Mesh and load distribution requirements for actuator line CFD simulations
Mesh and load distribution requirements for actuator line CFD simulations
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DOI：
10.1002/we.1546
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发表时间：
2012-08
期刊：
影响因子：
4.1
通讯作者：
M. Shives;C. Crawford
中科院分区：
文献类型：
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作者：
M. Shives;C. Crawford
已经进行了基本数值测试，以确定用于模拟动涡轮机的基于执行器线的计算流体动力学方法的网格密度和力分布指南。该方法通过使用不断变化的流场和表格翼型数据来计算来自升力表面（即机翼或叶片）的力。这些力作为动量源项施加到流动上，该动量源项按照关于叶片/机翼四分之一弦线的物理位置的高斯平滑函数分布。高斯分布的所选长度尺度会影响所得感应的大小和分布，并且需要最小网格分辨率才能获得准确的结果。已经进行了测试，通过使用具有恒定和椭圆翼展方向环流分布的无限展翼和有限展翼来确定适当的分布长度尺度和网格间距。选择这些测试用例是因为它们具有从升力线理论得出的简单解析解。最终目标是模拟涡轮转子；然而，这些基本测试案例提供了一种评估所需网格间距和适当分布长度尺度的方法，而无需对涡轮转子尾流进行复杂的建模。结果发现，源分布长度尺度 ϵ 应与局部翼型弦长 c 成正比，比率 ϵ/cof 约为 1/4，并且执行器线处的网格间距应满足 ϵ/ Δgrid≥ 4。此限制可能在某种程度上是特定于代码的，应针对用于执行器线模拟的所有解算器进行评估。版权所有 © 2012 约翰·威利父子有限公司
Fundamental numerical testing has been carried out to determine mesh density and force distribution guidelines for an actuator line‐based computational fluid dynamics method for simulating kinetic turbines. The method computes forces from lifting surfaces (i.e. wings or blades) by using the evolving flowfield and tabulated airfoil data. The forces are applied to the flow as momentum source terms distributed with a Gaussian smoothing function about the physical locations of the blade/wing quarter‐chord line. The chosen length scale of the Gaussian distribution affects the magnitude and distribution of the resulting induction and necessitates a minimum grid resolution for accurate results. Tests have been conducted to determine appropriate distribution length scales and mesh spacing by using an infinite span wing and finite span wings with constant and elliptical spanwise circulation distributions. These test cases were chosen because they have simple analytical solutions derived from lifting line theory. The eventual goal is to simulate turbine rotors; however, these fundamental test cases provide a means to evaluate the required mesh spacing and the appropriate distribution length scale without the complexity of modeling a turbine rotor wake. It was found that the source distribution length scaleϵshould be proportional to the local airfoil chord lengthcwith a ratioϵ/cof approximately 1/4 and that the mesh spacing at the actuator line should satisfyϵ/ Δgrid≥ 4. This limit is likely somewhat code specific and should be evaluated for all solvers used for actuator line simulations. Copyright © 2012 John Wiley & Sons, Ltd.