The Numerical Analysis About The Flow Noise Of Biological Safty Cabinets And The Study Of Noise Reduction

The biological safety cabinet is a safety device that can be used in scientificresearch, teaching and clinical trials which are in microbiology, biomedicine, animalexperiments and other areas, as well as the level protective barrier in laboratorybiosafety. Today, the production technology of biological safety cabinets has beenmature and the performance requirement of biological safety cabinets has reached ahigher level. However, the requirement of noise has no corresponding development, juststays in the initial level (less than67dB). The noise generated by the biological securitycabinet is the most intuitive influence to operator, but also determines the marketcompetitiveness ofthe biological security cabine. Thus, its noise reduction is animportant issue that can not be ignored on the basis of achievement to the performancerequirement of biological safety cabinets. This paper conducts a study on the flow noiseof biological safety cabinets, and proposes noise reduction measures.First, this paper conducts a theoretical study on the relationship between the flownoise and the flow field,as also as the mechanism of them. And it analyzes therelationship between the flow field of biological safety cabinets and its noise withaeroacoustics theory. The flow noise of biological safety cabinets is dipole sound source,mainly from the interaction of the air flow and air flow or air flow and solid surface.This paper establishes a mathematical air flow field model and a noise prediction modelof the biological safety cabinet. Then it conducts numerical simulation adout the flowand noise field of biological safety cabinets with FLUENT,then obtains spectrum of theflow sound field by fast Fourier transform,thereby to analyze the distribution andinfluencing factors of biological safety cabinets flow noise.This paper analyzes the the impact of filtration membrane resistance characteristicson the biological security cabinets flow noise, and stablishes noise calculation models ofdifferent resistance characteristics. By analyzing and comparing the results calculates:under the premise on achieving the cleaning performance requirements of safetycabinets, selecting the filter membrane with a smaller resistance can achieve the purposeof reducing noise. In addition, By comparativing and analysising the position and shape of the spoiler: Based on the stationary height, the semicircle shape radian creats aminimal noise.The flow field and the noise of biological safety cabinet were tested. The result ofthe experiment and simulation result coincide basically. Change tendency of the filterand guide plate optimization measures of biological safety cabinet have played a verygood effect of noise reduction. In this paper, the theory method of analysising flownoise reduction measures have certain theoretical guiding significance to designingbiological safety cabinet and other related equipment.