how mixing pressure Pm is calculated in gas ejector model of Matlab

how mixing pressure Pm is calculated in gas ejector model of Matlab

Answer 1

[Yifeng Tang]

This pm term is EVERYWHERE in the governing equations of the ejector. It's solved for implicitly to keep the system of equations satisfied. It's not "calculated" in a fashion that pm="some expression of other variables".

[Paris]

Hi Yifeng, is there an Simscape Example using an ejector? I am not sure how to connect ports A, B, and S nor how to save the outlet conditions.

[Yifeng Tang]

I don't remember seeing a shipping example. But it's not hard to make a simple test harness model. See attached. I just used reservoirs to set the pressures at each port.

The A port is the "primary" where the pressure is very high. The B port is the outlet at a much lower pressure. The S port is known as the secondary, whose pressure can be higher or lower than the B port but still lower than the primary port. The high pressure at the A port will lead to high velocity at the throat, which entrains the flow from the secondary port. I put some mass flow sensors in the model to show the mass flow throught each port.

[Paris]

Thank you very much!