How to link generic piston engine and propeller SimScape

I am attempting to model the energy demand of a ship, I have built the following system using Simscape driveline blocks but am having issues getting it to run. I get the following error messages:

nable to satisfy all initial conditions. The variables involved are listed below. The following variables are involved in a constraint that conflicts with their targets: 'Generic_Engine.engine_inertia.w' (Rotational velocity) 'Propeller_Inertia.w' (Rotational velocity)

Both the propeller and the engine have inertia but it appears the model will not run with them both defined? How would I go about solving this? I am very new to the software but I think I have set the model up correctly. Below is a screenshot of the model as built:

If more information is needed I would be more than happy to provide, building this has been extremely difficult so I will take any help I can!

Thanks

Answer 1

[Steve Miller]

Hi Tom,

I see your model is an extension of example Ship Propeller. To get this warning to go away, I recommend you set the priority Initial Target for Ship Propeller inertia to "None".

The warning is trying to tell you that you have requested initial speeds for the engine and the gear that are not consistent with the gear box between them (they need to have the same relationship as the gear box ratio). When they are inconsistent, Simscape has to pick values that are consistent. If you set the priority for the Ship Propeller Initial Target to "None", then it will use the value specified for the engine inertia initial speed to set the propeller initial speed.

I have attached to this response my version of your model which runs without warnings.

--Steve

[Tom Garwood]

That is incredible. Thank you Steve!

[Tom Garwood]

Hi Steve,

I am having a further issue with regards to the generic engine block responding to throttle inputs. As you saw from the previous model I am using a simple constant input to the throttle. However when I run the model the output engine power drops from the value under initial conditions to zero. How would I solve this issue? I have attached an image of the scope output to show what I mean.

Thanks

Tom

[Steve Miller]

Looks like you stalled the engine. Try reducing the load or increasing the engine torque until it spins.

[Tom Garwood]

Sorry to keep pressing you on this one, but I'm still having no luck in inducing the engine to spin.

I have adjusted the load through reducing the propeller size and tried every value of throttle input from 0.1-1 in steps of 0.1. The power of the engine is based on a real-life example I am trying to simulate