UNIVERSITY OF MARYLANDFrom outlet to airflow
Chapters 3–4 / Air supply
How much detail does an air outlet really need?
An air diffuser can have a complicated shape. Jelena studied ways to represent the flow it produces without modeling every geometric detail.
What the work showed
The right simplification depends on the diffuser. In the tested configurations, merging jets needed a different treatment from an already combined jet.
Simplify the geometry. Keep the important airflow behavior.
Thesis PDF · p. 78Pick one of the eight diffusers tested
Nozzle diffuserBox method recommended
84 small nozzles, 11.8 mm across, in four rows of 21, all angled 40° upward.
- Airflow
- 3.0 ACH
- Discharge speed U₀
- 3.80 m/s
- Open area ε
- 7%
- Momentum methodMissed the recirculation next to the diffuser on every grid tried.
- Box methodA small box in front of the nozzles was the only method that predicted the flow near the diffuser correctly; agreement was “excellent”.
Why: As the 84 jets merge they lose about 14% of their momentum, so a method that conserves momentum at the outlet cannot follow them.
Read the nozzle results · p. 87