*4.1.2 Influence of the lip rounding*

**Figure 5** shows the distribution of the vapor volume fraction for different values of rc and for inlet pressure *pin* = 50 bar and L2/d2 = 5. **Figure 5** shows the important effect of rc on the creation of cavitation within the injector. When rc = 0, cavitation develops over almost 1/3 the nozzle length and the cavitation zone extends to the combustion chamber. The cavitation area attached to the wall will be reduced by increasing the rc radius.

In order to study the effect of rc/d2 ratio on the flow characteristics, the discharge coefficient is calculated for two values of Reynolds number Re and for L2/d2 =5(**Figure 6**).

There are two zones: the first zone for rc/d2 < 0.1 and the second zone for rc/d2 > 0.1. In the first zone, the coefficient of discharge varies linearly with inlet roundness for the two values of Re.

In the second zone, the discharge coefficient remains constant for any value of rc/d2. This result is consistent with the literature [35, 36].
