Research Papers: Gas Turbines: Turbomachinery

An Experimental Investigation of the Performance Impact of Swirl on a Turbine Exhaust Diffuser/Collector for a Series of Diffuser Strut Geometries

[+] Author and Article Information
Song Xue

Techsburg, Inc.,
Christiansburg, VA 24073
e-mail: sxue@techsburg.com

Stephen Guillot

Techsburg, Inc.,
Christiansburg, VA 24073
e-mail: sguillot@techsburg.com

Wing F. Ng

Techsburg, Inc.,
Christiansburg, VA 24073
e-mail: wng@techsburg.com

Jon Fleming

Techsburg, Inc.,
Christiansburg, VA 24073
e-mail: jfleming@techsburg.com

K. Todd Lowe

Virginia Tech
Blacksburg, VA 24061
e-mail: kelowe@exchange.vt.edu

Nihar Samal

Solar Turbines,
San Diego, CA 92101
e-mail: samal_nihar_r@solarturbines.com

Ulrich E. Stang

Solar Turbines,
San Diego, CA 92101
e-mail: stang_ulrich_e@solarturbines.com

Contributed by the Turbomachinery Committee of ASME for publication in the JOURNAL OF ENGINEERING FOR GAS TURBINES AND POWER. Manuscript received November 12, 2015; final manuscript received December 30, 2015; published online March 22, 2016. Editor: David Wisler.

J. Eng. Gas Turbines Power 138(9), 092603 (Mar 22, 2016) (8 pages) Paper No: GTP-15-1526; doi: 10.1115/1.4032738 History: Received November 12, 2015; Revised December 30, 2015

A comprehensive experimental investigation was initiated to evaluate the aerodynamic performance of a gas turbine exhaust diffuser/collector for various strut geometries over a range of inlet angle. The test was conducted on a 1/12th scale rig developed for rapid and accurate evaluation of multiple test configurations. The facility was designed to run continuously at an inlet Mach number of 0.40 and an inlet hydraulic diameter-based Reynolds number of 3.4 × 105. Multihole pneumatic pressure probes and surface oil flow visualization were deployed to ascertain the effects of inlet flow angle and strut geometry. Initial baseline diffuser-only tests with struts omitted showed a weakly increasing trend in pressure recovery with increasing swirl, peaking at 14 deg before rapidly dropping. Tests on profiled struts showed a similar trend with reduced recovery across the range of swirl and increased recovery drop beyond the peak. Subsequent tests for a full diffuser/collector configuration with profiled struts revealed a rising trend at lower swirl when compared to diffuser-only results, albeit with a reduction in recovery. When tested without struts, the addition of the collector to the diffuser not only reduced the pressure recovery at all angles but also resulted in a shift of the overall characteristic to a peak recovery at a lower value of swirl. The increased operation range associated with the implementation of struts in the full configuration is attributed to the deswirling effects of the profiled struts. In this case, the decreased swirl reduces the flow asymmetry responsible for the reduction in pressure recovery attributed to the formation of a localized reverse-flow vortex near the bottom of the collector. This research indicates that strut setting angle and, to a lesser extent, strut shape can be optimized to provide peak engine performance over a wide range of operation.

Copyright © 2016 by ASME
Your Session has timed out. Please sign back in to continue.


