[Sharan Brar]

Hello,

I am trying to simulate flashing flow conditions in a pipe. It is a 2-D simulation. Till now, I have used Mixture Model>Evaporation-condensation Model>Lee Model (with UDF for Saturation Temeprature and Eulerian Model>Evaporation-Condensation Model>Lee Model (along with UDF for saturation Temperature). The convergence for both of these cases are good with quite low residuals but, I am not getting chocked flow/flashing conditions i.e. the velocity of the vapour phase is not reaching mach conditions as we expect them to. I am using pressure inlet with 100 bars inlets pressure and 583.15 K Temperature and 1 bar at the outlet with backflow temperature set at 500 K. Moreover, I am using UDFs for both water and vapour materials property ranging from 275 K till 635 K saturation conditions.

What can I do so that I can have choked/flashing in the pipe and the velocities reach higher values. I am using SST k-omega model right now. Can someone give me some advice. I can post the images of the simulation set-up if required.

Currently, I am trying with Eulerian>Evaporation-Condensation>Thermal Phase change (didnot change the tuning factor) along with two-resistance model. The velocities are now reaching almost 290m/s as compared to 180-200 m/s of the previous models but still not as we expect. But, the residulas are quite high in this case.

Can someone please provide some suggestions and help me out.

Thanks in advance.