The Research About Airflow Simulation And Noise Reduction Of The Class â…¡ Biological Safety Cabinet

With the rapid development of health, biology and medical cause, more and more biological safety cabinets are put into use in the fields of microbiology, animal experiments, biological products, gene recombination and other fields,it is the main safety equipment of biological safety protection barrier in the laboratory.In recent years, people have raised the requirement of working environment, the noise of safety cabinet is gradually becoming the focus of attention for enterprises and consumers. This paper is aimed at the problem of the safety cabinet’s noise, I will make numerical simulation and research about the flow field and noise of the biological safety cabinet,and put forward feasible measures for noise reduction.On the basis of researching the relationship between the pneumatic acoustics’ flow field and noise, I will establish the perfect three-dimensional model and noise prediction model about the air flow field in the biological safety cabinet. Some appropriate treatment is adopted in the process of establishing the safe cabinet model:multiple reference frame model(MRF)is used in the dynamic and static regions of the centrifugal fan; I will regard high efficiency filtration membrane as a porous media structure with fixed porosity.Then the model is imported into the FLUENT software to simulate the flow field and obtain the flow chart of air flow.Through the noise module Acoustic:FW-H of the FLUENT, then through the Fu Liye rapid transformation(FFT), the spectrum of the flow field is obtained.According to the results of numerical simulation, the noise of the biological safety cabinet is the superimposed results of the discrete noise and broadband noise, and the dipole sound source is the main flow noise source of the safety cabinet.The impeller rotating flow region and flow channel near the volute tongue are complex and disordered flow,belong to noise sources that have a great influence on the safety cabinet’s noise.The flow field around the front and back of the guide plate is unstable and produces vortexs, which lead to the coupling between the noise field and the flow field.,they also have a great influence on the safety cabinet’s overall noise.The guide plate is an important component of the safety cabinet and an important source of noise.Therefore, through changing the structure of impeller, volute tongue, guide plate and adjusting the appropriate distance from the fan outlet to the guide plate,to achieve the purpose of reducing noise.The noise of the safe cabinet is mainly distributed in the region of the centrifugal fan and the air flow with a larger flow rate over the high efficiency filtration membrane.By adjusting the appropriate speed of the fan to reduce the flow velocity and the inhomogeneity of the flow field,then to reduce the overall noise of the safety cabinet.Through experimental test for the air flow field and noise field of the biological safety cabinet,the experimental data and the simulation results are basically consistent,and then the validity of the biological safety cabinet’s model is verified.Through the numerical simulation and experimental study about the air flow field and noise for the biological safety cabinet,this paper provides a theoretical reference for the optimization analysis and noise reduction about safety cabinet and other related equipments.