吹吸一体式吸叶机CFD仿真与降噪研究

发布时间：2018-06-09 14:10

本文选题：吸叶机 + CFD　；参考：《东南大学》2015年硕士论文

【摘要】：吹吸一体式吸叶机工作时,噪声很大,操作舒适性能较差,严重危害操作者人体健康。目前有关降低吸叶机工作噪声的研究很少,大部分企业在吸叶机设计过程中依赖经验,采用仿制和实验的方法,成本高,研发效率低。本文将CFD(Computational Fluid Dynamics)仿真技术融入到吹吸一体式吸叶机优化设计中,以提高吸叶机气动性能和降低工作噪声为目的,对吸叶机工作部件和流道进行优化。首先,对吸叶机结构进行分析,确定需要优化的5个具体工作指标：吸叶时入口流量和入口静压、吹叶时出口流量、吹/吸状态噪声声压级。简化吸叶机部分次要结构,抽取吸叶机流道,通过合理的网格划分方式和求解条件获得吸叶机在吹叶和吸叶状态下的仿真模型,完成吸叶机的稳态流场仿真。在蜗壳出口处,由于设计不合理,产生涡旋,导致流动损失和噪声增大。平直蜗舌未能起到很好的导流作用,吹叶时,蜗舌附近处有空气回流。流场仿真的结果为结构优化设计提供参考。其次,为了提高计算精度,同时考虑到计算机性能,通过大涡模型与FW-H声模型结合的方法,计算吸叶机吹/吸状态下监测点处噪声。旋转噪声基频及倍频所在频带的噪声明显大于其他频段噪声,因此吸叶机气动噪声以旋转噪声为主。再次,按照风机气动性能和噪声测量标准,测量吸叶机吹叶时出口流量,吸叶时入口流量和静压,以及监测点处噪声声压级,分析采集的噪声信号和振动信号。将实验结果与仿真结果进行对比,验证了模型的正确性。最后,以叶片数、轮毂比和出口安装角为优化因素,采用正交试验法对叶轮进行结构优化。针对蜗壳结构的不合理,在蜗壳出口采用圆弧连接方式,用圆弧蜗舌替换平直蜗舌,减轻了气流对壁面的冲击；推拉式吹/吸转换装置减少了气流泄露,气动性能得到提高。当圆弧蜗舌半径为4.3mm时,气动性能和噪声达到最佳平衡点。依据相似定律,将转速降低2000rpm。最终吸叶机吹叶和吸叶时噪声明显降低,同时气动性能得到提高,很好地达到了优化目标。
[Abstract]:When the suction blower is working, the noise is great, the operating comfort is poor, and the operator's health is badly damaged. At present, there are few researches on reducing the working noise of the suction machine. Most enterprises rely on experience in the design process of the suction blye machine, using the method of imitation and experiment, the cost is high, and the R & D efficiency is low. This paper will be CFD (Computational). Fluid Dynamics) simulation technology is integrated into the optimization design of the blower suction blower. In order to improve the aerodynamic performance of the suction blower and reduce the working noise, the working parts and channel of the suction blower are optimized. First, the structure of the suction blower is analyzed, and 5 specific working indexes are determined: the inlet flow and entrance when the blade is sucked. Static pressure, outlet flow and sound pressure level of blowing / suction state. Simplify part of the secondary structure of the suction blower, extract the flow path of the suction blower, obtain the simulation model of the blade under the state of blower and leaf suction through reasonable grid division and solving conditions, and complete the simulation of the steady flow field of the suction blower. At the outlet of the worm shell, the design is unreasonable, The flow loss and noise increase. The straight worm tongue can not play a good diversion effect. When the blade is blown, the air flow is reflux near the worm tongue. The result of the simulation of the flow field provides a reference for the structural optimization design. Secondly, in order to improve the calculation accuracy and the computer performance, the combination of the large eddy model and the FW-H sound model is taken into consideration. The method is to calculate the noise at the monitoring point in the state of the blower blowing / suction. The noise of the fundamental frequency of the rotating noise and the frequency of the frequency doubling is obviously greater than that of the other frequency bands. Therefore, the aerodynamic noise of the suction blower is dominated by the rotating noise. Again, according to the pneumatic performance and noise measurement standard of the fan, the flow rate of the blade when the blade is blown and the inlet flow and static time of the blade are measured. Pressure, noise sound pressure level at the monitoring point, analysis of the noise and vibration signals collected. Comparing the experimental results with the simulation results, the correctness of the model is verified. Finally, the optimization factors are the number of blades, the hub ratio and the outlet installation angle, and the orthogonal test method is used to optimize the structure of the blade wheel. The outlet of the volute adopts a circular arc connection, replacing the straight worm tongue with a circular spiral tongue, reducing the impact of the air flow on the wall, and reducing the air leakage and improving the aerodynamic performance. When the radius of the circular spiral tongue is 4.3mm, the aerodynamic performance and noise reach the best balance point. The speed is reduced by 2000rpm according to the similarity law. Finally, the noise of the suction machine is obviously reduced when the blade is blown and the leaves are sucked, and the aerodynamic performance is improved.
【学位授予单位】：东南大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TU986.32

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