In this paper,we propose a novel probe to identify phases in any two-phase flows where one phase is conductive and the other *** can further obtain many parameters such as void fraction,bubble velocity,and interfacial...
详细信息
In this paper,we propose a novel probe to identify phases in any two-phase flows where one phase is conductive and the other *** can further obtain many parameters such as void fraction,bubble velocity,and interfacial area *** with the traditional probe,the novel probe has unique advantages that it is less dependent on water conductance or distance between the electrodes,and that the amplitude is bigger between high and low *** analyses showed that the measurement error became higher when water conductance decreases or distance increases,which is consistent with the theoretical *** results showed that the output signal kept constant with salt content of 0-5% and electrode distance of 0-30 mm in tap *** level difference was up to 6.4 V,resulting in identifying two phases *** traces of phase identification were completely consistent with the flow structures.
Electrical capacitance tomography technology is widely used in the field of flow regime identification. And image segmentation is one of the key technologies of flow regime identification. 2D Maximum Entropy Thr...
详细信息
The dynamic characteristics of molten droplets and hot particles at the very beginning of their fall into coolant pools are presented. The falling course of a single droplet or a single hot particle was recorded by a ...
详细信息
The dynamic characteristics of molten droplets and hot particles at the very beginning of their fall into coolant pools are presented. The falling course of a single droplet or a single hot particle was recorded by a highspeed camera and a curve of velocity vs. time was obtained. Emphasis was placed on the effects of the droplet's size and temperature, the coolant's temperature and properties, and the droplet's physical properties on the moving behavior. The results for the all cases showed that the velocity of a falling droplet/particle decreased rapidly but rebounded shortly, at the beginning of droplet/particle falling in the coolant. Following such a V-shaped evolution in velocity, the droplet/particle slows down gradually to a comparatively steady velocity. An increase in either coolant temperature or droplet temperature results in a larger velocity variation in the 'J-region', but a smaller deceleration when it moves out of the 'J-region'. The elevated volatility of a coolant leads to a steeper deceleration in the 'J-region' and beyond. The bigger size of a particle leads to a greater velocity variation in the 'J-region' and terminal velocity. A high melting point and thermal conductivity as well as lower heat capacity contribute to dramatic variation in the 'J-region' and low terminal velocity.
In the gas/solid twophase system, particles can accumulate a large number of electrostatic charges because of the collision, friction and separation between particles or between particles and wall. When particles movi...
详细信息
Capturing CO2 from the flue gas of a power plant based on chemical absorption method is an effective way to cut down the emission of CO2. However, the principal components in the solvent are very difficult to be measu...
详细信息
The principal pressure drop in a subsea riser is generally the gravitational pressure drop component due to liquid holdup. Surfactant is a kind of Chemical compound related to flow improvement. Gas‐liquid two‐phase ...
The principal pressure drop in a subsea riser is generally the gravitational pressure drop component due to liquid holdup. Surfactant is a kind of Chemical compound related to flow improvement. Gas‐liquid two‐phase flow in subsea riser with zero and small liquid flow rates was simulated in two vertical tubes with diameters of 40 mm and 65 mm, respectively. Liquid holdup reduction of subsea riser was investigated with surfactant. The simulation was conducted at low pressure, using air as the gas phase and water as the liquid phase. Pressure drop was measured by using differential pressure transducer and holdup was obtained by trapping the liquid in the pipe section. Different trace amounts of surfactant were used in this vertical two‐phase flow system. The liquid holdups were measured at different surfactant concentrations and different gas‐liquid flow ratios. Liquid holdups with and without surfactant additives are compared and analyzed. How the foamer influences the two‐phase flow pattern was observed and the range of foamer concentration corresponding to the best holdup reduction was obtained.
flow and temperature fields during the solidification of hypereutectic and hypoeutectic NH4Cl‐H2O solution in rectangular cavities were measured by a particle image velocimetry(PIV) and a weak perturbation thermocoup...
flow and temperature fields during the solidification of hypereutectic and hypoeutectic NH4Cl‐H2O solution in rectangular cavities were measured by a particle image velocimetry(PIV) and a weak perturbation thermocouple network, respectively. Double‐diffusive convections caused by the coupling effects of temperature and solute gradients were studied by the experiment. During the solidification of hypereutectic solution, the rejected water near the solidification interface will lead to dilute solute layers and double‐diffusive interfaces. As the continued rejection of water, the layer and interface will evolve into instability and a multi‐layer and multi‐interface structure will be formed. To the hypoeutectic solution, the rejection of NH4Cl near the solidification interface will form a dense solute layer. When the thickness of the dense solute layer is large enough, the coupling effects of stabilizing solute gradient and unstable temperature gradient will lead to new solute layers. The solute layers and double‐diffusive interfaces will evolve stably and have no breakup of the double‐diffusive interfaces during the solidification of hypoeutectic solution.
A model coupling two basic models, the model with interface tracking method and two‐fluid model, for simulation of incompressible gas‐liquid two‐phase flow is proposed. A united solution frame shared by the two bas...
A model coupling two basic models, the model with interface tracking method and two‐fluid model, for simulation of incompressible gas‐liquid two‐phase flow is proposed. A united solution frame shared by the two basic models is built. In the shared solution frame, the Navier—Stokes equations of the two basic models can be dealt with in a uniform form. In the proposed model, there are three phases, which are divided not only by physics but also by the length scale of interface, including the liquid phase, the large‐length‐scale‐interface gas phase and the small‐length‐scale‐interface gas phase. The special treatment named by “void fraction redistribution” is adopted for the special grids which contain all three phases. Based on the united solution frame, MCBA—SIMPLE algorithm is used to solve the equations. Two problems are calculated to show that the proposed model has the merits of the two basic models.
暂无评论