Increasing the figure of merit of propulsive rotors for vertical takeoff and landing (VTOL) vehicles is critical to improving the hover efficiency and flight endurance of rotorcraft. In this paper, a new flow control scheme is proposed where 60 synthetic jet actuators are utilized on a large-scale propulsive rotor and the jets' velocity is increased from the blade root to the blade tip in order maintain constant levels of momentum coefficient per blade module. The three-bladed rotor measures 2.58 m in diameter and contains a NACA 0012 airfoil with zero blade twist distribution. The rotor was tested at speeds of 250, 500, 750 and 1,000 revolutions per minute (RPM) and blade pitch angles of 2, 5, and 8 degrees. Rotor thrust and power were measured using a high-capacity load cell and current sensor, and the streamwise flow was measured using phased-locked laser Doppler velocimetry (LDV) techniques at two measurement planes near the blade root and near the blade tip along the suction surface of the airfoil. Two flow control schemes were tested and compared; the new constant momentum coefficient (constant $C_{\mu }$) and non-constant $C_{\mu }$ where the synthetic jet velocity is held constant throughout the rotor blade. When all 20 synthetic jets per blade are activated, it was found that constant $C_{\mu }$ improves low-speed rotor performance in terms of figure of merit, FM and thrust coefficient, $C_T$ at 250 RPM, while non-constant $C_{\mu }$ is marginally superior at higher rotor speeds. When both flow control schemes are applied for just the blade root module, an increase in performance compared to the baseline is observed at rotor speeds of 750 and 1000 RPM, however different values of FM and $C_T$ are achieved for each scheme. Near the blade tip the boundary layers undergo transition to turbulent flow combined with an increasing degree of adverse pressure gradient with rotor speed and blade pitch angle. Under these conditions where the normalized streamwise velocity profiles show significant velocity deficit in the near-wall flow, synthetic jets provide some momentum to delay separation as quantified by the boundary layer shape factor.

增加用于垂直起降（VTOL）车辆的推进旋翼的品质因数对于提高旋翼飞行器的悬停效率和飞行耐久性至关重要。在本文中，提出了一种新的流量控制方案，其中在大型推进转子上使用60个合成射流致动器，并从叶片根部到叶片尖端增加射流的速度，以保持每个叶片的动量系数恒定。模块。三叶片转子的直径为2.58 m，并包含具有零叶片扭曲分布的NACA 0012翼型。转子以每分钟250、500、750和1,000转（RPM）的速度以及2、5和8度的桨距角进行了测试。使用大容量称重传感器和电流传感器测量了转子的推力和功率，并使用锁相激光多普勒测速（LDV）技术在沿叶型吸力表面靠近叶片根部和靠近叶片尖端的两个测量平面上测量气流。测试并比较了两种流量控制方案；新的恒定动量系数（恒定$C_{\mu }$）和非常数 $C_{\mu }$合成射流速度在整个转子叶片上保持恒定。当每个叶片的所有20个合成喷嘴都被激活时，发现恒定$C_{\mu }$在品质因数，调频和推力系数方面提高了低速转子的性能，$C_{Ť}$ 在250 RPM时，而不是恒定的 $C_{\mu }$在较高的转子速度下略胜一筹。当两种流量控制方案仅适用于叶片根部模块时，在750和1000 RPM的转子速度下，与基线相比，性能会有所提高，但是FM和$C_{Ť}$每个方案都实现了。在叶片尖端附近，边界层过渡到湍流，同时随着转子速度和叶片桨距角的增加，逆向压力梯度的程度增加。在这些情况下，归一化的水流速度分布在近壁流中显示出明显的速度赤字，合成射流提供了一些动量来延迟分离（如边界层形状因子所量化）。