Local heat transfer and fluid flow characteristics for airflow oblique or normal to a square plate

Wind tunnel experiments have been performed to determine the local and average heat-transfer coefficients and the patterns of fluid flow for a square plate situated at various orientations to the flow direction. The naphthalene sublimation technique was employed for the transfer coefficient determinations while the flow patterns adjacent to the plate were made visible by the oil/lampblack technique. The plate orientations used for the average coefficient measurements extended the range previously studied, and the results of these measurements affirmed the insensitivity of the average coefficient to orientation. The local heat- (or mass-) transfer coefficients are presented as contour diagrams in which lines depicting constant values of the coefficient are plotted. In general, the highest heat-transfer coefficients occur near the edges of the plate. These high coefficients are closely coupled to edge-related hydrodynamic phenomena, which include not only the conventional leading edge boundary layer but other processes related to the finite size of the plate. Of particular interest is the fact that for a plate oriented normal to the flow, the lowest coefficients occur in a centrally positioned stagnation region and the coefficients increase from the center of the plate toward the edges. The fluid flow patterns are presented via photographs. The flow is shown to be highly complex and three dimensional. One of the interesting findings is that the stagnation region migrates from a central position at normal incidence to a more forward position as the plate is inclined.