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| 研究生： |
彭寶華 Peng, Bou-Hua |
|---|---|
| 論文名稱： |
探討不同縫寬開縫圓柱渦流流量計對於流場特性之影響 Influence of Widths of Slit on Vortex Shedding behind Slit circular cylinder |
| 指導教授： |
苗君易
Miau, Jiun-Jih |
| 學位類別： |
碩士 Master |
| 系所名稱： |
工學院 - 航空太空工程學系 Department of Aeronautics & Astronautics |
| 論文出版年： | 2008 |
| 畢業學年度： | 96 |
| 語文別： | 中文 |
| 論文頁數： | 153 |
| 中文關鍵詞： | 粒子影像測速儀 、渦流流量計 、希爾伯-黃轉換 |
| 外文關鍵詞： | vortex meter, PIV, HHT |
| 相關次數： | 點閱：104 下載：1 |
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如何改善渦流流量計流場一直是受到許多研究人員所重視，而利用開縫圓柱來改善流場之研究也行之有年。許多專家都已經證實開縫圓柱能有效加強量測訊號強度，並大幅改善訊號品質。但甚少有人探討開縫圓柱其縫寬對於其流場特性之影響。本論文利用熱線(hot-wire)測速儀在風洞中進行實驗，探討不同縫寬(s/d)之渦流流量計流場二維性，並且在水洞中利用粒子影像測速儀(PIV)及視流實驗觀測其流場之變化。
由PIV實驗結果得知，可透過縫寬比(s/d)的增加來使渦流流量計渦流溢放頻率相對提高。且當雷諾數介於2400至11400時，s/d=0.15之渦流流量計穩定度最高。且透過視流實驗，發現開縫圓柱渦流流量計縫寬比(s/d)越大，其流場分離點亦隨之往前。透過hot-wire實驗之量測，利用交叉相關係數分析兩根探針不同間距(z)之訊號，判斷其側向波長長度變化，且透過與信號雜訊分析結果結合，吾人發現當雷諾數30000及50000時，開縫圓柱渦流流量計的確具有大幅改善流場訊號品質及增加流場二維性之能力，且s/d=0.15之流場訊號品質及流場二維性皆最佳。最後透過希爾伯-黃轉換(HHT)分析，吾人發現當渦流流量計流場二維性越強，其輸出瞬時頻率強度越強且穩定。
The phenomenon of vortex shedding due to uniform flow over a circular cylinder with a normal slit was investigated in this study. Experiments were made for five cylinder models whose slit widths in terms of s/d, where s and d denote the width and the cylinder diameter, respectively, were 0, 0.05, 0.15, 0.20 and 0.30. For the experiments made in a water channel, the techniques of Particle Image Velocimetry (PIV) and flow visualization were employed. The PIV data obtained at the Reynolds numbers between 2,400 and 11,400 reveal a trend that the vortex shedding frequency reduced gets increased as s/d gets higher. More interestingly noted is that for the case of s/d= 0.15, the process of vortex shedding appears to be most periodic in time, which quantitatively can also be indicated by the signal quality defined. Results of flow visualization indicate that flow in the slit is oscillating in accordance with the frequency of vortex shedding, which in fact causes suction or blowing to flow over the circular cylinder. Thus, unsteady motions in the slit are realized very effective to modify the vortex shedding process.
Experiments made in a wind tunnel were aimed to examine the two-dimensionality of vortex shedding by means of spanwise correlation of hot-wire measurements at the Reynolds numbers between 30,000 and 50,000, for the five cylinder models studied. Results obtained indicate that the vortex shedding structures in the case of s/d=0.15 behave most two-dimensional. Hilbert-Huang Transformation (HHT) analysis of the velocity signals measured further show that among the five cases studied, the case of s/d=0.15 appears to be the one whose instantaneous vortex shedding frequency is most stabilized in time and its amplitude is the highest in value.
[1] Nakamura, Y.,” Vortex shedding from bluff bodies and a universal strouhal number ,” Journal of Fluids and Structures,Vol.10, No.2,1996,pp. 159-171.
