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Study on the characteristics of flow resistance under the condition of low frequency flow fluctuation

 LIU Yu-sheng1, GAO Pu-zhen2, TAN Si-chao3, and ZHANG Jia-jia4
 
1.        National Key Subject Laboratory of Nuclear Safety and Simulation Technology, Harbin Engineering University, Harbin, 150001 China (liuyusheng8866@163.com)
2.        National Key Subject Laboratory of Nuclear Safety and Simulation Technology, Harbin Engineering University, Harbin, 150001 China (gaopuzhen@hrbeu.edu.cn)
3.        National Key Subject Laboratory of Nuclear Safety and Simulation Technology, Harbin Engineering University, Harbin, 150001 China (tansichao@yahoo.com.cn)
4.        National Key Subject Laboratory of Nuclear Safety and Simulation Technology, Harbin Engineering University, Harbin, 150001 China (aijiajiahehe@yahoo.com.cn)
 
Abstract: The circulation of coolant in the cooling system of a nuclear reactor, under earthquake conditions, is a process of pulsating flow. When the fluctuating flow occurs in the loop, the fluid flow and heat transfer in the core are affected, making the study of flow fluctuation more important for practical applications.
Characteristics of flow resistance are investigated experimentally on a horizontal rectangular channel and a circular tube with a periodically fluctuating flow. The results are compared with the flow resistance characteristics of the steady state, showing that there is a relatively large difference between the results under a steady flow and a transient flow.
This article analyzes the influences of the flow fluctuation period and of the relative amplitude on the resistance characteristics of a circular tube flow. The results show that under the condition of flow fluctuation, a phase difference exists between flow rate and pressure drop. The results further show that the smaller the flow fluctuation period is, the larger the flow fluctuation relative amplitude will be, and the more influence the flow fluctuation will have on the fluid flow. Furthermore, an empirical correlation expressed as a function of the Reynolds number, the dimensionless frequency parameter, and the relative amplitude, is proposed for calculating a time-averaged friction coefficient.
Keywords: rectangular channel; circle tube; flow fluctuation; resistance characteristics
 
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