Experimental Study on Italian Regulatory Wind Tunnel: Performance Evaluation and Critical Aspects

The surge of atmospheric contaminants due to industrial and population expansion has led to increased public concern over olfactory annoyance, particularly in residential areas adjacent to agricultural, industrial, and waste management facilities. Characterizing passive area sources, which lack defined flows, in terms of odor emissions, represents a challenging task, exacerbated by the dual role of wind as both a dispersal agent and driving force for emission. Many sampling devices have been developed over the past decades. In particular, Flux Chambers have a mixed headspace and a non-directional flow, and Wind Tunnels have a directional flow that is predominantly parallel to the inspected surface. Besides the significant differences between the two devices, the issue is further complicated by the variety of designs proposed within the same family. Wind tunnel designs have evolved from large, portable hoods to compact versions to improve portability and fluid dynamic performances. In particular, Low-Speed Wind Tunnels have gained traction due to reduced dilution within the hoods. The aim of this study is to investigate the fluid dynamics and mass transfer of the current Italian regulatory LSWT, mentioned by the Italian legislation, with the purpose of highlighting its strengths and limitations. Fluid dynamic analysis on this device reveals non-homogenous airflow distribution within the hood, indicating the presence of a preferential channel in the central body of the wind tunnel. Mass transfer analysis demonstrates a concentration gradient along the outlet duct’s vertical direction, possibly affecting sample representativeness. Future developments may aim to achieve uniform flow and concentration distribution, ensuring accurate odor emission assessments from passive area sources.