Calculation of High-Lift Cascades in Low Pressure Turbine Conditions Using a Three-Equation Model
Calculation of High-Lift Cascades in Low Pressure Turbine Conditions Using a Three-Equation Model
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DOI：
10.1115/1.4001237
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发表时间：
2011-07
影响因子：
1.7
通讯作者：
R. Pacciani;M. Marconcini;A. Fadai-Ghotbi;S. Lardeau;M. Leschziner
中科院分区：
文献类型：
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作者：
R. Pacciani;M. Marconcini;A. Fadai-Ghotbi;S. Lardeau;M. Leschziner
将三方程模型应用于高升程、低雷诺数叶栅流动中分离诱导相变的预测。经典的湍流模型不能准确地预测层流分离和湍流再附着，通常会过高地预测分离长度，这主要是由于分离过程早期湍动能缓慢上升所致。所提出的方法是基于求解所谓的层流动能的附加输运方程，该方程允许考虑过渡前和过渡区内非湍流脉动的增加。该模型是从Lardeau等人的模型中得到的。(2004)，“模拟低雷诺数非线性涡粘闭合的绕流过渡”，Flow，Turble。Burust，73，pp.49-76)，它最初是用来预测附加流动的旁路转变的，受大范围的自由流湍流强度的影响。基于平均切变和层流涡粘概念，提出了一种新的产量项。在对承受不利压力梯度的平板边界层的模型进行验证后，选择最近在冯·卡曼研究所测试的T106和T2叶栅作为测试案例，以评估该模型在具有代表性的低压涡轮条件下预测高扬程叶栅周围流动的能力。在较宽的雷诺数范围内，叶片载荷分布、分离起始、再附着位置和损失与实验数据吻合较好。
A three-equation model has been applied to the prediction of separation-induced transition in high-lift low-Reynolds-number cascade flows. Classical turbulence models fail to predict accurately laminar separation and turbulent reattachment, and usually overpredict the separation length, the main reason for this being the slow rise of the turbulent kinetic energy in the early stage of the separation process. The proposed approach is based on solving an additional transport equation for the so-called laminar kinetic energy, which allows the increase in the nonturbulent fluctuations in the pretransitional and transitional region to be taken into account. The model is derived from that of Lardeau et al. (2004, "Modelling Bypass Transition With Low-Reynolds-Number Non-Linear Eddy-Viscosity Closure, " Flow, Turbul. Combust., 73, pp. 49―76), which was originally formulated to predict bypass transition for attached flows, subject to a wide range of freestream turbulence intensity. A new production term is proposed, based on the mean shear and a laminar eddy-viscosity concept. After a validation of the model for a flat-plate boundary layer, subjected to an adverse pressure gradient, the T106 and T2 cascades, recently tested at the von Karman Institute, are selected as test cases to assess the ability of the model to predict the flow around high-lift cascades in conditions representative of those in low-pressure turbines. Good agreement with experimental data, in terms of blade-load distributions, separation onset, reattachment locations, and losses, is found over a wide range of Reynolds-number values.