turbine design aspects - kth design aspects damian vogt ... • power shaft must rotate at constant...
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Turbomachinery Lecture Notes 1 2007-10-11
Compressor Design Aspects
Damian Vogt Course MJ2429
Axial Compressor Rotor Types
Rotors of drum and disk construction
Source [1]
KTH/EKV/DV
Turbomachinery Lecture Notes 2 2007-10-11
Multiple Rotors
Source [1]
Abbreviations:
• L.P. low pressure • H.P. high pressure
Advantages
• Single spool simple and robust construction • Twin spool optimum speed for LP and HP compressor; LP usually rotates slower
than HP
KTH/EKV/DV
Turbomachinery Lecture Notes 3 2007-10-11
Source [1]
Advantages of triple-spool engine:
• Optimum fan speed; fan speed is lower than LP and HO compressor (large diameter gives high blade tip speeds supersonic due to low speed of sound)
• Avoid having a geared fan (a gear box for these power ratings is heavy)
KTH/EKV/DV
Turbomachinery Lecture Notes 4 2007-10-11
Different problem for power generation turbine:
• Power shaft must rotate at constant speed. At part load behavior the compressor would however work in a better operating point at part speed.
• Solution: free power turbine
Solar Turbines mechanical drive
Source [2]
KTH/EKV/DV
Turbomachinery Lecture Notes 5 2007-10-11
Rotor Blade Mount
Source [1]
Comparison of compressor and turbine blade fixations:
• Turbine: fir tree • Compressor: dove tail
Reason: higher load at higher temperatures for turbines, fir tree distributes loads more efficiently but is more costly
KTH/EKV/DV
Turbomachinery Lecture Notes 6 2007-10-11
Stator Vane Mount
Source [1]
Variable Stage Geometry Variable guide vanes: control of stager angle of all blades in a blade row
Source [1]
Purpose:
• Minimize incidence at off-design operation • Pre-swirl for load regulation
KTH/EKV/DV
Turbomachinery Lecture Notes 7 2007-10-11
Inlet guide vanes
Rotor
Stator Zero swirl
Negative swirl
Positive swirl
Source [3]
KTH/EKV/DV
Turbomachinery Lecture Notes 8 2007-10-11
Surge Control (Bleed Valves)
Source [1]
Bleed valves are used to avoid compressor surge during fast acceleration. Their use during steady operation however would be very wasteful and is therefore not taken into consideration.
KTH/EKV/DV
Turbomachinery Lecture Notes 9 2007-10-11
Boundary Layer Control
Source [3]
KTH/EKV/DV
Turbomachinery Lecture Notes 10 2007-10-11
Aspiration
Source [4]
KTH/EKV/DV
Turbomachinery Lecture Notes 11 2007-10-11
Blade Twist
Source [1]
KTH/EKV/DV
Turbomachinery Lecture Notes 12 2007-10-11
References [1] Rolls-Royce, 1992, “The Jet Engine”, ISBN 0 902121 04 9, Derby, UK, 1992 [2] Boyce, M.P., 2002, “Gas Turbine Engineering Handbook”, Gulf Professional Publishing,
ISBN 0-88415-732-6, Houston, 2002 [3] Eckert, B., 1953, “Axialkompressoren und Radialkomprssoren”, Springer Verlag,
Berlin/Göttingen/Heidelberg, 1953 [4] Merchant, A., 1999, “Design and Analysis of Axial Aspirated Compressor Stages”, PhD
thesis, Massachusetts Institute of Technology, USA, Gas Turbine Laboratory, Boston, 1999
KTH/EKV/DV