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Why the volumic flow rate sensor (motion air) is registering a negative value?

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Karl Schaan
Karl Schaan le 3 Sep 2021
Hello,
I'm trying to modeling a Environmental Control System (ECS), where a DC Motor drive a Turbine (HVAC library). To do so I am using a 2-Port Constant Volume Chamber (MA). However, the Volumic Flow Rate Sensor (MA) is registering a negative value. The Pressure is 1.103 atm and the Temparture is 20 °C in the moist air network.
Is there a better way to model an ECS with the available Simscape resources? I have also tried to use the Rotational Mechanical Converter (MA) but it's the same problem.
I have attached the model.
Thanks in advance for any help.
Cheers,
Karl

Réponses (1)

Yifeng Tang
Yifeng Tang le 29 Juil 2022
As @VBBV mentioned in the comment, switching the A/B port is likely the solution.
Is this turbine block the same one as in theAircraft Environment Control System demo? If so, the flow is expect to flow into the A port when the R port has a positive rotation. I'm a bit confused by the A port of the turbine connected to "Out air" though. When air flows into the A port of the turbine, it's flow from the B port of the flow sensor to the A port. By the definition of the sign in this sensor, it's negative flow. In the documentation, it states: The relative orientation of ports A and B establishes the measurement sign. The sign is positive if flow occurs from port A to port B. Switching port connections reverses the measurement sign.

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