2020
GAS TURBINE PERFOMANCE
SAMENVATTING GAS TURBINE PERFORMANCE (BLOCK 5)
AVIATION, HOGESCHOOL VAN AMSTERDAM
,Inhoud
1.1 Explaining the way a propeller and a jet engine generate thrust. .......................................... 4
1.2 Calculating thrust from the velocity increase of the air .......................................................... 4
1.3 Calculating propulsive efficiency from the velocity increase of the air .................................. 4
1.4 Arguing the most efficient way of increasing air velocity ....................................................... 5
2.2 Describing the processes in the cycle of a reciprocating engine .................................................. 5
3.1 Describing the properties of an (ideal) gas ................................................................................... 5
3.2 Describing the quantities and units relevant to a reciprocating engine ................................. 6
3.3 Calculating the properties of the gas in an engine cylinder, based on the combined gas law 6
4.2 Using the first law, calculating the internal energy of, the heath added to and the work done by
the gas in the cylinder ......................................................................................................................... 6
5.1 Describing the difference between reversible and irreversible processes ................................... 8
5.2 Relating isobaric, isochoric, isothermal and adiabatic processes to the functioning of a piston
engine 8
5.3 Calculating changes in temperature, pressure and volume during an isobaric, isochoric,
isothermal or adiabatic process .......................................................................................................... 8
6.1 Relating the cycle in a reciprocating engine to the Otto cycle ...................................................... 9
6.2 Calculating the work done by the gas on the piston per cycle.................................................... 10
6.3 Calculating the thermal efficiency of a reciprocating engine...................................................... 10
6.4 Describing how the performance of a reciprocating engine can be improved........................... 10
6.5 Describing the cycles of a Diesel and Stirling engine and of a gas turbine ........................... 10
7.1 Describing the advantages of jet engines over reciprocating engines ........................................ 11
7.2 Describing the modules in gas turbines and their functions ....................................................... 11
7.3 Relating the differences in design between turboshaft, -prop, -fan, -jet and ramjet engines to
their function ..................................................................................................................................... 11
8.1 Describing the relationship between enthalpy and temperature, and total enthalpy and total
temperature ...................................................................................................................................... 12
8.4 Applying the First Law on inlet, outlet, compressor, turbine and combustion chamber ........... 14
8.6 Comparing the thermodynamic cycle in a jet engine with the Joule cycle. ................................ 15
8.7 Calculating the thermal efficiency of a gas turbine. .................................................................... 15
9.1 Describing the advantage of TSFC over total efficiency .............................................................. 15
9.2 Describing the difference between thrust and specific thrust.................................................... 16
9.3 Determining the fuel air ratio in two different ways .................................................................. 16
9.4 Describing the differences between choked and unchoked nozzles .......................................... 16
9.5 Describing the effect of the critical pressure and exhaust nozzle size when determining thrust
17
10.1 Describing the relationship between entropy and friction losses ............................................ 17
Pagina 1 van 43
,10.3 Describing the meaning and order of magnitude of engine efficiencies .................................. 18
10.4 Describing the effect of losses on the (T,S)-diagram of the Joule Cycle ................................... 20
11.3 Describing the effect of TIT, CPR, altitude and velocity on TSFC, Fspec and F .......................... 20
11.4 Describing flat rated thrust and derated thrust ........................................................................ 20
12.1 Comparing the single- and twin-spool configuration of a turbojet .......................................... 21
12.2 Comparing the flow of air in a turbojet with the flow of air in a turbofan ............................... 21
12.3 Comparing the calculation of the thermal efficiency of turbojet and turbofan ....................... 22
12.4 Describing (dis)advantages of the various ways a fan can be connected to the turbine ......... 22
12.5 Describing the parameters used to indicate thrust .................................................................. 22
12.7 Describing the effect of TIT, CPR, BPR and FPR on F and the thermal and propulsive efficiency
of a turbofan...................................................................................................................................... 22
13.1 Explaining the design of rotor and stator of a compressor ....................................................... 22
13.2 Explaining the design of the casing of a compressor ................................................................ 23
