Numerical investigation on air distribution characteristics and effect of the outlet opening mode on cross-shaped column attachment ventilation

The conventional (square and circular) column attachment ventilation theory has been developed for many years. However, it is still unclear whether the cross-shaped column can be effectively applied to column attachment ventilation. This paper compared three column attachment ventilation models (i.e., circular, square and cross-shaped) by numerical simulation and experimental methods, the latter of which were mainly employed to verify and optimize the CFD model. The air distribution of these three ventilation models was studied in isothermal mode. Five cross-shaped column air supply outlet opening modes under cooling conditions were proposed, and their effects on the thermal environment distribution in the occupied zone were investigated. The intersection of the two attached airflows in the inner concave surface of the cross-shaped column changed the trends of the axial velocity variation. The attached airflow created a larger impinging zone near the internal corner of the cross-shaped column compared with the other surfaces. With the fixed air supply parameters, the kinetic energy loss at the column bottom under cross-shaped column attachment ventilation (CS-CAV) increased by approximately 60 % compared with that under square column attachment ventilation (S-CAV). CS-CAV is not only an effective ventilation method but can also meet the comfort needs of different occupied zones, providing a design basis for CS-CAV in buildings.