Similitude and scale effects of air entrainment in hydraulic jumps

A hydraulic jump is characterized by some strong turbulence and air entrainment in the roller. New measurements were performed in two channels in which similar experiments with identical inflow Froude numbers and relative channel widths were conducted with a geometric scaling ratio of 2:1. Void fraction distributions showed the presence of an advection/diffusion shear layer in which the data followed an analytical solution of the diffusion equation for air bubbles. The data indicated some scale effects in the small channel in terms of void fraction and bubble count rate. Void fraction distributions implied comparatively greater detrainment at low Reynolds numbers yielding to lesser overall aeration of the jump roller. Dimensionless bubble count rates were significantly lower in the smaller channel especially in the mixing layer. The study is believed to be the first systematic investigation of scale effects affecting air entrainment in hydraulic jumps using an accurate air–water measurement technique.

[1]  H. Chansona,et al.  Physical modelling and similitude of air bubble entrainment at vertical circular plunging jets , 2004 .

[2]  John R. Chaplin,et al.  Air–water interface dynamic and free surface features in hydraulic jumps , 2007 .

[3]  Hubert Chanson,et al.  Air Entrainment in the Developing Flow Region of Plunging Jets—Part 2: Experimental , 1997 .

[4]  Hubert Chanson,et al.  The hydraulics of open channel flow , 2004 .

[5]  Hubert Chanson,et al.  Experimental assessment of scale effects affecting two-phase flow properties in hydraulic jumps , 2008 .

[6]  A. A. Kalinske,et al.  Entrainment of Air in Flowing Water: A Symposium: Closed Conduit Flow , 1943 .

[7]  Hubert Chanson,et al.  Air Entrainment in Two-Dimensional Turbulent Shear Flows with Partially Developed Inflow Conditions , 1995 .

[8]  M. Hanif Chaudhry,et al.  Closed-Conduit Flow , 1981 .

[9]  Hubert Chanson,et al.  Air Bubble Entrainment in Hydraulic Jumps: Similitude and Scale Effects , 2006 .

[10]  Hubert Chanson,et al.  Experimental study of the air–water shear flow in a hydraulic jump , 2000 .

[11]  Hubert Chanson,et al.  Air Entrainment in the Developing Flow Region of Plunging Jets—Part 1: Theoretical Development , 1997 .

[12]  Nallamuthu Rajaratnam,et al.  Structure of flow in hydraulic jumps , 1991 .

[13]  Hubert Chanson,et al.  Air entrapment and air bubble dispersion at two-dimensional plunging water jets (vol 53, pg 4113, 1998) , 1998 .

[14]  Subhash C. Jain,et al.  Open-Channel Flow , 2000 .

[15]  Larry J. Weber,et al.  The Hydraulics of Open Channel Flow: An Introduction , 2001 .

[16]  F. J. Resch,et al.  Le ressaut hydraulique : mesures de turbulence dans la région diphasique , 1972 .

[17]  Hubert Chanson,et al.  Air Bubble Entrainment in Free-Surface Turbulent Shear Flows , 1996 .

[18]  John R. Chaplin,et al.  Optical fibre probe measurements of bubbly flow in hydraulic jumps , 2005 .

[19]  Hubert Chanson,et al.  Experimental analysis of Froude number effect on air entrainment in the hydraulic jump , 2007 .

[20]  Michele Mossa,et al.  Flow visualization in bubbly two-phase hydraulic jump , 1998 .