Stabilization mechanisms of foams enhanced by xanthan gum and sodium carboxymethyl cellulose: Rheology-bubble structure interplay and predictive criteria for drainage delays.

Model for Plateau border drainage of power-law fluid with mobile interface and its application to foam drainage

This paper presents a preliminary study on the heat transfer in slug air-water flow in a slightly upward inclined tube, which is a widely appeared pattern in the inclined two-phase flow regime. Local heat transfer coefficients and flow parameters have been measured for slug air-water flow in a pipe [1.097 in (2.79 cm) I.D. and L/D = 100] at slightly upward inclination angles of 2° and 5°. The heat transfer data with slug air-water flow pattern were measured under a uniform wall heat flux boundary condition. The change on the heat transfer with inclination angle compared to the horizontal case is discussed in terms of the change in the overall heat transfer coefficient with respect to the superficial gas and liquid Reynolds numbers. For these data, the superficial Reynolds number ranged from about 3700 to 28000 for the water and from about 540 to 6500 for the air. The results indicate that there is an increase in the heat transfer with only slight increases in the inclination angle. However, the amount of increase is strongly dependent on the magnitudes of superficial liquid and gas Reynolds numbers.

A numerical investigation of the velocity, pressure and vorticity fields very near the injection of flat and thin two-dimensional gas jets or liquid sheets between two parallel high-speed gas coflows is performed. The motivation of this research is to uncover some basic physical mechanisms underlying twin-fluid atomization. Conservation equations and boundary and initial conditions are presented for both single-phase jets and two-phase liquid sheet/gas-stream systems. Both infinitely thin and thick solid walls are considered. Apart from the gas Strouhal and Reynolds numbers appearing in the dimensionless single-phase flow equations, the liquid Reynolds number, the momentum flux ratio, the gas/liquid velocity ratio and the Weber number enter the two-phase flow dimensionless formulation. The classical numerical techniques for single-phase jets are supplemented with the volume-of-fluid (VOF) method for interface tracking and the continuum surface force (CSF) method to include surface tension in two-phase flow systems. Ad hoc convection algorithms in combination with a developed version of the fractional-step scheme allows a significant reduction of the numerical diffusion, maintaining localized and sharp interfaces. The action of the surface tension is correctly found via the CSF with a smoothed scalar-field approximation. Results for single-phase jets with thin-wall injectors indicate qualitatively correct features and trends when varying the Reynolds number and the coflow/jet ratios: thick-wall injectors significantly modify the vorticity and pressure near fields; increasing the Reynolds number leads to larger flow disturbances; larger coflow/jet velocity ratios yield more perturbed near flow fields. For single-phase jets the Strouhal number as a function of the Reynolds number follows the usual trends of flows behind a circular cylinder. For two-phase flows, increasing the gas Reynolds number leads to larger liquid-sheet deformations and to a reduction of the breakup length; a plot of the gas Strouhal number, in the presence of a liquid sheet, as a function of the gas Reynolds number displays a monotonically decreasing curve, contrary to that for a gas jet. This observation strongly suggests that the gas vortex shedding mechanism is modified by the liquid-sheet motion. The gas vortex shedding frequency as a function of the liquid-sheet oscillation frequency follows a straight line with a slope of approximately $45^{\circ}$ for momentum flux ratios greater than roughly 0.45; for values below 0.45 the gas vortex shedding frequency remains constant while the liquid sheet varies its oscillation frequency. Increasing the surface tension leads to a larger breakup length. Thin trailing edges almost double the sheet oscillation frequency and more than halve the perturbation wavelength compared to thick trailing edges.

In this study, the atomization and spray characteristics of an effervescent ramp injector are experimentally investigated for various gas to liquid ratios and Reynolds numbers under fully developed conditions. High-speed shadowgraph images exhibit the spray characteristics for different flow regimes. Additionally, phase Doppler measurements are carried out at different axial locations to determine droplet sizes and their velocities. Initial study on pure liquid injection shows the spray characteristics are governed by the liquid Reynolds number. As the liquid Reynold number increases, the breakup length extends, and the droplet size reduces, with the near-field instabilities evolving from smooth surface waves in laminar flow to turbulence-driven fluctuations in higher Reynolds number. Furthermore, investigation reveals that by admitting a small amount of effervescent gas significantly enhances the atomization process. By increasing gas to liquid ratio, accelerate the atomization process. Based on the gas Reynolds number, the gas Weber number, and jet Reynolds numbers, various two-phase regimes, namely, bubbly, slug, annular, and their transitions, are identified and characterized. Among all these cases, the annular flow regime shows more stable and fine droplets.

