# Butterfly valve transfer function

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Thread Starter

#### anthony

Can anybody advise me on how to establish a transfer function for a butterfly valve. I am trying to model a system using matlab/simulink but I do not know how to integrate the valve. I am controlling the pressure of airflow in a duct with a butterfly valve and an analogue electronic controller. The valve will be actuated via an electric motor and gearing. Is there a way to model the valve with respect to the properties/dynamics of the air flowing through it?

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#### jmGiraud

> Can anybody advise me on how to establish a transfer function for a butterfly valve. I am trying to model a system using matlab/simulink but I do not know how to integrate the valve. I am controlling the pressure of airflow in a duct with a butterfly valve and an analogue electronic controller. The valve will be actuated via an electric motor and gearing. > > Is there a way to model the valve with respect to the properties/dynamics of the air flowing through it? _______________________ In the first place, consider that a design should be correct. Therefore, the actuator influence is negligible. Very rarely, the pressure variations upstream of a butterfly affect the valve characteristic. What's left ? the valve characteristic response curve. There are bysides considerations that will modify. For a simple project: just ignore these. Finally and for starting the model, consider the butterfly is = % (equal percentage), i.e: exponential rising from zero flow as the valve starts opening. From almost any catalog, you will find the graph or you can plot flow v/s % opening. The exponential being 1 at x=0 then in your transfer function, written ...-1+exp(a*x). you will have to match 'a' to suit that particular valve you have chosen.