The engine type represented in the drawing is a 951 ?
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Source: Telepilote theorique examen 32
When the combustion gases pass through a turbine the ?
Regarding a jet engine I The maximum thrust decreases as the pressure altitude increases II The specific fuel consumption is inversely proportional to pressure altitude at constant TAS ?
Regarding a jet engine i the maximum thrust increases as pressure altitude decreases ii the specific fuel consumption proportional to pressure altitude at constant tas I correct ii incorrect. 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. 
One of advantages of an annular combustion chamber A reduced thermal stress on turbine. A combustion chamber a very complex structure with its divergent convergent passages compare to old multi can combustion system annular combustion chamber are shorter lighter cheaper with improved combustion characteristics more power greater efficiency the main driver in combustion chamber development the need to equalise temperature flow around whole turbine entry ring in order to reduced thermal stress. 
The correct order of decreasing freezing points of three mentioned fuels Jet a jet a jet b. The accepted minimum fuel temperature safe flight for jet a 40°c jet a 1 47°c jet b 65°c. 
Labyrinth seals in lubrication system of a gas turbine engine are designed to provide a seal that Not completely tight allowing some movement between rotating static parts. The accepted minimum fuel temperature safe flight for jet a 40°c jet a 1 47°c jet b 65°c. Question 32-8
Regarding a jet engine i the maximum thrust decreases as pressure altitude increases ii the specific fuel consumption decreases slightly as pressure altitude increases at constant tas I correct 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. Question 32-9
The characteristics of an axial compressor are 1 a low pressure ratio stage2 a high pressure ratio stage3 possibility of compressing a large mass airflow4 inability of compressing a large mass airflowthe combination that regroups all of correct statements I correct ii correct. the key word here by stage! a centrifugal compressor will produce about 5 1 ratio per stage (ie impeller & diffuser) compared to a axial that gives about 1 2 1 per stage however use of multi stage axial compressors gives a bigger overall ratio. Question 32-10
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 remains constant in flow direction I correct ii correct. There a velocity decrease as air flows from a small inlet to a larger outlet. Question 32-11
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 remains constant in flow direction I correct ii correct. In a divergent duct with subsonic flow static pressure rises as does static temperature but total temperature remains constant. Question 32-12
Which of following statements correct about flow in a divergent subsonic gas turbine engine intake i the dynamic pressure decreases in flow direction ii the static temperature increases in flow direction I correct ii correct. In a divergent duct with subsonic flow static pressure rises as does static temperature but total temperature remains constant. Question 32-13
A flat rated turbofan engine has a constant maximum rated thrust level Up to a specific oat. the term flat rating so called because of flat nature of thrust versus ambient temperature curve the curve shows that from lowest operating temperature possible to specified temperature engine produces full thrust above this temperature full thrust will not be permitted a 'flat rate turbofan engine controlled in such a way that at constant ambient air pressure there no variation of take off thrust with air temperature up to some specified temperature limit above that limit engine operates in such a way that either fan speed or compressor speed constant or turbine inlet temperature constant and in either case thrust then decreases with increasing temperature. Question 32-14
Which of following statements correct about flow in a divergent subsonic gas turbine engine intake i the dynamic pressure decreases in flow direction ii the static temperature decreases in flow direction I correct ii incorrect. the term flat rating so called because of flat nature of thrust versus ambient temperature curve the curve shows that from lowest operating temperature possible to specified temperature engine produces full thrust above this temperature full thrust will not be permitted a 'flat rate turbofan engine controlled in such a way that at constant ambient air pressure there no variation of take off thrust with air temperature up to some specified temperature limit above that limit engine operates in such a way that either fan speed or compressor speed constant or turbine inlet temperature constant and in either case thrust then decreases with increasing temperature. Question 32-15
