研究生: |
彭韋綸 Wei-Lun Peng |
---|---|
論文名稱: |
衝擊距離對平板受振盪噴流衝擊之流場與熱傳特性的影響 Effects of Impinging Distance of a Pulsating Jet on Flow and Heat Transfer Properties |
指導教授: |
黃榮芳
Rong-Fung Huang 許清閔 Ching-Min Hsu |
口試委員: |
黃榮芳
Rong-Fung Huang 許清閔 Ching-Min Hsu |
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: | 2016 |
畢業學年度: | 104 |
語文別: | 中文 |
論文頁數: | 294 |
中文關鍵詞: | 振盪噴流 、衝擊距離 、噴流衝擊熱傳 |
外文關鍵詞: | pulsating jet, impinging distance, jet impingement heat teansfer |
相關次數: | 點閱:376 下載:0 |
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本研究使用振盪噴流衝擊一平板,以實驗方法探討衝擊距離、激擾史卓數及擾動強度對平板與噴流之間的流場特徵行為、壓力分佈與熱傳特性的影響。藉由調整揚聲器的頻率及電壓,控制振盪噴流的激擾史卓數與擾動強度。透過煙霧流場可視化技術的觀察,在激擾史卓數與擾動強度的域面上,流場行為可劃分為凝序性渦旋結構(coherent vortices)與具渦旋列之渦旋結構(vortex train)兩種特徵模態。藉由熱線風速儀量測噴流出口速度振盪及剪流層速度特性,分析時序圖及相對應的頻譜圖,並且根據流場可視化影像及熱線風速儀速度訊號,計算渦旋結構的群體移動速度。渦旋結構的群體移動速度隨著擾動強度與衝擊距離的提升而增加。利用壓力掃描器量測平板表面的壓力分佈,當衝擊距離減小與擾動強度增大時,在平板表面產生較大的壓力值。應用質點影像測速儀(PIV)量測全域速度場,量化流場結構、渦度場及紊流強度分佈。以紅外線熱顯像儀量測加熱平板的表面溫度分佈,比較自然對流、連續噴流及振盪噴流的紐塞爾數(Nusselt number)。具渦旋列之渦旋結構模態的紐塞爾數約為連續噴流的1.6至2.7倍,而凝序性渦旋結構模態的紐塞爾數約為連續噴流的1.2倍。因此,具振盪特性的衝擊噴流比連續噴流有較強的熱傳效果;振盪衝擊噴流在渦旋列模態時比凝序性模態有更顯著的熱傳效能。
The effects of impinging distance, excitation Strouhal number, and pulsation intensity on the instantaneous flow patterns, time-averaged velocity fields, pressure coefficients, and heat transfer characteristics of the pulsating jets impinging on a flat plate were experimentally investigated. According to the streak images of the laser-light sheet assisted smoke-flow visualization results, two characteristic flow modes, coherent vortices and vortex train, were identified in the domain of the excitation Strouhal number and pulsation intensity. The instantaneous velocities were measured simultaneously in the shear-layer near the jet exit and the flat plate by two hot-wire probes. The convection velocity of the vortical flow structure increases with increasing impinging distance and pulsation intensity. Surface pressure along a line on the flat plate across the center of the jet impinging area was measured by a pressure scanner. The results of pressure measurement showed that the averaged surface pressure increases with increasing pulsation intensity and decreasing impinging distance. The velocity field was quantified by employing the particle image velocimeter (PIV). The velocity vector field, streamline patterns, vorticity contours and turbulence intensity distribution were presented and discussed. The temperature distribution on the surface of the heated plate was measured by an infrared imaging system. The Nusselt numbers of the excited jet impingement are drastically larger than those of the unexcited jet. In the vortex train mode, the Nusselt numbers of the excited case are about 1.6 to 2.7 times of the unexcited case. In the coherent vortices regime, the Nusselt numbers of the excited case are about 1.2 times of the unexcited case.
[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] Tan, X. M. and Zhang, J. Z., “Flow and heat transfer characteristics under synthetic jets impingement driven by piezoelectric acturator,” Experimental Thermal and Fluid Science, Vol. 48, 2013, pp. 134-146.
[15] Forthemann, E., “Turbulent jet expansion,” NACA Technical Memorandums, No. 789, 1936, pp. 1-18.
[16] Glauert, M. B., “The wall jet,” Journal of Fluid Mechanics, Vol. 1, 1956, pp. 625-643.
[17] 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.
[18] Launder, B. E., “The turbulent wall jet – measurements and modeling,” Annual Review of Fluid Mechanics, Vol. 15, 1983, pp. 429-459.
[19] 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.
[20] 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.
[21] 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.
[22] 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.
[23] 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.
[24] 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.
[25] 張英育:「受聲波激勵噴流衝擊平板之流場與熱傳特徵」,機械工程技術研究所碩士論文,國立臺灣科技大學,台北(2015)
[26] 何錦輝:「壓電驅動及電磁驅動之合成噴流的流場特徵」,機械工程技術研究所碩士論文,國立臺灣科技大學,台北(2014)