Flow Loss Mechanism in a Supercritical Carbon Dioxide Centrifugal Compressor at Low Flow Rate Conditions  

作　　者：YANG Zimu JIANG Hongsheng ZHUGE Weilin CAI Ruikai YANG Mingyang CHEN Haoxiang QIAN Yuping ZHANG Yangjun 

机构地区：[1]State Key Laboratory of Automotive Safety and Energy,Tsinghua University,Beijing 100084,China [2]School of Mechanical Engineering,Shanghai Jiao Tong University,Shanghai 200240,China

出　　处：《Journal of Thermal Science》2024年第1期114-125,共12页热科学学报（英文版）

基　　金：supported by the National Key Research and Development Program of China (No. 2018YFB1501004)。

摘　　要：With the advantages of high efficiency and compact structure,supercritical carbon dioxide(sC02)Brayton cycles have bright prospects for development in energy conversion field.As one of the core components of the power cycle,the centrifugal compressor tends to operate near the critical point(304.13 K,7.3773 MPa).Normally,the compressor efficiency increases as the inlet temperature decreases.When the inlet temperature is close to the critical point,the density increases sharply as the temperature decreases,which results in quickly decreasing of volume flow rate and efficiency reducing.The flow loss mechanism of the sCO_(2) compressor operating at low flow rate is studied in this paper.Computational fluid dynamics(CFD) simulations for sCO_(2)compressor were carried out at various inlet temperatures and various mass flow rates.When the sCO_(2)compressor operates at low volume flow rate,the flow loss is generated mainly on the suction side near the trailing edge of the blade.The flow loss is related to the counterclockwise vortexes generated on the suction side of the main blade.The vortexes are caused by the flow separation in the downstream region of the impeller passage,which is different from air compressors operating at low flow rates.The reason for this flow separation is that the effect of Coriolis force is especially severe for the sCO_(2) fluid,compared to the viscous force and inertial force.At lower flow rates,with the stronger effect of Coriolis force,the direction of relative flow velocity deviates from the direction of radius,resulting in its lower radial component.The lower radial relative flow velocity leads to severe flow separation on the suction side near the trailing edge of the main blade.

关 键 词：supercritical CO_(2) centrifugal compressor flow loss mechanism Coriolis force 

分 类 号：TK14[动力工程及工程热物理—热能工程]