Effect of entrance conditions on the development of turbulent flow in circular pipes

New experimental data is presented on the stabilization length of the velocity profile in circular pipes as a function of entrance conditions. The experimental channel used was a machined pipe 145 mm in diameter consisting of 23 sections each 600 mm long. The sections were machined to second-class accuracy with an inner surface roughness of 0.32. The individual sections were connected and centered by sleeves. Packing grease was applied to the outer surface of the pipe against the fittings. The experiments were performed with a confined stream of air at a Reynolds number of 285,000. The velocity profiles and turbulence intensity were measured by the hot-wire anemometer method. The apparatus included a bridge with a constant temperature filament, an amplifier, a linearizer, and an RMS voltmeter.