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Research Papers

# Effect of Combustor Swirl on Transonic High Pressure Turbine Efficiency

[+] Author and Article Information
Paul F. Beard, Thomas Povey

Department of Engineering Science,
University of Oxford,
Oxford OX1 3PJ, UK

Andy D. Smith

Turbine Systems,
Rolls-Royce plc,
Moor Lane,
PCF-1, P.O. Box 31,
Derby DE24 8BJ, UK

Contributed by the International Gas Turbine Institute (IGTI) of ASME for publication in the Journal of Turbomachinery. Manuscript received June 8, 2012; final manuscript received March 25, 2013; published online September 20, 2013. Assoc. Editor: Kenichiro Takeishi.

J. Turbomach 136(1), 011002 (Sep 20, 2013) (12 pages) Paper No: TURBO-12-1064; doi: 10.1115/1.4024841 History: Received June 08, 2012; Revised March 25, 2013

## Abstract

This paper presents an experimental and computational study of the effect of inlet swirl on the efficiency of a transonic turbine stage. The efficiency penalty is approximately 1%, but it is argued that this could be recovered by correct design. There are attendant changes in capacity, work function, and stage total-to-total pressure ratio, which are discussed in detail. Experiments were performed using the unshrouded MT1 high-pressure turbine installed in the Oxford Turbine Research Facility (OTRF) (formerly at QinetiQ Farnborough): an engine scale, short duration, rotating transonic facility, in which M, Re, $Tgas/Twall$, and $N/T01$ are matched to engine conditions. The research was conducted under the EU Turbine Aero-Thermal External Flows (TATEF II) program. Turbine efficiency was experimentally determined to within bias and precision uncertainties of approximately ±1.4% and ±0.2%, respectively, to 95% confidence. The stage mass flow rate was metered upstream of the turbine nozzle, and the turbine power was measured directly using an accurate strain-gauge based torque measurement system. The turbine efficiency was measured experimentally for a condition with uniform inlet flow and a condition with pronounced inlet swirl. Full stage computational fluid dynamics (CFD) was performed using the Rolls-Royce Hydra solver. Steady and unsteady solutions were conducted for both the uniform inlet baseline case and a case with inlet swirl. The simulations are largely in agreement with the experimental results. A discussion of discrepancies is given.

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## Figures

Fig. 1

The Oxford Turbine Research Facility

Fig. 2

(a) Measured swirl vector at HP vane inlet in the OTRF (vectors scaled by secondary velocity magnitude); (b) measured HP vane inlet whirl angles at 10%, 50%, and 90% span

Fig. 3

Area-surveys results of stage inlet total pressure: (a) without and (b) with inlet swirl generation

Fig. 4

Area-survey results of total pressure at rotor exit: (a) near plane p03 and (b) far plane p04

Fig. 5

Vane and rotor computational meshes

Fig. 6

Vane surface isentropic Mach number distributions with and without inlet swirl

Fig. 7

Predicted radial changes in vane profile loss coefficient and turbine efficiency with inlet swirl

Fig. 8

Measured capacity of modern HP vane [28]

Fig. 9

Calculated radial changes in work function with inlet swirl

Fig. 10

Measured and predicted changes in NGV isentropic Mach number distributions at 10%, 50%, and 90% span

Fig. 11

Predicted change in total pressure loss coefficient at vane exit with inlet swirl

Fig. 12

Predicted change in vane exit conditions with inlet swirl and effect on work function

Fig. 13

Predicted changes in rotor inlet relative conditions with inlet swirl

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