Study on the Influence of Loading Rate on the Cascade Characteristics of Nanofluidic Systems

Abstract

The energy absorption density of the nanofluidic energy absorption system (NEAS) is much higher than that of traditional energy-absorbing materials. An NEAS based on different pore size combinations may exhibit cascade characteristics, which can achieve energy absorption of different grades. In this work, two NEAS models based on carbon nanotubes are constructed, which are DNEAS and SNEAS. In DNEAS, two tubes with both ends immersed in a water reservoir are used. In SNEAS, two tubes are connected end to end, with the end of the bigger tube immersed in the water reservoir. The effects of loading rate coupled to pore size on the infiltration processes of water molecules into two models were investigated. The fitting correlations between the critical pore size difference and temperature were established. It has been observed that an increase in loading rate will transform a single-stage system into a multistage system that displays cascade characteristics. The critical pore size difference for the system to display cascade characteristics decreases with an increase in the loading rate. In DNEAS, the infiltration processes of the large and small tubes are independent of each other, and the effect of the loading rate on energy absorption characteristics is the superposition of that of the corresponding single tube NEAS. In SNEAS, the water molecules fill up the bottom tube before infiltrating the top tube. The influence of the effective viscosity change caused by loading rate on infiltration pressure is greater than that of hydrogen bond loss during the entry of water molecules into the bottom tube. The critical infiltration pressure as well as the total energy absorption of the top tube in SNEAS were higher than that of the corresponding single tube NEAS. The research findings have expanded the fundamental database of cascade nanofluidic systems and offer valuable insights for the application design of such systems.