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Research Papers

Aerodynamic Performance of Turbine Center Frames With Purge Flows—Part I: The Influence of Turbine Purge Flow Rates

[+] Author and Article Information
Stefan Zerobin

Institute for Thermal Turbomachinery and
Machine Dynamics,
Graz University of Technology,
Graz 8010, Austria
e-mail: stefan.zerobin@tugraz.at

Andreas Peters

GE Aviation,
Munich 85748, Germany

Sabine Bauinger, Ashwini Bhadravati Ramesh, Michael Steiner, Franz Heitmeir

Institute for Thermal Turbomachinery and
Machine Dynamics,
Graz University of Technology,
Graz 8010, Austria

Emil Göttlich

Institute for Thermal Turbomachinery and
Machine Dynamics,
Graz University of Technology,
Graz 8010, Austria
e-mail: emil.goettlich@tugraz.at

1Corresponding author.

Contributed by the International Gas Turbine Institute (IGTI) of ASME for publication in the JOURNAL OF TURBOMACHINERY. Manuscript received November 23, 2017; final manuscript received January 16, 2018; published online May 3, 2018. Editor: Kenneth Hall.

J. Turbomach 140(6), 061009 (May 03, 2018) (11 pages) Paper No: TURBO-17-1223; doi: 10.1115/1.4039362 History: Received November 23, 2017; Revised January 16, 2018

This two-part paper deals with the influence of high-pressure turbine (HPT) purge flows on the aerodynamic performance of turbine center frames (TCF). Measurements were carried out in a product-representative one and a half-stage turbine test setup. Four individual purge mass flows differing in flow rate, pressure, and temperature were injected through the hub and tip, forward and aft cavities of the unshrouded HPT rotor. Two TCF designs, equipped with nonturning struts, were tested and compared. In this first part of the paper, the influence of different purge flow rates (PFR) is discussed, while in the second part of the paper, the impact of the individual hub and tip purge flows on the TCF aerodynamics is investigated. The acquired measurement data illustrate that the interaction of the ejected purge flow with the main flow enhances the secondary flow structures through the TCF duct. Depending on the PFR, the radial migration of purge air onto the strut surfaces directly impacts the loss behavior of the duct. The losses associated with the flow close to the struts and in the strut wakes are highly dependent on the relative position between the HPT vane and the strut leading edge (LE), as well as the interaction between vane wake and ejected purge flow. This first-time experimental assessment demonstrates that a reduction in the purge air requirement benefits the engine system performance by lowering the TCF total pressure loss.

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Figures

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Fig. 1

Sketch of the flow path of the test turbine with a detailed view of the cavities

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Fig. 2

TCF duct area distribution for configuration A and B

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Fig. 3

Streamwise vorticity (left and center) and pitch angle (right) at the TCF inlet for PFR = 0%, 100%, and 200% (view is A.L.F.)

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Fig. 4

Sketch of the superposition of stator and rotor vorticity

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Fig. 5

Basic vortical structures in the presence of hub purge flows

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Fig. 6

Mass-averaged radial profiles at the TCF inlet for PFR = 0%, 100%, and 200%

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Fig. 7

Purge streaks ejected from the hub cavity downstream of the HPT rotor; numerical result with total pressure contours (top) and oil flow visualization (bottom) (view is F.L.A.)

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Fig. 8

Oil flow visualizations on strut S2 for PFR = 0% and PFR = 100%; rotor wake windward (left) and leeward (right) strut surfaces

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Fig. 9

Oil flow visualizations on strut S1 for PFR = 0% and PFR = 100%; rotor wake windward (left) and leeward (right) strut surfaces

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Fig. 10

Definition of yaw angle α; numerical result of yaw angle at midspan

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Fig. 11

Contour plots of relative duct pressure loss and superimposed secondary flow velocity vectors at the TCF exit for PFR = 0%, 100%, and 200% (view is A.L.F.)

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Fig. 12

Mass-averaged radial profiles at TCF outlet for PFR = 0%, 100%, and 200%

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Fig. 13

Definition of TCF flow sectors

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Fig. 14

Mass-averaged radial profiles of relative total pressure loss for different TCF flow sectors

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Fig. 15

Relative total pressure loss for different TCF flow sectors

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Fig. 16

Relative total pressure loss for two different turbine center frame duct designs

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