Both gives the negative pressure.

The constant fluid properties of Nitrogen was imported from the Fluent Database. I am using the default values in case of constant fluid properties case. (Ref Tem 298.15K).

However, changing the evaporation coefficient for Cavitation model changes it. If I change the evaporation coefficient from 0.25 to 0.7, the  Absolute pressure value changes to positive. However, the mass flow reduces from the 0.22kg/s to 0.16kg/s, which is not desirable. The experimental mass flow rate is 0.28kg/s. Therefore, the mass flow error increases if I use evaporation coefficient of 0.7.

If I reduce the evaporation coefficient from 0.25 to lower values, the absolute pressure near the throat becomes more and more negative.