摘要
揉碎机是我国近年来研制出的一种新型饲草料加工设备,它是介于铡切与粉碎两种机械加工技术之间的一种新型加工方式。经揉碎后的秸秆为柔软、蓬松的丝状物,具有适宜的长度和粗细度,因而对于直接饲喂反刍家畜以及干燥、粉碎、制粒、压块(饼)、化学处理、生物处理等后续加工都极为有利。但是,揉碎机和大部分旋转机械一样,存在噪声高、振动强烈的缺点,严重阻碍了其进一步的推广和发展。
本文针对揉碎机的空气动力性噪声和机械噪声展开研究,结合理论分析、数值模拟和试验研究对其噪声产生机理和特性进行了分析研究,主要内容有以下:
(1)依据国家标准GB6971-86《粉碎机试验方法》和GB3768-83《噪声源声功率级的测定一简易法》分别对空载和负载下9R-40型揉碎机5个测点的噪声进行试验研究。得出空载和负载的主要噪声源都是空气动力性噪声,且都是旋转噪声。
(2)基于MATLAB提供的小波工具包,结合小波技术和频谱分析技术对揉碎机的噪声源进行识别。用db4小波基对采集的空载和负载第5测点的噪声信号进行尺度为6的小波分解,获得了7个频带的能量分布和百分含量。
(3)以导流板、齿板、锤片、风扇及其组合为试验因素进行揉碎机噪声分离研究,通过分析获得到影响揉碎机的噪声大小的主、次因素,即风扇旋转产生的空气动力性噪声是影响揉碎机噪声的主要噪声源,其次是锤片,导流板对噪声的影响不大,齿板具有吸声作用。
(4)获得了对噪声影响较大的转速、锤片数与声压级之间的关系:转速越高,噪声越大,且转速在2400-2800r/min范围内,最佳转速应选择2600r/min左右;锤片的数量只影响噪声幅值,对主要频率影响较小。
(5)通过振动试验得到揉碎机的主要零件的主要实际振动频率都集中在100-500Hz以内,而且转子存在严重的动不平衡,在x、y、z三个方向上的振动能量都很大,这对轴承的寿命,以及整机的振动都有严重的影响。
(6)基于结构力学和振动理论,运用有限元分析软件ANSYS对9R-40型揉碎·机上、下机壳的固有频率及振型进行分析。结合振动试验结果和模拟结果,从刚度角度提出结构优化方案,为揉碎机的改进和性能优化提供参考。
(7)为了对揉碎机空气扰动噪声源的产生机理、噪声特性及其规律进行研究,运用计算流体力学软件Fluent对9R-40型揉碎机内部的流场进行了三维模拟,直观显示了揉碎机腔体内的流场特性和流动状态。并且对计算所得的风速曲线和试验测得的值进行对比,结果表明,二者最大相对误差小于8%,且得到了转速为2800r/min运动时揉碎机流场的压力分布和内部流场速度分布。通过气流流场模拟结果分析表明,低速气流从进气口经高速旋转的转子作用后,产生了旋转噪声和涡流噪声;另外,在出料直管内形成一个回流区,易造成出料口堵塞,也会产生噪声。
Rubbing and breaking machine is a new type of forage processing equipment, which is developed in China in recent years. It is a new processing method which is between cutting and crushing process technologies. The rubbed straws are soft and fluffy filaments, which have appropriate length and coarseness. As a result, it is extremely beneficial for directly feeding、smashing、drying、grinding、granulating、briquetting (cake)、chemical processing、biological treatment and other subsequent processing However, the rubbing and breaking machine are the same as the most rotating machines that have the disadvantages of high noise and strong vibration, which seriously impedes the further promotion and development of rubbing and breaking machine. This paper is a study of aerodynamic noise and mechanical noise, which combined with theoretical analysis, numerical simulation and experimental study on the mechanism of its noise generation and characteristics, the main contents are as follow:
(1) According to national standard GB6971-86《mill test methods》and GB3768-83《noise source power level measurement method for simple》, the experiment had been conducted on five measurement points around 9R-40 rubbing and breaking machine under no-load and load conditions, The result is that aerodynamic noise is the main noise source whether it is no-loaded or loaded.
