科研之友
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摘要
An experimental investigation was undertaken to study the characteristics of curved turbulent water jets produced from a vertical slot diffuser with sharp protrusions at the exit plane. The experiments were performed at two different flow rates for which the Reynolds number based on slot width and average velocity were 2050 and 4100. A high resolution particle image velocimetry system was used to perform detailed velocity measurements which were post-processed to obtain the mean velocities, Reynolds stresses and turbulence kinetic energy. The decay of the centerline mean velocity and jet half-width were also obtained to evaluate the mixing characteristics of the present slot configuration vis-a-vis results reported in previous studies. It was observed that the mixing characteristics of the slot configuration investigated in this study are superior to most of the sharp-edged nozzle configurations and curved jets studied in the past. The effects of streamline curvature on the Reynolds stresses in the convex and concave regions were also examined. The results clearly demonstrated that streamline curvature significantly enhanced the level of the streamwise turbulence intensity in the convex region more than in the concave region. On the contrary, the Reynolds shear stress and transverse turbulence intensity are much larger in the concave region than in the convex region. These results, together with the distributions of the Reynolds stress ratios across the jet, provide clear indications that turbulence models that assume local equilibrium and isotropy will not be able to accurately reproduce the flow characteristics of curved turbulent jets.
- 出版日期2013-9
