Post on 13-Mar-2018
Gas Turbine
General Electric LM2500
Aircraft Engines
g/W
Turbines
Axial Turbine Stage
Nozzle
Impeller
Dimensionless Coefficients
Degree of Reaction
Flow Coefficient Head Coefficient Specific Speed
Dimensionless Coefficients
Design Coefficients
Nozzle
Isentropic Flow
Nozzle
co
c1
po
p1 , α1 , Ma
+ + +
- - -
p1
δ = α1 – α1s
Impeller
v2
v1
Impuls Turbine (R ~ 0)
Optimum Specific Work / Speed
Yt max;
(α1 ~ 12 – 25o)
Impuls Turbine
Optimum Efficiency
= ho – h1s
α1 ~ 12 – 25o (low)β2 low compared to β1uβ1u – β2 = 0 – 15o
Reaction Turbine (R ~ 0,5)
Optimum Specific Work / Speed
Yt max;
Yt max; uRT ~ 2 uIT
Reaction Turbine
Optimum Efficiency
α1 = β2
φd = φr
CurtisTurbine
Degree of Reaction
co ~c2c1z ~ c2z
Degree of Reaction
Impuls Turbine (R = 0)
Reaction Turbine (R = 0.5)
Main Losses
• Hydraulic (Flow-related)
• Disk Friction
• Ventilation
• Leakage
• Dens gas (Steam Droplets)
• Mechanical
Main Losses
Hydraulic (Flow-related)
Nozzle
Impeller
Annulus
Main Losses
Disk Friction and Ventilation
Disk Friction
Ventilation
Disk Friction and Ventilation
Main Losses
Leakage
Nozzle and Impeller
Reaction Turbine Impuls Turbine
Shaft End
p2 > pk
p2 < pk
Main Losses
Dens Gas Reaction TurbineImpuls Turbine
Mechanical
• Bearings• Seals• Auxiliary Systems
Main Losses
Efficiencies
Hydraulic Losses
Internal Losses
Hydraulic Efficiency
Efficiencies
Internal Efficiency
Hydraulic Losses
Internal Losses
Efficiencies
Total Efficiency
Shaft Power
Shaft Power
Multistage Turbines
Stage efficiency
Internal Efficiency (impeller stage)
Heat Recovery Factor
m ~ 1.03 – 1.04 ; z > 6 stagesm ~ 1.05 – 1.08 ; z > 12 stages
Average Internal Efficiency (turbine)
Multistage Turbines
Efficiency Steam Turbines
Multistage TurbinesNumber of Stages
Impuls Turbine Reaction Turbine
φr = 1.0β1u = β2
Yt IT = 2 Yt RT at fixed u
No of Stages;
Multistage TurbinesNumber of Stages
No of Stages;
Multistage TurbinesNumber of Stages
Reaction Turbine (R = 0.2 – 0.5)
Multistage Turbines
Main Dimensions
Turbines