(2) Based on wavelet tools package provided by MATLAB software, the main noise sources are identified using the technology of wavelet and spectrum analysis. The noise signals which are obtained on the no-load and load conditions are decomposed with db4 wavelet in the scale of 6, for the fifth measurement points.then the decomposed coefficients in seven different frequency band were obtained. According to the energy distribution of the 7 different frequency bands noise signals of the 9R-40 rubbing and breaking machine, the result is that the main signal of the rubber noise is mid-frequency noise.
(3) The separation study is carried out that take deflector、toothed plat、hammer and fan and combination of them as main factors. The result obtained that is aerodynamic noise was mainly caused by rotating fan, and secondary factors were hammers.Deflector has little effect on the noise, but tooth plate has an effect of sound absorption.
(4) The relationship between sound pressure level and rotating speed、the number of hammer which have great impact on the noise were obtained. The higher the speed is, the greater the noise is. And in the range of speed from 2400 r/min to 2800r/min, the optimum speed should be about 2600r/min. The numbers of hammer pieces are more related to noise size, but less related to noise frequency.
(5) By vibration testing, the actual vibration frequencies of the main parts of the rubbing and breaking machine focused on the range of 100-500Hz. Besides there was seriously rotor dynamic imbalance, and the vibration energy of bearing in the three directions of x, y, z are large, which has a lot of critical effects on the life of bearings and vibration of the whole machine.
(6) Based on structural mechanics and vibration theory, the natural frequency and vibration mode of the upper and lower shell of 9R-40 rubber were analyzed using the finite element analysis software ANSYS, combining with vibration test results and simulation results, the structural optimization program was purposed on the point of stiffness, which provide a theoretical reference for improving machine and performance optimization.
(7) For studying principle, property and law of producing air disturbulance noise, three dimensional inner flow fields were simulated with Fluent software. Properties and state of the flow fields were showed directly. Comparing numerical simulation curves with experiment data, the maximum relative error was indicated less than 8%. The distribution of pressure and velocity of flow fields were obtained from the simulation results at 2800 r/min. By analyzing the simulation results of flow field, both rotation noise and eddy current noise were produced when low airflow from inlet was affected by high rotating rotor. In addition, a reversed flow is formed in the outlet, which can cause a block and produce noise.
引文
1. 何渝生,邓兆祥.汽车噪声控制.机械工业出版社.1999.
2. 田玉军,巨天珍,任正武.国内城市环境噪声污染研究进展[J]重庆环境科学,2003,(03).
3. 姚玉红,彭斌,胡冰霜.城市区域环境噪声对人心理和生理功能影响研究进展[J].现代预防医学,2000,(04).
4. 吴婧,赵丹宇.噪声对人体健康影响分析[J].环境与可持续发展,2008,(02).
5. 胡琳琳.噪声时人体健康影响的分析[J]污染防治技术,2009,(01).
6. 曲长宏,庞宏.浅谈噪声对人体的危害[J].黑龙江环境通报,2003,27(2):22-23.
7. 张科仁,薛明.我国畜牧业的发展概况及其前景[J].科学中国人,1999,(04).
8. 李林,王春光,谢玉红.秸秆揉碎加工工艺与秸秆养畜[J].农业工程学报,1997,(s1).
9. 韩鲁佳,闫巧娟等.中国农作物秸秆资源及其利用现状.农业工程学报,2002(5):87-91.
10.吴树栋.我国农作物秸秆综合利用现状[J].人造通讯,2005(8):1-4.
11.李林,杨明韶,王春光,刘伟峰,赵秋荣.9R—40型揉碎机的研制与试验[J].内蒙古农牧学院学报,1997,(03).
12.李林,王春光,谢玉红,褚秀梅,谷振军.9R-40型揉碎机的试验研究[J].内蒙古农业大学学报(自然科学版),1997,(04).
13.周伟,刘伟峰,李国清,乌吉斯古楞,包那日那.9R-40型揉碎机揉碎过程机理研究[J].内蒙古农业大学学报(自然科学版).
14.李林,王春光,谢玉红.秸秆揉碎加工工艺与秸秆养畜[J].农业工程学报,1997(s1).
15.李林,刘伟峰,赵满全,张三强,崔红梅.揉碎机工作机理的分析与研究[A].走中国特色农业机械化道路——中国农业机械学会2008年学术年会论文集(下册)[C],2008.
16.王青云,李林,王娟,严秀芳.揉碎机噪声的研究[J].农村牧区机械化,2007(02).
17.王青云.揉碎机噪声测试与研究[D].内蒙古农业大学,硕士学位论文,2007.
