Abstract-The airfoil ventilation fan based on Coanda effect was studied, which was simulated by Fluent software. The inducing velocity was considered as an important influence factor on the characteristic of the flow field. The paper reports the results of the velocity distribution in the flow field and the induction rate of the model in different inducing velocities, which shows that with the inducing velocity increasing, the velocity contour develops further and the coverage area becomes larger along the positive X axis, and the induction rate of airfoil ventilation fan decreases when the inducing velocity reduces and approaching a steady value when the reducing velocity is greater than 25m/s. Through the change law of the airfoil inducing rate is explored, the article will give a reference for the choice of inducing velocity in the optimization of the airfoil ventilation fan, and reduce the fan of energy conservation.
Large-span air-conditioning plant rooms have a large roof area and suffer from serious solar radiation in summer. The outside roof surface temperature is very high, so cooling load of roof occupies a large proportion in the envelope structure cooling load of large-span air-conditioning plant rooms. Based on the Coanda airfoil air induction unit, the author combined with exhaust air in large-span air-conditioning plant rooms to design the roof air film cooling system of large-span air-conditioning plant rooms. The adherence air film formed on the outside surface takes away heat on the outside surface of the roof, so as to reduce outside roof surface temperature of the roof, decrease heat transfer temperature difference between inside and outside roof surfaces of, and reduce roof cooling cold. Furthermore, the mathematical model and numerical simulation method of considering fluid-structure interaction for heat transfer and influences of solar radiation on air film formation of outside surface and cooling were constructed. Moreover, the numerical simulation method was conducted the validation of effectiveness. Also, the author discussed the air film formation mechanism and air film cooling ability of outside surface in large-span air-conditioning plant rooms without natural wind, developed a new air film cooling technology for the roof of large-span air-conditioning plant rooms, and supplemented the existing roof cooling technology.
A suitable exhaust hood form has a great influence on the control effect of pollutants. This paper uses CFD technology to numerically simulate the airflow distribution characteristics and pollutant concentration distribution characteristics of the side hood before and after improvement. The results show that: (1) The airflow of the improved side suction hood is introduced from the front of hood to make the fresh air pass through the breathing area first and then takes away the hazardous substances, which is beneficial to the breathing health of workers. (2) When the exhaust velocity (V) is more than 3.5m/s, with the increase of the exhaust velocity, the concentration hazardous substances at each control point of the two forms of exhaust hood tends to be stable gradually. (3) When the exhaust velocity is less than 3.5m/s, the control effect of side suction hood with baffle is better than that without baffle, and the percentage of hazardous substances concentration at the same control point can be reduced by 12%-29%, or even higher.
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