Sovran, G. , and Klomp, E. D. , 1967, “ Experimentally Determined Optimum Geometries for Rectillinear Diffusers With Rectangular, Conical or Annular Cross-Section,” Fluid Mechanics of Internal Flow, G. Sovran , ed., Elsevier, Amsterdam, pp. 270–312.
Lohmann, P. , Markowski, S. J. , and Brookman, E. T. , 1979, “ Swirling Flow Through Annular Diffuses With Conical Walls,” ASME J. Fluids Eng., 101(2), pp. 224–229. [CrossRef]
Kumar, D. S. , and Kumar, K. L. , 1980, “ Effect of Swirl on Pressure Recovery in Annular Diffusers,” J. Mech. Eng. Sci., 22(6), pp. 305–313. [CrossRef]
Vassiliev, V. , Irmisch, S. , Claridge, M. , and Richardson, D. P. , 2003, “ Experimental and Numerical Investigation of the Impact of Swirl on the Performance of Industrial Gas Turbines Exhaust Diffusers,” ASME Paper No. GT2003-38424.
Pietrasch, R. Z. , and Seume, J. R. , 2005, “ Interaction Between Struts and Swirl Flow in Gas Turbine Exhaust Diffusers,” ASME J. Thermal Sci., 14(4), pp. 314–320. [CrossRef]
Goudkov, E. I. , Nikolaev, M. A. , Ris, V. V. , Smirnov, E. M. , and Tajc, L. , 2003. “ Influence of Tip-Clearance Jet Leakage on Efficiency of Working Fluid Injection Into the Diffuser as Applied for Reduction of Exhaust Hood Case,” 5th European Conference on Turbomachinery, pp. 761–770.
Guillot, S. , Ng, W. F. , Hamm, H. D. , Stang, U. E. , and Lowe, K. T. , 2014, “ The Experimental Studies of Improving the Aerodynamic Performance of a Turbine Exhaust System,” ASME Paper No. GT2014-25481.
Roach, P. E. , 1987, “ The Generation of Nearly Isotropic Turbulence by Means of Grids,” Int. J. Heat Fluid Flow, 8(2), pp. 82–92. [CrossRef]
Aeroprobe, 2006, “ Multi-Hole Probe User's Manual for 5-Hole and 7-Hole Probes,” Vol. 1.21, Aeroprobe Corp., Christiansburg, VA.
Boehm, B. P. , 2012, “ Performance Optimization of a Subsonic Diffuser-Collector Subsystem Using Interchangeable Geometries,” M.S. thesis, Department of Mechanical Engineering, Virginia Polytechnic Institute and State University, Blacksburg, VA.
Coladipietro, R. , Schneider, J. M. , and Sridhar, K. , 1974, “ Effects of Inlet Flow Conditions on the Performance of Equiangular Annular Diffuser,” Trans CSME, 3(2), pp. 75–82.
Hoadley, D. , and Hughes, D. W. , 1969, “ Swirling Flow in an Annular Diffuser,” Department of Engineering, University of Cambridge, Cambridge, UK, Report No. CUED/A-Turbo/TR5.
Hunt, J. C. R. , Abell, C. J. , Peterka, J. A. , and Woo, H. , 1978, “ Kinematical Studies of the Flows Around Free or Surface-Mounted Obstacles; Applying Topology to Flow Visualization,” J. Fluid Mech., 88(1), pp. 179–200. [CrossRef]
Owczarek, J. A. , Warnock, A. S. , and Malik, P. , 1989, “ A Low Pressure Turbine Exhaust End Flow Model Study,” Latest Advances in Steam Turbine Design, Blading, Repairs, Condition, Assessment, and Condenser Interactions, D. M. Rasmussen , ed., ASME, New York, pp. 77–88.
Zhang, W. , Paik, B. G. , Jang, Y. G. , Lee, S. J. , Lee, S. E. , and Kim, J. H. , 2007, “ Particle Image Velocimetry Measurements of the Three-Dimensional Flow in an Exhaust Hood Model of a Low-Pressure Steam Turbine,” ASME J. Eng. Gas Turbines Power, 129(2), pp. 411–419. [CrossRef]
Yoon, S. , Stanislaus, F. J. , Mokulys, T. , Singh, G. , and Claridge, M. , 2011, “ A Three-Dimensional Diffuser Design for the Retrofit of a Low Pressure Turbine Using In-House Exhaust Design System,” ASME Paper No. GT2011-45366.
Shimizu, Y. , and Sugino, K. , 1980, “ Hydraulic Losses and Flow Patterns of a Swirling Flow in U-Bends,” Bull. JSME, 23(183), pp. 1443–1450. [CrossRef]
Anwer, M. , and So, R. M. C. , 1993, “ Swirling Turbulent Flow Through a Curved Pipe,” Exp. Fluids, 14(1–2), pp. 85–96.
Kalpakli, A. , and Örlü, R. , 2013, “ Turbulent Pipe Flow Downstream a 90 deg Pipe Bend With and Without Superimposed Swirl,” Int. J. Heat Fluid Flow, 41, pp. 103–111. [CrossRef]


Grahic Jump Location
Fig. 1

Section view of the 1/12th scale facility: (a) diffuser–collector model (profiled struts) and (b) diffuser only model (no struts)

Grahic Jump Location
Fig. 2

(a) Upstream view of the circumferential radial traverse plane and (b) pressure tap locations on hub

Grahic Jump Location
Fig. 3

Isometric view of the exit traverse plane (collector back wall and hub removed)

Grahic Jump Location
Fig. 4

Profiled strut geometry

Grahic Jump Location
Fig. 5

Measured inlet static pressure coefficient circumferential distribution (radial averaged), diffuser–collector, and 7 deg inlet swirl

Grahic Jump Location
Fig. 6

Recovery versus inlet angle (diffuser only configuration)

Grahic Jump Location
Fig. 7

Recovery versus inlet angle (diffuser–collector configuration)

Grahic Jump Location
Fig. 8

Velocity in collector exit plane for strutless configuration: (a) 7 deg angle, (b) 14 deg angle, (c) 21 deg angle, and (d) 35 deg angle

Grahic Jump Location
Fig. 9

Velocity in collector exit plane for profiled strut: (a) 7 deg angle, (b) 14 deg angle, (c) 21 deg angle, (d) 35 deg angle

Grahic Jump Location
Fig. 10

Oil flow visualization—diffuser/collector model/no struts at 21 deg swirl: back wall (forward looking aft)

Grahic Jump Location
Fig. 11

Oil flow visualization—diffuser/collector model no struts at 21 deg inlet angle: hub surface

Grahic Jump Location
Fig. 12

Oil flow visualization—diffuser/collector model/profiled struts at 21 deg inlet angle, back wall (forward looking aft)

Grahic Jump Location
Fig. 13

Oil flow visualization—diffuser/collector model/profiled struts at 21 deg inlet angle, hub surface

Grahic Jump Location
Fig. 14

Oil flow visualization—diffuser/collector model/profiled struts at 35 deg inlet angle: (a) shroud view and (b) hub view




Some tools below are only available to our subscribers or users with an online account.

Related Content

Customize your page view by dragging and repositioning the boxes below.

Related Journal Articles
Related eBook Content
Topic Collections

Sorry! You do not have access to this content. For assistance or to subscribe, please contact us:

  • TELEPHONE: 1-800-843-2763 (Toll-free in the USA)
  • EMAIL: asmedigitalcollection@asme.org
Sign In