ASHRAE ST-16-023

Abstract

Scope: This paper details experimental measurements and mathematical modeling of airflow through a perforated duct with an openarea of22%that is capped at the end.Measurementswere conducted on ducts with uniform diameters of 12, 10, and 8 in. (0.30, 0.25, and 0.20 m). All ducts were 20 ft (6.10 m) long, and inlet flow rates ranged from approximately 350 to 700 cfm (165 to 330 L/s). Flow rates were measured along the length of the duct using the pitot traverse method. The static pressure was also measured. The flow through the duct was modeled assuming one-dimensional flow, and a differential equation was derived using the mass, momentum, and energy equations. The resulting differential equation was solved numerically and the results were compared to the experimental measurements. Good agreement was achieved when comparing the experimental and model flow rates for all test runs with a maximum difference of 14.0% and an average difference of 2.0%. Results for the static pressure showed the same trends between the experiments and the model. The pressure was largest at the capped end of the duct, where the experimental measurements exceeded the model results by a maximum of 21.8%.