- Author
- Kapoor, K. | Jaluria, Y.
- Title
- Mixed Convection Flow Due to a Buoyant Wall Jet Turning Downward at a Corner.
- Coporate
- Rutgers, State University of New Jersey, New Brunswick
- Sponsor
- National Institute of Standards and Technology, Gaithersburg, MD
- Contract
- NIST-GRANT-60NANB7D0743
- Book or Conf
- American Society of Mechanical Engineers (ASME). National Heat Transfer Conference, 28th. Mixed Convection Heat Transfer, 1991. HTD-Vol. 163. July 28-31, 1991, Am. Soc. of Mechanical Engineers, New York, NY, Minneapolis, MN, Pepper, D. W.; Armaly, B. F.; Ebadian, M. A.; Oosthuizen, P. H., Editors, 119-128 p., 1991
- Keywords
- ceiling jets | convective flow | corners | heat transfer | buoyancy
- Abstract
- A detailed experimental investigation has been carried out on the flow characteristics of a horizontal buoyant ceiling jet which turns downward at a corner to yield a vertical negatively buoyant wall flow. Such mixed convection flows are frequently encountered in thermal energy storage problems in electronic systems and in room fires. However, not much work has been done to understand the basic fluid flow mechanisms of such flows, particularly the flow near the corner. In this study, a two-dimensional horizontal jet of heated air is discharged adjacent to the lower surface of an isothermal horizontal plate. An isothermal vertical plate is attached at the other end of the horizontal surface, making a right angle corner. The vertical penetration distance of the resulting downward flow is measured and is related to the inflow conditions, particularly, the temperature and velocity at the jet discharge. The penetration distance was also found to increase as the distance between the discharge location and the corner was reduced. Extensive velocity and temperature measurements were carried out over the flow region, particularly near the surfaces and the corner. These measurements indicate that the ceiling flow separates from the horizontal surface just before reaching the corner and then reattaches itself to the vertical wall at a finite distance vertically below the corner. The local surface heat flux measurements show a minimum in the heat transfer rate before the corner and a meximum just after the turn, indicating a recovery in the heat transfer rate at the corner. All these results confirm the existence of a small recirculation zone near the corner. The net mass flow entrainment into the ceiling jet was also measured and correlated with the jet discharge conditions. The study is directed largely at the resulting mixed convection flow, on the effect of thermal buoyancy in the flow and the transport processes near the corner.