Effect of SiO2 nanoparticle size on initiation and intensity of bubble formation in a water pump

• Cavitation has been studied in a water pump with different sizes of SiO2 nanoparticles.
• Experiments are done in two sizes and three temperatures.
• Used methods: visually observing of bubbles and pump characteristic curves analysis.
• From both methods, increasing the SiO2 nanoparticle size reduces the extent of cavitation.
• Higher SiO2 size, lower cavitation and it is more noted at higher temperatures.

The objective of this paper is to examine the effect of SiO2 nanoparticle size on cavitation in a centrifugal water pump. In this study a backward-curved blade centrifugal pump, with maximum capacity of 12 l/min and maximum head of 2.4 m is used. The size of nanoparticles and the temperature are considered as key parameters. 7 nm and 14 nm SiO2 particles with the same density of 2143 kg/m3 are added to distilled water to prepare constant concentration of 0.1% (ml SiO2/ml H2O). Furthermore, the experiments are achieved at three different temperatures of 10 °C, 25 °C and 40 °C to investigate the effect of fluid temperature on cavitation initiation and intensity for these two sizes of nanoparticle. This study is attained by two methods: (1) Visual observation of bubbles population in the flow; (2) characteristic curve analysis. Results show that the intensity of the bubble growth is reduced with increasing the size of nanoparticles notably. This effect is more pronounced at higher temperatures. Therefore, it can be concluded from both methods that cavitation initiation can be well postponed by increasing the size of SiO2 nanoparticles.