Author(s): K. M. Lam; L. P. Xia

Linked Author(s): Kit Ming Lam

Keywords: Jets; Turbulence; Coflow

Abstract: Flow velocities are measured in submerged round jets in stagnant ambient and in coflow using laser-Doppler anemometry. Measurements are made at jet Reynolds numbers between 1000 and 5000 and coflow-to-jet velocity ratios from 0 to 0. 43. Different behaviors of jet mixing are found in jets at three different ranges of Reynolds number in which the jets are classified as initially laminar, transitional or turbulent. In the zone of established flow, the centerline mean velocity is found to decay with downstream distance at different rates in the three groups of jets. For jets in coflow, axial development of normalized forms of centerline mean excess velocity at different velocity ratios can be reasonably well collapsed onto universal trends through the use of the momentum length scale. Turbulence properties inside a jet are increased by the presence of a strong coflow. Self-similarity of radial profiles of mean velocity or excess velocity, and turbulence intensities is explored in the zone of established flow. The length of zone of flow establishment increases from the turbulent jets, to the transition jets and to the laminar jets. Jet turbulence properties are measured inside the zone of flow establishment.

DOI:

Year: 2007