Experimental Study On The Relationship Between The Optimum Oscillatory Frequencies For Pulsatile Flow

As the basic structure unit of heat exchanger equipment, the characteristics of fluid mechanics and the mechanism of heat and mass transfer in 2-D and 3-D wavy-walled tube have been focused widely. The current experiments and numerical simulation works out the best Oscillatory frequencies for heat and mass enhancement in 3-D wavy-walled tube under different operational conditions, but the connection of the Oscillatory frequencies between different operational conditions have not been clarified. This investigation mainly focuses on the flow characteristics, the relationships between mass transfer enhancement and oscillatory frequencies under different operational conditions in 3-D wavy-walled tube. Through the obtained data of optimum oscillatory frequencies, the article also demonstrates the relationships between different optimum Oscillatory frequencies under different operational conditions, which provide references to the design of efficient heat and mass transfer equipment as well as the research of technique of heat and mass transfer. The details are as follows:Chapter 1 summaries the development of relevant researches of various scholars home and abroad. It elaborates the flow characteristics in different 2-D and 3-D channels under different flows. The present study shows that the research of 2-D and 3-D channels under steady flow is convincing, and the experimental results comply with the numerical results well; however, the research in 3-D channels under pulsatile flow appears less convincing than that in 2-D channels, it is yet to be improved and extended specially on determining the optimum operational conditions in 3-D channels.Chapter 2 introduces the experimental equipments, principles and related operation procedures. The experimental devices include wavy-walled flow system and electrochemical measurement system. Based on related theory of fluid mechanics, the experiment applies electrochemical technology to measure mass transfer rate.Chapter 3 demonstrates the optimum Oscillatory frequencies, and indicates the relationships between different operational conditions and optimum Oscillatory frequencies through analyzing the experimental results. The experimental results shows that oscillatory frequencies have a significant impact on mass transfer enhancement, it must exist an optimum oscillatory frequency that corresponds to the best mass transfer effect under different oscillatory fraction of the flow rate and net flow Reynolds numbers; Higher oscillatory fraction of the flow rate contributes to a better mass transfer enhancement, and it can obtain better effect for mass transfer enhancement under medium net flow Reynolds number; The optimum oscillatory frequencies show a decreasing linear relationship with Res under different oscillatory fraction of the flow rate, meanwhile, the effects of Res increases with oscillatory fraction of the flow rate increasing. The above results have an important guidance on actual operation of heat exchanger.Chapter 4 summarizes the achievement of this article. Chapter 5 points out the possible contents of future research.