Polymer-induced turbulence modifications in an impinging jet

impinging jet;polymers;Particle-image velocimetry (PIV)

Mejia Alvarez, Ricardo ; Christensen ; Kenneth T.

关键词: impinging jet;    polymers;    Particle-image velocimetry (PIV);   

Others  :  https://www.ideals.illinois.edu/bitstream/handle/2142/16174/MejiaAlvarez_Ricardo.pdf?sequence=2&isAllowed=y

美国|英语

来源: The Illinois Digital Environment for Access to Learning and Scholarship

【 摘 要 】

This effort explores the impact of dilute polymer solutions on the turbulence characteristics in a submersed liquid impinging-jet configuration. Turbulent impinging jets are commonly used in technological applications such as drying, scouring, cooling or heating due to an enhancement in transport characteristics in the impingement region under certain nozzle-to-wall configurations.Previous efforts have identified significant turbulence modifications in the presence of dilute concentrations of polymer (i.e., the Toms effect) in both bounded (suppression) and unbounded (either suppression or enhancement) flows.To this end, particle-image velocimetry measurements were made for an axisymmetric turbulent impinging jet with a nozzle-to-wall distance H/D=6.8 and Reynolds number Re_D=23000.Measurements were made for both plain water and dilute polymer solutions of polyethylene oxide at concentrations of 50 and 100 ppm. The mean and turbulence characteristics of these three flows are contrasted and it is observed that the 50 ppm case yields a slight enhancement of the turbulence while the 100 ppm case exhibits clear suppression of the turbulence.