Applicability of Wall-Function Approach in Simulations of Turbomachines
Applicability of Wall-Function Approach in Simulations of Turbomachines
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DOI：
10.1115/gt2015-42014
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发表时间：
2015-06
期刊：
影响因子：
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通讯作者：
Kay Juckelandt;F. Wurm
中科院分区：
文献类型：
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作者：
Kay Juckelandt;F. Wurm
对低比转数离心泵的数值模拟表明，计算效率与实验值相差很大。这导致设计师避免使用CFD方法，而坚持使用原型。对数值模拟在这些泵上的适用性进行了研究。对低比转数泵进行了非定常数值模拟。本文的重点是边界层处理，因为在低比转数泵中，边界层流动的损失占主导地位。边界层处理采用壁函数和低雷诺数方法。介绍了一种计算壁函数法局部建模误差的方法。在一台试验泵上进行了实验，以验证模拟的有效性。得到了性能曲线、局部高分辨压力分布和速度分布。模拟得到的边界层分辨率与实验数据吻合很好。结果表明，模拟效率对边界层处理很敏感。壁面函数模拟在非设计流量下，特别是在过载时，会产生很大的偏差。分析表明，壁函数法的建模误差是造成损耗预测不准确的主要原因。计算了局部建模误差分布，导出了低比转数泵的啮合准则。版权所有©2015，由ASME
Numerical simulations of centrifugal pumps with low specific speed show significant differences in calculated efficiency from experiments. This causes designers to refrain from CFD methods and stick to prototyping. Investigations regarding the applicability of numerical simulations on these pumps are carried out. Unsteady simulations of a low specific speed pump are performed. The focus of this paper is boundary layer treatment, as losses due to boundary layer flow are dominant in low specific speed pumps. The wall-function as well as the low-Reynolds-number method is applied for boundary layer treatment. A method to calculate the local modeling error of the wall-function method is introduced. Experiments on a test pump are conducted to validate the simulations. Performance curves, locally highly resolved pressure distributions and velocity profiles are obtained. Simulations with resolved boundary layers match experimental data very good. It is shown that simulated efficiency is sensitive to the boundary layer treatment. The wall-function simulations deviate significantly at off-design flow rate, particularly at overload. The analysis reveals that modeling errors of the wall-function method mainly contribute to incorrect loss prediction. A local modeling error distribution is calculated and a meshing guideline for low specific speed pumps is derived.Copyright © 2015 by ASME