管壁局部粗糙对水平超临界二氧化碳湍流传热的影响  

Influence of Regional Wall Roughness on the Turbulent Heat Transfer of Horizontal Supercritical Carbon Dioxide Flows

作　　者：王建勇 杨军 雷玟 WANG Jianyong;YANG Jun;LEI Wen(School of Aeronautics and Astronautics,Shenzhen Campus of Sun Yat-sen University,Shenzhen 518107,Guangdong Province,China;School of Aeronautics and Astronautics,Sun Yat-sen University,Guangzhou 510275,Guangdong Province,China)

机构地区：[1]中山大学·深圳航空航天学院,广东省深圳市518107 [2]中山大学航空航天学院,广东省广州市510275

出　　处：《中国电机工程学报》2023年第23期9214-9223,共10页Proceedings of the CSEE

基　　金：国家自然科学基金项目(52006248);深圳市科技计划资助(RCBS20210706092408013)。

摘　　要：为改善水平管内超临界二氧化碳(supercritical carbon dioxide,S-CO_(2))湍流传热,该文对管壁引入简易的均匀砂粗糙,并基于水平超临界流动传热特征,创新性地提出上壁面(传热恶化)附近特定区域粗糙化方案。模拟计算中,采用k-ωSST湍流模型并对其关于粗糙管流传热预测进行了验证以展示其可靠性,而后对管径d=4.57mm水平管道内S-CO_(2)的流动传热展开探究,并讨论局部粗糙化范围以及关键因素浮升力的影响。结果表明:管道上壁面特定区域粗糙化能显著降低上壁面温度,增强该区域S-CO_(2)传热性能,继而有效改善周向传热均匀性。低热流密度时,管壁粗糙面积在湍动能整体水平较低的加热管流前半部分影响较为明显;随着热流密度的增加,浮升力效应增强,上壁面附近高温区域逐渐扩大,而不同工况条件下使粗糙范围集中于此高温区域能够获得兼顾水平S-CO_(2)传热效率与附加流动阻力更优的综合性能。In order to improve the turbulent heat transfer of supercritical carbon dioxide(S-CO_(2))flowing in the horizontal tube,the simple and practical uniform sand-grain roughness is introduced into the pipe wall.Based on the heat transfer characteristics of horizontal supercritical fluids,an innovative roughening scheme targeting at the specific heat transfer degradation area near the top wall is proposed.During the simulations,k-wSST turbulence model is employed and its predictions on the heat transfer of the rough piping flows have been validated against the experiments.Then,using the reliable simulation tool,the turbulent heat transfer of S-CO_(2)within the 4.57mm-diameter horizontal tube is investigated,and the influences of regional roughness range and buoyancy strength are discussed.The results show that the regional roughness focusing on the top wall is able to significantly reduce the wall temperatures,enhance S-CO_(2)heat transfer performances,and effectively improve the circumferential heat transfer uniformity.The effect of roughness areas is obvious within the upstream of the heated piping flow where the turbulent kinetic energy level is relatively low under the studied low-heat-flux condition.With the increase in heat flux,the buoyancy effect intensifies,and the high-temperature area near the top wall gradually expands.Under different operating conditions,the partially-roughen approach concentrating the high-temperature area of deterioration can obtain good performances,accounting both the heat transfer and extra flow resistance,can be achieved.

关 键 词：超临界二氧化碳 水平圆管 砂粗糙 局部粗糙 浮升力效应 

分 类 号：TK121[动力工程及工程热物理—工程热物理]