結合實驗與數值方法研析波浪型前緣葉片應用於垂直軸風力機時之流場與氣動力特性

Combined Experimental and Numerical Study on the Flow Structure and Aerodynamic Characteristics of the Wavy Leading-edge Blade Applied on the VAWT

陳俊羽(Jyun-Yu Chen)

指導教授 ： 鄭仁杰

國立虎尾科技大學/工程學院/飛機工程系航空與電子科技碩士班/碩士(2017年)

摘要

座頭鯨有極佳的追捕獵物能力，這可歸功於其具有突起狀前緣之鰭狀肢(flipper)，觀察發現其鰭狀肢突起狀前緣(tubercle leading-edge)能發揮類似被動式流場控制的功能，透過流體通過非平滑翼前緣產生渦旋，有延遲氣流分離、增加失速攻角的效用。本文採用風洞實驗與數值模擬，分析三維具波浪型前緣葉片單葉片及波浪型前緣葉片三葉片垂直軸風力機在不同波高、波長及尖速比TSR的流場特性及氣動力性能。
　　在波浪型前緣單葉片穩定狀態在自由流風速12m/s的靜態分析中，發現當空氣經過波浪型葉片時，波峰區會產生渦流並向後延伸，在波谷處產生的流體分離現象較平滑形葉片明顯，但在波峰處流體分離的現象較不明顯。探討靜態單葉片中波高影響中發現，當波浪型葉片之波高增加，在攻角＞12°時，波浪型前緣機翼能使升力係數提高，隨著波高增加趨勢，攻角≦12°時，當波高增加其升力係數有下降的趨勢，波高越小其升力係數越接近平滑型其效果有所提升。
　　探討具波浪型前緣葉片三葉片垂直軸風力機在葉片模型以NACA0012為葉片之剖面，葉片高度H為0.2m，展弦比AR=3，波浪型前緣葉片波長WL=0.5c~3c、波高A=0.05c~0.3c，來流風速V∞=6m/s，R/c=1.726，風機半徑R=0.115m，尖速比TSR=0.05~1。當波長增加時，CQ最大值也隨著增加，增益值也逐漸增加，但同時具有CQ最小值也隨之降低，由各測試案例中，在TSR=0.095、0.191、0.287、0.383、0.5、1時其最大增益值分別為20.02%、22.66%、26.05%、19.15%、16.72%、6.91%。波浪型前緣葉片三葉片風力機數值模擬在波高的改變中，隨著波高增加 CQ最大值也隨著增加，整體波浪型前緣葉片之CQ值均高於平滑型前緣葉片，但僅A=0.3c時則略低於平滑型前緣葉片。各測試案例中，在TSR=0.095、0.191、0.287、0.383、0.5、1時其最大增益值分別為23.89%、22.23%、13.52%、12.71%、12.56%、-0.29%，僅有在TSR=1時最大增益值為負增益。
　　波浪型前緣葉片三葉片風力機在風洞實驗與數值模擬的結果中顯示，波長的改變中，風機功率P_W(W)隨波長與TSR增加而提升。數值模擬在TSR=0.05、0.06、0.07、0.08時其最大增益值分別為，40.05%、39.63%、24.91%、22.02%，風洞實驗在TSR=0.05、0.06、0.07、0.08時其最大增益值分別為，40.31%、44.65%、37.34%、48.88%。在波高的改變中，風機功率P_W(W)隨波高與TSR增加而提升。數值模擬在TSR=0.05、0.06、0.07、0.08時其最大增益值分別為，15.66%、18.69%、12.62%、14.65%，風洞實驗在TSR=0.05、0.06、0.07、0.08時其最大增益值分別為，9.64%、21.36%、23.95%、37.66%。數值結果較實驗的結果有較明顯高估現象，各測試案例之平均誤差為14.35%。