13.3 Explaining the way blades are mounted ................................................................................... 23
14.1 Describing the air-flow using absolute and relative velocity .................................................... 24
14.2 Describing the relationship between blade angles and the air flow angles ............................. 25
14.3 Identifying the design choices to obtain the highest possible pressure ratio........................... 25
14.4 Identifying the design choices to obtain the appropriate degree of reaction .......................... 26
14.5 Describing how and why blades are twisted ............................................................................. 26
15.2 Describing choke, stall and surge .............................................................................................. 26
15.3 Describing the causes of choke and stall................................................................................... 27
15.4 Avoiding stall and choke when starting the engine .................................................................. 27
16.1 Describing the difference in construction compared with axial compressors .......................... 27
16.2 Describing the (dis)advantages compared with axial compressors .......................................... 28
16.4 Being able to describe the relative and absolute velocity triangles ......................................... 28
16.5 Describing the difference in construction compared with axial compressors .......................... 28
16.6 Being able to describe the total pressure and total temperature curves ................................. 29
17.1 Being able to describe the relative and absolute velocity curves ............................................. 29
17.2 Describing the design choices relating to the highest possible pressure ratio ......................... 29
17.3 Describing the impact of the degree of reaction on the blade shape ...................................... 30
17.4 Describing why a particular degree of reaction is chosen ........................................................ 30
18.1 Describing the reasons for cooling blades, discs and the casing, and the methods used for this
30
18.2 Describing the causes of stress in blades .................................................................................. 32
18.3 Calculating the tensile stress on the cross-section of a blade .................................................. 32
18.4 Describing the causes, effects and prevention of creep, fatigue and corrosion....................... 32
Pagina 2 van 43
, 19.1 Describing the relationship between a stoichiometric mixture and the air flow in the
combustion chamber ........................................................................................................................ 33
19.2 Describing the air flow through the combustion chamber ....................................................... 33
19.3 Describing the operation of swirl vanes and fuel injector nozzles............................................ 33
19.4 Describing the operation of dump valve and drain point ......................................................... 34
19.5 Describing stability limit diagrams ............................................................................................ 34
19.6 Describing the (dis)advantages of various types of combustion chambers.............................. 34
20.1 Describing the purpose of the GPU, jet starter, APU and starter when starting a gas turbine 35
20.2 Describing the operation of the igniter and exciter box ........................................................... 36
20.4 Describing the changes in N1, N2 and EGT when starting a gas turbine .................................. 37
20.5 Describing common problems during starts and how to solve them ....................................... 37
21.1 Describing the steady state, acceleration and deceleration lines in a fuel control diagram .... 37
21.2 Describing the prohibited area in a fuel control diagram ......................................................... 37
21.3 Describing the effect of the Outside Air Temperature (OAT) on a fuel control diagram .......... 38
22.1 Describing the fuel flow from the tanks to the injector nozzles ............................................... 39
23.1 Describing the relationship between the MEC, FCU, PMC, FADEC, EEC, ECU en HMU ............ 39
23.2 Describing the basic components of a fuel control system ...................................................... 40
23.3 Describing the mechanical links between the MEC and the power lever (23, 44), N2 (24, 29,
30) and air pressure (37) ................................................................................................................... 40
23.4 Describing the operation of the droop cam (20, 32) and the 3D cam (21, 31) ......................... 41
23.5 Describing the operation of the MEC at different combinations of the power lever position
and N2 41
23.7 Describing MEC and PMC inputs and output ............................................................................ 41
24.1 Describing the functions of a FADEC ......................................................................................... 42
24.3 Describing signal processing by a FADEC .................................................................................. 42
24.5 Describing FADEC inputs and outputs ....................................................................................... 42
Pagina 3 van 43
