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Aeroelastic response of a propulsive rotor blade with synthetic jets
Journal of Fluids and Structures ( IF 3.6 ) Pub Date : 2021-10-29 , DOI: 10.1016/j.jfluidstructs.2021.103411
Victor Maldonado 1 , Nicolas Peralta 1 , Serdar Gorumlu 1 , Wolduamlak Ayele 1 , Dioser Santos 1
Affiliation  

Understanding the aeroelastic response of a propulsive rotor blade is critical to implementing active flow control techniques to mitigate blade structural vibration. In this experimental study, the coupling between rotor blade aerodynamic loading and first flap mode bending and torsion is explored. The three-bladed rotor is 2.58 m in diameter, and contains a NACA 0012 airfoil with zero pre-built twist. Each blade contains 20 high-performance synthetic jet actuators distributed along the span and are activated with a constant mean jet velocity of 66.3 m/s. The rotor was tested at rotor speeds, Ω of 250, 500, 750, and 1000 revolutions per minute (RPM) and collective blade pitch angles, θc of 2, 5, and 8 degrees. Rotor thrust and torque were measured using a high-capacity load cell, and the flow near the blade tip was measured using laser Doppler velocimetry (LDV) techniques. Blade bending and torsion was measured at three equally spaced radial stations on the blade root, middle, tip regions defined by r/R = 0.32, 0.64, and 0.96 respectively using three onboard electronic accelerometers. Synthetic jets reduce the near-wall streamwise velocity deficit and turbulence intensity in the near wall flow, improving the sectional lift coefficient of the blade and delaying flow separation which results in marginally higher thrust and lower torque loading of up to 7.4% and 4.3 % respectively. At higher rotor speeds of 750 and 1000 RPM, there is a pronounced non-linear increase in bending and torsion along blade span. In the blade tip region, the streamwise flow undergoes a significant decrease in velocity and momentum, which contributes to instabilities in the boundary layer with early-stage unsteady flow separation at θc = 8°. This is correlated to a dramatic rise in the baseline power spectral density (PSD) at the blade’s natural frequency along with an increase in root mean square (rms) of bending acceleration and blade pitch angle, where the maximum values measured are arms = 0.74 g and θrms = 1.45°.



中文翻译:

具有合成射流的推进转子叶片的气动弹性响应

了解推进转子叶片的气动弹性响应对于实施主动流动控制技术以减轻叶片结构振动至关重要。在这项实验研究中,探索了转子叶片气动载荷与第一襟翼模式弯曲和扭转之间的耦合。三叶转子直径为 2.58 m,包含一个 NACA 0012 翼型,预制扭曲为零。每个叶片包含 20 个沿跨度分布的高性能合成射流执行器,并以 66.3 m/s 的恒定平均射流速度启动。转子在转子速度下进行测试,Ω 250、500、750 和 1000 转/分钟 (RPM) 和总桨距角, θC2、5 和 8 度。转子推力和扭矩使用高容量称重传感器测量,叶尖附近的流量使用激光多普勒测速 (LDV) 技术测量。叶片弯曲和扭转是在由下式定义的叶片根部、中部和尖端区域上的三个等距径向站测量的r/电阻 =0.32、0.64 和 0.96 分别使用三个板载电子加速度计。合成射流减少了近壁流中的近壁流向速度缺陷和湍流强度,提高了叶片的截面升力系数并延迟了流动分离,从而导致略高的推力和更低的扭矩负载,分别高达 7.4% 和 4.3% . 在 750 和 1000 RPM 的更高转子速度下,沿叶片跨度的弯曲和扭转明显非线性增加。在叶尖区域,流向流动的速度和动量显着降低,这导致边界层不稳定,在θC =8°。这与叶片固有频率处基线功率谱密度 (PSD) 的急剧上升以及弯曲加速度和叶片桨距角的均方根 (rms) 的增加有关,其中测量的最大值为一种r = 0.74 克和 θr = 1.45°。

更新日期:2021-10-29
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