關鍵字

波浪型葉片 ； 流場控制 ； 空氣動力 ； 數值模擬 ； 實驗 ； 垂直軸風力發電機

並列摘要

Humpback whales utilize extremely mobile, wing-like flipper for banking and turning. The tubercles on the leading edge act as passive-flow control devices that improve performance and maneuverability of flipper. Theexperiment and 3-D numerical simulation are performed in this study to thoroughly investigate the flow structure and aerodynamic characteristics of 3-blade VAWT applyingthe designed wavy wing with different amplitude, wave lengthand aspect ratio, which is simulated from the tubercles flipper on humpback whales.
For the static single blade cases withV∞=12m/s, the flow separation is stronger at the wave trough than at the wave crest due to the counter-rotating vortex induced by the flow pass through the wavy leading edge. Comparing with the smooth leading edge, the lift coefficient of wavy wing is lower in low angle of attack, but is superior at higher angle of attack. The effect of the wavy wing strongly depends on the wave length and amplitude of the wavy leading edge. For higher wave length cases, the average lift is rise as amplitude isincreased. Similarly, the improvement is more obvious for lower wave length case as amplitude is decreased.
　　For the three blades vertical axis wind turbine cases withV∞=6m/s, R/c=1.726, 0.05c ≦ A ≦to 0.3c, 0.5c≦ WL ≦ to 3c and tip speed ratio 0.095≦ TSR≦1,the wind turbineperformance of wavy wing is obviouslyimproved.Comparing with the smooth leading edge, the maximum average torque coefficient CQ enhancement of wavy wing with amplitude variationare20.02%, 22.66%, 26.05%, 19.15%, 16.72%, 6.91% as TSR=0.095, 0.191, 0.287, 0.383, 0.5, 1 respectively.The maximum average torque coefficient CQ enhancement of wavy wing with wave length variationare23.89%, 22.23%, 13.52%, 12.71%, 12.56%, -0.29% as TSR=0.095, 0.191, 0.287, 0.383, 0.5, 1 respectively.
The wind turbine power analysis also implemented with numerical simulation and wind tunnel measurement. Comparing with the smooth leading edge, the maximum power enhancement of wavy wing with amplitude variationare40.05%, 39.63%, 24.91%, 22.02% as TSR=0.05, 0.06, 0.07, 0.08 respectively with numericalsimulation; and the enhancements are40.31%, 44.65%, 37.34%, 48.88% as TSR=0.05, 0.06, 0.07, 0.08 respectivelywith wind tunnel measurement.

並列關鍵字

Wavy blade ； Flow control ； Aerodynamic ； Numerical Simulation ； Experiment ； VAWT

參考文獻

[1] F. E. Fish, P. W. Weber, M. M. Murray and L. E. Howle, "The tubercles on Humpback Whales’ Flippers: Application of Bio-Inspired Technology", Integrative and Comparative Biology, Vol. 51, No.1 pp.203-213, 2011

[4] Majid Asli, Behnam Mashhadi Gholamali, and Abolghasem Mesgarpour Tousi, "Numerical Analysis of Wind Turbine Airfoil Aerodynamic Performance with Leading-edge Bump", Vol. 2015, Article ID 493253, 8 pages

[6] D. S. Miklosovic, M. M. Murray, L. E. Howle, and F. E. Fish, "Leading-Edge Tubercles Delay Stall on Humpback Whale (Megaptera novaeangliae) Flipper", Physics of Fluids, Vol. 16, No.5, pp.39-42, 2004

[7] H.S. Yoon , P.A. Hung , J.H. Jung , M.C. Kim, "Effect of the wavy leading-edge on hydrodynamic characteristics for flow around low aspect ratio wing", Computers & Fluids, Vol. 49, Issue1, October 2011, Pages 276-289

[9] J. Favier, A. Pinelli, U. Piomelli, "Control of the separated flow around an airfoil using a wavy leading-edge inspired by humpback whale flippers", comptes Rendus Mecanique, 340,pp.107-114, 2012.