Direct numerical simulation of the flow around an aerofoil in ramp-up motion
Direct numerical simulation of the flow around an aerofoil in ramp-up motion
复制标题
斜升运动中机翼周围流动的直接数值模拟
DOI：
10.1063/1.4941529
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发表时间：
2016
影响因子：
4.6
通讯作者：
A. Pinelli
中科院分区：
文献类型：
--
作者：
M. Rosti;M. Omidyeganeh;A. Pinelli
本文用直接数值模拟的方法，对Rec = 2 × 104的NACA 0020翼型作斜升运动时的绕流进行了详细的分析。在机动过程中，迎角随时间在0°和20°之间线性变化，变化率恒定为αrad=0.12U∞/c。当迎角达到最终值时，升力经历第一次过冲，然后突然减小到静态失速渐近值。瞬态瞬时流动主要由动态失速涡的产生和分离所控制，动态失速涡是由后缘处的不稳定性产生的小尺度涡合并而形成的大尺度结构。使用一些后处理技术的涡度动力学导致的升力超调，升力危机，阻尼振荡周期，逐渐匹配的稳定条件进行了讨论。这些措施包括详细分析的流量合奏平均统计和相干…
A detailed analysis of the flow around a NACA0020 aerofoil at Rec = 2 × 104 undergoing a ramp up motion has been carried out by means of direct numerical simulations. During the manoeuvre, the angle of attack is linearly varied in time between 0° and 20° with a constant rate of change of αrad=0.12U∞/c. When the angle of incidence has reached the final value, the lift experiences a first overshoot and then suddenly decreases towards the static stall asymptotic value. The transient instantaneous flow is dominated by the generation and detachment of the dynamic stall vortex, a large scale structure formed by the merging of smaller scales vortices generated by an instability originating at the trailing edge. New insights on the vorticity dynamics leading to the lift overshoot, lift crisis, and the damped oscillatory cycle that gradually matches the steady condition are discussed using a number of post-processing techniques. These include a detailed analysis of the flow ensemble average statistics and coheren...