Turbulence Measurements in the Wall Jet Layer of Impinging Round Jet

Abstract

The objective of this thesis is to understand how turbulence affects the impinging jet flow and heat transfer mechanism under acoustic actuaion. This work is based upon the experimental work including velocity and turbulence measurements in various cases and is a continuation of studies of Necati Bilgin and Orcun Kor . Acoustic actuation is provided by a loudspeaker controlled by a function generator. Acoustic waves generated by the loudspeaker reaches nozzle and formed periodic fluctuations in flow. Strouhal number, which is dimensionless reperentation of actuation frequeny, is varied in the range of 0<St<1. Nozzle exit velocity is controlled by Reynolds number whics is kept constant around 10000. Velocity and turbulence measurements were performed by using a hot-wire sensor. Measurements are performed in the radial direction ranging from the jet centerline (x/D=0) to 2.4D for jet profile data and to 8.5D for near wall data. Wall normal measurement locations are at z/D=5.8, 5, 4, 3, 2, 1, 0.2 for jet profile data and at z/D=5.8 for near wall data. The distance between data points is kept at 0.1D.