PowerPointPrsentation

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2nd International Conference on Industrial Gas
Turbine Technologies CAME-GT April 29/30, 2004,
Bled, Slovenia
TURBULENCE IN A TIP-LEAKAGE VORTEX A FACTOR
INFLUENCING THE GAS TURBINE EXHAUST DIFFUSER FLOW
R. Willinger, H. Haselbacher Institute of Thermal
Powerplants Vienna University of Technology
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• Overview
• Introduction
• Cascade Geometry
• Pneumatic Instrumentation
• Hot-Wire Instrumentation
• Experimental Results
• Mean Flow Quantities
• Turbulence Quantities
• Summary and Conclusions

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Introduction

• Gas Turbine Exhaust Diffuser
• Annular Diffuser (with Struts)
• Sudden Expansion
• Conical Diffuser

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Introduction

• Diffuser Pressure Recovery Factor
• depends on
• Diffuser Geometry
• Inlet Conditions
• Rotor Blade Wakes
• Hub Boundary Layers
• Swirl
• Tip-Leakage Flow
• Reynolds Number
• Mach Number
• Turbulence Intensity

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Cascade Geometry
Bindon (1987) ?/c 1.5 to 2.5 present ?/c
2.5
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Pneumatic Instrumentation

• Pitot Tube (? 3mm)
• Pt 100 Thermometer
• Five-Hole Probe (? 3mm)
• DANTEC Traversing
• 40 Blade Pressure Taps
• HP 3852A System
• Software LabVIEW

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Hot-Wire Instrumentation

• Single-Probe 55P11
• Triple-Probe 55P91 (cone ? 35)
• Thermocouple
• DANTEC 90N10 CTA-System
• DANTEC 90H02 Flow Unit
• DANTEC Traversing
• Software StreamWare3

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Cascade Operating Conditions
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Experimental Results
Static Pressure Coefficient Cp at Midspan
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Experimental Results
Downstream Measurement Plane at x/cax 1.3
pitchwise 37 stations spanwise 11
stations total 407 points
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Experimental Results
Secondary Velocity Vectors
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Experimental Results
Nondimensional Streamwise Vorticity ?sc/w1,CL -
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Experimental Results
Total Pressure Coefficient Cpt2 -
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Experimental Results
Turbulence Intensity Tu
Moore et al. (1994) Tu ? 30
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Experimental Results
Nondimensional Reynolds Normal Stresses
(streamwise)
(pitchwise)
(spanwise)
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Experimental Results
Nondimensional Reynolds Shear Stresses
(streamwise-pitchwise)
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Experimental Results
Nondimensional Reynolds Shear Stresses
(streamwise-spanwise)
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Experimental Results
Nondimensional Reynolds Shear Stresses
(pitchwise-spanwise)
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• Summary and Conclusions
• Flow and turbulence is investigated for ?/c 2.5
  
• Turbulence intensities from 2 to nearly 30
  (TLV)
• Reynolds normal stresses in the blade wake are
  anisotropic
• Reynolds normal stresses in the TLV are
  anisotropic
• Linear eddy viscosity concept gives Reynolds
  shear stresses
• Extended inlet boundary conditions for diffuser
  CFD