Augmentation of stagnation region heat transfer due to turbulence from a DLN can combustor

Heat transfer measurements have been made in the stagnation region of a flat plate with a circular leading edge. Electrically heated aluminum strips placed symmetrically about the leading edge stagnation region were used to measure spanwise-averaged heat transfer coefficients. The maximum Reynolds number obtained, based on leading edge diameter, was about 100,000. The model was immersed in the flow field downstream of an approximately half-scale model of a can-type combustor from a low NO(x), ground-based power-generating turbine. The tests were conducted with room temperature air; no fuel was added. Room air flowed into the combustor through six vane-type fuel/air swirlers. The combustor can contained no dilution holes. The fuel/air swirlers all swirled the incoming airflow in a counterclockwise direction (facing downstream). A five-hole probe flow field survey in the plane of the model stagnation point showed the flow was one big vortex with flow angles up to 36 deg at the outer edges of the rectangular test section. Hot-wire measurements showed test section flow had very high levels of turbulence, around 28.5%, and had a relatively large axial-length scale-to-leading edge diameter ratio of 0.5. X-wire measurements showed the turbulence to be nearly isotropic. Stagnation heat transfer augmentation over laminar levels was around 77% and was about 14% higher than predicted by a previously developed correlation for isotropic grid-generated turbulence.

[1]  G. J. Van Fossen,et al.  Three-Dimensional Flow Field Measurements in a Transonic Turbine Cascade , 1996 .

[2]  R. Simoneau,et al.  Influence of Turbulence Parameters, Reynolds Number, and Body Shape on Stagnation-Region Heat Transfer , 1994 .

[3]  J. C. R. Hunt,et al.  Free-stream turbulence near plane boundaries , 1978, Journal of Fluid Mechanics.

[4]  Forrest E. Ames,et al.  Experimental Study of Vane Heat Transfer and Aerodynamics at Elevated Levels of Turbulence , 1994 .

[5]  S. Yavuzkurt.  A Guide to Uncertainty Analysis of Hot-Wire Data , 1984 .

[6]  D. R. Zimmerman,et al.  Laser anemometer measurements at the exit of a T63 combustor , 1979 .

[7]  G. J. Vanfossen,et al.  Increased heat transfer to elliptical leading edges due to spanwise variations in the freestream momentum: Numerical and experimental results , 1992 .

[8]  Y. S. Touloukian,et al.  Tables of thermal properties of gases , 1955 .

[9]  R. I. Vachon,et al.  The effect of turbulence on heat transfer from heated cylinders , 1975 .

[10]  S. J. Kline,et al.  Describing Uncertainties in Single-Sample Experiments , 1953 .

[11]  W. H. Giedt.  Effect of Turbulence Level of Incident Air Stream on Local Heat Transfer and Skin Friction on a Cylinder , 1951 .

[12]  Ching-Pang Lee,et al.  Measurements of Combustor Velocity and Turbulence Profiles , 1993 .

[13]  Arnold M. Kuethe,et al.  Effects of Turbulence on Laminar Skin Friction and Heat Transfer , 1966 .

[14]  R. J. Simoneau,et al.  Heat transfer distributions around nominal ice accretion shapes formed on a cylinder in the NASA Lewis Icing Research Tunnel , 1984 .