transition between 2 cases in case structure

[Sjoerd Pater]

Hello!

Does anyone know if it is possible to make a smooth transition between 2 cases in a case structure. For me it is not desired that the cases change very sudden.

Hope someone can help.
\SJOERD

[johnsold]

Only one case executes each time the Case stucture is called. So a transition between cases really does not occur.

Can you post an example of what you are trying to do or give a more complete explanation?

Lynn

[Sjoerd Pater]

Thanks for the reaction!

Well, I want to control a combustion setup. Different expensive fuels are specified. I want to heat up the whole setup with cheap fuel and when that is done turn to the other fuel. The fuels are supplied by mass flow controllers, which need a set point and give a measured value to Field Point.

When I go from one fuel to another in a sudden way, the mass flow controllers (which are slow) may have difficulties in going fast to the set point. Which can cause extinction.

The fuels are specified in Case Structures in LabView and so it would be really nice if a smooth transition between 2 cases (fuel modes) would be possible.

If that is not possible, what would you suggest?

\SJOERD

[johnsold]

Sjoerd,

I think the problem is not the case statement but the flow controllers. Consider the following as a possibilty:
Case: Heat up = 100% cheap fuel
Case: Transition 1 = 75% cheap fuel + 25% other fuel
Case: Transition 2 = 50% cheap fuel + 50% other fuel
Case: Transition 3 = 25% cheap fuel + 75% other fuel
Case: Test Expensive = 100% expensive fuel.

Run the Heat up case until the desired temperature is reached. Then run the Transition cases for a time that is based on how fast your flow controllers can switch, perhaps a second for each case.

You can extend this concept for multiple test fuels.

Of course you will need check valves or other safety devices to prevent mixing of the fuels in the tanks or supply lines.

Lynn

[Sjoerd Pater]

Dear Lynn,

That might be a good option. I will give it a try and see if it works. Thanks a lot!

\SJOERD