Prof. Sameh A. Nada :: Publications:

Free convection heat transfer from the outside surface of a vertical and inclined semicircular cylinder was investigated experimentally at different orientations. The experiments were carried out to study the effect of the inclination angle and the orientation angle of the semicircular cylinder on the distribution of the wall temperature, local and average heat transfer coefficients and local and average Nusselt numbers for a wide range of Grashof numbers. Also, correlations for the coefficient of heat transfer by free convection from a vertical and inclined semicircular cylinder were obtained in a dimensionless form as a function of Rayleigh numbers, inclination angles, and orientation angles of the cylinder. The experiments were carried out at four inclination angles of the semicircular cylinder, namely at & = 0º, 30º, 45º and 60º measured from the vertical. For each inclination three different orientations of the semicircular cylinder were investigated: (1) the flat part of the semicircular cylinder is facing up (' = 0º), (2) the flat part of the semicircular cylinder is vertical (' = 90º), and (3) the flat part of the semicircular cylinder is facing down (' = 180º). The experiments were conducted at constant heat flux. The results showed that: (i) the average Nusselt number increases as the inclination angle of the semicircular cylinder (measured from the vertical) increases for the three different orientations of the cylinder, and (ii) At any inclination of the cylinder, the Nusselt number for the orientation ' = 90º is higher than that of the orientation ' = 0º which in turn is higher than that of ' = 180º. Correlations were developed to predict the average Nusselt number of the semicircular cylinder in terms of the Rayleigh number, the inclination angle, and the orientation angle of the cylinder. The trend of the present results was compared with that available in the literature and fair agreement was found.