Azore® CFD advances the technology for fan array flow testing
By Robert Mudry, P.E.
A continuing trend in the HVAC industry is using a bank of fans (“fan array”) to supply flow for heating and cooling. Data centers, hospitals, clean rooms, manufacturing plants, wind tunnels, and many other applications rely on fan arrays for the redundancy, efficiency, and performance they offer over single large fans.
Manufacturers need to test their fans both fan-by-fan and as a system to characterize performance. In fact, the Air Movement and Control Association (AMCA) created a new standard for performance testing of fan arrays in 2023. This test protocol, “Laboratory Methods of Aerodynamic Testing Fan Arrays for Rating,” is denoted as AMCA Standard 270-23.
Typical fan array- Image courtesy of Q-PAC
An air flow measurement chamber, also referred to as an air flow tunnel, is used to test the fans and generate the flow vs. pressure rise curves (P-Q curves) that govern performance. These flow tunnels can be very large, with sophisticated instrumentation and components. The tunnels are required to be very accurate (<2% error), and thus careful design is critical to success.
The Azore CFD software was recently selected as the simulation tool to design the very first certified AMCA 270 flow tunnel. This tunnel, designed and supplied by Airflow Sciences Corporation (Livonia, Michigan), is capable of 70,000 CFM with a static pressure of 12 inches of water column. The tunnel has an overall size of 12'x12'x30' and can test fans at both positive and negative pressure (the AMCA “Figure 12” or “Figure 15” arrangements). Flow is supplied by 16 fans, and measurement is via a wall of 16 AMCA-style flow nozzles at the middle of the tunnel. Robotic actuators allow any of the nozzles to be open/closed automatically, allowing for flow rates ranging from 2,000 to 70,000 CFM.
CFD results for the AMCA 270 flow tunnel with 70,000 CFM capacity
The CFD modeling examined a wide range of operating conditions for the tunnel, ranging from 2,000 to 70,000 CFM and with a varied number of measurement nozzles in service.
Two key objectives of the tunnel design are flow uniformity over the cross section and accuracy of static pressure measurement at various test planes. Azore CFD was used to design the flow settling screens and other flow control devices to confirm the AMCA 270 requirements are met. Once the tunnel was built, Airflow Sciences ran field measurements to check the CFD predictions against reality. The results matched, confirming that the tunnel's accuracy meets both AMCA's standard and Airflow Sciences' own specifications, giving the industry its first fully validated AMCA 270 test facility.
Azore CFD results ensure that velocity uniformity requirements of the AMCA 270 standard are met
The following link features a video animation of the flow patterns generated by the Azore CFD user interface. https://share.airflowsciences.com/s/SRZjBw4coK3Wje9
According to AMCA personnel, the Airflow Sciences tunnel is the very first large flow tunnel in the world to be built and commissioned to meet the AMCA 270 standard for fan array testing. The tunnel, located at the Q-PAC headquarters in Elkton, Florida, has been operational since February 2026. Q-PAC, a manufacturer of multimotor plenum fans for commercial fans, uses this tunnel for product performance certification and R&D of new fan systems.
Q-PAC ACMA 270 flow tunnel, 70,000 CFM capacity, commissioned February 2026
Photos from the construction of the AMCA 270 flow tunnel
Azore Software, LLC, of Livonia, Michigan, USA, is the developer of the advanced CFD simulation package Azore. Since 2007, Azore has been a leader in accurate and affordable flow and heat transfer modeling for a wide range of industries. To learn more about how Azore CFD transforms fluid dynamics simulation, or to schedule a demonstration, visit www.azorecfd.com