The influence of SiO2 nanoparticles on cavitation initiation and intensity in a centrifugal water pump

The main objective of this paper is to examine the effect of SiO2 nanoparticles on cavitation initiation in a centrifugal water pump. A backward-curved blade centrifugal pump with a nominal head and flow rate of 2.4 m and 12 l/min has been used. Furthermore, 7 nm SiO2 particles are added to deionized water in order to prepare the nanofluid with 0.1%, 0.4%, and 0.7% (ml SiO2/ml H2O) concentrations. The tests are also performed at three different temperatures (10 °C, 25 °C and 40 °C) to investigate the cavitation initiation and its intensity through the blade passages of the pump. The key parameters of this research are: (a) SiO2 nanoparticles concentration and (b) fluid temperature. Cavitation initiation through the blade passages is identified using two different methods: (a) visually observing the population of bubbles in the flow with a high speed camera and (b) pump characteristic curves analysis. Results show that SiO2 nanoparticles can effectively postpone cavitation initiation and notably decrease the cavitation growth rate. Moreover, it has been found that the bubble growth is reduced when increasing the nanoparticles concentration and this is more pronounced at higher temperatures.