Experimental Studies on the Air Flow Characteristics Induced by a High Sidewall Grill in a Climate Chamber

Abstract

The air flow characteristics induced by discharging air into a climatechamber with and without a high sidewall grill were studied experimentally. Over five hundred and thirty thousand values of the air speed were collected at positions above the floor level, near the supply inlet and the exhaust outlet. The thermal comfort indices due to temperature and air speed were measured under five flow conditions, two with a diffuser and three without a diffuser. An evalua tion of thermal comfort using the air diffusion performance index (ADPI) and percentage dissatisfied (PD) was made. Macroscopic numbers describing the air flow studied were, the Archimedes number, the Reynolds number and the jet momentum number. The Reynolds number and the jet momentum num ber increased as the total supply flow rate increased. However, the Archimedes number decreased with increasing flow rates. The Archimedes number was found to be correlated with the Reynolds number, which might be because they are defined by parameters related to the air velocity V and temperature difference (T2 - T1). The ADPI was found to be linearly related to the jet momentum number and related directly to the PD. The throw of the diffuser was found to be related to the corrected Archimedes number. The jet momen tum number and Archimedes number are related to the air speed, the root mean square of the air speed and the turbulence intensity.