受聲波激勵噴流衝擊平板之流場與熱傳特性｜國立臺灣科技大學博碩士論文系統

簡易檢索 / 詳目顯示

回結果列表

研究生：	張英育 Ying-Yu Chang
論文名稱：	受聲波激勵噴流衝擊平板之流場與熱傳特性 Flow and Heat Transfer Characteristics of an Acoustically Excited Jet Impinging on a Flat Plate
指導教授：	黃榮芳 Rong-Fung Huang 許清閔 Ching-Min Hsu
口試委員:	陳家 none 張家和 none
學位類別：	碩士 Master
系所名稱：	工程學院 - 機械工程系 Department of Mechanical Engineering
論文出版年：	2015
畢業學年度：	103
語文別：	中文
論文頁數：	336
中文關鍵詞：	聲波激勵噴流
外文關鍵詞：	Acoustically Excited Jet
相關次數：	點閱：232 下載：0
分享至:	分享至facebook 分享至twitter

查詢本校圖書館目錄查詢臺灣博碩士論文知識加值系統勘誤回報

上一筆

本研究藉由實驗方法，研究振盪噴流衝擊平板時之流場衍化過程與熱傳特徵。噴流的雷諾數Rej = 325，噴流出口直徑d = 5 mm，噴流出口與平板的距離H = 10 d。使用揚聲器作為激擾噴流的裝置，激擾頻率fexc = 40 ~ 200 Hz (Stexc = 0.2 ~ 1.0)，激擾強度Ip = 0.5 ~ 9.0。藉由雷射光頁輔助之煙霧流場可視化技術搭配高速攝影機，擷取瞬時流場影像；利用熱線風速儀與高速數據擷取系統，量測噴流出口的振盪速度以及剪流層渦漩結構通過熱線風速儀探針的時變速度。應用高速質點影像測速儀量測全場域的流場速度，並轉換成紊流強度與渦度。利用紅外線熱顯像系統量測加熱平板的溫度分佈。分析振盪噴流衝擊平板的流場結構之連續衍化照片，在噴流擾動強度Ip對應於聲波激擾史卓數Stexc的域面，可觀察到受激擾的噴流有兩種流場特徵模態，分別是coherent vortices與vortex breakup。在coherent vortices模態時，渦漩結構衝擊平板前無破碎的現象；在vortex breakup模態時，渦漩結構在未撞擊平板前已破碎成小結構。分隔兩種模態的臨界Ip值在較小的Stexc時比在較大的Stexc值大。例如較小的Stexc = 0.2時，Ip > 2.3為vortex breakup模態，Ip < 2.3為coherent vortices模態；Stexc = 1.0時，Ip > 0.5為vortex breakup模態，Ip < 0.5為coherent vortices模態。比較受激擾噴流的紐賽爾數Nuf與未受激擾噴流的紐賽爾數Nuc：在vortex breakup模態時的紐賽爾數Nuf大約為Nuc的1.5 ~ 2.0倍；在coherent vortices模態時的紐賽爾數Nuf大約為Nuc的0.9 ~ 1.1倍。激擾噴流在coherent vortices模態的熱傳效果與未受激擾噴流相似。激擾噴流在vortex breakup模態比coherent vortices模態對於熱傳增加的效果更明顯。

The flow and heat transfer characteristics of the pulsating jet impinging on a flat plate were experimentally investigated. Jet pulsations were generated by means of acoustic excitation. Streak pictures of the smoke-flow patterns, illuminated by a laser-light sheet in the median plane, were recorded by a high-speed digital camera. A hot-wire anemometer was used to measure the local velocities at the jet exit and the shear layer. A high-speed particle image velocimetry (PIV) was employed to measure the velocity field. The turbulence intensity and vorticity were calculated based on the measured velocity data. The temperature distribution on the surface of the heated plate was measured by an infrared imaging system. Two characteristic flow modes (coherent vortices, vortex breakup) were identified in the domain of the jet perturbation intensity and the Strouhal number. In the coherent vortices mode at small Ip, the vortices induced by the acoustic excitation did not break up before impinging the flat plate. After impingement, the vortices split into smaller coherent vortices and travelled radially away from the impingement area. At large Ip, the vortices were broken up into small eddies after impingement. In the vortex breakup mode, the vortices induced by the acoustic excitation were broken up into small eddies before impinging the flat plate. The Nusselt numbers of the excited jet impinging the heated flat plate were drastically larger than those of the unexcited jet. In the vortex breakup regime, the Nusselt numbers of the excited case were about 1.5 to 2.0 times of the unexcited case. In the coherent vortices regime, the Nusselt numbers of the excited case were about 0.9 to 1.1 times of the unexcited case.