18.李林,王青云,崔红梅.9R-40型揉碎机噪声产生机理的测试研究[J].内蒙古农业大学学报,2008,29(1).
19.武佩,柏大棨(1994)锤片式粉碎机噪声的测试分析[J]内蒙古农牧学院学报,1994,15(3)69-72.
20.武佩,柏大棨.饲料粉碎机噪声研究[D].内蒙古农牧学院,硕士学位论文,1989.
21.许涛,何万泉,宋为民.饲料粉碎机噪声的测试分析[J].农机试验与推广.1998,3
22.赵凡琳,胡继云,于翠萍.锤片式粉碎机隔振系统的设计[J].粮食与饲料工业.2000.
23.蔡红梅.爪式粉碎机旋转噪声的提取与降噪改进设计[D].内蒙古农业大学.硕士学位论文.2002.
24.徐红梅.锤片磨损对粉碎机转子振动影响的研究[D].华中农业大学,硕士学位论文2003.
25.杜小强,宗力.基于虚拟样机的锤片式粉碎机转子动力学特性研究[[J].农业机械学报,2005.36(7):53—56.
26.董艇舰,周福民,宋艳萍,曹文龙.锤片式粉碎机转子轴组固有频率及振幅的分析(J].天津理工学院学报,2003,19(2):61-63.
27.范文海,锤片式粉碎机机座结构优化与振动噪声分析[D],江南大学,硕士学位论文,2009.
28. Wan-Ho Jeon, Duck-Joo Lee. A numerical study on the flow and sound fields of centrifugal impeller located near a wedge[J]. Journal of sound and viberation, 2003(266):785-804.
29. D. V.hope, M. Padole Experiment and theoretical analysis of noise of centrifugal fan impeller [J]. Mechanism and Machine Theory,2004(39):1257-1271.
30.毛义军,祁大同,刘秋洪.基于非定常流场的离心风机气动噪声分析[J].西安交通大学学报,2005,39(9):989—993.
31.向阳.壳体零件振动噪声的分析和控制[D].重庆大学,硕士学位论文,2005.
32. Wang-Yong Kim, Seouing-Jin SEO. Shape optimization of forward-curved-blade centrifugal fan with Nervier-Stokes analysis [J].JSME international Journal,2006,49(1)
33.周侣勇.研究风机振动噪声分析与数值模拟研究[D].武汉理工大学,硕士学位论文,2007
34.方开翔,李豪杰,高慧.基于Fluent 6.0的风机流场模拟与噪声预估[J].江苏科技大学学报(自然科学版),2008,22(4):42—47.
35. The Applications of Wavelet Transform in Vibration Analysis [A]. Proceedings of the 3rd International Symposium on Test and Measurement[C],1999.
36.傅瑜.小波分析在旋转机械故障诊断中的应用[D].西安电子科技大学,1998.
37.张贤达,保铮.非平稳信号分析与处理[M].北京:国防出版社,1 998.
38. Fractal-based Machine Fault Diagnosis [A]. Proceedings of the 5th International Symposium on Test and Measurement (Volume 1) [C],2003.
39.马大酞.现代声学理论基础[M].北京:科学出版社,2004.
40.许肖梅.声学基础.北京:科学出版社,2003.
41.杜功焕等著.声学基础.[M]南京:南京大学出版社,2001.
42. M. J. Crocker, J. P. Arenas. Fundamentals of the direct measurement of sound intensity and practical applications [J]. Acoustical Physics,2003,49, (2).
43.牟向东.噪声源分析方法及其应用[J].湖北汽车工业学院学报,1999,13(3):1-2.
44.黎志勤,黎苏.汽车排气系统噪声与消声器设计[M].中国环境科学出版社,1991.
45.周岩,杨启明.应用频谱分析法检测诊断风机故障实例[J].风机技术,2005,(06).
46.刘月辉,郝志勇,韩松涛,付鲁华.车用发动机表面辐射[M].噪声源识别的研究汽车技术,2002(3):15-18.
47.薛玮飞,机械噪声源辨识与特征提取的研究[D],上海交通大学,硕士学位论文,2007,3,8-9.
48. Zhang JunHong, Han Bing.Analysis of engine front noise using sound intensity techniques. Mechanical System and Signal Processing.2005,19:213-221.
49.毛晓群等.使用阵列技术识别高速行驶轿车的辐射生源[J],汽车技术,2003(9),6-9.
