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首页> 外文期刊>Experiments in Fluids: Experimental Methods and Their Applications to Fluid Flow >Performance recovery of a thick turbulent airfoil using a distributed closed-loop flow control system
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Performance recovery of a thick turbulent airfoil using a distributed closed-loop flow control system

机译：使用分布式闭环流量控制系统恢复厚湍流翼型的性能

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This paper describes an experimental study aimed at controlling the performance of a thick airfoil, typical to the root section of a wind turbine blade. The main purpose is recovering decreased performance due to degraded surface quality, leading to decreased lift and increased drag. Since wind turbines are designed to operate for decades, the blades' surface quality degradation due to environmental effects is unavoidable. This process promotes early transition to turbulent flow, leading to premature boundary layer separation in the post-transitional regime. In addition, non-uniform and unsteady wind speeds cause dynamic loads on the blade and on the overall turbine structure. Controlling unsteady and non-uniform loads by changing the blades' (or its cross-section) performance will allow building larger, lighter and more durable to aging wind turbines. Active flow control (AFC) is a possible remedy to boundary layer separation, including rough surface effects. Currently, three arrays of synthetic jet actuators are controlled based on state estimation provided by feedback from hot-film and pressure sensors. The unsteady pressure sensors' data are used to estimate the lift while the unsteady and un-calibrated hot-films data are used to determine the flow separation location and define the relative magnitude of actuation imparted by each of the three actuator rows. The aerodynamic results demonstrate that the "clean" turbine blade performance, with lift-based controller, is recovered by the closed-loop active flow control system at Reynolds numbers around half a million and excitation at Strouhal numbers larger than 10. The total closed-loop AFC system energy efficiency was measured and shown to increase by up to 60 % compared to the airfoil with degraded surface quality. The current results indicate the potential of a closed-loop AFC system to provide significant increase in the net energy harvesting capability of a wind turbine blade with degraded surface quality over a wide range of incidence angles and Reynolds numbers.
机译：本文介绍了一项旨在控制厚翼型件性能的实验研究，该特性是风力涡轮机叶片根部的典型特征。主要目的是恢复由于降低的表面质量而导致的性能下降，从而导致升力降低和阻力增大。由于风力涡轮机的设计运行了数十年，因此不可避免地会因环境影响而降低叶片的表面质量。这个过程促进了向湍流的早期过渡，导致过渡后时期边界层的过早分离。另外，风速的不均匀和不稳定会在叶片和整个涡轮机结构上产生动载荷。通过改变叶片（或叶片横截面）的性能来控制不稳定和不均匀的载荷，将能够制造出更大，更轻，更耐用的老化风力涡轮机。主动流控制（AFC）是解决边界层分离（包括粗糙表面效应）的一种可能方法。当前，基于由热膜和压力传感器的反馈提供的状态估计来控制三排合成射流致动器。非稳定压力传感器的数据用于估计升力，而非稳定和未校准的热膜数据用于确定流分离位置并定义三个执行器行中的每行所赋予的相对驱动大小。空气动力学结果表明，采用基于升程的控制器的“清洁”涡轮叶片性能可通过闭环主动流量控制系统以雷诺数约100万和斯特劳哈尔数大于10的励磁来恢复。测量了环路AFC系统的能源效率，结果表明与表面质量下降的机翼相比，它最多可提高60％。当前结果表明，闭环AFC系统有可能在很大的入射角和雷诺数范围内显着提高具有降低的表面质量的风力涡轮机叶片的净能量收集能力。

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