CFD Online Discussion Forums - Interested in Biodiesel? Need CFD help please

Here's the scenario.. TOTALLY NON-PROFIT JUST FOR FUN PROJECT - CHECK OUT WWW.TDICLUB.COM FOR MORE INFO We are considering running biodiesel (a form of diesel fuel made from vegetable or fatty oils) in a new (2004 and newer) Volkswagon diesel engine. This engine uses a unit injector design capable of injecting at or near 2000 bar. Biodiesel has a slightly higher viscosity so we are curious to find out what happens to the injection pressure when running biodiesel. I would like to see the results of a simple model of a contracting volume of fuel(with a variable rate based on engine RPM) forced through a tiny orfice 0.205mm. You could just vary the volume of fuel and the rate of the volume change until you get a pressure of about 2000 bar - then change the viscosity to a higher value and just let me know what the approximate change of pressure is.

I would really appreciate your time if you could look into this for us. We do not want to exceed the maximum rated pressure of the injectors and would like to understand the physics of the process first.

Thanks in advance, Tony