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Research Papers

Experimental Measurements of Ingestion Through Turbine Rim Seals—Part II: Rotationally Induced Ingress

[+] Author and Article Information
Carl M. Sangan, Gary D. Lock

Department of Mechanical Engineering,
University of Bath,
Bath, BA2 7AY, UK

Kunyuan Zhou

Department of Engineering Thermophysics,
School of Jet Propulsion,
Beihang University,
Beijing, 100191, PRC

Contributed by the International Gas Turbine Institute (IGTI) of ASME for publication in the JOURNAL OF TURBOMACHINERY. Manuscript received July 4, 2011; final manuscript received October 27, 2011; published online November 8, 2012. Editor: David Wisler.

J. Turbomach 135(2), 021013 (Nov 08, 2012) (9 pages) Paper No: TURBO-11-1098; doi: 10.1115/1.4006586 History: Received July 04, 2011; Revised October 27, 2011

Part I of this two-part paper presented experimental results for externally-induced (EI) ingress, where the ingestion of hot gas through the rim seal into the wheel-space of a gas turbine is controlled by the circumferential variation of pressure in the external annulus. In Part II, experimental results are presented for rotationally-induced (RI) ingress, where the ingestion is controlled by the pressure generated by the rotating fluid in the wheel-space. Although EI ingress is the common form of ingestion through turbine rim seals, RI ingress or combined ingress (where EI and RI ingress are both significant) is particularly important for double seals, where the pressure asymmetries are attenuated in the annular space between the inner and outer seals. In this paper, the sealing effectiveness was determined from concentration measurements, and the variation of effectiveness with sealing flow rate was compared with theoretical curves for RI ingress obtained from an orifice model. Using a nondimensional sealing parameter Φ0 the data could be collapsed onto a single curve, and the theoretical variation of effectiveness with Φ0 was in very good agreement with the data for a wide range of flow rates and rotational speeds. It was shown that the sealing flow required to prevent RI ingress was much less than that needed for EI ingress, and it was also shown that the effectiveness of a radial-clearance seal is significantly better than that for an axial-clearance seal for both EI and RI ingress.

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References

Figures

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Fig. 2

Sealing-ring model

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Fig. 1

(a) Cooled turbine stage; (b) double seal on blade

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Fig. 3

Experimental test section

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Fig. 4

Simplified diagram of ingress and egress (a) Φ0 < Φmin (b) Φ0 = Φmin

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Fig. 8

Comparison between theoretical effectiveness curves and experimental data for axial-clearance seal with RI ingress. (Open symbols denote ε data; closed symbols denote Φi,RImin,RI data; solid lines are theoretical curves.)

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Fig. 9

Comparison between theoretical effectiveness curves and experimental data for radial-clearance seal with RI ingress. (Open symbols denote ε data; closed symbols denote Φi,RImin,RI data; solid lines are theoretical curves.)

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Fig. 10

Comparison of sealing effectiveness for EI and RI ingress. (Open symbols denote radial-clearance seal; solid symbols denote axial-clearance seal; solid lines are theoretical curves.)

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Fig. 5

Effect of sealing flow rate on measured radial variation of effectiveness on stator surface for axial-clearance seal. Open symbols denote RI ingress; solid symbols denote EI ingress.

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Fig. 6

Effect of Reφ on measured variation of εc with Cw,o for RI ingress. (Open symbols denote radial-clearance seal; solid symbols denote axial-clearance seal.)

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Fig. 7

Measured variation of sealing effectiveness with Φ0 for RI ingress. (Open symbols denote radial-clearance seal; solid symbols denote axial-clearance seal.)

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