Entrainment Analysis Based on the Field Synergy Principle and Air Terminal Device Design

The degree of jet entrainment is affected by the exit conditions and thus affect the air terminal device design. While investigations of jet exit conditions have been carried out by experiments and simulations, it can be considerable advanced by the theoretical analysis. Effect of velocity profile and turbulence intensity at jet exit on jet entrainment are examined based on the field synergy theory by calculating the mass transfer field synergy number, that is the synergy between the velocity vectors and the species concentration gradients for a given jet flow rate. It showed that the entrainment increases with the increase of the mass transfer field synergy number, and vice versa. The mass transfer field synergy number can be changed by the boundary conditions to strengthen or weaken the convective mass transfer of jet entrainment. This work has resulted in a better understanding of the convective mass transfer phenomenon of jet entrainment and give a guide for air terminal device design. (C) 2017 The Authors. Published by Elsevier Ltd.