50.刘松林,李才良,马吉胜,郑海起.近场声压法在定位柴油机故障中的应用[J].应用声学,2002,(04).
51.王诗恩.声压法识别小型客车主要噪声源[J].汽车技术,1996,(11).
52.杨殿阁等.运动声源的全息识别方法声学学报[J].2002,27(4),357-358.
53.何渝生,邓兆祥.汽车噪声控制[M].机械工业出版社.1999.
54. G. Busch, R. Maurell, J. Meyer. Investigations on influence of engine block design features on noise and vibration. [J]. SAE paper911071,1991:1509-1526.
55. F. Scarpa, Parametric sensitivity Analysis of Coupled Acoustic-Structural Systems [J]. Journal of Vibration and Acoustics. APRIL2000. vol.122.
56. Zhang Y Kevin, Lee Ming-Ran, Stanecki Paul, Brown Gordon, M. Allen Tom E.Forbes, Jarnes, W. Jia Z Howard. Vehicle Noise and Weight Reduction Using Panel Acoustic Contribution Analysis [J].SAE Paper.
57. D. J. Nefske. Vehicle interior acoustic design using finite element methods [J]. Journal of vehicle design.vol6 no (1),1985.
58. D. J. Nefske. Automobile interior noise prediction using a coupled structure-acoustic finite element model [J]. Journal of vehicle design. Vol.6 no.1,1986
59.杨云,王庭佛.关于噪声测试中背景噪声修正方法的探讨[M],噪声与振动控制,2000(1),24-26.
60.冯国胜,李劲松,刘鹏.基于小波变换的客车车内振动噪声源识别[J].振动测试与诊断,2006,26(3):196-199.
61.张蕾.基于小波能量谱的轴承振动噪声缺陷辨识方法[D],中国海洋大学,硕士学位论文,2005
62.杜丽萍.现代谱估计在噪声源识别中的应用.[D].东北师范大学,硕士学位论文,2007
63.王宏禹.非平稳随机信号分析与处理[M].北京:国防工业出版社,1999.
64.方舟群,空气动力性噪声与消声器[M].科学出版社,1978.(8).
65. Michael J. Allen, Stochastic Analysis of tructural/acoustic systems [D]. Michigan:University of Michigan,2001.
66.蔡红梅,爪式粉碎机旋转噪声的提取与降噪改进设计[D].呼和浩特:内蒙古农业大学,硕士学位论文,2002.
67.马大酞.现代声学理论基础[M].科学出版社,
68.李吉,旋转机械结构噪声及其控制机理研究[D],大连理工大学.博士学位论文,2007.
69. E.H.Chui, G. D. Raithby. Computation of radiant heat transfer on a non-Orthogonal mesh using the finite-volume method. Numerical heat transfer [J],1993,269-288.
70.刘敏.基于数值模拟及实验的贯流风扇气动噪声特性研究[D].武汉.华中科技大学,2009.
71.王瑞金.张凯,王刚.Fluent技术基础与应用实例[M].北京:清华大学出版社:115—190.
72.王福军.计算流体动力学分析—CFD软件原理与应用[M].北京:清华大学出版,2004:122—138.
73.王军,冉苗苗,姚姗姗.多翼离心风机的气动噪声预测[J].工程热物理学报,2008,29(7):1144—1146.
74.毛义军,祁大同,刘秋洪.基于非定常流场的离心风机气动噪声分析[J].西安交通大学学报,2005,39(9):989—993.
75.方开翔,李豪杰,高慧.基于Fluent6.0的风机流场模拟与噪声预估[J].江苏科技大学学报(自然科学版),2008,22(4):42—47.
76.龚俊,宋永奇,郭润兰.湍流超细粉碎机粉碎腔内单项流场的数值模拟[J].粉体加工与处理,2006(6):28—30.
77.周侣勇.风机振动噪声分析与数值模拟研究[D].武汉:武汉理工大学,2007.
78. Xavier Gloerfelt, Christopher Bogey, Christopher Bailly. LES of the noise radiated by a flow over a rectangular cavity. International workshop on "LES for Acoustics", 2002,
79. Xavier Amandolese, Pascal Hemon. Study of the acoustic oscillations by flows over cavities, ASME,2002.
80.翟之平.叶片式抛送装置抛送机理研究与参数优化[D].内蒙古农业大学,博士毕业论文.2008.
81.侯立国.湍流超细粉碎设备的流场数值模拟[D].兰州理工大学,硕士毕业论文,2005.
