Liquid Swirl Research Articles

Experimental Investigation of Swirl and Non-Swirl Gas Injections Into Liquid Baths Using Submerged Vertical Lances

The behaviour of the flow of swirl and non-swirl gas injections into a liquid bath was investigated experimentally, using water as modelling fluid to gain an understanding of the mixing process of the Sirosmelt top submerged gas injection system. The effects of swirl intensity, gas injection rates and lance submergence levels on the gas-liquid interaction were determined by measuring the velocity fields and the generation of turbulence in the bath. The results indicate that the swirl gas injection promoted high liquid velocities and high turbulent kinetic energy and hence better mixing in the tank. When two-thirds of the lance was submerged better mixing and high liquid velocities resulted for both gas injection rates investigated. The applicability of the concept of isotropic turbulence for the liquid bath was examined. It was found that the assumption of isotropic turbulence may hold outside the plume region. However, there are a clear indication that turbulence is non-isotropic in the vicinity of the wall region. These findings have implications in the mathematical modelling of gas injection processes.On a étudié expérimentalement le comportement d'écoulement d'injections de gaz, avec et sans tourbillon, dans un bain liquide. On a utilisé des modèles aqueux afin d'obtenir un aperçu du procédé de mélange du système Sirosmelt submergé d'injection de gaz, par le haut. On a déterminé l'effet de l'intensité du tourbillon, des taux d'injection de gaz et des niveaux d'immersion de la lance sur l'interaction gaz-liquide en mesurant les champs de vitesse et la génération de turbulence dans le bain. Les résultats semblent montrer que l'injection de gaz avec tourbillon stimulait des vitesses élevées dans le liquide et une énergie cinétique turbulente élevée et, ainsi, un meilleur mélange dans le réservoir. Les taux élevés d'injection de gaz, comme on s'y attendait, ont produit des vitesses élevées du liquide dans tout le réservoir. L'immersion aux deux tiers de la lance a résulté en un meilleur mélange et en des vitesses élevées du liquide, aux deux taux d'injection de gaz étudiés. On a examiné l'applicabilité au bain liquide du concept de turbulence isotrope. On a trouvé que l'assomption de turbulence isotrope pouvait être retenue en dehors de la région d'injection. Il y a cependant des indications claires que, dans le voisinage de la paroi, la turbulence est non-isotrope. Ces découvertes ont des implications sur la modélisation mathématique des procédés d'injection de gaz.

Study on Hybrid Airblast Atomization

To provide a better understanding of the performance of the hybrid atomizer, where the atom ization process is accomplished under the combined effects of liquid pressure and airblast, an investigation has been conducted. Several fuel-injector configurations were selected in such a way to enable the evaluation of the actual role played by the air/liquid relative velocity and other key factors in the atomization process. A number of pressure swirl liquid atomizers that varied significantly in flow capacity, and several air nozzles of different flow areas, were employed in the tests. A calculation approach was formulated to ensure that more realistic liquid and air velocities at the exit of the atomizer were estimated. The spray measurements were performed using a Malvern particle analyzer. The results indicated that the utilization of the airblast effect in the atomizer was not always beneficial. It was also observed that the liquid pressure associated with minimum relative velocity did not coincide with the value that resulted in the least efficient atomization at a given air pressure drop. It was, thus, concluded that the relative velocity was not the only parameter controlling the spray quality. The separate effect of the air/liquid ratio on atomization was found to be most beneficial under low air pressure drop and over a range of low air/liquid ratios. The relative importance of various parameters was investigated by conducting the test under conditions selected in such a way to maintain the same relative velocity while varying either liquid pressure or air pressure drop. The results demonstrated that better atomization could be achieved under high liquid pressure than that obtained under low liquid pressure for the same level of relative velocity. The effects of both liquid pressure and relative velocity were significantly reduced at a higher air pressure drop.

Effect of Chamber Height on Centrifugal Separation Performance of a Gas-Liquid Vortex Chamber.

The effect of vortex chamber height on the characteristics of gas-liquid centrifugal separation in a vortex chamber has been investigated experimentally. It was made clear that the stable swirling liquid flow could be formed along the outer wall of the vortex chamber with the height of 20mm to 40mm. However, the unstable radial drop flow was observed in the height of 80mm over the range where the separated liquid fraction dropped steeply. In the shorter chamber, the radial width of separated liquid flow and the separated liquid fraction became larger. The data obtained here could be useful for designing a short vortex chamber.

Wave propagation in isotropic- or composite-material piping conveying swirling liquid

An analysis is presented for the propagation of free harmonic waves in a thin-walled, circular cylindrical shell of orthotropic or isotropic material conveying a swirling flow. The shell motion is modeled by using the dynamic orthotropic version of the Sanders improved first-approximation linear shell theory and the fluid forces are described by using inviscid incompressible flow theory. Frequency spectra are presented for pipes made of isotropic material and composite materials of current engineering interest.

Some Studies of Nonlinear Lateral Sloshing in Rigid Containers

Some experimental data, primarily on total force response, are presented for nonlinear lateral sloshing in rigid tanks of various geometries. Some effect of excitation amplitude on liquid swirl boundaries in an open circular cylindrical tank is noted. Data for the circular cylindrical tank are also compared with theoretical predictions. The primary nonlinear effects observed in all tanks were decreasing response frequency with increasing excitation amplitude and jump phenomena.