Robin11112 Posted January 5, 2023 Report Share Posted January 5, 2023 I'm building a ventsim model that explains airflow when fan goes off According to the Ventsim manual model On: Fan is running, in this case fan pumps out 30m3/s of air Off: Fan dissapears, in this case, 25m3/s of air is flowing into the underground mine Auto Close: Fan exist, mechanical pieces create additional resistance. According to the manual, air flows to underground but less than 25m3/s. However, ventsim model shows airflow as 0m3/s. Real measurement data was 7m3/s of air is flowing into the underground Have anyone faced similar problem? Quote Link to comment Share on other sites More sharing options...
Martin Griffith Posted January 17, 2023 Report Share Posted January 17, 2023 Hi Robin, The autoclose option on the fan shuts off the flow entirely. If the autoclose option is not used, then it is completely open when the fan is off. In your case, the off fan is adding some resistance, but not shutting off entirely. If your simulation with the fan running is accurately predicting 30 m3/s, then in order to simulate the off fan, it would be valid for you to remove the fan and then add a resistance representing the off fan that reduces the flow to 7 m3/s. Note, that resistance that is added through the fan definition (Tools | Fans) will still be added when the fan is off. But if you add resistance, then you may have to adjust your fan curve, which can be difficult. Quote Link to comment Share on other sites More sharing options...
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