June 09, 2003
PIPE FLOW MODELING SEMINAR HELD IN COLORADO
Another of AFT's regularly scheduled pipe flow modeling seminar's was held in Woodland Park, Colorado, last week, with attendees from as far away as Italy and Peru.
With the first two days covering AFT Fathom and parallel courses on AFT Arrow and AFT Impulse the last two days, attendees had the opportunity to cover multiple subjects during the week. Indeed, 80% of attendees in the AFT Fathom course did just that, also taking either the AFT Arrow or AFT Impulse course.
It's always interesting to talk with attendees about their piping system modeling applications and this seminar was no different. One of the most interesting came from Fiat Avio who use AFT Fathom to model test loops for the liquid oxygen pumps they manufacture for the European Space Agency's Arianne rocket.
Our next regularly scheduled seminar will be held Oct. 21-24, 2003. Complete information about this seminar may be found at http://www.aft.com/services/training/seminar.php?seminar=3.
Interesting Applications
BILL ORY ENGINEERING COOLING SYSTEM MODELING
Bill Ory of Bill Ory Engineering had been enlisted to advise on problems experienced with a Texas plant's induced fan oil cooling system. Bill started by building an AFT Fathom model of the cooling system consisting of 130' of 1-1/2" sch40 steel pipe, numerous bends and valves and the oil cooler. While the model verified the design should deliver the required cooling water flow of approximately 45 gpm, field data in conjunction with calibrating the model to this data indicated the cooler was only receiving about 14 gpm. Inspection revealed the problem to be caused by biological fouling in the supply piping.
When asked to quantify the extent of fouling by the plant operators, Bill provided two real world comparisons; one, what additional length of 1-1/2" pipe would cause this reduction of flow and two, what equivalent size of tubing at the original length would have the same effect. In the first example the line length of 1-1/2", clean pipe would have to increase from the actual 130' to 8,850' to cause this magnitude of flow reduction. Alternatively, the supply line would have to be reduced from a 1-1/2" pipe to 16 BWG tubing between 5/8" and 3/4" OD. These examples provided those with less hydraulics knowledge than Bill a real world indication of the magnitude of the fouling present.
This is an example of one of the many benefits of piping system modeling. Once developed, modifying the model to make investigations likes this is both easy and quick, and since AFT Fathom accurately models the interdependencies of all the components, the system wide effect of changing any variable is automatically captured. Tips -
SETTING THE WORKSPACE SIZE
All of AFT's piping system modeling software allows the user to set the Workspace size from the View menu. The Workspace Size window graphically displays the size of the Workspace as blocks. When a new model file is created the size is initially set to 1 x 1. If you're model is bigger than this, you'll need a bigger Workspace size.
Before changing the Workspace size it's worthwhile to remember how it relates to the model size. An analogy is a building and plot size, where the building is analogous to the model and plot size analogous to the Workspace size. A Workspace size much bigger than the model can be inconvenient because it makes scrolling around the model more difficult. Whenever a Workspace larger than 1 x 1 is selected, vertical and horizontal scroll bars will be displayed. To scroll half the distance in either direction you can simply drag the scroll bar half its travel. If the Workspace just fits the model size, this action will also scroll about half the distance along the model. If you're Workspace size is much bigger than your model, scrolling half the Workspace may place the model out of view (of course you can always 'find' the model easily by zooming out).
While you can always set Workspace size manually, there are a couple of automatic sizing functions to keep in mind. First, if you expand the size of your model beyond the present Workspace boundaries, its size will be automatically increased to accommodate the model. Secondly, if your Workspace size is excessively large and you want to reduce it, simply open 'Workspace Size' from the View menu and select the smallest size by clicking on the block in the upper left hand corner. The Workspace size will be automatically set to the minimum that will accommodate the current model size.
VIEWING OUTPUT ON THE WORKSPACE
You probably already know that you can quickly view a summary of the input data for any object in your model with the Inspection Window. Simply place the cursor over a pipe or junction and 'right click' your mouse ('left click' for you lefties).
Think how handy it would be if you could also see a summary of output information on the Workspace. You can and it's as easily done as viewing the Inspection Window by holding the 'ctl' key down as you right click.
P.S. - In case you didn't already know, holding the 'shift' key down while right clicking will display an object's status, including what information is still needed to define an object.