Jet drop models for control of non-isothermal free jets in a side-wall multi-inlet ventilation system
Models for the jet drop distance of a free jet is presented for a side-wall multi-inlet ventilation system with 
adjustable flaps. The models are expressed in terms of the jet drop factor, which is a function of the inlet Archimedes 
number, the equivalent hydraulic diameter of the inlet opening and the inlet height above the floor. Jet drop models based 
on the room corrected Archimedes number are established for comparison. Measurements of non-isothermal jets were 
conducted in order to validate the models. Three identical pre-manufactured inlets with bottom hinged flaps and guiding 
plates were used in the experiments. The experiments were carried out in a full-scale room with floor dimensions of 5 m × 
11 m. The inlets were placed symmetrically in the inlet wall at a horizontal distance of 1.25 m between centers. The height 
from the floor to the top of the inlet frames was 1.9 m. The jet drop distances were determined for five operating pressures, 
three temperature differences, three inlet opening heights and two guiding plate angles above horizontal. The method for 
modeling the jet drop distance, as developed by Zhang et al. (1996) for a single wall inlet, is shown to be applicable to a 
multi-inlet system with three inlets. Using the room corrected Archimedes number instead of the jet drop factor gave similar 
results. In a ventilation control system, the jet drop distance may be used as a criterion for control of the inlets. The desired 
jet drop distance may be controlled indirectly by regulating the operating pressure and the inlet opening.