Persistent froth is becoming more and more common in coal and mineral flotation plants and presents safety and operational challenges.No effective method has been developed to destabilise persistent froth.As a new ini...Persistent froth is becoming more and more common in coal and mineral flotation plants and presents safety and operational challenges.No effective method has been developed to destabilise persistent froth.As a new initiative,this study examined the structural difference between persistent foam and coal froth,based on which a solution was developed to maximumly destabilise coal froth.Destabilisation test,oscillatory rheology measurement and scanning electron microscopy(SEM) analysis indicated that the coal froth was more stable than the foam due to the formation of thin capillaries and tightly arranged coal particles on bubble surfaces.Although 107 μm silicone oil droplet could completely destabilise the foam at 2 mmol/L concentration,it only destabilised less than 50% coal froth even at 6 mmol/L concentration.To maximumly destabilise the coal froth formed by-38 and-20 μm particles,24 and 18 μm silicone oil droplets were required to pass through the thin capillaries and enter the bubble films,respectively.However,smaller silicone oil droplets could not bridge the bubble films to destabilise coal froth and therefore a critical droplet size occurred depending on the size of particles stabilising the froth.展开更多
A gliding arc plasma fuel atomization actuator suitable for aeroengines was designed,and a gliding arc plasma fuel spray experimental platform was built to address the fuel atomization problem in aeroengine combustion...A gliding arc plasma fuel atomization actuator suitable for aeroengines was designed,and a gliding arc plasma fuel spray experimental platform was built to address the fuel atomization problem in aeroengine combustion chambers.The spray characteristics for different airflows,fuel flows,and discharge voltages were analyzed using laser particle size analysis.The research shows that the fuel atomization effect is improved from the increased airflow.The decreased fuel flow not only reduces the injection pressure of the fuel but also changes the discharge mode of the gliding arc,which affects reductions in the discharge power and inhibits fuel atomization.Gliding arc discharges accelerate the breaking,atomization,and evaporation of fuel droplets while reducing the particle size,which increases the proportion of small droplets.Compared with the working conditions of plasma-assisted atomization without the gliding arc,the D0.5,D0.9,and average particle size of the fuel droplets are reduced by 4.7%,6.5%,and 4.1%,respectively,when the modulation voltage of the gliding arc power supply is 200 V.展开更多
The spray behaviors of the combined trapezoid spray tray(CTST) have a significant effect on the gas-liquid interface. In this paper, the spray process of CTST in a column, 570 mm in diameter, was experimentally invest...The spray behaviors of the combined trapezoid spray tray(CTST) have a significant effect on the gas-liquid interface. In this paper, the spray process of CTST in a column, 570 mm in diameter, was experimentally investigated by using a high-speed camera, and a theoretical model of the average droplet size was established according to the unstable wave theory. The results demonstrated that gas velocity passing through the hole is the key factor affecting the spray angle, which increases gradually with an increase in the gas velocity. When the gas velocity exceeds 7.5 m/s, the spray angle becomes stable at around 55°. The average flow velocity of the liquid sheet at the spray-hole increases significantly with an increase in the gas velocity, and decreases slightly with an increase in the liquid flow rate; moreover, it increases from the bottom of spray hole upward to the top. The density of liquid drops distribution in the spray area can be described by the RosinRammler function. In addition, the liquid drops are mainly concentrated in the area of spray angle ranging from 20° to 40°, and they gradually become uniform with the increase in the gas velocity and the liquid flow rate. The average liquid drop size deceases with an increase in the gas velocity, and increases slightly with an increasing liquid flow rate. In the normal working range, the average liquid drop size is about 1.0 mm to 2.5 mm in diameter.展开更多
基金ACARP (Australian Coal Association Research Program) project C24040 for financial supportscholarship provided by the University of QueenslandChina Scholarship Council。
文摘Persistent froth is becoming more and more common in coal and mineral flotation plants and presents safety and operational challenges.No effective method has been developed to destabilise persistent froth.As a new initiative,this study examined the structural difference between persistent foam and coal froth,based on which a solution was developed to maximumly destabilise coal froth.Destabilisation test,oscillatory rheology measurement and scanning electron microscopy(SEM) analysis indicated that the coal froth was more stable than the foam due to the formation of thin capillaries and tightly arranged coal particles on bubble surfaces.Although 107 μm silicone oil droplet could completely destabilise the foam at 2 mmol/L concentration,it only destabilised less than 50% coal froth even at 6 mmol/L concentration.To maximumly destabilise the coal froth formed by-38 and-20 μm particles,24 and 18 μm silicone oil droplets were required to pass through the thin capillaries and enter the bubble films,respectively.However,smaller silicone oil droplets could not bridge the bubble films to destabilise coal froth and therefore a critical droplet size occurred depending on the size of particles stabilising the froth.
基金supported by National Natural Science Foundation of China(Nos.91741112 and 52276142)。
文摘A gliding arc plasma fuel atomization actuator suitable for aeroengines was designed,and a gliding arc plasma fuel spray experimental platform was built to address the fuel atomization problem in aeroengine combustion chambers.The spray characteristics for different airflows,fuel flows,and discharge voltages were analyzed using laser particle size analysis.The research shows that the fuel atomization effect is improved from the increased airflow.The decreased fuel flow not only reduces the injection pressure of the fuel but also changes the discharge mode of the gliding arc,which affects reductions in the discharge power and inhibits fuel atomization.Gliding arc discharges accelerate the breaking,atomization,and evaporation of fuel droplets while reducing the particle size,which increases the proportion of small droplets.Compared with the working conditions of plasma-assisted atomization without the gliding arc,the D0.5,D0.9,and average particle size of the fuel droplets are reduced by 4.7%,6.5%,and 4.1%,respectively,when the modulation voltage of the gliding arc power supply is 200 V.
基金supported by the Science and Technology Research and Development Plan of Hebei Province, China (12276710D)
文摘The spray behaviors of the combined trapezoid spray tray(CTST) have a significant effect on the gas-liquid interface. In this paper, the spray process of CTST in a column, 570 mm in diameter, was experimentally investigated by using a high-speed camera, and a theoretical model of the average droplet size was established according to the unstable wave theory. The results demonstrated that gas velocity passing through the hole is the key factor affecting the spray angle, which increases gradually with an increase in the gas velocity. When the gas velocity exceeds 7.5 m/s, the spray angle becomes stable at around 55°. The average flow velocity of the liquid sheet at the spray-hole increases significantly with an increase in the gas velocity, and decreases slightly with an increase in the liquid flow rate; moreover, it increases from the bottom of spray hole upward to the top. The density of liquid drops distribution in the spray area can be described by the RosinRammler function. In addition, the liquid drops are mainly concentrated in the area of spray angle ranging from 20° to 40°, and they gradually become uniform with the increase in the gas velocity and the liquid flow rate. The average liquid drop size deceases with an increase in the gas velocity, and increases slightly with an increasing liquid flow rate. In the normal working range, the average liquid drop size is about 1.0 mm to 2.5 mm in diameter.