[2] Adrian, R. J., “Twenty years of particle image velocimetry”, Experiments In Fluids 39,,2005,pp. 159-169
[3] 鮑鋒,苗君易,陳子良,”粒子影像測速技術及其在航太科學研究中的應用”. The 30th National Conference on Theoretical and Applied Mehwanics , DYU , Hwanghwa , Taiwan , R.O.C ,December 15-16,2006.
[4] Willert, C., Raffel, M., Kompenhans, J.,“Recent applications of particle image velocimetry in large-scale industrial wind tunnels “, Instrumentation in Aerospace Simulation Facilities, 1997. ICIASF '97., Record International Congress on 29 Sept.-2 Oct. 1997 ,pp. 258 – 266.
[5] Lawson, N. J., Wu , J.,” Three-dimensional particle image velocimetry：error analysis of stereoscopic tehwniques”, Measurement Science and Tehwnology, Vol 8,No. 8, 1997, pp. 894-900.
[6] Lehr, A. , Bölcs, A..,” Application of a Particle Image Velocimetry (PIV) System to the Periodic Unsteady Flow Around an isolated compressor blade“, presented at the 15th Bi-annual Symposium on Measurement Tehwniques in Transonic and Supersonic Flow in Cascades and Turbomahwines, University of Florence,21-22 Sept. 2000
[7] Raffel, M., Willert, C., Kompenhans, J. ,“Particle Image Velocimetry“ ,A Partical Guide, Springer-Verlag, Berlin (Germany),1998
[8] Kaneko, M. , Ikeda, Y., Nakajima, T.,” Spatial Evaluation of In-Cylinder Turbulence Flow Using High-Resolution PIV”,10th International Symposium on Application of Laser Tehwniques to Fluid Mehwanics , 2000
[9] 蔡星汶，”圓柱表面流場在臨界區之空氣動力實驗研究”,成大航太碩士論文,2006
[10] Ahwenbahw, E.,” Distribution of local pressure and skin friction around a circular cylinder in cross-flow up to Re=5×106.”, J. Fluid Mehwanics 34(4), 1968,pp. 625-639.
[11] Roshko, A.,”Experiments on the flow past a circular cylinder at very high Reynolds number” Journal of Fluid Mehwanics 10,1960, pp. 345-356.
[12] Roshko, A. , “On the Development of Turbulent Wakes from Vortex Streets”, NACA Report 1911, 1954.
[13] Hama, F.R., ”Three dimensional vortex pattern behind a circular cylinder.” J. Aero. Sci. ,Vol.24, 1957, pp.156-157.
[14] Bloor, M.S. ,“The transition to turbulence in the wake of a circular cylinder.”, Journal of Fluid Mehwanics, Vol.19, 1964, pp.290-304.
[15] Williamson, C.H.K. ,“The existence of two stages in the interaction to three-dimensionality of a cylinder wake.”, Phys. Fluids ,Vol.31, 1988,pp. 3165-3168.
[16] Williamson, C.H.K.,”Oblique and parallel modes of vortex shedding in the wake of a circular cylinder at low Reynolds numbers.”, Journal of Fluid Mehwanics, Vol.206, 1989, pp. 579-267.
[17] Eisenlohr, H. , Eckelmann, H. ,“ Vortex splitting and its consequences in the vortex street wake of cylinders at low Reynolds number.”, Physics of Fluids: Fluid Dynamics , Vol.1, 1989,pp. 189-192.
[18] Williamson, C.H.K.,” The natural and forced formation of spot-like'vortex dislocations' in the transition of a wake.”, Journal of Fluid Mehwanics,Vol. 243, 1992,pp. 393-441.
[19] Gerrard, J.H. ,“The wake of cylindrical bluff bodies at low Reynolds number.“, Phil. Trans. R. Soc. Lond., Vol. A 288, 1978, pp. 351-382.
[20] Williamson, C.H.K., ”Three-dimensional transition in the near wake of a cylinder.”, Physics of Fluids, Vol. 30, 1987,pp. 2283-2285.