GAS TURBINE PERFOMANCE
SAMENVATTING GAS TURBINE PERFORMANCE (BLOCK 5)
AVIATION, HOGESCHOOL VAN AMSTERDAM
,Inhoud
1.1 Explaining the way a propeller and a jet engine generate thrust. .......................................... 4
1.2 Calculating thrust from the velocity increase of the air .......................................................... 4
1.3 Calculating propulsive efficiency from the velocity increase of the air .................................. 4
1.4 Arguing the most efficient way of increasing air velocity ....................................................... 5
2.2 Describing the processes in the cycle of a reciprocating engine .................................................. 5
3.1 Describing the properties of an (ideal) gas ................................................................................... 5
3.2 Describing the quantities and units relevant to a reciprocating engine ................................. 6
3.3 Calculating the properties of the gas in an engine cylinder, based on the combined gas law 6
4.2 Using the first law, calculating the internal energy of, the heath added to and the work done by
the gas in the cylinder ......................................................................................................................... 6
5.1 Describing the difference between reversible and irreversible processes ................................... 8
5.2 Relating isobaric, isochoric, isothermal and adiabatic processes to the functioning of a piston
engine 8
5.3 Calculating changes in temperature, pressure and volume during an isobaric, isochoric,
isothermal or adiabatic process .......................................................................................................... 8
6.1 Relating the cycle in a reciprocating engine to the Otto cycle ...................................................... 9
6.2 Calculating the work done by the gas on the piston per cycle.................................................... 10
6.3 Calculating the thermal efficiency of a reciprocating engine...................................................... 10
6.4 Describing how the performance of a reciprocating engine can be improved........................... 10
6.5 Describing the cycles of a Diesel and Stirling engine and of a gas turbine ........................... 10
7.1 Describing the advantages of jet engines over reciprocating engines ........................................ 11
7.2 Describing the modules in gas turbines and their functions ....................................................... 11
7.3 Relating the differences in design between turboshaft, -prop, -fan, -jet and ramjet engines to
their function ..................................................................................................................................... 11
8.1 Describing the relationship between enthalpy and temperature, and total enthalpy and total
temperature ...................................................................................................................................... 12
8.4 Applying the First Law on inlet, outlet, compressor, turbine and combustion chamber ........... 14
8.6 Comparing the thermodynamic cycle in a jet engine with the Joule cycle. ................................ 15
8.7 Calculating the thermal efficiency of a gas turbine. .................................................................... 15
9.1 Describing the advantage of TSFC over total efficiency .............................................................. 15
9.2 Describing the difference between thrust and specific thrust.................................................... 16
9.3 Determining the fuel air ratio in two different ways .................................................................. 16
9.4 Describing the differences between choked and unchoked nozzles .......................................... 16
9.5 Describing the effect of the critical pressure and exhaust nozzle size when determining thrust
17
10.1 Describing the relationship between entropy and friction losses ............................................ 17
Pagina 1 van 43
,10.3 Describing the meaning and order of magnitude of engine efficiencies .................................. 18
10.4 Describing the effect of losses on the (T,S)-diagram of the Joule Cycle ................................... 20
11.3 Describing the effect of TIT, CPR, altitude and velocity on TSFC, Fspec and F .......................... 20
11.4 Describing flat rated thrust and derated thrust ........................................................................ 20
12.1 Comparing the single- and twin-spool configuration of a turbojet .......................................... 21
12.2 Comparing the flow of air in a turbojet with the flow of air in a turbofan ............................... 21
12.3 Comparing the calculation of the thermal efficiency of turbojet and turbofan ....................... 22
12.4 Describing (dis)advantages of the various ways a fan can be connected to the turbine ......... 22
12.5 Describing the parameters used to indicate thrust .................................................................. 22
12.7 Describing the effect of TIT, CPR, BPR and FPR on F and the thermal and propulsive efficiency
of a turbofan...................................................................................................................................... 22
13.1 Explaining the design of rotor and stator of a compressor ....................................................... 22
13.2 Explaining the design of the casing of a compressor ................................................................ 23
