Flow through a pipe problem

 Register Blogs Members List Search Today's Posts Mark Forums Read

 July 25, 2002, 06:34 Flow through a pipe problem #1 Mark Wisom Guest   Posts: n/a Hi All, My problem is that I have a product that needs to be oil cooled and I have some CFD work that I haven't got a clue where to start. Basically I have a pipedblocked off at one end and a pump on the other end pumping oil in. Then there are a number of holes in the pipe where the oil squirts out of (into a chamber of oil at a different pressure). It's sort of like a garden sprinkler. Anyway I have to work out the velocites at which the oil comes out of these holes. We have modelling software but in reality there will be hundreds of holes in this pipe and we don't have the computing power for that. Any idea what hand-calculations I can do to get some idea of the velocities of the oil as it leaves through the holes. Thanks Mark

 July 25, 2002, 07:15 Re: Flow through a pipe problem #2 Thomas P. Abraham Guest   Posts: n/a Hello Mark, Try something like FLOWMASTER. This approach should not be too intensive computationally. Thanks, Thomas

 July 25, 2002, 10:03 Re: Flow through a pipe problem #3 Volker Guest   Posts: n/a Hi, For an easy hand-calculation, just take the flow rate of your oil and the total area of holes to calculate the average velocity. If your pipe isn't very long, the holes of the same diameter, the velocity in the pipe not too high and the surrounding pressure uniform, this should give you a reasonable result. If that is too trivial, you can try and simulate a segment of the pipe Hope that helps, Volker

 July 25, 2002, 12:18 Re: Flow through a pipe problem #4 babyface Guest   Posts: n/a Your case must be 3D which means time consuming. Try using the periodic BCs to reduce the whole grids Regards

 July 25, 2002, 13:20 Re: Flow through a pipe problem #5 Jim Park Guest   Posts: n/a You may find it useful to assume that the flow in the pipe is just that; parabolic pipe flow. That's essentially a one-dimensional analysis (pressure is constant across any section of the pipe). Solve the parabolic distribution with an unknown outflow velocity along the wall - to do this assume that the wall is uniformly porous. You can try assuming that the radial distribution of flow out of the pipe is uniform. Note that the assumptions are better if the pressure drop across the pipe wall is a large fraction of the overall pressure drop serviced by your pump. This is all pen-and-paper analysis. If you equate the mass flow through the (hypothetical) porous wall with the total flow through the holes [as suggested above], you should be able to work out an effective permeability to model flow through the wall as a function of the pressure drop. You can use this to express the pressure drop and flow across the wall as functions of the pressure drop along the inside of the pipe. Eventually, I think all the algebra leads to direct coupling of the supply pressure to conditions inside your low pressure tank. This removes the pipe and holes from the computational problem. The remaining problem of flow in the low pressure volume can be solved using CFD. The velocities you seek come from that solution. The devil's in the details. Good luck!

 Thread Tools Display Modes Linear Mode

 Posting Rules You may not post new threads You may not post replies You may not post attachments You may not edit your posts BB code is On Smilies are On [IMG] code is On HTML code is OffTrackbacks are On Pingbacks are On Refbacks are On Forum Rules

 Similar Threads Thread Thread Starter Forum Replies Last Post Sachin U. Nimbalkar FLUENT 4 January 2, 2014 13:20 Michiel CFX 17 April 21, 2010 10:14 keng Main CFD Forum 1 March 5, 2010 11:40 Min FLUENT 5 April 10, 2007 17:23 Tom Cloutier Main CFD Forum 0 April 20, 2003 13:19

All times are GMT -4. The time now is 10:18.