pressurizing valves not opening at scheduled fuel pressure setting
incorrect scheduling of hp compressor igv variable stators
turbine section damage. 15 The blades in an axial flow compressor decrease in size from Low pressure to high pressure stages in an attempt to sustain axial velocity.
the blades size reduces from inlet until output of compressor. 16 Regarding a jet engine i the maximum thrust decreases slightly as pressure altitude decreases ii the specific fuel consumption increases slightly as pressure altitude decreases at constant tas I incorrect ii correct. Jet engines are more efficient at higher altitudes because less fuel needed a given thrust due to reduction in lift drag lower temperatures through inlet cause a significant reduction in specific fuel consumption up to tropopause
specific fuel consumption the amount of fuel burnt per unit of thrust for jets it reduces with altitude up to tropopause
notice as pressure altitude decreases means 'at a lower altitude'. 17 Which of following statements correct about flow in a divergent subsonic gas turbine engine intake i the speed decreases in flow direction ii the total pressure decreases in flow direction I correct ii incorrect. In a divergent intake flow speed decreases the static pressure increases dynamic pressure decreases total pressure remains unchanged. 18 Which of following statements correct about flow in a divergent subsonic gas turbine engine intake i the static pressure increases in flow direction ii the total temperature increases in flow direction I correct ii incorrect. In a divergent intake flow speed decreases the static pressure increases dynamic pressure decreases total pressure remains unchanged. 19 Both gas turbine and piston engines use a cycle made up of induction compression combustion and exhaust phases which of these statements about a gas turbine are correct or incorrect i the process in a gas turbine engine intermittent ii theoretically combustion occurs at constant volume I incorrect ii incorrect.
piston engine combustion process intermittent governed the rythm of back forth movements of piston in a cylinder the combustion occurs at constant volume in cylinder
turbine engine combustion process continuous occurs at constant pressure. 20 Which of following statements correct about flow in a divergent subsonic gas turbine engine intake i the speed remains constant in flow direction ii the total pressure remains constant in flow direction I incorrect ii correct. There a velocity decrease as air flows from a small inlet to a larger outlet. Exclusive rights: Content under private and protected license, reproduction prohibited and prosecuted.