13.3 Explaining the way blades are mounted ................................................................................... 23
14.1 Describing the air-flow using absolute and relative velocity .................................................... 24
14.2 Describing the relationship between blade angles and the air flow angles ............................. 25
14.3 Identifying the design choices to obtain the highest possible pressure ratio........................... 25
14.4 Identifying the design choices to obtain the appropriate degree of reaction .......................... 26
14.5 Describing how and why blades are twisted ............................................................................. 26
15.2 Describing choke, stall and surge .............................................................................................. 26
15.3 Describing the causes of choke and stall................................................................................... 27
15.4 Avoiding stall and choke when starting the engine .................................................................. 27
16.1 Describing the difference in construction compared with axial compressors .......................... 27
16.2 Describing the (dis)advantages compared with axial compressors .......................................... 28
16.4 Being able to describe the relative and absolute velocity triangles ......................................... 28
16.5 Describing the difference in construction compared with axial compressors .......................... 28
16.6 Being able to describe the total pressure and total temperature curves ................................. 29
17.1 Being able to describe the relative and absolute velocity curves ............................................. 29
17.2 Describing the design choices relating to the highest possible pressure ratio ......................... 29
17.3 Describing the impact of the degree of reaction on the blade shape ...................................... 30
17.4 Describing why a particular degree of reaction is chosen ........................................................ 30
18.1 Describing the reasons for cooling blades, discs and the casing, and the methods used for this
30
18.2 Describing the causes of stress in blades .................................................................................. 32
18.3 Calculating the tensile stress on the cross-section of a blade .................................................. 32
18.4 Describing the causes, effects and prevention of creep, fatigue and corrosion....................... 32
Pagina 2 van 43
, 19.1 Describing the relationship between a stoichiometric mixture and the air flow in the
combustion chamber ........................................................................................................................ 33
19.2 Describing the air flow through the combustion chamber ....................................................... 33
19.3 Describing the operation of swirl vanes and fuel injector nozzles............................................ 33
19.4 Describing the operation of dump valve and drain point ......................................................... 34
19.5 Describing stability limit diagrams ............................................................................................ 34
19.6 Describing the (dis)advantages of various types of combustion chambers.............................. 34
20.1 Describing the purpose of the GPU, jet starter, APU and starter when starting a gas turbine 35
20.2 Describing the operation of the igniter and exciter box ........................................................... 36
20.4 Describing the changes in N1, N2 and EGT when starting a gas turbine .................................. 37
20.5 Describing common problems during starts and how to solve them ....................................... 37
21.1 Describing the steady state, acceleration and deceleration lines in a fuel control diagram .... 37
21.2 Describing the prohibited area in a fuel control diagram ......................................................... 37
21.3 Describing the effect of the Outside Air Temperature (OAT) on a fuel control diagram .......... 38
22.1 Describing the fuel flow from the tanks to the injector nozzles ............................................... 39
23.1 Describing the relationship between the MEC, FCU, PMC, FADEC, EEC, ECU en HMU ............ 39
23.2 Describing the basic components of a fuel control system ...................................................... 40
23.3 Describing the mechanical links between the MEC and the power lever (23, 44), N2 (24, 29,
30) and air pressure (37) ................................................................................................................... 40
23.4 Describing the operation of the droop cam (20, 32) and the 3D cam (21, 31) ......................... 41
23.5 Describing the operation of the MEC at different combinations of the power lever position
and N2 41
23.7 Describing MEC and PMC inputs and output ............................................................................ 41
24.1 Describing the functions of a FADEC ......................................................................................... 42
24.3 Describing signal processing by a FADEC .................................................................................. 42
24.5 Describing FADEC inputs and outputs ....................................................................................... 42
Pagina 3 van 43
