- Author
- Kapoor, K. | Jaluria, Y.
- Title
- Penetrative Natural Convection Flow Due to an Isothermal Vertical Surface Immersed in a Thermally Stable Two-Layer Environment.
- 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). Winter Annual Meeting. Fundamentals of Natural Convection, 1991. HTD-Vol. 178. December 1-6, 1991, Am. Soc. of Mechanical Engineers, New York, NY, Atlanta, GA, Che, T. S.; Chu, T. Y., Editors, 65-72 p., 1991
- Keywords
- natural convection | convective flow | heat transfer
- Identifiers
- isothermal surface
- Abstract
- An experimental investigation has been carried out on the penetrative natural convection flow over and the resulting thermal transport from an isothermal vertical surface immersed in a thermally stable, two-layer, ambient medium, in which an essentially isothermal heated layer overlies a relatively cooler isothermal layer of the same fluid. This flow is frequently encountered in many practical problems of interest, such as heat rejection, energy storage and enclosure fires. However, not much work has been done on such penetrative convection problems. In the present study, an isothermal vertical plate is exposed to a extensive two-layer thermally stable environment, resulting in a natural convection flow adjacent to the surface due to the temperature differences that exist. Detailed measurements of the thermal field are carried out for several surface temperatures and the corresponding isotherms obtained to characterize the penetration of the wall flow. The surface temperature is taken as lower than the upper layer temperature in this study so that a downward natural convection flow is generated adjacent to the surface in the upper zone. If the wall temperature is equal to the lower layer temperature, it is found that the natural convective wall flow penetrates into the lower cooler region, becomes negatively buoyant and then rises toward the interface between the two layers. It again becomes negatively buoyant in the upper zone, drops down toward the interface and finally flows outward, away from the vertical surface, staying close to the interface. Velocity and temperature profiles are measured at the interface of the two-layer environment and the mass flow rate penetrating downward across the interface as well as that penetrating into the upper zone are estimated. The local heat transfer rates to and from the surface are also measured at various locations on the isothermal plate, for several surface temperatures. For the circumstance of the surface temperature lying between the upper and lower layer temperatures, an upward flow is generated in the lower region and a downward flow in the upper region. The two flows collide near the interface, giving rise to transport across the interface. Thus, several interesting circumstances are obtained and studied.