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Research Papers

Effects of Blade Deformation on the Performance of a High Flow Coefficient Mixed Flow Impeller

[+] Author and Article Information
Hamid Hazby

PCA Engineers Ltd.,
Studio 2,
Deepdale Enterprise Park, Nettleham,
Lincoln LN2 2LL, UK
e-mail: h.hazby@pcaeng.co.uk

Ian Woods

PCA Engineers Ltd.,
Studio 2,
Deepdale Enterprise Park, Nettleham,
Lincoln LN2 2LL, UK
e-mail: ian.woods@pcaeng.co.uk

Michael Casey

PCA Engineers Ltd.,
Biberlinstrasse 20,
Zürich CH-8032, Switzerland
e-mail: michael.casey@casey-s.ch

Ryusuke Numakura

Turbo Machinery and Engine
Technology Department,
IHI Corporation,
1, Shin-Nakahara-cho, Isogo-ku,
Yokohama-shi, Kanagawa 235-8501, Japan
e-mail: ryuusuke_numakura@ihi.co.jp

Hideaki Tamaki

Corporate Research and Development,
IHI Corporation,
1, Shin-Nakahara-cho, Isogo-ku,
Yokohama-shi, Kanagawa 235-8501, Japan
e-mail: hideaki_tamaki@ihi.co.jp

Manuscript received July 16, 2015; final manuscript received July 30, 2015; published online September 23, 2015. Editor: Kenneth C. Hall.

J. Turbomach 137(12), 121005 (Sep 23, 2015) (9 pages) Paper No: TURBO-15-1149; doi: 10.1115/1.4031356 History: Received July 16, 2015; Revised July 30, 2015

The effects of blade deformation under running conditions on the performance of a highly loaded transonic mixed flow impeller were investigated. Two impellers were manufactured, one using the “running” blade profiles as designed and one using the converted “unrunning” or “cold” geometry. Both impellers were tested experimentally and investigated numerically. The test data taken with smooth casing showed that at maximum speed, the isentropic efficiency and pressure ratio of the running geometry was higher than the unrunning geometry by about 0.4% and 1.4%, respectively. However, the difference in performance diminished in the presence of recirculating casing treatment. Numerical calculations suggested that the differences at high speeds were mainly due to the variation in the impeller tip clearance. The calculations using deformed blade profiles under centrifugal load only, predicted performance differences which were about twice as high as the measured values. However, closer predictions were obtained when the effects of pressure loads on blade deformation were included using closely coupled fluid-structural analyses.

Copyright © 2015 by ASME
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References

Figures

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Fig. 1

(a) Sections of an axial transonic fan, showing positive lean in the front part of the blade; (b) the tip section moves against the direction of rotation under centrifugal load

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Fig. 2

(a) Sections of a centrifugal impeller, showing negative lean in the front part of the blade; (b) the tip section moves in the direction of rotation under centrifugal load

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Fig. 3

Investigated impeller geometry

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Fig. 4

FE mesh of main vane

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Fig. 5

FE mesh of main vane and disk

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Fig. 6

Running and unrunning vane profiles

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Fig. 7

Configuration of casing treatment in the test rig

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Fig. 8

Measured total-to-total pressure ratio and isentropic efficiency of impeller R2 and impeller UR2 with smooth casing wall

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Fig. 9

Measured total-to-total pressure ratio and isentropic efficiency of impeller R2 and impeller UR2 with casing treatment

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Fig. 10

Performance of impeller R2, with and without centrifugal deformation

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Fig. 11

Predicted performance parameters of impeller R2 and impeller UR2. Centrifugal deformation was applied to both impellers.

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Fig. 12

Variation of the inlet blade angle and throat width at the tip section of impeller R2 with operating speed

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Fig. 13

Variation of tip clearance size with rotational speed at leading edge and trailing edge of impeller R2 and impeller UR2

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Fig. 14

Vane geometries of impeller UR2 and impeller R2 with modified tip clearance

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Fig. 15

Predicted performance of impeller R2 using the tip clearance sizes of impeller UR2 at corresponding operating speeds

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Fig. 16

Variation of pressure deformation at impeller tip relative to centrifugal deformation versus corrected mass flow rate and speed

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Fig. 17

Effects of centrifugal and pressure loads on the performance of impeller R2

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