Hi, I'm trying to create some simple air plow system with pneumatics: pressure source-pipe1-pipe2-constant volume chamber. (two pipes ith different pressure losses, e.g. air filter and dryer). But it seems that Pneumatic are highly unstable: if I use just one pipe – everything works fine, but if I use two pipes (air filter and dryer) simulink crashes and produce crasy errors: one of them is like "chamber volume non-finite". Another strange thing – I built more complicated model: pressure source generates compressed air flow, air flows through two dryers, and then through three air filters. At first it didn't work. But after two rebuildings from scratch it work just fine, but (!!!!) after several simulations it crashed and never worked again. Is it because pneumatics is new in simscape or what?
MATLAB: Simscape pneumatics
pneumaticsSimscape
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There are two blocks in the Pneumatic Foundation library that allow you to add heat to the system. These are the Constant Volume Pneumatic Chamber and the Pneumatic Piston Chamber blocks. Both blocks have a thermal port, labeled H, which can connect to Thermal domain blocks.
If the heat is added to a variable volume of gas in an actuator, then you should use the Pneumatic Piston Chamber block. If the heat is added to a constant volume, e.g., a pipe, you should use the Constant Volume Pneumatic Chamber.
For the latter case, a pneumatic pipe can generally be modeled using the construct in the image below. It's very common to do this.
- Sebastian
In SimHydraulics, basic fluid properties such as density, viscosity, and liquid bulk modulus are assumed to be constant during simulation run. Their values are computed before the simulation depending on the specified temperature. All of them are assumed to remain constant with pressure changes except fluid bulk modulus. The bulk modulus of the fluid, which is treated as a mixture of liquid and non-dissolved gas, varies with pressure and this relationship is described in the documentation for the Constant Chamber block.
As a workaround, consider the following submission on MATLAB Central:
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