Forced-Convective Turbulent-Flows a Through Horizontal Ducts with Isosceles-Triangular Internal Cross-Sections

摘要

Three electrically heated triangular ducts were used to simulate the thermal behaviours of turbulent air-flows through triangular passages in compact heat-exchangers (Fig. 1). Three sharp-cornered isosceles-triangular dura- lumin ducts were fabricated, each of the same length of 2.4 m and hydraulic diameter of 0.44m, but with three different apex-angles, namely 40℃, 60℃ and 90℃. The experimental investigations were performed over a wide range of Reynolds number (Re), namely 5000 < Re_D < 20000. Non-dimen- sional correlations were deduced from the measurements to enable the average convective heat-transfer coefficient for convection from the walls of the isosceles-triangular duct (of specified apex-angle) to the turbulent air to be predicted.