Experimental study on one-side confined jets from a parallel-flow outlet in a push–pull ventilation system

Abstract

This study conducted a series of experiments on the airflow characteristics of one-side confined jets from a parallel-flow outlet with a two-tier perforated plate and a honeycomb in a push–pull ventilation system. Maximum velocity, maximum temperature and airflow trajectory were analysed and compared with previous studies about different outlets. The results showed that the dimensionless turbulence coefficient of the parallel-flow outlet was smaller than either the cased axial fan with open grille’s or the swirl diffuser’s turbulence coefficients from isothermal condition. Different development laws for the parallel-flow outlet discharging a hot air jet ( Ar0 = 0.024) on the floor were put forward. Furthermore, it was found that the velocity decay rate of the hot air jets with a parallel-flow outlet on the floor was slower than with the circular aperture over a flat surface. When Ar0 ranged from 0.024 to 0.044, a semi-empirical equation was established to describe the trajectory of the hot jets from a parallel-flow outlet in a push–pull ventilation system. In addition, the baffle height of the suction outlet could be determined and corrected appropriately.