Velocity flow field of an elliptic pipe jet
Date of Issue2017-05-30
School of Mechanical and Aerospace Engineering
This study presents the velocity measurements obtained for a jet with a smooth fiberglass pipe of length 999mm and an elliptic exit profile of 50mm by 25mm. The aim of this study is to chart the flow development of an elliptic pipe jet, contrasting it to an elliptic contraction jet so as to investigate any possible relationships. Velocity measurements were obtained by moving a single hot-wire probe along the major (y-axis) and minor (z-axis) planes in different streamwise locations (x-axis). The jet exit velocity was maintained at 24.5±0.5 m/s, corresponding to a Reynolds number of approximately 55500. Local mean velocities as well as fluctuating components were documented in this study. The smooth fiberglass pipe provided for fully developed turbulent flow at the nozzle exit. A thinner momentum thickness was observed in the minor axis, giving rise to a larger spreading rate and axis switching at 15 𝑥/𝐷𝑒. The length of the potential core was determined as 4 𝑥/𝐷𝑒. Preliminary self-preservation was seen in the near-field region while full self-preservation was achieved by mean velocities in the far-field region, at 10 𝑥/𝐷𝑒 in the major axis and 9 𝑥/𝐷𝑒 in the minor axis. Jet spreading rates, velocity half-width growth and centerline velocity decay rate were also measured and found to vary in a linear fashion.
Final Year Project (FYP)
Nanyang Technological University