# A Review on the Erosion Mechanism in Cavitating Jets and Their Industrial Applications
## 3 Erosion Mechanism in Cavitating Jets
### Effect of Fluid Temperature  
The other important parameters which affect cavitation erosion are fluid properties and particularly, its temperature. The temperature effect on cavitation was studied in [57; 58; 59; 60]. [PERSON] et al. [61] found that the erosion rate increases with the water temperature and reaches a peak before decreasing. The peak is about the average of the freezing and boiling relative temperatures. The erosion rate increased by 1% per 1 \({}^{\circ}\)C between 5 and 45 \({}^{\circ}\)C of relative temperatures, and decreased by 2% per 1 \({}^{\circ}\)C between 45 and 80 \({}^{\circ}\)C. The experiments were conducted at an upstream pressure of 17.4 MPa and a cavitation number \(\sigma=0.015\). The mass loss vs. exposure time at different temperatures is shown in Figure 12 for pure copper samples. It can be seen that for all temperatures, the incubation period is about 15-20 min and the maximum erosion rate (local slope) is achieved at 40 \({}^{\circ}\)C.  
Similar results were found by [PERSON] et al. [62] using deionized water. In this study, cavitation erosion tests were conducted using silver plated coatings at a constant cavitation number of 0.03. The results for mass loss rate are shown in Figure 13. Relative temperature in this figure is equal to (test temperature-melting point)/(boiling point-melting point). It can be seen that for ethanol, the temperature that corresponds to the maximum mass loss rate is higher than that of deionized water.  
It is more complicated to generate cavitation at low temperatures (close to 0 \({}^{\circ}\)C for water) but the bubble implosion is much more violent. The quantity of cavitation bubbles increases with temperature, but the implosion energy decreases. The decrease in the  
Figure 11: Erosion pattern vs. angle of attack [52].  
Figure 12: Mass loss vs. exposure time at different temperatures [61].  
implosion at elevated temperature (close to 100 \({}^{\circ}\)C for water) happens because of the bubbles' inability to trap vapor inside them, their volume grows and they implode. An ideal balance between quantity of the cavitation bubbles and implosion power is achieved at 40-50 \({}^{\circ}\)C [63].  
A summary of the jet and flow parameters for different studies is presented in Table 2.  
\begin{table}
\begin{tabular}{c c c c c c c c} \hline \hline \multirow{2}{*}{**Study**} & **Cavitation** & \multirow{2}{*}{**Nozle Type**} & **Standoff Distance** & **Attack** & **Nozzle’s Surface** & \multirow{2}{*}{**Temperature**} & **Fluid** \\  & **Number** & & & & & & \\  & & & & & & & \\  & & & & & & & \\  & & & & & & & \\  & & & & & & & \\  & & & & & & & \\ \hline \multirow{2}{*}{[PERSON] et al. [44]} & 0.01- & organ-pipe & 25–30 nozzle’s diameter & jet is normal & 0.8, 1.6, 3.2, 6.3 & & & \\  & 0.0017 & self-resonating & (diameter 2 mm) & & & & \\  & & & & & & \\  & & & & & & & \\  & & & & & & \\  & & & & & & & \\  & & & & & & \\  & & & & & & \\  & & & & & & & \\  & & & & & & \\ \hline \multirow{2}{*}{[PERSON] et al. [52; 53]} & 0.04–0.014 & cylindrical & nozzle & \(\approx\)47 nozzle’s diameters & \(105^{\circ}\), & & & \\  & & & & & & \\  & & & & (timtim