An experimental study on the aerody

An experimental study on the aerodynamic and aeroacoustic performance of a baseline propeller and several sawtooth serrated trailing edge (SSTE) propellers with different serration sizes (λ/h=0.3, 0.6, 0.9 and 1.2) was conducted at hover and forward flight conditions. The sound measurement results at hover motion revealed that the SSTE propellers could reduce the noise levels. We also found that the large serration had better noise attenuation effects than the smaller serration sizes. The comparison results of the force measurements among baseline model and SSTE propellers revealed that the saw-tooth serrated trailing edge had no significant effect on the aerodynamic performance at low Reynolds numbers (5×104) at hover flight. The force measurement results at forward flight indicated that the SSTE propellers could maintain the same lift while reducing the rotational speed. The PIV measurement results revealed that the SSTE propellers with different serration sizes generated almost same mean flow at hover and forward flight conditions. However, it significantly changed the wake shape and size of the flow passing the trailing edge. This phenomenon increases the flow mixing at the tailing edge. For small size propellers, the material strength needed to be considered carefully to account for undesirable structural effects associated with serration sizes that are too fine.Otherwise, the serration deformation would significantly reduce the aerodynamic efficiency and increase the noise level.

結果 (繁體中文) 1:

上的基線螺旋槳和若干鋸齒的空氣動力學和空氣聲學性能的實驗研究鋸齒形後緣（SSTE）螺旋槳具有不同鋸齒尺寸（λ/ H = 0.3，0.6，0.9和1.2）在盤旋和向前飛行條件下進行的。該在懸停動作聲音測量結果表明，SSTE螺旋槳可以減少噪音水平。我們還發現，大鋸齒有比小鋸齒尺寸更好的噪聲衰減效應。基線模型和SSTE螺旋槳之間的力測量的比較結果顯示，鋸齒鋸齒狀後緣對處懸停飛行低雷諾數（5×104）的空氣動力性能沒有顯著效果。在向前飛行力測量結果表明，SSTE螺旋槳可以維持相同的升力，同時減小轉速。的PIV測量結果表明，用不同的鋸齒尺寸的SSTE螺旋槳產生在盤旋和向前飛行條件幾乎相同的平均流量。然而，它顯著改變經過後緣流的尾流的形狀和大小。這種現象增加的流動在所述拖尾邊緣的混合。對於小尺寸螺旋槳，需要仔細考慮以考慮與鋸齒的尺寸相關的不希望的結構的效果的材料強度過於fine.Otherwise，鋸齒變形會顯著降低空氣動力學效率和增加噪音水平。的PIV測量結果表明，用不同的鋸齒的SSTE螺旋槳大小不一產生在盤旋和向前飛行條件幾乎相同的平均流量，但顯著改變經過後緣流的尾流的形狀和大小。這種現象增加的流動在混合拖尾邊緣。對於小尺寸螺旋槳，材料強度需要仔細考慮以考慮與鋸齒尺寸過於fine.Otherwise相關的不期望結構效應，鋸齒變形會顯著減小空氣動力效率，增加的噪聲水平。的PIV測量結果表明，用不同的鋸齒的SSTE螺旋槳大小不一產生在盤旋和向前飛行條件幾乎相同的平均流量，但顯著改變經過後緣流的尾流的形狀和大小。這種現象增加的流動在混合拖尾邊緣。對於小尺寸螺旋槳，材料強度需要仔細考慮以考慮與鋸齒尺寸過於fine.Otherwise相關的不期望結構效應，鋸齒變形會顯著減小空氣動力效率，增加的噪聲水平。這種現象增加的流動在後緣混合。對於小尺寸螺旋槳，需要仔細考慮以考慮與鋸齒尺寸過於fine.Otherwise相關的不期望的影響的結構材料的強度，鋸齒變形會降低顯著空氣動力學效率並增加噪音水平。這種現象增加的流動在後緣混合。對於小尺寸螺旋槳，需要仔細考慮以考慮與鋸齒尺寸過於fine.Otherwise相關的不期望的影響的結構材料的強度，鋸齒變形會降低顯著空氣動力學效率並增加噪音水平。

結果 (繁體中文) 2:

Anexperimental study on the aerodynamic 和 aeroacoustic performance a baseline propeller 和 several sawtooth serrated trailing edge （SSTE） propellers with different serration size （#0.3， 0.3， 0.9， 0.9， 1.2） rward flight 條件。 Sound measurement results the SSTE propellers could reduce the noise levels。 We also found the large serration had better noise attenuation effects than the smaller serration sizes。 The comparison results of the force measurements among baseline model and SSTE propellers revealed that the saw-tooth serrated trailing edge had no significant effect on the aerodynamic performance at low Reynolds numbers (5×104) at hover fligh t. formeasurement results forward forlight indicated the SSTE propellers could maintain the same lift lift reducing the rotation speed。 The PIV measurement results revealed that the SSTE propellers with different serration sizes generated almost same mean flow at hover and forward flight conditions. However， it signifantly changed wake shape 和 size the flow passing the trailing edge。 這個 phenomenon increases the flow mixing the tailing edge For small size propellers, the material strength needed to be considered carefully to account for undesirable structural effects associated with serration sizes that are too fine. 其他， serration deformation wouldsignicantly reduce the aerodynamic efficiency and increasethe the noise level。

結果 (繁體中文) 3:

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