Local Mass Transfer From Circular Cylinders in Cross Flow

Abstract

This is an investigation of the distribution of the local rate of mass transfer from 4.2-in-diam naphthalene cylinders to air at ordinary temperature and pressure, flowing normal to the axis. The air speeds are near and within the critical zone of the drag. The results in the laminar region are compared with approximate boundary-layer calculations of H. Schuh and of H. J. Merk and with corresponding heat and mass-transfer experimentation in the literature. It is shown that the calculations after Merk are reliable from the point of stagnation to the predicted point of separation.

Surface Injection Effect on Mass Transfer From a Cylinder in Crossflow: A Simulation of Film Cooling in the Leading Edge Region of a Turbine Blade

“…4), the Si s p distribution at 90° < 8 < 180°f or spanwise injection (Fig. 8) resembles a circumferential distribution over the rear portion of an impermeable cylinder at critical and supercritical Red, (Schmidt et al, 1941;Giedt, 1949;Achenbach, 1975;and Sogin et al, 1961). .…”

“…In the region most influenced by injection (8i n j < 8 < 120°), 3'^isp values located immediately downstream of injection fall sharply as 8 increases, reaching a minimum near the laminar boundary layer separation angle (8 = 80°-90°) ; a second peak is observed at 6 = 110° -120°. At 80° < 8 < 180°, STi s p has a pattern similar to a Nu(Sh) distribution over an impermeable circular cylinder at critical and supercritical Red (Schmidt and Wenner, 1941;Giedt, 1949;Achenbach, 1975;and Sogin and Subramanian, 1961) At high Reynolds numbers (Red > 2x10 5 ), the down- • 1 220- stream portion of the cylinder boundary layer becomes turbulent producing a sharp increase of heat (mass) transfer, and the separation angle is between 110 0 and 150°. It is possible that the additional momentum supplied by the jets causes a delay in the boundary layer separation, and over some portions of the cylinder span a transitional or turbulent boundary layer exists at 8 = 90° -130°.…”

Unsteady heat convection over circular cylinders

“…In Figure 9 we display the outer flow distributions of the velocity based on experimental data. It is seen in this figure that for a single cylinder our interacted solution approximates with a maximum error of 3% the experimental fit represented by the Hiemenz (Saxena and Laird, 1978) and Sogin (Sogin and Subramanian, 1961) curves. In the same figure the bundle solution displays much larger values of the velocity, which are attributed to the blockage effect.…”

Surface Injection Effect on Mass Transfer From a Cylinder in Crossflow: A Simulation of Film Cooling in the Leading Edge Region of a Turbine Blade

“…In the region most influenced by injection (8i n j < 8 < 120°), 3'^isp values located immediately downstream of injection fall sharply as 8 increases, reaching a minimum near the laminar boundary layer separation angle (8 = 80°-90°) ; a second peak is observed at 6 = 110° -120°. At 80° < 8 < 180°, STi s p has a pattern similar to a Nu(Sh) distribution over an impermeable circular cylinder at critical and supercritical Red (Schmidt and Wenner, 1941;Giedt, 1949;Achenbach, 1975;and Sogin and Subramanian, 1961) At high Reynolds numbers (Red > 2x10 5 ), the down- stream portion of the cylinder boundary layer becomes turbulent producing a sharp increase of heat (mass) transfer, and the separation angle is between 110 0 and 150°. It is possible that the additional momentum supplied by the jets causes a delay in the boundary layer separation, and over some portions of the cylinder span a transitional or turbulent boundary layer exists at 8 = 90° -130°.…”

“…4), the Si s p distribution at 90° < 8 < 180°f or spanwise injection (Fig. 8) resembles a circumferential distribution over the rear portion of an impermeable cylinder at critical and supercritical Red, (Schmidt et al, 1941;Giedt, 1949;Achenbach, 1975;and Sogin et al, 1961). For all injection locations, at M = 2°0 Pi s p values in the downstream portion of the wake (8 = 180° ± 50°) are lower than the impermeable wall distribution [ Fig.…”