Foams Reynolds number

Re, Re Particle Reynolds number, foam Reynolds number. —... 

M. Amon and C. D. Denson [33-34] attempted a theoretical and experimental examination of molding a thin plate from foamed thermoplastic. In the first part of the series [33] the authors examined bubble growth, and in the second [34] — used the obtained data to describe how the thin plate could be molded with reference to the complex situation characterized in our third note. Here, we are primarily interested in the model of bubble growth per se, and, of course, the appropriate simplification proposals [33]. Besides the conditions usual for such situations ideal gets, adherence to Henry s law, negligible mass of gas as compared to mass of liquid, absence of inertia, small Reynolds numbers, incompressibility of liquid, the authors postulated [33] several things that require discussion ... 

Calderbank and Rennie (C4) and Rennie and Evans (R5) have found Sauter mean bubble diameters both photographically and from foam densities by y-ray absorption technique. Their bubble size could be predicted by the equation of Leibson et al. (L2) with a frothing system, for orifice Reynolds numbers between 2000 and 10,000. Thus,... 

High Viscosity and Surface Tension Bravo (Paper presented at the AIChE Spring National Meeting, Houston, Tex., 1995) studied a system that had 425-cP viscosity, 350 mN/m surface tension, and a high foaming tendency. He found that efficiencies were liquid-phase-controlled and could be estimated from theoretical HTU models. Capacity was less than predicted by conventional methods which do not account for the high viscosity. Design equations for orifice distributors extended well to the system once the orifice coefficient was calculated as a function of the low Reynolds number and the surface tension head was taken into account. 

The simplest relation between the volumes of foam formed and gas consumed is realised in the barbotage methods when the volume rate of gas supply is low (low Reynolds numbers). This dependence becomes more complicated when foam is generated by dispersion of gas on gauzes. In the other methods of foam formation mentioned shaking a solution in closed vessel, beating up solution with various devices and pouring solution, the dependence foam volume vs. solution properties and conditions of the foaming process is the least clear. 

According to [116] Hmax IQ remains constant under a dynamic foaming regime when Reynolds number Re < 100 (such a tube diameter is accepted as a characteristic size). When 250 > Re > 100, Hmax/Q first increases and then decreases. Similar dependences have been observed by Pattle [117],... 

Figure 20. Normalized pressure drop factor variation with modified Reynolds number for the fine foam (32).

By using Fanning friction factor, generalized Reynolds number, and CIP approach, Kenyon (43) analyzed Tan and McGowen (40) field data for C02 foam fluids and developed the following correlation ... 

The values of / were calculated from the experimental data and correlated as a function of a modified Reynolds number, fie = (r F where p/ = viscosity of foam. In making the correlation it was assumed (1) that the average foam density was one-third the density of the normal liquid, (2) that the viscosity of the foam, p/, was one-third the true viscosity of the liquid, and (3) that Lo was equal to two times the hydrostatic head in the outlet calming section. Thus,... 

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