Solving such a problem with SWFS could be done only if you're prepared to do a workaround and some assumptions. On paper, it is not supported since Flow Simulation can't handle multiphase flows, being the jet stream the liquid phase and surrounding air the gaseous one.
Take this with a grain of salt, though: If you model the problem with a wall boundary around the stream, and prescribe a "sliding condition" on it, it could resemble the real thing rather well. This boundary should be modelled with certain degree of outward draft, just enough to minimize pressure readings on walls since the real thing is not radially constrained.
The thing is, a real jet stream does not cross the distance towards the vane undisturbed. Friction with surrounding still air slows down its outer layers creating a velocity profile which is not quite constant from jet axis.
Vane forces on Pelton´s depend almost entirely on fluid momentum changes so i think this could sort of work. Test it and show us how it went.
Thanks for the reply. That is unfortunate. I'm not quite sure if I'll be able to do that as another purpose of the study was to examine the angle of the reflected jet but that's not really possible if I'm choosing the direction when constraining it.
Unfortunately I think I'll have to use some other software. Thank you anyways!
If all you are looking for is the force on a Pelton turbine bucket a manuall calculation miohgt be the best place to start, if only to have a good estimate of the magnitude of the force. When modeling with Flow, start with a simplistic model that cannot fail so that you do not get too tied up with two phase flow which the solver cannot resolve. In other words, you may not be able to directly model a condition that involves two phase flow, but the proportion of the phase distributioon may not be significant (?).
Just start with a simple model and then increase the complexity until the "wheels fall off". Simplify the model to make the analysis work, and thenadd the complexity until the program no longer can provide a reasonable result.