Study On The Effect Of Fume Collector Hood Structure On The Flow Structure Characteristics In The Negative Pressure Zone Of The Range Hood

The main function of the range hood is to reduce kitchen fumes pollutants and improve the cooking environment.The intake of the range hood can be approximated as a point sink suction process.A negative pressure area is formed at the inlet of the fan and the rising fume flows along the pressure gradient and finally enters the fan.The negative pressure area at the inlet of the fan directly affects the collection efficiency of the fume hood for oil fume.Based on actual needs,this article takes a small commercial range hood fume hood as the research object and combines CFD technology to explore the influence law of the fume collection hood structure on the negative pressure zone of the range hood inlet,so as to improve the flow condition in the fume collection hood and achieve the purpose of improving the performance of the range hood.The specific contents are as follows:(1)The influence of the diameter of the air inlet on the performance of the range hood is explored.A comparative analysis of the air volume of the range hood and the pressure distribution in the cross section of the fume collection hood is carried out.It was found that when the diameter of the air inlet matches the diameter of the collector,the flow loss of the range hood is small and the performance is the best.Above this conclusion,the influence of the shape of the hood on the negative pressure area was studied.By analyzing the pressure distribution,velocity distribution and CO concentration distribution in different sections of the hood,it is showed that increasing the inclination of the top of the hood can help increase the gas flow rate in the hood,reduce the inlet and outlet pressure of the hood,expand the area of the negative pressure area at the inlet of the fan and improve the collection efficiency of the hood for fume.(2)Based on the quadrangular pyramid fume collecting hood,the effect of the position of the outlet on the flow field characteristics in the fume collecting hood was investigated by offsetting the fume collecting hood outlet.The airflow of the range hood,the area of the negative pressure area and the velocity vector in the hood are compared and analyzed when the outlet position is shifted in different directions.The results show that there is a tendency for fume to flow upward along the wall,the position of the outlet of the fume collection hood to the side of the wall helps to improve the vortex phenomenon in the fume collection hood and reduce the flow loss and the pressure distribution in the fume collection hood is more uniform.(3)By designing flat deflectors with different sizes at different heights of the prototype hood and designing a new type of deflector based on flow field analysis,the influence of the type of deflector on the flow of fume in the hood is explored.The flow loss,the distribution of the negative pressure area at the inlet of the fan and the distribution of fume concentration in the fume hood have been compared and analyzed to determine the appropriate size and installation location of the deflector.Optimized design of the flat type deflector,the inclined lower surface and the curved upper surface of the new type deflector improve the flue gas velocity in the fume hood and improve the fume accumulation on the lower surface of the deflector.By exploring the influence law of the fume collecting hood structure on the fan inlet flow field characteristics,the fume collecting hood is optimized for design,which expands the area of the fan inlet negative pressure area and provides certain theory and data support for the optimal design of the range hood.