One reason to fit a tip shroud to a turbine blade is to ? Study > Manual
Increase turbine efficiency. The shrouded blades form a band around perimeter of turbine which serves to reduce blade vibrations the shrouds improve airflow characteristics increase efficiency of turbine the shrouds also serve to cut down gas leakage around tips of turbine blades.
The most important oil system instrument indication during gas turbine engine start is ?
The most important oil system instrument indication during gas turbine engine start Increase turbine efficiency. The shrouded blades form a band around perimeter of turbine which serves to reduce blade vibrations the shrouds improve airflow characteristics increase efficiency of turbine the shrouds also serve to cut down gas leakage around tips of turbine blades.
Turbine blade stages may be classed as either 'impulse' or 'reaction' In an impulse turbine stage ?
Turbine blade stages may be classed as either 'impulse' or 'reaction' in an impulse turbine stage The pressure drops across stator blades remains constant across rotor blades.
nozzle guide vanes = stator
the pressure drops across stator blades remains constant across rotor blades. When a gas turbine engine fitted with can type combustion chambers A total of only two igniters are usually fitted since chambers are inter connected. Most gas turbine engines only have two igniters typically located diagonally opposed in fact engine would probably start quite readily with only one operating however because there are only two another means of passing starting flame between combustion chambers has to be found this the interconnector. The purpose of gas turbine engine trending To enhance maintenance planning detect anomalies. Engine trending performance analysis monitoring diagnostics permit to enhance maintenance planning to detect anomalies. The flexible take off mode 1 can be used only if engines are recent2 reduces engine wear3 can be used in situations where take off can be executed without need full engine power4 can only be used with an auto throttlethe combination that regroups all of correct statements To enhance maintenance planning detect anomalies. Engine trending performance analysis monitoring diagnostics permit to enhance maintenance planning to detect anomalies. Concerning flexible take off mode temperature selected in fms Higher than ambiant airfield temperature in order to achieve a reduced power setting.
extract from boeing fcom (flight crew operations manual)
assumed temperature reduced thrust
regulations permit use of up to 25 takeoff thrust reduction operation with assumed temperature reduced thrust use of assumed temperature reduced thrust not allowed with anti skid inoperative or on runways contaminated with standing water ice slush or snow use of assumed temperature reduced thrust not recommended if potential windshear conditions exist
a takeoff thrust less than full rated thrust may be achieved using an
assumed temperature that higher than actual temperature. 8 One reason to fit a tip shroud to a turbine blade to Reduce blade vibrations limit marginal leaks. The shrouded blades form a band around perimeter of turbine which serves to reduce blade vibrations the shrouds improve airflow characteristics increase efficiency of turbine the shrouds also serve to cut down gas leakage around tips of turbine blades. 9 On a high pass ratio fan engine reverse thrust achieved reversing Only direction of fan airflow. On high bypass turbofan engines reverse thrust achieved reversing only direction of fan airflow in order to save costs mass
it not impossible to reverse hot exhaust gas but it complex the gain in reverse thrust will be less than 20 an increase in maintenance costs a higher inflight consumption due to weight of system. 10 If an abortive start hung start occurs when starting a gas turbine engine correct action to Only direction of fan airflow. On high bypass turbofan engines reverse thrust achieved reversing only direction of fan airflow in order to save costs mass
it not impossible to reverse hot exhaust gas but it complex the gain in reverse thrust will be less than 20 an increase in maintenance costs a higher inflight consumption due to weight of system. 11 Compressor surge may be controlled means of Only direction of fan airflow. On high bypass turbofan engines reverse thrust achieved reversing only direction of fan airflow in order to save costs mass
it not impossible to reverse hot exhaust gas but it complex the gain in reverse thrust will be less than 20 an increase in maintenance costs a higher inflight consumption due to weight of system. 12 The use of igniters in a gas turbine engine required 1 throughout operating range of engine2 during engine acceleration3 on ground starts4 in flight relights5 during in flight turbulence6 under heavy rains or icing conditionsthe combination that regroups all of correct statements Only direction of fan airflow. Normally in flight no igniters are in use as combustion self sustaining during engine start for take off landing igniters are in use
you have to use igniters in case of moderate or severe precipitation turbulence or icing or an in flight relight. 13 Vibration sensors are used in a gas turbine engine to indicate Imbalance of one or both of spools. Normally in flight no igniters are in use as combustion self sustaining during engine start for take off landing igniters are in use
you have to use igniters in case of moderate or severe precipitation turbulence or icing or an in flight relight. 14 The fan of a turbo fan engine driven Imbalance of one or both of spools. Normally in flight no igniters are in use as combustion self sustaining during engine start for take off landing igniters are in use
you have to use igniters in case of moderate or severe precipitation turbulence or icing or an in flight relight. 15 Regarding a jet engine i the maximum thrust increases as pressure altitude decreases ii the specific fuel consumption increases slightly as pressure altitude decreases 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. 16 One of causes of high oil temperature in a gas turbine engine at constant power setting Malfunction of heat exchanger.
the fuel/oil heat exchanger located in tanks it cools oil heats fuel so if at constant power setting you have a high oil temperature it may come from a malfunction of heat exchanger. 17 Given following information about an aeroplane with a turbojet engine mass air flow 50 kg/s tas 90 m/s exhaust nozzle gas velocity 150 m/s exhaust nozzle static pressure1050 hpa ambient static pressure 1000 hpa cross sectional area of nozzle 0 10 m net engine thrust equals Malfunction of heat exchanger. Jaredleto
the formula required to answer this question is
total thrust = mass thrust + pressure thrust
or t = m(vj vv) + a(pj p0)
where m = mass air flow vj = exhaust velocity vv = tas
a = exhaust cross section area pj = exhaust static pressure and
p0 = static ambient pressure
in this instance pressures are given in hpa need to be converted to n/sq m
therefore t = 50 (150 90) + 0 1 (105000 100000) which gives answer of 3500 n. 18 A turbofan engine with an inlet air mass flow of 1000 kg/s and a bypass mass flow of 889 kg/s has a bypass ratio Malfunction of heat exchanger.
1000 889 = 111
889 / 111 = 8 01
bypass ratio = bypass mass flow / hp compressor mass flow. 19 Exhaust gas temperature sensing usually taken Between gas generator turbine the free power turbine.
1000 889 = 111
889 / 111 = 8 01
bypass ratio = bypass mass flow / hp compressor mass flow. 20 Flat rated jet engines are designed to provide constant maximum take off thrust up to a certain level of Between gas generator turbine the free power turbine.
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. Exclusive rights: Content under private and protected license, reproduction prohibited and prosecuted.