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 decreases in flow direction I incorrect ii incorrect. The speed flow reduced static pressure increases dynamic pressure decreases total pressure remains unchanged there no total temperature changes but static temperature increases while dynamic temperature decreases. Question 32-16
Which of following statements correct about flow in a divergent subsonic gas turbine engine intake i the static pressure remains constant in flow direction ii the total temperature decreases in flow direction I incorrect ii incorrect. Static pressure increases dynamic pressure decreases total pressure remains unchanged there no total temperature changes. Question 32-17
Which of following statements correct about flow in a divergent subsonic gas turbine engine intake i the dynamic pressure remains constant in flow direction ii the static temperature remains constant in flow direction I incorrect ii incorrect. Static pressure increases dynamic pressure decreases total pressure remains unchanged there no total temperature changes but static temperature increases while dynamic temperature decreases. Question 32-18
Which statement correct about flow in a divergent jet engine inlet i the speed increases in flow direction ii the total pressure increases in flow direction I incorrect ii incorrect. The flow speed decreases static pressure increases dynamic pressure decreases total pressure remains unchanged. Question 32-19
Which of following statements correct about flow in a divergent subsonic gas turbine engine intake i the static pressure decreases in flow direction ii the total temperature increases in flow direction I incorrect ii incorrect. Static pressure increases dynamic pressure decreases total pressure remains unchanged there no total temperature changes but static temperature increases while dynamic temperature decreases. Question 32-20
Which of following statements correct about flow in a divergent subsonic gas turbine engine intake i the dynamic pressure increases in flow direction ii the static temperature decreases in flow direction I incorrect ii incorrect. Static pressure increases dynamic pressure decreases total pressure remains unchanged there no total temperature changes but static temperature increases while dynamic temperature decreases. Question 32-21
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 continuous ii theoretically combustion occurs at constant pressure I correct ii correct. 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. Question 32-22
A twin spool engine with an inlet air mass flow of 220 kg/s and a hp compressor mass flow of 220 kg/s has a bypass ratio of I correct ii correct. bypass ratio = bypass mass flow / hp compressor mass flow 220 220 = 0 0/220 = 0 bypass ratio = 0. Question 32-23
A turbofan engine with an inlet air mass flow of 200 kg/s and a hp compressor mass flow of 20 kg/s has a bypass ratio of I correct ii correct. bypass ratio = bypass mass flow / hp compressor mass flow 200 20 = 180 180/20 = 9. Question 32-24
A turbofan engine with an inlet air mass flow of 220 kg/s and a hp compressor mass flow of 20 kg/s has a bypass ratio of I correct ii correct. bypass ratio = bypass mass flow / hp compressor mass flow 220 20 = 200 200 / 20 = 10. Question 32-25
A turbofan engine with a bypass air mass flow of 200 kg/s and a hp compressor mass flow of 20 kg/s has a bypass ratio of I correct ii correct. bypass ratio = bypass mass flow / hp compressor mass flow 200/20 = 10. Question 32-26
A turbofan engine with an inlet air mass flow of 220 kg/s and a bypass mass flow of 200 kg/s has a bypass ratio of I correct ii correct. bypass ratio = bypass mass flow / hp compressor mass flow 220 200 = 20 200 / 20 = 10. Question 32-27
The throttle lever angle tla information of a fadec controlled gas turbine engine provided To electronic engine control unit a direct electrical wiring connection. Tla (thrust lever angle) indicates position of thrust lever in control stand from a reference point usually this 0° when thrust lever at idle increases up to 40° when thrust lever advanced to take off position this thrust lever connected mechanical linkages to an electrical resolver synchro sensor called thrust lever angle resolver the resolver has a stator rotor the angle of rotor with respect to stator reference point changes as thrust lever moved this angle called thrust lever resolver angle (tra) this resolver connected to electronic engine control(eec) to control engine thrust different positions of thrust lever. Question 32-28
A twin spool engine with a bypass mass flow of 250 kg/s and a hp compressor mass flow of 250 kg/s has a bypass ratio of To electronic engine control unit a direct electrical wiring connection. bypass ratio = bypass mass flow / hp compressor mass flow 250 / 250 = 1. Question 32-29