摘要 .......................................................................................................... i
Abstract .................................................................................................... ii
致謝 ........................................................................................................ iii
目錄 ........................................................................................................ iv
符號索引 ............................................................................................... vii
圖表索引 ................................................................................................ ix
第一章 緒論 ........................................................................................... 1
1 研究動機 ...................................................................................... 1
2 文獻回顧 ...................................................................................... 1
2.1 振盪噴流 ............................................................................... 1
2.2 壁面噴流 ............................................................................... 3
3 研究目標 ...................................................................................... 5
第二章 實驗設備、儀器與方法 ............................................................ 6
1 電磁式致動器的振盪噴流模型 .................................................. 6
2 實驗儀器與方法 .......................................................................... 6
2.1 噴流流速量測 ....................................................................... 6
2.2 熱線風速儀 ........................................................................... 7
2.3 煙霧流場可視化 ................................................................... 9
2.4 質點影像速度儀 ................................................................ 12
2.5 溫度量測 ............................................................................. 14
第三章 振盪噴流之速度特性與流場特徵 ......................................... 16
1 噴流出口的速度特性 ................................................................ 16
2 流場特徵行為 ............................................................................ 21
2.1 連續噴流的流場特徵 ......................................................... 22
2.2 激擾頻率為fexc = 40 Hz 的流場特徵 ................................. 22
2.3 激擾頻率為fexc = 80 Hz 的流場特徵 ................................. 23
2.4 激擾頻率為fexc = 120 Hz 的流暢特徵 ............................... 25
2.5 激擾頻率為fexc = 160 Hz 的流場特徵 ............................... 26
2.6 激擾頻率為fexc = 200 Hz 的流場特徵 ............................... 27
3 渦漩結構的破碎特性 ................................................................ 28
4 渦漩結構速度特性 .................................................................... 30
第四章 振盪噴流衝擊平板之速度特性與流場特徵 ......................... 34
1 模態分區 .................................................................................... 34
2 流場特徵行為 ............................................................................ 35
2.1 連續噴流的流場特徵 ......................................................... 35
2.2 激擾頻率為fexc = 40 Hz 的流場特徵 ................................. 35
2.3 激擾頻率為fexc = 80 Hz 的流場特徵 ................................. 37
2.4 激擾頻率為fexc = 120 Hz 的流場特徵................................. 40
2.5 激擾頻率為fexc = 160 Hz 的流場特徵 ............................... 42
2.6 激擾頻率為fexc = 200 Hz 的流場特徵 ............................... 44
3 渦漩結構破碎特性 .................................................................... 45
4 渦漩結構速度特性 .................................................................... 47
4.1 瞬時速度分析 ..................................................................... 47
2.2 群體速度分析 ..................................................................... 50
第五章 振盪噴流有無衝擊平板之流場特徵比較 ............................. 53
1 流場特徵的比較 ........................................................................ 53
2 渦漩結構破碎特性的比較.......................................................... 53
3 渦漩結構速度特性的比較.......................................................... 54
第六章 振盪噴流衝擊平板之速度場 ..................................................56
1 速度流線圖 ................................................................................ 56
2 紊流特性 .................................................................................... 60
2.1 紊流強度分佈圖 ................................................................. 60
2.2 速度分佈特性 ..................................................................... 63
3 渦度特性 .................................................................................... 69
第七章 振盪噴流衝擊平板之溫度場特徵 ......................................... 72
1 自然對流下的熱傳特性 ............................................................ 72
2 強制對流下的熱傳特性(連續噴流) .......................................... 73
2.1 銅片發熱瓦數P = 2W .......................................................... 73
2.2 銅片發熱瓦數P = 3.5 W ...................................................... 74
3 強制對流下的熱傳特性(振盪噴流) .......................................... 74
3.1 銅片發熱瓦數P = 2 W ......................................................... 75
3.2 銅片發熱瓦數P = 3.5 W ...................................................... 80
第八章 結論與建議 ............................................................................. 85
1 結論.............................................................................................. 85
2 建議.............................................................................................. 87
參考文獻 ............................................................................................... 89

                                

