Thermo-fluid-dynamic characteristics of confluent jets for distribution of treated air in small environment

The diffusion of the air through nozzles and/or diffusers has been studied extensively thanks to the numerous examples of environmental conditioning systems and in general of systems in which the flow of matter escapes from particular openings. In this paper, we studied closed and small environments requiring thermo-hygrometric and ventilation control. Air jets are used to mix the treated air within the environment. The widespread diffusion of this technology, mainly conceived for large environments, justifies the characterization of a particular type of system realized by the authors. The first results of experimental tests carried out with a particular air conditioning system are showed in the present work. The particularity of the system consists in a low construction cost, possibility of modifications and operation according to the characteristics and needs to different agricultural species. This initial phase of the research related to the isothermal regime, allowed by the conditioning system, aimed to characterize the fluid-dynamic behaviour of the air diffusion systems realized with perforated surfaces. First tests were carried out in a specifically designed climatic room whose climate conditions are strictly controlled by a suitable control system under isothermal conditions. Moreover, an ad-hoc designed experimental device was used. It consists of a pantograph kinematic structure carrying the probes around in the fluid dynamic field. It allows measuring air velocity in different points in stationary or slowing enough transient conditions. The experimental data was used to validate the computational fluid dynamics (CFD) model to predict the internal airflow velocity distribution.