kevinbrighton@bigpond.com

There appears to be a problem in my model where custom airway profiles are not being retained, and the profile reverts to square after saving, or other random commands. Also some of the profiles in the edit box do not match the profiles shown in presets. Finally some of the custom profiles are being identified as 'invalid', when running a simulation. The model in question is a system model compiled from a few individual models, with a 'dwg' reference as a starting point. I've made sure the profiles are unique, i.e. say a section from one model does not overwrite a section from a different model with the same section name. Can you help please.

Okay Martin, I've done that. Regards, Kevin Brighton.

Thanks Martin, all of that noted. There is something going on with the model which I don't understand. With Jet fan turned off, the flow in that airway is 28.7 m3/s, which is about what I would expect. The input flow rate is 70 m3/s, and there are exhaust points upstream. Changing nothing else, if I turn the fan on the air flow in that airway goes to 263.4 m3/s, which violates continuity. Any ideas? Regards, Kevin Brighton.

This one has me stumped. Attached is a screen shot of a Jet Fan booster I've added to a design. The Jet Fan spec as entered gives 15.4 m3/s (21.5 kW) for flow, but when implemented and simulated the system returns 263.4 m3/s (24 kW)? Am I missing something? Regards, Kevin Brighton.

Okay thanks Martin I'll check that out.

Thanks Martin. Actually I've already tried a shock loss of 1, I'll try a higher one. Is there any sort of rationale I can use as a guide, so that I'm not just guessing?

Dear colleagues, I'm looking for some help with an application. I have flow along an underground longitudinal concrete lined cavern under construction, with vertical shafts of smaller cross sectional area. The latter are used for spoil removal and worker access etc. Looking at the simulation, most air escapes through the vertical shaft, which is driving me to add booster fans. However looking at the fan throw, my feeling is much more air should flow bypass the shaft, based upon it's momentum and the fact that is the boundary layer rather than the peak velocity that is open to the shaft. My research shows network models that account for the momentum, but what I'm really looking for is a sensible work around in Ventsim that I could use to tune the model. Thoughts?

Awesome thank you team for making that happen, it will reduce a source of frustration for sure. Best regards, Kevin.

Here's one from the archives, with all fans and ducting removed. It's simulating an underground excavation, the vertical sections are access shafts. If you pick either of the vertical sections and try and edit the end, it looses orientation. I know Ventsim was developed for mines, but it is used in civil construction so some user needs are a little different. Thanks for your help. Test.vsm

Thanks Martin. Attached is an example, the vertical duct simulates air flow through a penetration in the concrete slab above. When trying to draw it vertically, it has no rotational constraint so getting alignment is very difficult. I'm usually able to fluke it by a combination of adding ducts to the free end and using end edit. It's always time consuming. I recognise it doesn't matter a hoot from a simulation point of view, but makes presentations messy if it's not right. I'm using Ventsim, maybe HVAC would be better? Best regards Kevin Brighton.

Is there a way to constrain rectangular ducts when drawing vertically, to prevent uncontrolled rotation about the axis?

Ok sorted it. The coordinates update automatically when airways are inserted, but do not update to reference geometry.

I'm having difficulty changing the coordinates range of 1,000m in x and y in settings. My model is 2,000m long (rail layout). I change it, but it straight away defaults back to 1,000m. Thoughts?