Amylose and hydrocolloids may influence the rheology of dough and quality parameters of gluten-free cookies. The present study addresses an aspect of the effect of rice varieties (IR50404, Song Hau and Jasmine) and hydrocolloids (hydrocolloids (carboxymethyl cellulose, CMC, and xanthan gum, XG) with concentrations from 1.0 to 3.0% on rice cookie quality parameters (moisture content, water activity, density, expansion ratio, hardness and sensory value). The results noted that amylose content of rice varieties mainly influenced the hardness, expansion and thickness of cookies. The CMC was strongly and positively correlated with hardness while XG had a sharply positive relation with hardness, expansion ratio and water activity of cookies. Their interaction contributed mainly to the density of the rice cookie. The most appropriate hydrocolloid contents were 2% of CMC and 1% of XG for making good quality cookies from the Song Hau rice variety with medium amylose content.

Instabilities of a gas-liquid flow between two inclined plates analyzed using the Navier–Stokes equations

In-situ rheological and structural characterization of milk foams in a commercial foaming device

Kinetics and dynamics of Gas-liquid separation and bubble generation in surfactant solutions: Role of bulk/interfacial properties and hydrodynamic conditions

Drag reduction in the turbulent pipe flow of polymers

The comparison of the effect of sodium caseinate, calcium caseinate, carboxymethyl cellulose and xanthan gum on rice-buckwheat dough rheological characteristics and textural and sensory quality of bread

Summary Foam drilling offers advantages such as reduced formation damage and faster drilling in underbalanced drilling (UBD) operations. The efficacy of foam drilling is influenced by factors including pressure, temperature, salt content, foam quality, and pH levels. However, a gap exists in the evaluation of foam properties under rigorous conditions, particularly those involving high pH and mixed salt environments common in drilling scenarios, highlighting the need for further research. In this study, a high-pressure, high-temperature (HPHT) foam analyzer and rheometer were employed to examine the stability and rheological behavior of ammonium alchohol ether sulfate (AAES) foam under simulated alkaline drilling conditions. The foaming solution, designed to replicate such conditions, consisted of synthetic seawater (SW) with a salt mixture totaling approximately 67.70 g/L and a 0.5 wt.% foaming agent adjusted to a pH of 9.5. This approach differs from the individual salt studies prevalent in existing literature and provides a unique perspective on foam stability and behavior. Driven by environmental sustainability considerations, the effects of eco-friendly surfactant AAES and various drilling fluid additives: polyanionic cellulose (PAC), carboxymethyl cellulose sodium (CMC), and xanthan gum (XG), were investigated for foam formulation. The apparent viscosity of the AAES foam was evaluated at different pressures and temperatures across varying shear rates. A consistent decrease in foam viscosity with increasing shear rates was observed, irrespective of pressure and temperature. An increase in foam viscosity was also noted with higher pressures (from 14.7 psi to 3,000 psi) at low shear rates, with values rising from 8.04 cp to 14.74 cp, and from 3.71 cp to 5.79 cp at high shear rates of 1,000 s⁻¹. Increasing foam quality from 65% to 85% resulted in significant improvements in viscosity, approximately 37% at low shear rates and about 79% at high shear rates. The introduction of additives to AAES foam at 1,000 psi and 90°C led to a substantial increase in viscosity, with PAC showing the most significant enhancement: 33.28 cp at low shear rates and 18.15 cp at high shear rates. Conversely, the viscosity of both base AAES foam and additive-enhanced foams decreased with rising temperatures, although PAC exhibited the greatest resistance to viscosity variations due to temperature changes. The addition of PAC also resulted in a notable increase in foam yield stress, potentially leading to more efficient cuttings transport and hole cleaning. Furthermore, foam stability was significantly improved by the additives, with XG and CMC doubling stability to 48 minutes, and PAC resulting in a threefold increase in half-life to 65 minutes. This study presents AAES and the tested additives as viable components for eco-friendly foam formulations, promoting enhanced properties suitable for UBD applications.

A phase-resolved force analysis of bubble trapping behind cylinders in liquid-gas flows

Improvement of hydrocolloid characteristics added to angel food cake by modifying the thermal and physical properties of frozen batter

Effect of the recess length on the dynamic characteristics of liquid-centered swirl coaxial injectors

Linear and nonlinear instabilities of a co-current gas-liquid flow between two inclined plates analyzed using the Navier–Stokes equations