82. Miche R. Broad. Band fan noise prediction using single airfoil theory [A]. France, Fan Noise,2nd International SymposinmSenlis,2003.
83. Salesky, A. Hennemand, V, Kouidri, S. et al. modeling the aeroacoustics of axial fans from CFD calculations [J]. The Journal of the Acoustical Society of America, 2002(5):2427-2427.
84. Michel, T., Zoubida, E. H, Alex, R. Investigation of the tonal noise radia.ted by subsonic fans using the aero-acoustic analogy [J].Fan Noise 2003 International Symposium semis,2003:23-25.
85. Wan, H.J., Cho, J. H. Numerical analysis of unsteady flow field and flow noise of a fan system [J].The 33rd International Congress and Exposition on Noise Control Engineering. Prague:2004.
86. Maaloun, A., Kouidri, S., Rey, R. Aeroacoustic performance evaluation of axial flow fans based on the unsteady pressure field on the blade surface[J].Applied Acoustics,2004,65(4):367-384.
87. Flavien, D.Saidnaji, M. L. Prediction of aeroacoustic noise in automotive centrifugal fans [J]. validation of cfd and acoustic simulation techniques. AIAA 2005-2921.
88. Rafael, B.T., Sandra, V S., Juan, P. H. C. Noise prediction of a centrifugal fan numerical results and experimental validation [J]. Journal of Fluids Engineering, 2008,130:2-11.
89. Sherry, M. G, Douglas, L. S. Hybrid prediction of fan tonal noise [J]. AIAA 2008-2992.
90.李黎明,ANSYS有限元分析实用教程[M],北京:清华大学出版社,2005.
91.博嘉科技,有限元分析软件ANSYS融会于贯通[M],北京:中国水利水电出版社,2002.
92.刘国庆,杨庆东,ANSYS工程应用教程—机械篇[M],北京:中国铁道出版社,2003.
93.邵蕴秋,ANSYS8.0有限元分析实例导航[M],北京:中国铁道出版社,2004.
94. B. A. Nicolaso Structural Acoustics and Vibration Behavior of Complex Panels [J]. Applied Acoustics,1994,43(3),185-215.
95. F. Scarpa, Parametric. Sensitivity Analysis of Coupled Acoustic Structural Systems [J]. Journal of Vibration and Acoustics. APRIL2000. vol.122
96. OH J E. Identification of vibration induced noise radiated from compressor shell [D] West Lafayette, Purdue University Press,1994:259-264.
97. Muller, N. Gade, S. Operational modal analysis on an exhaust system[J]. Proceedings of SPIE-The International Society for Optical Engineering, v4753H,2002,998-1003
98. Lee K, etal. Conditions of frictional contact in disk brakes and their effects on brake judder[J]. SAE980598,1998.
99.刘志勇.摩托车车架有限元模型及其动态特性分析[D].重庆:重庆大学,2003,30-36.
100.向阳.壳体零件振动噪声的分析和控制[D].重庆大学,2005.
101.冯振东,吕振华.振动系统实模态参数灵敏度分析[J].固体力学学报,1989,(04)
102. LEE. J. H, KIM J.Sound transmission through cylindrical shell of hermetic compressors [D] West Lafaye, Purdue University Press.2000:933-940.
103.张亚欧,谷志飞,宋勇.ANSYS7.0有限元分析实用教程.清华大学出版社.2004
104.邓晓龙,张宗杰,胡昆鹏.内燃机油底壳模态分析及噪声预测.噪声与振动控制,2003(2).
105.黄士振,有限元法,南京:南京理工大学,1986
106. Matsui H, Murakami H, etc. Analysis of disk brake squeals. SAE920553,1992
107.彭万波,张云静,张然,Pro/Engineer 2001实例精解,北京:清华大学出版社,2002
108. ANSYS动力学分析指南.美国ANSYS公司北京办事处.30
109.邓兆祥.粘性阻尼振动系统的复模态摄动分析及应用.重庆大学学报,1997.2
110.胡世猛.板壳结构强度与声学特性分析[D].武汉:武汉理工大学,2006
111. M. Tinnsten, B. Esping, M. Jonsson. Optimization of acoustic response [J]. Structural Optimization,1999,18, (1).
112. A. D. Belegundu, R. R. Salagame, G. H. Koopmann. A general optimization strategy for sound power minimization [J]. Structural Optimization,1994,8, (2-3).