Neutral plane

This paper analyzed the influence of neutral plane on natural ventilation in workshop. For several typical heights of neutral plane of a molding workshop, its influence on ventilation was simulated by means of CFD. In designing natural ventilation, to coordinate the dimensions between the inlet and outlet openings and to play down the neutral plane properly may be the effective measures to increase ventilation efficiency.

The buoyancy-driven natural ventilation of a room with large lower and higher level openings is investigated by both theoretical analysis and CFD simulation. Pressure-based formulae are developed for the prediction of the height of neutral plane and airflow rate, and three different flow modes are identified according to the position of the neutral level: (I) when the neutral height is at intermediate level of the lower opening; (II) when the neutral height has no intersection with openings; (III) when the neutral height is at the intermediate level of the higher opening.