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Research Papers

Experimental and Numerical Investigation of Secondary Flow Structures in an Annular Low Pressure Turbine Cascade Under Periodic Wake Impact—Part 1: Experimental Results

[+] Author and Article Information
Martin Sinkwitz

Chair of Thermal Turbomachines
and Aeroengines
Department of Mechanical Engineering,
Ruhr-Universität Bochum,
Bochum, 44801, Germany
e-mail: martin.sinkwitz@rub.de

Benjamin Winhart, David Engelmann, Francesca di Mare

Chair of Thermal Turbomachines
and Aeroengines
Department of Mechanical Engineering,
Ruhr-Universität Bochum,
Bochum, 44801, Germany

Ronald Mailach

Chair of Turbomachinery and Flight Propulsion,
Institute of Fluid Mechanics,
Technische Universität Dresden,
Dresden, 01062, Germany

Manuscript received February 15, 2018; final manuscript received September 19, 2018; published online January 31, 2019. Assoc. Editor: Coutier-Delgosha Olivier.

J. Turbomach 141(2), 021008-021009-8 (Jan 31, 2019) (8 pages) Paper No: TURBO-18-1035; doi: 10.1115/1.4042284 History: Received February 15, 2018; Revised September 19, 2018

Experimental studies have been conducted on a modified T106 low pressure turbine (LPT) profile in an annular 1.5 stage axial turbine rig at the Chair of Thermal Turbomachines and Aeroengines, Ruhr-Universität Bochum. The rig setup allows the highly resolved measurement of unsteady wake–stator flow interaction in both space and time. Incoming wakes are generated by a variable-speed driven rotor equipped with cylindrical bars. In the present paper, an experimental approach to the investigation of unsteady phenomena is proposed. Time-averaged and instantaneous measurement data from 2D flow field traverses at the stator exit are provided for the analysis of the periodically unsteady vortex formation, displacement, and suppression. Additional time-accurate blade pressure data are used to study the relationship between the flow structures downstream of the stator row and the immediate intermittent wake impact on the blades. Bar wake kinematics is also discussed in relation to the observations.

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References

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Sinkwitz, M. , Engelmann, D. , and Mailach, R. , 2017, “ Experimental Investigation of Periodically Unsteady Wake Impact on Secondary Flow in a 1.5 Stage Full Annular LPT Cascade With Modified T106 Blading,” ASME Paper No. GT2017-64390.
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Winhart, B. , Sinkwitz, M. , Schramm, A. , Engelmann, D. , di Mare, F. , and Mailach, R. , 2017, “ Experimental and Numerical Investigation of Secondary Flow Structures in an Annular LPT Cascade Under Periodical Wake Impact—Part 2: Numerical Results,” ASME J. Turbomach. (accepted).

Figures

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Fig. 1

Test facility. The sectional view of the test section (a), 3D illustration (b), and view onto the T106RUB stator row (c).

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Fig. 5

Time-resolved flow field at 0.15 C downstream of TE. Time-space evolution of AVO (isocontours) between R/H =0% and R/H =100% (Sr = 1.55 and ϕ = 0.83).

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Fig. 4

Time-resolved flow field at 0.15C downstream of TE. Time-space evolution of Δc (top) and AVO (bottom) for three positions at constant span (Sr = 1.55 and ϕ = 0.83).

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Fig. 3

Time-averaged flow field at 0.15 C downstream of TE. AVO distributions for the undisturbed case (a) and for wake disturbed inflow (Sr = 1.55 and ϕ = 0.83) (b).

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Fig. 2

T106RUB blade for time-resolved profile pressure measurements. SS view, prepared for Kulite LQ-125 instrumentation (a), and the arrangement of sensors (b).

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Fig. 6

Time-averaged cp distributions at T106RUB midspan for three different operating points. The magnification of situation at LE (details A + B) and TE (detail C).

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Fig. 7

Time-space evolution of T106RUB profile pressure fluctuations (midspan) for operating points with light (a), intermediate (b), and heavy (c) perturbation

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Fig. 8

T106RUB profile pressure fluctuations at midspan. Temporal evolution for one bar passing, divided into four time instants (Sr = 1.55 and ϕ = 0.83).

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