I am trying to excite a relatively simple hydraulic circuit, using SimHydraulics. I want to cause frequency dependent perturbations to determine the stability of my system at certain frequency of excitation effectively I am trying to make a Bode plot by hand.
A snippet of the model is below
I have no problem sending a Sine wave to the control valve as shown below, the minimum of the control signal cause a 10% decrease in flow(855) when the valve remains in that position indefinitely, while the max of the control signal is the valve in a fully open position (flow = 950)
However because of the nature of a Gate valve the passage area is not linearly proportional to displacement of the valve, thus the pressure differential is not linearly proportional to valves displacement. Thus when I try to send I sine wave control signal I don't get a sine wave response in the flow or pressure. As shown below
ABS PRESSURE @ GAUGE SHOW ABOVE
FLOW @ GAUGE SHOWN ABOVE
What I am trying to do is cause a sine wave perturbation in pressure. What is the best way to do this?
- Is there a control valve which has a pressure differential response linearly proportional to valves position?
- Is there another way I can "dead head" the system, using another type of block to cause a pressure differential proportional relative to time. Which would mean I would just have to replace the gate valve but everything else would stay largely the same.
- Can I use a custom control signal to cause sine wave response in pressure using the valve I am currently using, if so how do you specify a custom equation? apposed to the sine wave disturbance I am using now
Andrew
Best Answer