[21] Noack, B. , Koenig, M., Eckekmann, H., ”Three-dimensional stability analysis of the periodic flow around a circular cylinder.”, Physics of Fluids,Vol. A 5, 1993, pp. 1279-1281.
[22] Mansy, H., Yang, P.M., Williams,D.R.,” Quantitative measurements of three-dimensional structures in the wake of a circular cylinder.”, Journal of Fluid Mehwanics, Vol. 270, 1994, pp. 277-296.
[23] Thompson, M., Hourigan, K., Sheridan, J., “Three-Dimensional Instabilities in the Wake of a Circular Cylinder”, Experimental Thermal and Fluid Science, 1996, pp.190-196
[24] Igarashi, T.,” Flow Hwaracteristics around a Circular Cylinder with a Slit-1st report”, Bulletin of JSME, Vol.21, No.154, April, 1978, pp.656-664
[25] Igarashi , T.,” Flow Hwaracteristics around a Circular Cylinder with a Slit : 2nd Report, Effect of Boundary Layer Suction”, Bulletin of JSME, Vol.25, No.207, September, 1982, pp.1389-1397, pp.337-340.
[26] Pankanin, G.L.,” Influence of vortex meter configuration of measure signalparameters”, Instrumentation and Measurement Tehwnology Conference, 1993.
[27] Sophie, G.D.,” Linearity of the vortex meter as a function of fluid viscosity”, Flow Measurement and Instrumentation, 1995 – Elsevier
[28] Bentley, J.P., Benson, R.A., Shanks, A.J.,” The development of dual bluff body vortex flowmeters”,Flow Measurement and Instrumentation, 1996 – Elsevier
[29] Olsen, J.F., Rajagopalan, S.,” Vortex shedding behind modified circular cylinders”, Journal of Wind Engineering & Industrial Aerodynamics, 2000, pp.55-63.
[30] Pankanin, G.L., Kulińczak, A., Berliński, J.,” Investigations of Karman vortex street using flow visualization and image processing”, Sensors & Actuators: A. Physical, 2007 – Elsevier
[31] Peng, J., Fu, X., Hwen, Y.,” Flow measurement by a new type vortex flowmeter of dual triangulate bluff body” ,Sensors & Actuators: A. Physical, 2004 – Elsevier
[32] Bentley, J.P., Mudd, J.W.,” Vortex shedding mehwanisms in single and dual bluff bodies”, Flow Measurement and Instrumentation, 2003 – Elsevier
[33] 巫清文,”兩不同平面垂直灣館下游渦流流量計渦流溢放信號品質分析.”, 國立成功大學航空太空研究所碩士論文,2000.
[34] 葉建鋒,”渦流流量計信號與信號分析.”, 國立成功大學航空太空研究所碩士論文,2003
[35] Huang, N.E., Shen, Z., Long, S.R., Wu, M.C., Shih, H.H. , Zheng, Q., Yen, N.C. , Tung, C.C. , Liu, H.H.,” The empirical mode decomposition and the Hilbert spectrum for nonlinear and non-stationary time series analysis.”, Proc. R. Soc. Lond., Vol. A454,1998, pp. 903-995.
[36] Zhi-qiang, S.U.N., Jie-min, Z. , Ping, Z.,” Application of Hilbert-Huang transform to denoising in vortex flowmeter.”,中南工業大學學報(英文版), 2006
[37] 呂冠樺,”應用MEMS熱膜感測器於三維風速計設計.” , 國立成功大學航空太空研究所碩士論文,2008
[38] 曾雅淇,”紊流場中鈍形體渦流溢放之三維非定常擾動行為.”, 國立成功大學航空太空研究所碩士論文,2007
[39] 杜榮國,”次臨界雷諾數下鈍形體非定常三維特性研究.”, 國立成功大學航空太空研究所博士論文,2007.
[40] Leweke, T. , Williamson, C.H.K.,” Three-dimensional instabilities in wake transition.” European Journal of Mehwanics/B Fluids, 1998, pp. 571-586.
校內：立即公開校外：2008-07-30公開