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Heat exchanger fan pressure analysis

Hello,

I'm attempting to set up a simulation to see the suction pressures generated by a heat exchanger fan. I ran into an issue with setup that I could use some help with. I have very limited information on the heat exchanger itself (dimensions and CFM). Is there a way to have a set CFM or velocity through an outlet and have the inlet act as open atmosphere? My first attempt was to set the inlet on the atmosphere side and have the outlet at 0 pressure but this gave me the opposite of what I wanted, forcing air into the system rather than pulling it out the fan.

Thanks

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HyperMesh CFD

v2021.2

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acupro

Maybe an image/picture of the simulation domain would help us determine how to assist here. Generally, with a single inlet and a single outlet, specifying the known velocity condition (velocity, mass flow rate, volume flow rate) at the inlet is more robust. But it's a bit difficult to determine exactly what is the simulation you want to perform.

Erik Dahlman

Maybe an image/picture of the simulation domain would help us determine how to assist here. Generally, with a single inlet and a single outlet, specifying the known velocity condition (velocity, mass flow rate, volume flow rate) at the inlet is more robust. But it's a bit difficult to determine exactly what is the simulation you want to perform.

Sure. This is the setup I'm running. The idea was that the sides (currently marked inlet) would be open to atmosphere and the outlet would be pulling a set amount of air out of the system based on my known CFM. As I stated previously, this setup did not work since the result was forcing air into the system rather than pulling it out.

Thanks,

Community-Pasted-Attachment-1638396210595.png

acupro

Sure. This is the setup I'm running. The idea was that the sides (currently marked inlet) would be open to atmosphere and the outlet would be pulling a set amount of air out of the system based on my known CFM. As I stated previously, this setup did not work since the result was forcing air into the system rather than pulling it out.

Thanks,

While what goes in has to go out (for conservation) you will get different flow profiles depending on whether you specify those at the inlets or at the outlets. In this case, you could potentially specify a stagnation pressure inlet, and a standard outlet, then add a Surface Integrated Condition (I think under Advanced in HWCFD) for the outlets to set the mass flux (mass flow rate in kg/s). You may also want to move the domain boundaries farther from the entrance to the tubes, as that will have quite a lot of impact on how the fluid enters from the turns.