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Title: Influence of Real Gas Properties on Aerodynamic Losses in a Supercritical CO2 Centrifugal Compressor
题目：真实气体物性对超临界二氧化碳离心压缩机气动损失的影响
Authors: YANG Mingyang,CAI Ruikai,ZHUGE Weilin,YANG Bijie,ZHANG Yangjun
作者：杨名洋，蔡锐楷，诸葛伟林，杨弼杰，张扬军
单位：上海交通大学机械与动力工程学院；清华大学车辆与运载学院；帝国理工学院；
Journal of Thermal Science, 2024, 33(6): 2032-2046.
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摘要
Abstract: Supercritical carbon dioxide (SCO2) centrifugal compressor is a key component of a closed Brayton cycle system based on SCO2. A comprehensive understanding of the loss mechanism within the compressor is vital for its optimized design. However, the physical properties of SCO2 are highly nonlinear near the critical point, and the internal flow of the compressor is closely related to its properties, which inevitably influences the generation of aerodynamic losses within the compressor. This paper presents a comprehensive investigation of the compressor’s loss mechanism with an experimentally validated numerical method. The real gas model of CO2 embodied in the Reynolds-Averaged Navier-Stokes (RANS) model was used for the study. Firstly, the numerical simulation method was validated against the experimental results of Sandia SCO2 compressor. Secondly, performance and loss distribution of the compressor were compared among three fluids including SCO2, ideal CO2 (ICO2) and ideal air (IAir). The results showed that the performance of SCO2 was comparable to IAir under low flow coefficient, however markedly inferior to the other two fluids at near choke condition. Loss distribution among the three fluids was distinctive. In the impeller, SCO2 was the most inefficient, followed by ICO2 and IAir. The discrepancies were magnified as the flow coefficient increased. This is due to a stronger Blade-to-Blade pressure gradient that intensifies boundary layer accumulation on walls of the shroud/hub. Furthermore, owing to the reduced sonic speed of SCO2, a shock wave appears earlier at the throat region and SCO2 encounters more intense boundary layer separation.
摘要：超临界二氧化碳(SCO2)离心压缩机是SCO2闭式布雷顿循环系统中的关键部件。深入了解压缩机内部的损失机制对于优化设计至关重要。然而，接近临界点时，SCO2的物理特性高度非线性，压缩机内部流动与其特性密切相关，这不可避免地影响了压缩机内气动损失的产生。本文通过实验验证的数值方法对压缩机的损失机制进行了全面分析。首先，数值模拟方法针对Sandia SCO2压缩机的实验结果进行了验证。其次，比较了使用SCO2、理想二氧化碳（ICO2）和理想空气（IAir）三种流体时压缩机的性能和损失分布。结果显示，在低流量系数下，SCO2的性能与IAir相当，但在接近堵塞条件下明显不如其他两种流体。三种流体中的损失分布有明显区别。在叶轮中，SCO2效率最低，其次是ICO2和IAir。随着流量系数的增加，这些差异被放大。这是由于更强的叶顶区域周向压力梯度加剧了在轮盖/轮毂端壁上的边界层累积。此外，由于SCO2的声速降低，激波在喉部区域更早出现，导致SCO2叶轮内出现显著的边界层分离现象。
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引用格式
YANG Mingyang,CAI Ruikai,ZHUGE Weilin,YANG Bijie,ZHANG Yangjun, Influence of Real Gas Properties on Aerodynamic Losses in a Supercritical CO2 Centrifugal Compressor, Journal of Thermal Science, 2024, 33(6):2032-2046..
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