| Budget Amount *help |
¥2,700,000 (Direct Cost: ¥2,700,000)
Fiscal Year 1998: ¥600,000 (Direct Cost: ¥600,000)
Fiscal Year 1997: ¥2,100,000 (Direct Cost: ¥2,100,000)
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| Research Abstract |
Natural convection induced over the upward-facing horizontal, heated plate have been investigated both experimentally and analytically. Special concerns are directed to the turbulent transition mechanisms and the local heal transfer characteristics in the transitional region. The investigations have been carried out with water at room-temperature and with the test plate of constant wall heat flux, In order to obtain basic insight into the flow and temperature fields over the plate, the flow over the plate and the surface temperatures of the plate were visualized with dye and liquid crystal thermometry. The results showed that the following phenomena occur over the plates : (i) The laminar boundary layer flow develops over the plate in the vicinity of the leading edge. (ii) The flow separates three-dimensionally at certain distance from the edge. (iii) The separated flow, then, fluctuate irregularly and a fully turbulent state is realized in the central portion of the plate when the plate is wide enough. Among these phenomena, the three-dimensional separation and the succeeding turbulent transition are of particular importance, because these regions occupy considerable portion of the total surface area. Thus, we next carried out the numerical simulation on these phenomena. A time-dependent, three-dimensional analysis has been developed for this purpose. The results are quite satisfactory. Present analysis well predicted the occurrence of the flow separation and the succeeding transition to turbulence. Moreover, the local heat transfer coefficients are in good agreement between the analysis and experiment.
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