Modeling jet drop distances for control of a nonisothermal, flap-adjusted ventilation jet
1996
Zhang, G. | Morsing, S. | Strom, J.S.
In order to find criteria which can be used to control the trajectory of the air jet into a ventilated airspace, modeling the drop distance using the Archimedes number is proposed. The term "jet drop distance", defined as the horizontal distance from the inlet to the point where the jet reaches the occupational zone, is used to describe the status of the jet. Following an analysis of jet trajectory models for round inlet openings, jet drop distance models for a rectangular inlet with a bottom hinged flap are described. The models are functions of the inlet Archimedes number, the inlet opening hydraulic diameter and the inlet height above the floor. Two experiments on nonisothermal jets were conducted for modeling the drop distance. Premanufactured inlets were used in the experiments. They were of the same type but different sizes, with a bottom-hinged flap and a guiding plate on top. It is shown that the jet drop distance depends on the inlet Archimedes number, the inlet opening, and the inlet configuration. The minimum R-squared and the maximum mean squares values of a parameter estimation were 0.91 and 0.4, respectively. The models may be used to predict and control jet drop distances. The use of the models in a practical on-line control process is also described. In such a system, the jet drop distance is used as a criterion for control of trajectories, and desired drop distances of jets may be controlled indirectly by regulating the operating pressure and the inlet opening.
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