Dust distribution and control in a coal roadway driven by an air curtain system: A numerical study

Numerical investigation of dust dispersion in a coal roadway with hybrid ventilation system

Gas–solid two-phase flow in an underground mine with an optimized air-curtain system: A numerical study

Dust dispersion in a coal roadway driven by a hybrid ventilation system: A numerical study

Experimental investigation on Influencing Factors of air curtain systems barrier efficiency for mine refuge chamber

ABSTRACTThe complexity of urban tunnel structure increases the risk of tunnel fire, and the air curtain system plays an important role in controlling the spread of fire smoke and ensuring the safety of personnel. Based on theoretical analysis and tunnel model experiments, the isolation effect of different air curtain jet conditions on high‐temperature fire smoke in bifurcated tunnel was studied. The results show that the air curtain system can effectively isolate the high‐temperature smoke. For different firepower, compared to angle and thickness, wind speed has the best control effect on high‐temperature smoke. The control effect of air curtain thickness takes second place. The effect of angle change is the least obvious. Meanwhile, based on the analysis of experimental results, it was found that when the air curtain parameters are selected as wind speed of 2.5 m/s, angle of 15°, and thickness of 0.16 m, the air curtain system has better smoke prevention efficiency. Finally, dimensionless analysis yielded a power law equation relating upstream temperature rise, firepower, and wind speed. This supports theoretically analyzing the air curtain's smoke prevention effect.

High clearance sprayers are widely used in field operations because of their high ground clearance and good passing performance, which can solve the problem of spraying high-stalk crops in the middle and late stages. In this paper, an air curtain system was designed to address the phenomenon of droplet drift in the operation of high clearance sprayers. Based onstatic pressure recovery theory, the design and optimization of the flow velocity at the outlet of the air curtain were carried out. Using SolidWorks software for modeling, ICEM CFD software to divide meshes, and Fluent software to solve the problem, the air duct model was simulated and drift characteristics of droplets were studied through continuous phase and discrete phase coupling calculation. Using three-factor and three-level orthogonal test, the optimal solution of the model was obtained as follows: a spray pressure of 0.4 MPa, a horizontal wind speed of 2 m/s, a fan frequency of 40 Hz, and a droplet drift rate of 9.38%. According to the degree of influence from large to small, the factors are arranged as follows: horizontal wind speed, fan frequency, and spray pressure. An air curtain system test prototype and a droplet drift rate test platform was built, and flow rate of the air duct outlet and the droplet drift rate were tested under multiple working conditions. Experimental results showed that: when the horizontal wind speed was 2 m/s and 4 m/s, the droplet drift rates were the lowest when frequency was 25 Hz and 35 Hz, respectively, which were 13.65% and 23.88%, respectively. When the horizontal wind speed was 6 m/s and 8 m/s, the droplet drift rates reached the lowest when frequency was 45 Hz, which were 27.02% and 29.78%, respectively. When the horizontal wind speed was 2 m/s, 4 m/s, 6 m/s, and 8 m/s, the droplet drift rates of the optimal auxiliary airflow were reduced by 17.33%, 34.51%, 50.62%, and 67.54%, respectively. Experiments show that the optimal auxiliary air velocity changes when the horizontal wind speed is different. Keywords: air curtain system, CFD numerical simulation, droplet drift rate, multiple working conditions DOI: 10.25165/j.ijabe.20241706.8253 Citation: Song Y Y. Analysis of air curtain system flow field and droplet drift characteristics of high clearance sprayer based on CFD. Int J Agric & Biol Eng, 2024; 17(6): 38–45.

Air curtain systems have been proposed as a supplementary smoke control strategy for vehicle tunnels, particularly where structural constraints limit the installation or upgrading of conventional ventilation systems. However, most previous studies rely on numerical simulations or fixed experimental facilities, while flexible experimental platforms and the influence of vehicle obstruction on smoke behavior remain less explored. This study experimentally investigates the smoke confinement performance of an air curtain using a 1:18 modular detachable scaled vehicle tunnel model. The modular configuration enables flexible assembly and adjustment of the experimental setup for different test conditions. A series of laboratory experiments was conducted using a liquefied petroleum gas (LPG) burner to simulate a vehicle fire. Temperature measurements and smoke visualization were performed under different air curtain jet velocities and vehicle obstruction conditions to analyze the interaction between the air curtain jet and buoyancy-driven smoke flow. The results show that the air curtain significantly restricts the upstream propagation of hot smoke and modifies the thermal field inside the tunnel. When the jet velocity reached approximately 5 m/s, the temperature in the protected region decreased by about 25–35% compared with the case without an air curtain. In addition, the presence of vehicle models altered the airflow structure and increased heat accumulation in the middle region of the tunnel cross-section. These results demonstrate that the proposed modular tunnel model provides a reliable experimental platform for tunnel fire research and highlights the importance of considering vehicle obstruction effects in tunnel smoke control studies.

