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Research Papers

Experimental Comparison of Axial Turbine Performance Under Steady and Pulsating Flows

[+] Author and Article Information
A. St. George

Gas Dynamics and Propulsion Lab,
Department of Aerospace Engineering,
University of Cincinnati,
Cincinnati, OH 45221
e-mail: andrew.stgeorge@gmail.com

R. Driscoll

Gas Dynamics and Propulsion Lab,
Department of Aerospace Engineering,
University of Cincinnati,
Cincinnati, OH 45221
e-mail: r.b.driscoll.85@gmail.com

E. Gutmark

Gas Dynamics and Propulsion Lab,
Department of Aerospace Engineering,
University of Cincinnati,
Cincinnati, OH 45221
e-mail: ephraim.gutmark@uc.edu

D. Munday

Gas Dynamics and Propulsion Lab,
Department of Aerospace Engineering,
University of Cincinnati,
Cincinnati, OH 45221
e-mail: david.munday@uc.edu

Contributed by the International Gas Turbine Institute (IGTI) of ASME for publication in the JOURNAL OF TURBOMACHINERY. Manuscript received July 7, 2014; final manuscript received July 21, 2014; published online August 26, 2014. Editor: Ronald Bunker.

J. Turbomach 136(11), 111005 (Aug 26, 2014) (11 pages) Paper No: TURBO-14-1117; doi: 10.1115/1.4028115 History: Received July 07, 2014; Revised July 21, 2014

The performance of an axial turbine is studied under close-coupled, out-of-phase, multiple-admission pulsed air flow to approximate turbine behavior under pulsed detonation inflow. The operating range has been mapped for four frequencies and compared using multiple averaging approaches and five formulations of efficiency. Steady performance data for full and partial admission are presented as a basis for comparison to the pulsed flow cases. While time-averaged methods are found to be unsuitable, mass-averaged, work-averaged, and integrated instantaneous methods yield physically meaningful values and comparable trends for all frequencies. Peak work-averaged efficiency for pulsed flow cases is within 5% of the peak steady, full admission values for all frequencies, in contrast to the roughly 15–20% performance deficit experienced under steady, 50% partial admission conditions. Turbine efficiency is found to be a strong function of corrected flow rate and mass-averaged rotor incidence angle, but only weakly dependent on frequency.

Copyright © 2014 by ASME
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References

Figures

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Fig. 5

Schematic of turbine geometry

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Fig. 4

Schematic of traversable, high speed pitot probe with embedded transducer

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Fig. 3

Sector layout (facing the turbine inlet) with notional pulse progression for the system

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Fig. 2

Overview of the integrated turbine rig in the UC PDE test facility

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Fig. 1

Schematic of Garrett JFS-100-13A power generation turbine unit (from Garrett User Manual)

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Fig. 8

Pulse shape sensitivity to frequency for 0.78 kg/s and 0.40 kg/s

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Fig. 9

Evolution of swirl at the turbine (a) inlet and (b) exit at 10 Hz, 0.60 kg/s for varying pitot probe rotational angles

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Fig. 7

Total pressure evolution at the turbine inlet plane at 10 Hz for (a) 0.40 kg/s, (b) 0.60 kg/s, and (c) 0.78 kg/s

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Fig. 6

Steady, full and 50% partial admission performance maps for (a) MFP and (b) efficiency, for N′/N′DES characteristics

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Fig. 10

Comparison of pressure ratio formulations relative to work-averaged definition

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Fig. 11

Corrected mass flow (via work-averaging) versus pressure ratio for all pulsation frequencies

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Fig. 12

Flow rate evolution for a turbine inlet sector at 20 Hz, for maximum turbine loading

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Fig. 13

Comparison of efficiency calculation methods for 10 Hz, 53% design corrected speed

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Fig. 14

(a) Incidence evolution over pulse cycle (b) effect of mass-averaged rotor incidence on cycle efficiency for 10 Hz pulsations

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Fig. 15

Work-averaged efficiency performance maps: (a) 5 Hz, (b) 10 Hz, (c) 15 Hz, and (d) 20 Hz

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