Entrainment in a Free Jet Generated by a Positive Pressure Ventilator

Results of a simple flow model to describe the entrainment into the air cone created by a positive pressure ventilator (PPV) fan are compared to experimental data. Velocity profiles measured in the air cone of a conventional PPV ventilator are used. The entrainment coefficient and the cone angle were determined for the fan investigated. The correspondence between calculated and measured values is discussed and disparities explained. The findings from the tests are turned into practical guidance for the fire brigade and the advantages and limitations of the simplified model are discussed.