Results of a detailed study concerning the influence of geometric as well as fluid mechanic parameters on the performance of a plane model combustor diffuser in cold flow are presented. For a qualitative insight into the complex flow field inside the prediffuser, the sudden expansion region, and the flow field around the flame tube dome, results of a flow visualization study with the hydrogen bubble method as well as with the ink jet method are presented for different opening angles of the prediffuser and for different flame tube distances. Also, quantitative data from detailed measurements with LDV and conventional pressure probes in a geometrically similar air-driven setup are presented. These data clearly demonstrate the effect of boundary layer thickness as well as the influence of different turbulence levels at the entry of the prediffuser on the performance characteristics of combustor diffusers. The possibility of getting an unseparated flow field inside the prediffuser even at large opening angles by appropriately matching the diffuser’s opening angle and the flame tube distance is demonstrated. Also, for flows with an increased turbulence level at the entrance—all other conditions held constant—an increased opening angle can be realized without experiencing flow separation. The comparison of the experimental data with predictions utilizing a finite-volume-code based on a body-fitted coordinate system for diffusers with an included total opening angle less than 18 deg demonstrates the capability of describing the flow field in combustor diffusers with reasonable accuracy.

Issue Section:
Gas Turbines: Combustion and Fuels
Topics:
Combustion chambers, Diffusers, Flow (Dynamics), Performance characterization, Flames, Turbulence, Boundary layers, Bubbles, Domes (Structural elements), Flow separation, Flow visualization, Fluids, Hydrogen, Inks, Pressure, Probes
1.
Ainley, D. G., 1945, “Investigations of Air Flow Through Some Annular Diffusers,” Power Jet Report 1151.
2.
Adkins, R. C., 1983, “A Simple Method for Designing Optimum Annular Diffusers,” ASME Paper No. 83-GT-42.
3.
Adkins
R. C.
, and
Wardle
M. H.
,
1990
, “
A Method for the Design of Optimum Annular Diffusers of Canted Configuration
,”
ASME JOURNAL OF ENGINEERING FOR GAS TURBINES AND POWER
, Vol.
114
, pp.
8
–
12
.
4.
Bauer, H.-J., 1989, “U¨berpru¨fung numerischer Ansa¨tze zur Beschreibung turbulenter elliptischer Stro¨mungen in komplexen Geometrien mit Hilfe konturangepaßter Koordinaten,” Dissertation, Universita¨t Karlsruhe, Institut fu¨r Thermische Stro¨mungsmaschinen, Germany.
5.
Benz, E., and Wittig, S., 1992, “Prediction of the Interaction of Coolant Ejection With the Mainstream at the Leading Edge of a Turbine Blade: Attached Grid Application,” presented at the Int. Symp. Heat Transfer in Turbomachinery, Aug. 24-28, Athens, Greece.
6.
Biaglow, J. A., 1971, “Effect of Various Diffuser Designs on the Performance of an Experimental Turbojet Combustor Insensitive to Radial Distorsion of Inlet Air Flow,” NASA TMX-2216.
7.
Fishenden, C. R., and Stevens, S. J., 1974, “The Performance of Annular Combustor-Dump Diffusers,” AIAA Paper No. 74-1097.
8.
Hestermann, R., Kim, S., and Wittig, S., 1991, “Geometrical Dependence of the Fluid Dynamic Performance Parameters of Plane Combustor Model Diffusers,” ISABE 91-7105, pp. 995–1001.
9.
Hoffmann
J. A.
, and
Gonzalez
G.
,
1984
, “
Effects of Small-Scale, High Intensity Inlet Turbulence on Flow in Two-Dimensional Diffusers
,”
ASME Journal of Fluids Engineering
, Vol.
106
, pp.
121
–
124
.
10.
Howard, J. H. G., Thornton-Trump, A. B., and Henseler, H. J., 1967, “Performance and Flow Regimes for Annular Diffusers,” ASME Paper No. 67-WA/FE-21.
11.