Performance evaluation for a coupled push–pull ventilation and air curtain system to restrict pollutant dispersion in a factory building

Numerical Simulation of Environmental Control for Relics Preservation in the Funerary Pit by Air Curtain System

In this study, a tunnel temperature field model test bed is built according to the similarity principle to study the variation law of temperature in the tunnel in the cold season. According to the variation law of temperature in the tunnel, a new active thermal insulation measure, namely, an air curtain system, is developed. According to the principle of flow function superposition and heat balance, the governing equation of air curtain system is obtained. Taking the Zhengpantai tunnel as an example, the feasibility of the air curtain system is verified, and the jet angle of air curtain is optimized. The research results show that outside temperature and surrounding rock temperature are the main factors affecting the temperature field of tunnels in cold regions. The calculation results show that the air curtain system can effectively prevent tunnel freezing damage. The optimal jet angle of air curtain system should be 30°–40°. When the outside temperature is extremely low, multiple air curtains can be used in series to heat the temperature in the tunnel, and it is recommended that the distance between the two air curtains is not less than 20 m.

Creating and maintaining the microclimate in livestock buildings is associated with numerous engineering and technical challenges. Together with adequate feeding, the microclimate determines the health, reproductive ability, and production potential of the animals (obtaining a maximum amount of high-quality products). One of the deciding steps in improving the parameters of microclimate, i.e., temperature and humidity in agricultural facilities, particularly in livestock buildings, is to develop reliable and highly efficient air curtains in the vestibules. The objective of the manuscript is to investigate the parameters of the microclimate in livestock buildings using the air curtain, supported by automation and ICT technologies for rational operating modes. The presented theoretical and experimental studies on improving the microclimate parameters in livestock buildings were carried out using an innovative air curtain system. Its power is calculated based on the dimensions of the room, and the flow rate of warm air near the floor level is three times lower than at the installation site. The use of air curtains reduces consumption of thermal energy needed to maintain an optimal microclimate for livestock by 10–15%. Furthermore, the use of an automated digital control system maintains an optimal microclimate in the building. The developed energy-saving system for creating an optimal micro-climate in livestock buildings using air curtains was tested in a pigsty of the Research and Training Farm “Vorzel” of the National University of Life and Environmental Sciences of Ukraine, located in the Kiev region. The developed automated microclimate system using air curtains significantly improves the microclimate parameters and significantly reduces power consumption. The system can be further developed by adding remote control based on the Internet of Things (IoT) technology.

Air leakage in the goaf is a fundamental reason for the high-temperature heat damage of the coal mining face and the gas concentration in the upper corner exceeding the limit. Combined with the boundary layer theory, this study analyzes the airflow state of the coal mining face. We propose installing a new air curtain system to prevent air leakage in the goaf. The length of the intake air curtain is determined by solving the theoretical equation. Numerical simulation is used to study different layout schemes of air curtains, and the spatial distribution law of different air volumes inside the working face is analyzed. The simulation results are compared with the field-measured data. The results show that when the length of the air curtain on the air inlet side is 20 m, the wind flow on the working face can be approximated as a state of attached jet, and a diffuse turbulent flow area will be formed outside the air curtain. Gas concentration will increase in this area. The air leakage prevention effect is best when the air curtains with a length of 20 m for the inlet air and 10 m for the return air are arranged at both ends of the working face. This air curtain system can reduce the temperature of the working face and the gas concentration in the upper corner and has certain guiding significance for the air leakage prevention work in the goaf.

Air distribution systems generally focus on diluting contaminants and distributing conditioned air. However, this strategy has a potential for spreading particulate matter or bioaerosols. Thus, it is considered to be useful to create a non-uniform indoor environment to prevent such dispersion of particulate matter or bioaerosols, and an air curtain could serve for this purpose. This study investigates the effects of an air curtain system in a ventilated office to prevent the dispersion of expiratory droplets that are generated locally, while also considering thermal comfort. Droplets dispersion was modelled with computational fluid dynamics (CFD) with the Lagrangian method. In the CFD simulations, an air curtain system was installed in the middle of an office with varied factors of design, orientation and jet velocity of the air curtain system. Numerical results showed that unless there was an independent inlet and outlet for each region, the air curtain system alone could not create a non-uniform thermal environment; however, it was effective in removing and preventing dispersion of the expiratory droplets. The droplet removal performance of an air curtain system was not proportional to its jet velocity, but a velocity of 3 m/s was found to be feasible for this office. The air curtain system showed better performance than an air cleaner used to exhaust and filter the expiratory droplets.

Air curtain dust-collecting technology: Investigation of industrial application in tobacco factory of the air curtain dust-collecting system

Influences of the optimized air curtain at subway entrance to reduce the ingress of outdoor airborne particles