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.