Abstract The objective of this work is to optimize the internal shape of a single-started helically ribbed heat exchanger. Large Eddy Simulation (LES) is used to simulate the turbulent flow in a wall-resolved periodic channel configuration, heated via a uniform heat flux at the wall. In order to enhance the heat exchange with the flow, the inner surface of the channel features rounded rib. This however increases the pressure loss, and an optimum shape of the rib is to be found. The rib pitch and height as well as rib discontinuities are the geometrical parameters to optimize, allowing a wide variety of inner wall roughness. To limit the number of LES, the optimization procedure is based on a surrogate model constructed from Gaussian Process Regression and adaptive resampling with the Efficient Global Optimization (EGO) method [1]. The optimization consists in the maximization of the cost function proposed by Webb and Eckert [2], which aims at maximizing the heat transfer efficiency for similar pumping power. Results show that a rib induced swirling motion in the near wall region significantly decreases the heat transfer efficiency, leading to an optimum roughness shape featuring large and multiple discontinuities. Moreover, the efficiency of helically dimpled tubes is also found sensitive to the shape of the transitions between the discontinuous parts of the rib. Smoother transitions lead to lower pressure loss but also to lower heat transfer due to smaller recirculation zones.

中文翻译：

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使用高斯过程的换热器设计优化

摘要 这项工作的目的是优化单头螺旋肋换热器的内部形状。大涡模拟 (LES) 用于模拟壁解析周期性通道配置中的湍流，通过壁处的均匀热通量加热。为了加强与流动的热交换，通道的内表面具有圆形肋。然而，这会增加压力损失，因此需要找到肋的最佳形状。肋节距和高度以及肋不连续性是要优化的几何参数，允许各种内壁粗糙度。为了限制 LES 的数量，优化程序基于一个代理模型，该模型由高斯过程回归和自适应重采样构建，并使用高效全局优化 (EGO) 方法 [1]。优化包括最大化 Webb 和 Eckert [2] 提出的成本函数，旨在最大化类似泵送功率的传热效率。结果表明，肋在近壁区域引起的涡流运动显着降低了传热效率，导致具有大和多个不连续性的最佳粗糙度形状。此外，还发现螺旋波纹管的效率对肋的不连续部分之间的过渡形状敏感。更平滑的过渡会导致较低的压力损失，但也会由于较小的再循环区域而导致较低的热传递。结果表明，肋在近壁区域引起的涡流运动显着降低了传热效率，导致具有大和多个不连续性的最佳粗糙度形状。此外，还发现螺旋波纹管的效率对肋的不连续部分之间的过渡形状敏感。更平滑的过渡会导致较低的压力损失，但也会由于较小的再循环区域而导致较低的热传递。结果表明，肋在近壁区域引起的涡流运动显着降低了传热效率，导致具有大和多个不连续性的最佳粗糙度形状。此外，还发现螺旋波纹管的效率对肋的不连续部分之间的过渡形状敏感。更平滑的过渡会导致较低的压力损失，但也会由于较小的再循环区域而导致较低的热传递。