[1] Belvins, R. D., Applied Fluid Dynamics Handbook, Van Nostrand Reinhold Co., New York, 1984.
[2] Smith, B. L. and Glezer, A., “The formation and evolution of synthetic jets,” Physics of Fluids, Vol. 10, No. 9, 1998, pp. 2281-2297.
[3] Krishnan, G. and Mohseni, K., “An experimental study of a radial wall jet formed by the normal impingement of a round synthetic jet,” European Journal of Mechanics B/Fluids, Vol. 29, 2010, pp. 269-277.
[4] Smith, B. L. and Swift, G. W., “A comparison between synthetic jets and continuous jets,” Experiments in Fluids, Vol. 34, 2003, pp. 467-472.
[5] McGuinn, A., Farrelly, R., Persoons, T., and Murray, D. B., “Flow regime characterization of an impinging axisymmetric synthetic jet,” Experimental Thermal and Fluid Science, Vol. 47, 2013, pp. 241-251.
[6] Cater,J.E. and Soria, J., “The evolution of around zero-net-mass-flux jets,” Journal of Fluid Mechanics, Vol. 472, 2002, pp. 167-200.
[7] Al-Atabi, M., “Experimental investigation of the use of synthetic jets for mixing in vessels,” Journal of Fluids Engineering (ASME Transactions), Vol. 133, 2011, 094503.
[8] Santhanakrishnan, A. and Jacob, J. D., “Flow control with plasma synthetic jet actuators,” Journal of Physics D: Applied Physics, Vol. 40, 2007, pp. 637-651.
[9] Santhanakrishnan, A., Reasor, J., and Lebeau, R., “Characterization of linear plasma synthetic jet actuators in an initially quiescent medium,” Physics of Fluids, Vol. 21, 2009. 043602.
[10] Pavlova, A. and Amitay, M., “Electronic cooling with synthetic jet impingement,” Journal of Heat Transfer, Vol. 128, 2006, pp. 897-907.
[11] Arik, M., “Local heat transfer coefficients of a high frequency synthetic jets during impingement cooling over flat surfaces,” Heat transfer Engineering, Vol. 29, 2008, pp. 763-773.
[12] Chaudhari, M. B., Puranik, B., and Agrawal, A., “Heat transfer characteristics of synthetic jet impingement cooling,” International Journal of Heat and Mass Transfer, Vol. 53, 2010, pp. 1057-1069.
[13] Chaudhari, M. B., Puranik, B., and Agrawal, A., “Effect of orifice shap in synthetic jet based impingement cooling,” Experimental Thermal and Fluid Science, Vol. 34, 2010, pp. 246-256.
[14] Forthemann, E., “Turbulent jet expansion,” NACA Technical Memorandums, No. 789, 1936, pp. 1-18.
[15] Glauert, M. B., “The wall jet,” Journal of Fluid Mechanics, Vol. 1, 1956, pp. 625-643.
[16] Bradshaw, P. and Gee, M. T., “Turbulent wall-jets with and with external stream,” Aeronautics Research Council Reports and Memoranda, No. 3252, 1960, pp. 1-48.
[17] Launder, B. E., “The turbulent wall jet – measurements and modeling,” Annual Review of Fluid Mechanics, Vol. 15, 1983, pp. 429-459.
[18] Gogineni, S. and Shih, C., “Experimental investigation of the unsteady structure of a transitional plane wall jet,” Experiments in Fluids, Vol. 23, No. 2, 1997, pp. 121-129.
[19] Gogineni, S. and Shih, C., “Phase-resolved PIV measurements in a transitional plane wall jet: a numerical comparison,” Experiments in Fluids, Vol. 27, No.2, 1999, pp. 126-136.
[20] Schwarz, W. H. and Caswell, B., “Some heat transfer characteristics of the two-dimensional laminar incompressible wall jet,” Chemical Engineering Science, Vol. 16, 1961, pp. 338-351.
[21] Bhattacharjee, P. and Loth, E., “Simulations of laminar and transitional cold wall jets,” International Journal of Heat and Fluid Flow, Vol. 25, 2004, pp. 32-43.
[22] Kanna, P. R. and Das, M. K., “Conjugate forced convection heat transfer from a flat plate by laminar plane wall jet flow,” International Journal of Heat and Mass Transfer, Vol. 48, 2005, pp. 2896-2910.
[23] Kanna, P. R. and Das, M. K., “Conjugate heat transfer study of two dimensional laminar incompressible offset jet flows,” Numerical Heat transfer, Part A, Vol. 48, 2005, pp. 671-691.

全文公開日期 2020/06/26 (校內網路)
全文公開日期本全文未授權公開 (校外網路)
全文公開日期本全文未授權公開 (國家圖書館：臺灣博碩士論文系統)

簡易檢索 / 詳目顯示

相關論文