Transitional boundary layer flow and heat transfer over blocked surfaces with influence of free stream velocity and block height

摘要

Velocity, turbulent intensity, static pressure and temperature measurements over the flat plate and blocked surfaces were investigated in a low speed wind tunnel in the presence of free stream velocity and block height. The experiments were carried out for free stream velocities of 5, 7 and 10 tn/s encompassing the transitional region and for block heights of 10, 15 and 20 mm forming the different flow samples. A constant-temperature anemometer, a micro-manometer and copper-constant thermocouples were used for measurements of velocity and turbulent intensity, static pressure and temperature, respectively. The results showed that the flow separations and reattachments occurred on the blocked surfaces which enhanced the average heat transfer up to 1.54, 1.71 and 1.84 fold of the flat plate value at 5 m/s for the rising block height, 1.49, 1.68 and 1.80 at 7 m/s, and 1.44, 1.63 and 1.78 at 10 m/s, respectively.