Study On The Structural Optimization And Noise Reduction For Leaf Blower

With the improvement of living standard,the noise pollution is becoming a hot topic. Hearing loss may be caused by long time exposed to high noise environment and people tend to feel uncomfortable or even have headaches. As a hand-held garden tools, the leaf blower needs to be operated by workers in a close distance for a long time, so the noise affects the user’s comfort level directly. Leaf blower is a kind of centrifugal fan, the main noise source of it can be divided into mechanical noise, aerodynamic noise, gas-solid coupled noise and etc.The aerodynamic noise ranks a high proportion of all the noise source has been studied by many researchers,so this paper mainly targets this kind of noise source.In order to ensure the existing flow field performance and reduce the noise effectively, this paper studies the optimization design of the whole structure by using acoustical theory and optimization algorithm, and finally the optimization scheme is set out through data analysis and numerical calculation.Firstly, three-dimensional modeling software UG is used to establish the whole machine,and the grid software HyperMesh is used to mesh the model reasonably. Then,CFD software Fluent is used in the flow field numerical simulation according to the turbulent model, solving method, noise model and etc.In the end, the sound pressure level of noise points in blowing and breathing condition is calculated according to the velocity field and pressure field result.Then, in a semi-anechoic laboratory, the flow and noise test of the machine is used to certify the flow flux and sound pressure level of the existing model. The result shows the correctness of the numerical simulated model compared with the real model.Then, double-objective-optimization plans are made based on flow and acoustic pressure level. The main structures concerning the noise reduction is the blades in impeller, the export structure of. the spiral case, the helix angle of volute and resistance muffler in pipe. These design schemes are calculated in Fluent software to certify the effectiveness. Because the optimized leaf blower gains huge improvement in flux and static pressure, so the rolling speed is reduced for the reduction if noise.In this paper, the optimization scheme effectively reduces the noise by 8 dBA when blowing,and also 2 dBA when breathing. The finial model of this paper meets the design goals, the flow flux is improved and the noise of the machine is reduced. The results of the analysis in the process of research can provide theoretical and data support for the follow-up analysis, and has a certain application prospect.