Perforated ventilation ducts .1. A model for air flow distribution

A model based on the energy and momentum equations was formulated to make predictions concerning air flow in performed ventilation ducts. It has the advantage of allowing direct measurements of the discharge and regain coefficients without the need to evaluate the frictional losses. The model includes the discharge angle in the calculation of the outlet air flow, and indicates that the discharge coefficient is constant over the length of the duct. The basic assumptions of the model are capable of validation by experimentally proving the equivalence of the frictional loss expressions derived independently from the energy and momentum equations. The unit values of the corresponding correction factors inferred from the model can be verified by experiments on turbulent flow in a duct. This forms the subject of a Part 2 paper. (C) 1997 Silsoe Research Institute.