# Speed by rotating parts

Question asked by Kristofer Skyttner on Oct 21, 2009
Latest reply on Dec 1, 2009 by Rich Bayless

Hello

I've been modelling an underwater vehicle in Flow Simulation and are trying to figure out how much I can simulate without going into Motion Studies.

I've been modelling a propeller in still water with 200rad/s rotation which results in about 2000 N force (Both global goal and surface goal on the propeller blades) in oposit to the flow direction. I assume that this force is how much the propeller would pull on the object it's attached to (correct?).

If this propeller where attached to a not very aerodynamic box and placed in a windtunnel (pipe/box with in and outlet boundary conditions), would a parametric study that would change the inlet flow until a global force of around 0 N is achived tell me the speed? Im thinking that the inlet flow to the windtunnel pipe would correspond to the speed of the model if the drag force of the flow is equal to the pull force of the propeller. Does this sound correct?

Would this approach work on a larger scale with multiple propellers on a large body to determine what underwater speed its capable of?

//Kristofer