1990 Volume 16 Issue 2 Pages 275-279
Experiments were performed to investigate the effect of suction through a slit on the characteristics of heat transfer. A suction slit 160 mm wide and 3 mm long was arranged in a laminar boundary layer formed on a flat plate and across the main stream at a distance 100 mm downstream from the leading edge of the flat plate. Heat transfer coefficients and characteristics of flow were measured for air flow with a Reynolds number from 2.0 x104 to 7.0 x105 and with a suction rate from 0.01 to 0.2.
Conclusions obtained are as follows. The local heat transfer coefficient increases remarkably near the slit, and after a decrease within the stagnant region of the flow it gradually approaches the value at laminar flow.
The starting point of transition from laminar to turbulent tends to shift downstream with the increase in suction rate. The turbulent transition in the average heat transfer coefficient starts somewhat earlier than that in the flow. The velocities in the boundary layer are influenced markedly by suction and are accelerated, especially at the immediate rear of the slit. The turbulent transition in flow develops for the inner layer from the outer edge of the shear layer.
