The flow fields of four diffusers situated at the rear of a one-stage axial flow compressor were experimentally investigated. Through modification of the compressor operating point, a wide range of variations of the side wall boundary layers and the radial velocity distribution outside of the boundary layers at diffuser inlet could be achieved. The three-dimensional flow field at both diffuser inlet and outlet is analyzed. Changes of inlet blockage and radial velocity distribution and their resulting effects on pressure recovery are thoroughly presented. Compared with the results of measurements at diffusers, typically with ducted flow inlet conditions, higher values of pressure recovery are observed. Established design rules, based on investigations of diffusers with carefully developed inlet flow, are checked regarding their applicability for diffusers in turbomachine environments.

Issue Section:
Research Papers
Topics:
Axial flow, Diffusers, Flow (Dynamics), Boundary layers, Pressure, Compressors, Design, Turbomachinery
1.
Adenubi
S. O.
,
1976
, “
Performance and Flow Regime of Annular Diffusers With Axial Turbomachine Discharge Inlet Conditions
,”
ASME Journal of Fluids Engineering
, Vol.
98
, pp.
236
–
243
.
2.
Carlson
J. J.
,
Johnston
J. P.
, and
Sagi
C. J.
,
1967
, “
Effects of Wall Shape on Flow Regimes and Performance in Straight, Two-Dimensional Diffusers
,”
ASME Journal of Basic Engineering
, Vol.
89
, pp.
151
–
160
.
3.
Hoffmann
J. A.
, and
Gonzales
G.
,
1984
, “
Effects of Small-Scale, High Intensity Inlet Turbulence on Flow in a Two-Dimensional Diffuser
,”
ASME Journal of Fluids Engineering
, Vol.
106
, pp.
121
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124
.
4.
Johnson, I. A., and Bullock, R. O., 1965, “Aerodynamic Design of Axial-Flow Compressors,” National Aeronautics and Space Administration, Washington, DC.
5.
Klein
A.
,
1981
, “
Review: Effects of Inlet Conditions on Conical-Diffuser Performance
,”
ASME Journal of Fluids Engineering
, Vol.
103
, pp.
250
–
257
.
6.
Kreitmeier, F., 1992, “Spacing-Averaging 3D Flows Using Strictly Formulated Balance Equations in Turbomachinery,” Presented at the ASME Cogen 1992.
7.
Lohmann
R. P.
,
Markowski
S. J.
, and
Brookman
E. T.
,
1979
, “
Swirling Flow Through Annular Diffusers With Conical Walls
,”
ASME Journal of Fluids Engineering
, Vol.
101
, pp.
224
–
229
.
8.
Pfeil, H., and Sieber, J., 1986a, “Characteristic Factors of a Compressor Rotor in Comparison With Two-Dimensional Cascade Data,” ASME Paper No. 86-GT-29.
9.
Pfeil, H., and Sieber, J., 1986b, “Velocity Distribution and Decay Characteristics of Wakes Behind a Compressor Rotor-Blade,” ASME Paper No. 86-GT-115.
10.
Pfeil
H.
, and
Go¨ing
M.
,
1987
, “
Measurements of the Turbulent Boundary Layer in the Diffuser Behind an Axial Flow Compressor
,”
ASME JOURNAL OF TURBOMACHINERY
, Vol.
109
, pp.
405
–
412
.
11.
Pfeil
H.
, and
Mu¨ller
T.
,
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, “
Velocity Profile Model for Two-Dimensional Zero-Pressure Gradient Transitional Boundary Layers
,”
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12.
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13.
Rencau
L. R.
,
Johnston
J. P.
, and
Kline
S. J.
,
1967
, “
Performance and Design of Straight, Two-Dimensional Diffusers
,”
ASME Journal of Basic Engineering
, Vol.
89
, pp.
141
–
150
.
14.
Schlichting
H.
, and
Gersten
K.
,
1961
, “
Berechnung der Stro¨mung in rotationssymmetrischen Diffusoren mit Hilfe der Grenzschichttheorie
,”
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135
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140
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15.
Sovran, G., and Klomp, E. D., 1967, “Experimentally Determined Optimum Geometries for Rectilinear Diffusers With Rectangular, Conical or Annular Cross-Section,” Fluid Mechanics of Internal Flow, Elsevier Publishing Company, Amsterdam-London-New York.
16.
Sprenger, H., 1959, “Experimentelle Untersuchungen an geraden und gekru¨mmten Diffusoren,” Dissertation, ETH Zu¨rich, Switzerland.
17.
Stevens
S. J.
,
Nayak
U. S. L.
,
Prenston
J. F.
,
Robinson
P. J.
, and
Scrivener
C. T. J.
,
1980
, “
The Influence of Compressor Exit Conditions on the Performance of Combustor Dump Diffusers
,”
Journal of Aircraft
, Vol.
15
, No.
8
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482
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488
.
18.
Stevens
S. J.
, and
Williams
G.
,
1980
, “
The Influence of Inlet Conditions on the Performance of Annular Diffusers
,”
ASME Journal of Fluids Engineering
, Vol.
102
, pp.
357
–
363
.
19.
Stevens, S. J., and Wray, A. P., 1985, “The Influence of Blade Wakes on the Performance of Outwardly Curved Combustor Pre-diffusers,” AIAA Paper No. 85-1291.
20.
Wolf
S.
, and
Johnston
J. P.
,
1969
, “
Effects of Nonuniform Inlet Velocity Profiles on Flow Regimes and Performance in Two-Dimensional Diffusers
,”
ASME Journal of Basic Engineering
, Vol.
91
, pp.
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–
474
.
21.
Zierer, Th., 1992, “Experimentelle Untersuchung der Stro¨mung in Diffusoren mit verschiedenen Erweiterungsverha¨ltnissen hinter einem Axialverdichter,” Doctoral Thesis, TH Darmstadt, Darmstadt, Germany.
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