An experimental and numerical investigation was conducted to study the turbulent velocities and stresses behind a two-dimensional bluff body. Simultaneous three-component laser-Doppler velocimeter (LDV) measurements were made in the isothermal incompressible turbulent flowfield downstream of a bluff body placed at midstream in a rectangular test section. Mean velocities and Reynolds stresses were measured at various axial positions. Spanwise velocity measurements indicated that the flow is three dimensional in the recirculation zone of the bluff body. Confidence in the accuracy of the data was gained by calculating the mass fluxes at each axial station. These were found to agree with each other to within ±3 percent. A parallel Computational Fluid Dynamics (CFD) study was initiated to gage the predictive accuracy of currently available CFD techniques. Three solutions were computed: a two-dimensional steady-state solution using the standard k-ε model, a two-dimensional time-accurate solution using the standard k-ε model, and a two-dimensional time-accurate solution using a Renormalized-Group (RNG) k-ε turbulence model. The steady-state solution matched poorly with the data, severely underpredicting the Reynolds stresses in the recirculation zone. The time-accurate solutions captured the unsteady vortex shedding from the base of the bluff body, providing a source for the higher Reynolds stresses. The RNG k-ε solution provided the best match to the data.

Issue Section:
Gas Turbines: Combustion and Fuels
Topics:
Computational fluid dynamics, Flow (Dynamics), Flux (Metallurgy), Gages, Lasers, Steady state, Stress, Turbulence, Velocimeters, Velocity measurement, Vortex shedding
1.
Arnal, M., and Friedrich, R., 1991, “Large-Eddy Simulation of a Turbulent Flow With Separation,” Turbulent Shear Flows 8, Springer-Verlag.
2.
Avva, R., 1993, “CFD-ACE: Theory Manual,” CFDRC Report GR-93-1.
3.
Choudhury, D., and Kim, S., 1993, “Calculation of Turbulent Separated Flows Using a Renormalization Group Based k-ε Turbulence Model,” Separated Flows, ASME FED-Vol. 149.
4.
Franke, R., and Rodi, W., 1991, “Calculation of Vortex Shedding Past a Square Cylinder With Various Turbulence Models,” Turbulent Shear Flows 8, Springer-Verlag.
5.
Geropp, D., and Leder, A., 1985, “Turbulent Separated Flow Structures Behind Bodies With Various Shapes,” presented at the International Conference on Laser Anemometry—Advances and Application, Manchester, United Kingdom.
6.
Gould, R., Stevenson W., and Thompson, D., 1988, “Turbulence Characteristics of an Axisymmetric Reacting Flow,” NASA Contractor Report 4110.
7.
Gould, R., 1994, “Analysis of Laser Doppler Velocimetry Data,” Final Report for Summer Research Program, WL, AFOSR.
8.
Hosokawa, S., Ikeda, Y., Minato, M., and Nakajima, T., 1993, “Flow Measurements Behind V-Gutter Under Non-combusting Condition,” Paper No. AIAA-93-0020.
9.
Kim, J., Kline, S., and Johnston, J., 1978, “Investigation of Separation and Reattachment of a Turbulent Shear Layer: Flow Over a Backward-Facing Step,” Report MD-37, Thermo Sciences Division, Dept. of Mechanical Engineering, Stanford University.
10.
Kodali, V., and Amano, R., 1986, “Prediction of Turbulent Flows Behind Bluff Bodies by Using an Algebraic-Stress Model,” Paper No. AIAA-86-1061.
11.
Larousse, A., Martinuzzi, R., and Tropea, C., 1991, “Flow Around Surface-Mounted, Three-Dimensional Obstacles,” Turbulent Shear Flows 8, Springer-Verlag, pp. 127–139.
12.
Mansingh, V., and Oosthuizen, P., 1990, “Effects of Splitter Plates on the Wake Flow Behind a Bluff Body,” AIAA Journal, pp. 778–783.
13.
Martensson, H., Eriksson, L., and Albraten, P., 1991, “Numerical Simulations of Unsteady Wakeflow,” 10th International Symposium on Air-Breathing Engines (ISABE), Vol. 2, Nottingham, England.
14.
Pearce
J.
,
Qasim
A.
,
Maxwell
T.
, and
Paramesawaran
S.
,
1992
, “
A Computational Study of Coherent Wake Structures Behind 2-D Bluff Bodies
,”
J. of Wind Engineering and Industrial Aerodynamics
, Vol.
41-44
, pp.
2853
–
2861
.
15.
Perry
A.
, and
Steiner
T.
,
1987
, “
Large-Scale Vortex Structures in Turbulent Wakes Behind Bluff Bodies: Part 1. Vortex Formation Processes
,”
J. Fluid Mech.
, Vol.
174
, pp.
233
–
270
.
16.
Przulj, V., and Younis, B., 1993, “Some Aspects of the Prediction of Turbulent Vortex Shedding,” Separated Flows, ASME FED-Vol. 149.
17.
Raffoul, C., Nejad, A., Spring, S., Kirkendall, C., and Smith, C., 1994, “Entrainment and Mixing Characteristics of Bluff Body Flameholders: an Experimental and Numerical Study,” Paper No. AIAA 94-0710.
18.
Ryden, R., Eriksson, L., and Olovsson, S., 1993, “Large-Eddy Simulation of Bluff Body Stabilised Turbulent Premixed Flames,” ASME Paper No. 93-GT-157.
19.
Sjunnesson, A., Olovsson, S., and Sjoblom, B., 1991, “Validation Rig—A Tool for Flame Studies,” presented at the 10th International Symposium on Air Breathing Engines (ISABE), Nottingham, England.
20.
Speziale, C., and Thangam, S., 1992, “Analysis of an RNG Based Turbulence Model for Separated Flows,” NASA CR 189600.
21.
Werner, H., and Wengle, H., 1991, “Large-Eddy Simulation of Turbulent Flow Over and Around a Cube in a Plate Channel,” Turbulent Shear Flows 8, Springer-Verlag.
22.
Yakhot
V.
, and
Orszag
S.
,
1986
, “
Renormalization Group Analysis of Turbulence. I. Basic Theory
,”
J. Sci. Comput.
, Vol.
1
, p.
3
3
.
23.
Yakhot, V., Orszag, S., Thangan, S., Gatski, T., and Speziale, C., 1992, “Development of Turbulence Models for Shear Flows by a Double Expansion Technique,” Phys. Fluids, Vol. A.4(7).
24.
Yang, K., and Ferziger, J., 1993, “Large-Eddy Simulation of Turbulent Obstacle Flow Using a Dynamic Subgrid-Scale Model,” AIAA Journal, Vol. 31, No. 8.
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