标题： 来流湍流对风力涡轮机尾流相干动力学的影响 显示英文标题

标题： Effect of freestream turbulence on the coherent dynamics of a wind turbine wake

摘要： 模型风力涡轮机在不同湍流特性的自由来流湍流（FST）作用下的尾流被通过粒子图像测速实验进行研究。 FST情况下的湍流强度（T_i）范围为1% < T_i < 13.1%，积分长度尺度（L_v）范围为0.01D < L_v < 0.11D（其中D为涡轮模型的直径）。 在这个范围内增加T_i和L_v导致了尖端涡旋更早的破裂，从而导致尾流恢复更早开始。 通常，在FST存在的情况下，尾流摆动的振幅增加，但并不是随着T_i或L_v单调变化。 功率谱中低频区域（典型的是尾流摆动频率）的性质随着FST水平的增加从更离散变为更宽带，突显了在有无FST情况下尾流摆动性质的根本变化。 通过多尺度三重分解的相干动能预算分析，获得了在FST存在下各种相干运动（由特定频率表征）的起源及其后续演化的深入见解。 在FST存在下，尾流摆动模式被证明能更好地利用平均速度剪切，从平均流动中提取更多能量，同时其他来源如非线性三元相互作用和扩散的重要性也有所增加。 显示英文摘要

摘要： The wake of a model wind turbine exposed to freestream turbulence (FST) with a variety of turbulent characteristics is studied through Particle Image Velocimetry experiments. The FST cases spanned turbulent intensities (T_i) in the range 1% < T_i < 13.1 % and integral length scales (L_v) in the range 0.01D < L_v < 0.11D (where D is the diameter of the turbine model)}. Increasing T_i and L_v in this range resulted in an earlier breakdown of the tip vortices which in turn resulted in an earlier onset of wake recovery. Typically, the amplitude of wake meandering increased in the presence of FST, but not monotonically with either T_i or L_v. The nature of the low frequency region (typical of wake meandering frequencies) of the power spectra changed from a more discrete to a more broadband one as FST level was increased, highlighting a fundamental change in the nature of wake meandering with/without FST. Deeper insights into the origins, and subsequent evolution, of the various coherent motions (characterised by particular frequencies) in the presence of FST are obtained through analysis of the multi-scale triple-decomposed coherent kinetic energy budgets. The wake meandering modes in the presence of FST are shown to better utilize the mean velocity shear, extracting more energy from the mean flow while other sources such as non-linear triadic interactions and diffusion also gain in importance.