Scale-model Study of Airflow Characteristics in Non-isothermal Ceiling Slot-ventilated Enclosures

Abstract

Airflow characteristics in non-isothermal condition are more close to the realphenomenon than in isothermal condition. Air-jet issued from ceiling slot is a two-dimensional planewall jet which affects room environmental quality. Scale-model study of a non-isothermal ceiling slotventilatedenclosure was investigated in both airspeed field and thermal field. Results of airflowpattern, centerline velocity decay, centerline temperature decay, airflow boundary layer growth,thermal boundary layer growth, velocity profile, and temperature profile were regressed or analyzedto establish semi-empirical prediction equation. The results also compared with previous research tovalidate the physical behavior of air-jet. Data of centerline velocity decay showed similar airflowcharacteristics as isothermal air-jet with Ar < 0.004, which performed as pseudo-isothermal airflow.The centerline temperature decay was regressed well as the form of Li et al.s (1993) results. Airflowboundary layer growth was agreed better with Rajaratnams (1976) conclusion and the thermalboundary layer growth was fit both Albright and Scott (1974) and Wilson et al.s (1970) results. Boththe velocity profile and temperature profile agreed with the results of literatures. Analysis of airflowperformance in non-isothermal condition make progress in predicting air quality inside the enclosuresand guide the design concepts of ventilation system in animal houses.