Johnston, I. H., 1953, “The Effect of Inlet Conditions on the Flow in Annular Diffusers,” British Aeronautical Research Council, C. P. No. 178.
12.
Kim, S., 1976, “Experimentelle Untersuchung zur Gas-Flu¨ssigkeitsfilm-Grenzfla¨chenstro¨mung mit ma¨ßigem positivem Druckgradient,” Dissertation, Institut fu¨r Thermische Stro¨mungsmaschinen, Universita¨t Karlsruhe, Germany.
13.
Kim, S., 1979, “Einfaches Berechnungsverfahren verlustarmer Diffusoren fu¨r verschiedene Druckgradienten unter Verwendung der Eigenschaften der A¨quilibriumsgrenzschicht,” Festschrift zum 70. Geburtstag von R. Friedrich, Universita¨t Karlsruhe, Germany.
14.
Klein
A.
,
1988
, “
The Relation Between Losses and Entry-Flow-Conditions in Short Dump Diffusers of Combustors
,”
ZfW
, Vol.
12
, pp.
286
–
292
.
15.
Kline
S. J.
,
Abbott
E. E.
, and
Fox
R. W.
,
1969
, “
Optimum Design of Straight-Walled Diffusers
,”
ASME Journal of Basic Engineering
, Vol.
81
, pp.
321
–
331
.
16.
Koutmos
P.
, and
McGuirk
J. J.
,
1989
, “
Numerical Calculations of the Flow in Annular Combustor Dump Diffuser Geometries
,”
Proc. Inst. Mech. Engrs.
, Vol.
203
, Part C: Journal of Mechanical Engineering Science, pp.
319
–
331
.
17.
Little, A. R., and Manners, A. P., 1993, “Predictions of the Losses in 2D and 3D Model Dump Diffusers,” ASME Paper No. 93-GT-184.
18.
Noll, B., 1986, “Numerische Berechnung brennkammertypischer Ein- und Zweiphasenstro¨mungen,” Dissertation, Universita¨t Karlsruhe, Institut fu¨r Thermische Stro¨mungsmaschinen, Germany.
19.
Noll
B.
,
Bauer
H.-J.
,
Wittig
S.
,
1989
, “
Gesichtspunkte der numerischen Simulation turbulenter Brenn-kammerstro¨mungen
,”
ZFW
, Vol.
13
, No.
3
, pp.
178
–
187
.
20.
Noll
B.
, and
Wittig
S.
,
1991
, “
Evaluation of a Bounded High-Resolution Scheme for Combustor Flow Computations
,”
AIAA Journal
, Vol.
30
, No.
1
, pp.
64
–
69
.
21.
Reneau, L. R., Johnston, J. P., and Kline, S. J., 1967, “Performance and Design of Straight, Two-Dimensional Diffusers,” ASME Journal of Basic Engineering, Mar., pp. 141–150.
22.
Shyy
W.
,
1985
, “
A Numerical Study of Annular Dump Diffuser Flows
,”
Computer Methods in Applied Mechanics and Engineering
, Vol.
53
, pp.
47
–
65
.
23.
Sovran, G., Klomp, E. D., 1967, “Experimentally Determined Optimum Geometries for Rectilinear Diffusers With Rectangular, Conical or Annular Cross Section,” in: G. Sovran, ed., Fluid Mechanics of Internal Flow, Elsevier, New York, pp. 270–319.
24.
Stevens
S. J.
, and
Williams
G. J.
,
1980
, “
The Influence of Inlet Conditions on the Performance of Annular Diffusers
,”
ASME Journal of Fluids Engineering
, Vol.
102
, pp.
357
–
363
.
25.
Wagner, W. B., Tanrikut, S., and Sokolowski, D. E., 1980, “Performance of Annular Prediffuser-Combuster Systems,” ASME Paper No. 80-GT-15.
This content is only available via PDF.
Copyright © 1995
 by The American Society of Mechanical Engineers
You do not currently have access to this content.