Which of following statements regarding variable inlet guide vanes vigvs and variable stator vanes vsvs on a high bypass engines correct Vigvs are located at front of hp compressor and together with vsvs control compressor airflow. The compression system usually split into two units a low pressure (lp) compressor mounted on one shaft followed an high pressure (hp) compressor mounted on hp shaft driven its own (hp) turbine the fan blades of general electric engine on a boeing 747 800 behind fan compressor inlet guide vanes (inner circle) variable stator vanes (outer circle) can be seen. Question 32-30
A turbofan engine with an inlet air mass flow of 300 kg/s and a hp compressor mass flow of 50 kg/s has a bypass ratio Vigvs are located at front of hp compressor and together with vsvs control compressor airflow. bypass ratio = bypass mass flow / hp compressor mass flow 300 50 = 250 250 / 50 = 5. Question 32-31
A turbofan engine with a bypass mass flow of 250 kg/s and a hp compressor mass flow of 50 kg/s has a bypass ratio of Vigvs are located at front of hp compressor and together with vsvs control compressor airflow. bypass ratio = bypass mass flow / hp compressor mass flow hp compressor mass flow = 50 bypass = 250 250 / 50 = 5. Question 32-32
A turbofan engine with an inlet air mass flow of 300 kg/s and a bypass mass flow of 250 kg/s has a bypass ratio of Vigvs are located at front of hp compressor and together with vsvs control compressor airflow. bypass ratio = bypass mass flow / hp compressor mass flow inlet = 300 bypass = 50 hp compressor mass flow 300 50 = 250 bypass ratio = 250 / 50 = 5. Question 32-33
A turbofan engine with a bypass mass flow of 888 kg/s and a hp compressor mass flow of 111 kg/s has a bypass ratio of Vigvs are located at front of hp compressor and together with vsvs control compressor airflow. bypass ratio = bypass mass flow / hp compressor mass flow 888 / 111 = 8. Question 32-34
Bleeding air from hp compressor of a turbofan whilst maintaining thrust increases Vigvs are located at front of hp compressor and together with vsvs control compressor airflow. oscarjp if there less air flow coming in egt will rise in function of that because there a loss on efficiency due to bleed more work demanded to system so fuel flow increases. Question 32-35
A twin spool engine with an inlet air mass flow of 500 kg/s and a bypass mass flow of 250 kg/s has a bypass ratio bpr of Vigvs are located at front of hp compressor and together with vsvs control compressor airflow. bypass ratio = bypass mass flow / hp compressor mass flow inlet = 500 bypass = 250 > compressor = 250 250 / 250 = 1. Question 32-36
Compressor stall due to An excessively high angle of attack of rotor blades. Like stall of a wing compressor stall caused a breakdown of airflow if your wing suitable high speed you fly at low speed large angle of attack stall most likely to occur a compressor stall most likely to occur when air flow stagnates in rear stages of compressor a compressor blade hitting oncoming airflow at an angle of attack that determined a combination of rotational speed the incoming airflow when incoming speed low angle of attack will be high when angle of attack gets too high blade stalls so when axial flow in a compressor backs up blades stall (pressure increase in rear stages this slows down flow) you can prevent this dumping some late stage air to atmosphere (via bleed valves). Question 32-37
A turbofan engine with an inlet air mass flow of 1000 kg/s and a hp compressor mass flow of 111 kg/s has a bypass ratio of An excessively high angle of attack of rotor blades. bypass ratio = bypass mass flow / hp compressor mass flow bypass mass flow = 1000 111 = 889 889 / 111 = 8 01. Question 32-38
Which of these statements about an reaction turbine are correct or incorrect i the pressure drops across nozzle guide vanes ii the pressure remains constant across rotor blades I correct ii incorrect. There a pressure drop a velocity increase across stator of a reaction turbine. Question 32-39
The electronic engine control of a fadec gas turbine engine checks All input output data. The full authority digital engine control system (fadec) receives all necessary data engine operation takes over virtually all of steady state transient control functions which includes compressor airflow control (vigv's vsv's etc). Question 32-40
Jet engine total efficiency indicates efficiency at which Chemical power in fuel transformed into propulsive power (t x v). The full authority digital engine control system (fadec) receives all necessary data engine operation takes over virtually all of steady state transient control functions which includes compressor airflow control (vigv's vsv's etc).
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