Brownian dynamics simulation is conducted for a dilute surfactant solution under a steady uniaxial elongational flow. A new inter-cluster potential is used for the interaction among surfactant micelles to determine th...
详细信息
Brownian dynamics simulation is conducted for a dilute surfactant solution under a steady uniaxial elongational flow. A new inter-cluster potential is used for the interaction among surfactant micelles to determine the micellar network structures in the surfactant solution. The micellar network is successfully simulated. It is formed at low elongation rates and destroyed by high elongation rates. The computed elongational viscosities show elongation- thinning characteristics. The relationship between the elongational viscosities and the mierostructure of the surfactant solution is revealed.
The effect of Ca-Fe-Ce series catalyst on the characteristics of anthracite combustion was investigated by thermo-gravimetric analysis. The results showed that there may be a synergetic effect among the components in ...
详细信息
The effect of Ca-Fe-Ce series catalyst on the characteristics of anthracite combustion was investigated by thermo-gravimetric analysis. The results showed that there may be a synergetic effect among the components in the composite catalyst and the composite catalyst exhibits better performance than the single one for the anthracite combustion. The combustion characteristics of anthracite are affected by the dispersion of catalyst, heating rate and combustion atmosphere. The catalytic effect is enhanced by increasing the catalyst dispersion. The reduction degree of ignition temperature increases with the increase of heating rate. The ignition temperature decreases significantly with the increase of O2 concentration.
Eulerian granular multiphase model with a drag coefficient correction based on the energy-minimization multi-scale (EMMS) model was used to simulate a semi-industry scale circulating fluidized bed (CFB). Three-dim...
详细信息
Eulerian granular multiphase model with a drag coefficient correction based on the energy-minimization multi-scale (EMMS) model was used to simulate a semi-industry scale circulating fluidized bed (CFB). Three-dimensional (3D), time-dependent simulation of a full-loop CFB revealed that the axial profiles of cross-sectionally averaged solid volume fraction, and the radial profiles of solid axial velocity and solid volume fraction were in reasonable agreement with experimental data. Based on this agreement, database derived from experiments not yet accomplished was replenished with such simulations, and fluid regime diagrams and pressure balance around the CFB loop were derived accordingly. This work presents an integrated viewpoint on CFB and unfolds a fresh paradigm for CFB modeling, which can be expected to help resolve certain issues long in dispute but bard for experiments.
In present paper a turbulent mixing layer with the velocity ratio 4:1 which was produced by a special designed splitter plated placed in a vertical rectangular channel was experimentally investigated by PIV. The Reyno...
详细信息
In present paper a turbulent mixing layer with the velocity ratio 4:1 which was produced by a special designed splitter plated placed in a vertical rectangular channel was experimentally investigated by PIV. The Reynolds number based on the velocity difference of two steams and hydraulic diameter of the channel ranges from 4400-158400. It is found that the scale of coherent vortex structure increases with increasing the Reynolds number and then decreases with continuously increasing the Reynolds number. The injected bubble will delay or hinder the evolution of the coherent structures. Afterwards the statistical and instantaneous distributions of Reynolds stress, turbulent intensity, vorticity and swirling strength are obtained. The results show that all these turbulent parameters exist only in a very narrow conical region in the downstream of the mixing layer. The Reynolds stress and turbulent intensity first increase and then decrease with increasing the Reynolds number and decrease with the evolution of mixing layer, while vorticity and swirling strength increase with increasing the Reynolds number and decrease with the evolution of mixing layer.
An experimental study has been performed to investigate pool water instantaneous flash evaporation in a rectangle chamber. The water level was at 40 mm, 60 mm, 100 mm, 150 mm. Initial conditions of the liquid varied f...
详细信息
An experimental study has been performed to investigate pool water instantaneous flash evaporation in a rectangle chamber. The water level was at 40 mm, 60 mm, 100 mm, 150 mm. Initial conditions of the liquid varied from 55 to 88C temperature and 3 to 35C superheat. Visualization of the phenomenon using a CCD camera lets us firstly point out the influence of the initial conditions on the flashing phenomenon. The experimental results show that at a constant initial water temperature, the greater the superheat approaches, the more quickly the liquid temperature will decrease. At a constant superheat, the initial water temperature has little influence on the decrease rate of the water temperature. The higher the water level will be, the slower the water temperature will decrease as well as the higher the water temperature will be when the flashing is finished. Experimental study allows us to correlate the water temperature with the initial water temperature and the superheat while flashing is going.
