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Research Papers: Gas Turbines: Controls, Diagnostics, and Instrumentation

Unsteady Flow Field and Coarse Droplet Measurements in the Last Stage of a Low-Pressure Steam Turbine With Supersonic Airfoils Near the Blade Tip

[+] Author and Article Information
Ilias Bosdas

Laboratory for Energy Conversion,
Department of Mechanical and
Process Engineering,
ETH Zurich,
Zurich 8092, Switzerland
e-mail: bosdas@lec.mavt.ethz.ch

Michel Mansour

Laboratory for Energy Conversion,
Department of Mechanical and
Process Engineering,
ETH Zurich,
Zurich 8092, Switzerland
e-mail: michel.mansour@lec.mavt.ethz.ch

Anestis I. Kalfas

Department of Mechanical Engineering,
Aristotle University of Thessaloniki,
Thessaloniki 54124, Greece
e-mail: akalfas@auth.gr

Reza S. Abhari

Laboratory for Energy Conversion,
Department of Mechanical and
Process Engineering,
ETH Zurich,
Zurich 8092, Switzerland
e-mail: rabhari@lec.mavt.ethz.ch

Shigeki Senoo

Mitsubishi Hitachi Power Systems, Ltd.,
3-1-1, Saiwai,
Hitachi 317-0073, Ibaraki, Japan
e-mail: shigeki1_senoo@mhps.com

Contributed by the Controls, Diagnostics and Instrumentation Committee of ASME for publication in the JOURNAL OF ENGINEERING FOR GAS TURBINES AND POWER. Manuscript received July 26, 2016; final manuscript received February 15, 2017; published online April 11, 2017. Editor: David Wisler.

J. Eng. Gas Turbines Power 139(9), 091601 (Apr 11, 2017) (11 pages) Paper No: GTP-16-1364; doi: 10.1115/1.4036011 History: Received July 26, 2016; Revised February 15, 2017

The largest share of electricity production worldwide belongs to steam turbines. However, the increase of renewable energy production has led steam turbines to operate under part load conditions and increase in size. As a consequence, long rotor blades will generate a relative supersonic flow field at the inlet of the last rotor. This paper presents a unique experiment work that focuses at the top 30% of stator exit in the last stage of an low pressure (LP) steam turbine test facility with coarse droplets and high wetness mass fraction under different operating conditions. The measurements were performed with two novel fast response probes: a fast response probe for three-dimensional flow field wet steam measurements and an optical backscatter probe for coarse water droplet measurements ranging from 30 μm up to 110 μm in diameter. This study has shown that the attached bow shock at the rotor leading edge is the main source of interblade row interactions between the stator and rotor of the last stage. In addition, the measurements showed that coarse droplets are present in the entire stator pitch with larger droplets located at the vicinity of the stator's suction side. Unsteady droplet measurements showed that the coarse water droplets are modulated with the downstream rotor blade-passing period. This set of time-resolved data will be used for in-house computational fluid dynamics (CFD) code development and validation.

Copyright © 2017 by ASME
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References

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Figures

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Fig. 1

FRAP-HT heated probe schematic and temperature measurement locations

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Fig. 2

FRAP-OB probe tip with purging interface for windows protection from water contamination and beam deflection

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Fig. 3

MHPS' low-pressure steam turbine test facility where FRAP-HTH and FRAP-OB measurements were conducted

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Fig. 4

Test section schematic of MHPS's steam turbine test facility. The measurement plane of the probe at L-0 stator exit is indicated as well.

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Fig. 5

Circumferentially area-averaged spanwise distribution of Cpt (-) (a) and Cps (-) (b) with the minimum and maximum values obtained from the time-resolved data

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Fig. 6

Circumferentially area-averaged spanwise distribution of delta flow yaw angle (deg) (a) and dimensionless flow pitch angle (-) (b) with the minimum and maximum values obtained from the time-resolved data

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Fig. 7

Circumferential distribution of Cps (-) at L-0 stator exit for OP-1 at 90% (a) and 75% (b) span

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Fig. 8

Total and static pressure coefficients at 90% span for OP-1 at t/T = 1.5

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Fig. 9

Circumferential distribution of delta yaw angle (deg) at L-0 stator exit for OP-1 at 90% span

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Fig. 10

Time-averaged results of droplet rate (#droplet/rev) for (a) OP-3 and (b) OP-2 at L-0 stator exit

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Fig. 11

Time-averaged results of Sauter mean droplet diameter (μm) for (a) OP-3 and (b) OP-2 at L-0 stator exit

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Fig. 12

Time-averaged results of droplet mass rate (mg/rev) for (a) OP-3 and (b) OP-2 at L-0 stator exit

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Fig. 13

Sauter mean droplet diameter for OP-2 (Tin = 270 °C) and OP-3 (Tin = 220 °C) at L-0 stator exit

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Fig. 14

Droplet diameter distribution for OP-2 at 75% for four different circumference locations at pitch: −0.25, −0.5, +0.5, and +0.25 (see Fig. 12(b))

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Fig. 15

Circumferential distribution of measured droplet mass rate (mg/s) at L-0 stator exit for OP-2 at 78% span

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Fig. 16

Circumferential distribution of Cps (-) (a) and nondimensional streamwise vorticity (-) (b) at L-0 stator exit for OP-2 at 78% span

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Fig. 17

Circumferential distribution of measured droplet mass rate (mg/s) at L-0 stator exit for OP-2 at 71% span

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Fig. 18

Circumferential distribution of Cps (-) (a) and nondimensional streamwise vorticity (-) (b) at L-0 stator exit for OP-2 at 71% span

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