downcast and upcast shaft

[xiao]

Hi,

the mine which i have modeled works mainly with natural ventilation throughout autumn to spring, which means no main ventilators running during that time. It has also the same level of downcast and upcast shaft.

when I ran the simulation for the first time, Ventsim seemed to simulate the airflow oppositly. To avoild this, I added a fixed air temperatur to the upcast shaft. Is there a better way to run the simulation correctly?

[Martin Griffith]

Hi Xiao, 

When simulating with natural ventilation ONLY, then there can be some inconsistency in results; for example in some circumstances the flow may go in a certain direction only because it began in that direction before starting the simulation. 

Generally, we recommend turning on the natural ventilation option in a model only once you have a well-configured and reasonably accurate Heat Simulation, since ultimately the flow is driven by differences in air density, created by different temperatures. This would be even more important if it is a natural ventilation ONLY model.

For your model, I suggest reviewing your Heat Simulation. You will need to configure the Rock Strata heat correctly, as well as account for any heat sources from underground vehicles or equipment. I suggest the following thread for some tips on configuring the Heat Simulation: 

That would be the first step. Let us know how you go. Feel free to send through any questions or model. 

[xiao]

Hey Martin,

the surface data and rock property data are quite well defined under "Settings". The 20 year old small sized mine is now "on hold"  so there is rarely some traffic going on. 

The current ventilation direction comes from the first 5 (or more ) years of ventilation with the help of the main fans and now the fans are only needed in summer. But of course the model could't know the history.