Novel wall-attached multidirectional jets: Mathematical formulation, CFD modeling and experimental validation

Abstract

Achieving a healthy and comfortable indoor air environment has long been an objective of human endeavors. For a novel ventilation system, the wall-attached multidirectional jet pattern, the mathematical model describing the jet trajectory, temperature and velocity changes was first proposed to predict airflow attachment and separation moments from walls, covering a densimetric Froude number range from 0.5 to 4.0. Subsequently, this mathematical model was solved using a comprehensive numerical methodology and validated by full-scale experiments, which demonstrated that this established model could accurately depict the wall-attached multidirectional jet flow, with controllable errors — 16.4% for jet trajectory and 8.2% errors for jet axis temperature — when maintaining a supply velocity of 0.2 m/s. Also, the flow characteristics within a room featuring internal heat sources were analyzed, varying air supply velocities from 0.1 to 0.8 m/s and jet angles from 0° to 60°. Finally, this flow pattern of the wall-attached multidirectional jet was further confirmed and reproduced through CFD modelling which illustrated temperature stratification ranging from 18.1 °C to 25.2 °C, similar to the pattern observed in displacement ventilation. Present research could be valuable for the development of wall-attached multidirectional jet and the establishment of a healthy indoor air environment in practical applications.