caa a22 4500 477093310 CHVBK 20180405111520.0 cr unu---uuuuu 170330e19960301xx s 000 0 eng 10.1007/BF00191016 doi (NATIONALLICENCE)springer-10.1007/BF00191016 Velocity and spanwise vorticity measurements in an excited mixing layer of a plane jet [Elektronische Daten] [S. Rajagopalan, N. Ko] The mixing layer of a plane jet was subjected to periodic weak excitation at two different frequencies corresponding to shear layer mode (St θ=0.012) and preferred mode (St D =0.36). The nozzle exit boundary layer was identical for the unexcited and excited flows. Measurements of mean velocity, longitudinal and lateral velocity fluctuations, Reynolds shear stress and spanwise component of fluctuating vorticity were made over a longitudinal distance x/D of 6 for both the unexcited and the excited flows. Even weak excitation was observed to influence the development of the mixing layer. Under shear layer mode of excitation, the width of the layer and longitudinal turbulence level decrease compared to the naturally developing (unexcited) flow whereas preferred mode of excitation results in increase in the width and turbulence levels. The rms spanwise vorticity showed an increase for shear layer mode of excitation whereas the preferred mode of excitation resulted in a decrease compared to the values in an unexcited flow. Spectra of velocity and vorticity fluctuations exhibited subharmonic peaks, suggesting the possible occurrence of vortex pairing in both unexpected and excited flows. The influence of excitation is found to decrease as x/D increases and is not significant at x/D=6. Springer-Verlag, 1996 Rajagopalan S. Department of Mechanical Engineering, University of Hong Kong, Hong Kong aut Ko N. Department of Mechanical Engineering, University of Hong Kong, Hong Kong aut Experiments in Fluids Springer-Verlag 20/5(1996-03-01), 346-357 0723-4864 20:5<346 1996 20 348 https://doi.org/10.1007/BF00191016 text/html Onlinezugriff via DOI 1 research-article jats NATIONALLICENCE 856 40 https://doi.org/10.1007/BF00191016 text/html Onlinezugriff via DOI NATIONALLICENCE 700 1- Rajagopalan S. Department of Mechanical Engineering, University of Hong Kong, Hong Kong aut NATIONALLICENCE 700 1- Ko N. Department of Mechanical Engineering, University of Hong Kong, Hong Kong aut NATIONALLICENCE 773 0- Experiments in Fluids Springer-Verlag 20/5(1996-03-01), 346-357 0723-4864 20:5<346 1996 20 348 Metadata rights reserved Springer special CC-BY-NC licence nationallicence BK010053 XK010053 XK010000 NATIONALLICENCE NATIONALLICENCE NL-springer