A new tandem double-capillary tube refrigeration system for refrigerator-freezers is proposed. A capillary tube was added between the two evaporators in the fresh and frozen food storage chests to raise the evaporatio...
详细信息
Liquid foam is a dense packing of gas bubbles in a small amount of surfactant solution. Liquid drains out of foams until equilibrium is reached due to the compromise between gravity and capillarity, which greatly affe...
详细信息
Liquid foam is a dense packing of gas bubbles in a small amount of surfactant solution. Liquid drains out of foams until equilibrium is reached due to the compromise between gravity and capillarity, which greatly affects the stability of foam. Based on a series of work on foam structure and drainage we conducted previously, this paper reports the results on coalescence of an original forced drainage wave at a low flow rate with subsequent drainage waves with higher flow rates. The evolutions of viscous energy and surface energy during the process of coalescence are theoretically analyzed.
Slug initiation and subsequem evolution along a 5.0 cm ID, 16m long horizomal pipe are experimentally studied. The transient characteristics of interfacial structures are described by using simultaneous measuremeres o...
详细信息
Slug initiation and subsequem evolution along a 5.0 cm ID, 16m long horizomal pipe are experimentally studied. The transient characteristics of interfacial structures are described by using simultaneous measuremeres of the liquid height at multiple locations along the pipe. Various effects of superficial gas and liquid velocities and pressure oscillation on the slug initiation and evolution along the pipe are illustrated. It is found that the slug is initiated by a deterministic orocess with reolenishmem and deoletion of liquid near the inlet for the superficial gas velocity USG〈3.0m·s^-1 and by a stochastic process with wave coalescence along the pipe for USG〉3.0m·s^-*** evolution of the slugs is strongly attected by superhclal gas and liquid veloclties for USG〈3.0m·s^-1 but weakly affected by the superficial gas velocity for USG〉3.0 m·s . The suppression of pressure oscillation at the pipe inlet significantly delays the onset of slugging, with slugs forming postponed further downstream. The slug frequency at the outlet is, however, not affected by the variation in the pressure oscillation.
With the rapid development of computer and optical technique, as a powerful measuring method in hydrodynamics, flow visualization technique is able to get much flow field information in practical engineering. It also ...
With the rapid development of computer and optical technique, as a powerful measuring method in hydrodynamics, flow visualization technique is able to get much flow field information in practical engineering. It also has an important meaning to projects and environmental areas. The image processing is the key to flow visualization for gaining flow field information. In terms of the PIV principles, the algorithm of PIV based on Fast Fourier Transformation (FFT) is studied, and the image mosaic program based on genetic algorithm has been compiled. The flow field of seabuckthorn flexible dam has been calculated and analyzed by using those methods as above-mentioned, and in the meanwhile, the application of flow visualization technique to measure the outdoor flow field has been studied exploringly, which proves that it is feasible to apply this technique to measure the large-scale outdoor flow field.
The conversion of nitrogenous gas products during coal pyrolysis is investigated in a drop tube reactor. Four raw coals and two demineralized coals have been used for pyrolysis at 500°C, 700°C, 900°C an...
详细信息
The conversion of nitrogenous gas products during coal pyrolysis is investigated in a drop tube reactor. Four raw coals and two demineralized coals have been used for pyrolysis at 500°C, 700°C, 900°C and 1100°C. The results indicate that the yields of N 2 and NO precursors, such as HCN and NH 3 , increase with increasing temperature. Coal type has significant effect on the yield of nitrogenous gas products. For lower rank coal, the conversion of fuel nitrogen is higher. Majority of fuel nitrogen in high rank coals is built into condensed aromatic structures to form Char-N. The mineral matters in coal can promote the conversion of fuel nitrogen to N 2 , but they can also suppress the conversion of fuel nitrogen to HCN and NH 3 .
暂无评论