It seems like Simscale is having trouble simulating my axial water jet engine. “Attempt 2 velocity in” will show that the pump I designed is working in reverse. There is a huge pressure increase IN FRONT of the rotor, not after the rotor. When I dropped the RPM to half the design RPM the pressure increased even more. When I ran a pressure in, pressure out simulation I got results that look more like a pump should look (pressure increase behind the rotor). I find this a little disturbing because I don’t know what data to trust. Did I really engineer a rotor that is so poorly designed that it works in reverse? Or should I trust the pressure in data? Another problem is that I need to know the flow rate that this pump generates and I am not sure how to get that data off of the pressure in/pressure out simulation. ggiraldof if you or any other engineer could shed a little light on this problem I would be very appreciative.
in order to your simulation setup and data to trust. In general when generating a pressure curve for the pump, you will work with a stagnation pressure inlet and fixed pressure outlet, so that the pressure difference for the pump is constant.
You can use either use a surface control item, or the statistics tool to measure the flow rate for this given RPM.
You can find more about result control items here:
So Pressure Inlet and Pressure Outlet? I have the parameters so this should be easy. And then using Area Average to get Uy (y in my case)? Uy gives the velocity?
yes, that would be my approach to this.
usually for pump curve, you don’t change the RPM just the flow rates
So either you would change the flow rates, which will give you a change in pressure, or change the pressure which will change the flow rate.
When changing the RPM you will get a new pressure curve for that RPM.
For data analysis you can also use a area integral which will automatically give you the flow rate.
