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Gas Turbines: Combustion, Fuels, and Emissions

Integrated Combustor Turbine Design for Improved Aerothermal Performance: Effect of Dilution Air Control

[+] Author and Article Information
Altug M. Basol1

 Laboratory for Energy Conversion, Department of Mechanical and Process Engineering, ETH Zurich, Zurich CH-8092, Switzerlandbasola@lec.mavt.ethz.ch

Regina Kai

 Laboratory for Energy Conversion, Department of Mechanical and Process Engineering, ETH Zurich, Zurich CH-8092, Switzerlandregina@lec.mavt.ethz.ch

Anestis I. Kalfas

 Aristotle University of Thessaloniki, School of Engineering, 52124 Thessaloniki, Greeceakalfas@auth.gr

Reza S. Abhari

 Laboratory for Energy Conversion, Department of Mechanical and Process Engineering, ETH Zurich, Zurich CH-8092, Switzerlandabhari@lec.mavt.ethz.ch

1

Corresponding author.

J. Eng. Gas Turbines Power 134(9), 091501 (Jul 18, 2012) (8 pages) doi:10.1115/1.4006671 History: Received September 18, 2011; Accepted January 31, 2012; Published July 17, 2012; Online July 18, 2012

The effect of dilution air control in a combustor on the heat load distribution of an axial turbine with nonaxisymmetric endwall profiling is examined. Endwall profiling is a more common design feature in new engine types, due to its effectiveness in reducing secondary flows and their associated losses. In the present work, the effect of dilution air control is examined by using two different circumferentially nonuniform hot-streak shapes; the two cases differ in their spanwise extents either side of the stator and, therefore, represent different approaches for dilution air control. This numerical study details the impact of these two different strategies for dilution air control on the rotor blade heat load distribution. The inlet boundary conditions simulate the experiment that is conducted in the axial research turbine facility LISA at ETH Zurich. A circumferential nonuniformity in the spanwise migration pattern of the hot streak inside the stator is observed that is found to be alleviated by the effect of the endwall profiling. Due to the observed spanwise migration pattern inside the stator the two hot-streak cases result in considerably different heat load distributions on the rotor blade, emphasizing the importance of the integrated combustor turbine approach. Finally, the implications for dilution air control on the liner are discussed for the realization of the simulated hot-streak shapes in real combustors.

Copyright © 2012 by American Society of Mechanical Engineers
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Figures

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Figure 4

Convection of the eddy viscosity imposed at the stator inlet generated as a result of the interaction of the hot-streak generator with the free stream

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Figure 5

Variation of static pressure at the inlet of the rotor domain at midspan. The variation is periodic due to the stator–rotor interaction.

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Figure 6

Time-averaged relative total pressure distributions downstream of the rotor (rotor relative frame of reference)

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Figure 7

Time-averaged relative total temperature distributions downstream of the rotor (rotor relative frame of reference)

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Figure 8

Distribution of the particles migrating to the rotor blade tip among all released from the area shown by the black curve upstream of the stator with nonaxisymmetric endwalls. The temperature distribution at the stator inlet plane is shown in the background contour.

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Figure 9

Distribution of the same particles shown in Fig. 8 at the stator outlet plane. The particles are colored according to the change in their spanwise positions relative to the radii of their starting positions in the stator inlet plane. The total pressure distribution is shown in the background contours.

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Figure 10

Distribution of the particles migrating to the rotor blade tip among all released from the area shown by the black curve upstream of the stator with axisymmetric endwalls. The temperature distribution at the stator inlet plane is shown in the background contour.

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Figure 11

Comparison of the distribution of the number of the particles migrating to the rotor blade tip released from each circumferential position upstream of the stators with and without nonaxisymmetric endwall profiling. (The stator leading edge is at zero stator pitch.)

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Figure 13

Total temperature distribution at the stator inlet plane for baseline (left) and modified (right) hot-streak cases

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Figure 14

Circumferentially mass averaged total temperature profiles at the inlet of the stator for both hot-streak shapes

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Figure 15

Difference in the rotor blade adiabatic wall temperatures between the two hot-streak shapes imposed upstream of the stator with nonaxisymmetric endwall profiling (ΔTaw=Taw,baseline-Taw,modified)

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Figure 16

Difference in the rotor blade adiabatic wall temperatures between the two hot-streak shapes imposed upstream of the stator with axisymmetric endwalls (ΔTaw=Taw,baseline-Taw,modified)

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Figure 17

Difference in the rotor blade tip adiabatic wall temperatures between the two hot-streak shapes imposed upstream of the stator (a) with nonaxisymmetric endwall profiling (b) with axisymmetric endwalls (ΔTaw=Taw,baseline-Taw,modified)

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Figure 1

Layout of the turbine showing the location of the hot-streak generator. The three measurement planes A, B, and C are also shown.

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Figure 2

Surface meshes on the stator and rotor blades and the rotor hub. Along the stator hub, the contours show the geometry of the nonaxisymmetric endwall profiling. The inserts show details of the mesh at the leading and trailing edges of the rotor tip.

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Figure 3

Measured total temperature (left) and total pressure deviation (right) at plane A. These measured data are used as the inlet boundary conditions for the solver.

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Figure 12

Variation in the radial positions of the streamlines with respect to the axial chord of the stators released from either side of the stators with and without endwall profiling (stator leading edge is at zero axial chord)

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