Evaluation of linear losses in ventilation ducts with a rounded rectangle cross-section

The paper presents a new ventilation system characterized by the cross-section of the channels in the shape of a rounded rectangle. The basic research problem was the determination of local losses in the system components. To achieve this goal, it is necessary to know the linear losses in the ducts. The principle of determining both types of losses was presented. The friction coefficients of linear pressure losses referred to the unit of the straight length of the duct section zeta(i)[m(-1)] as well as generalized dimensionless friction coefficient of linear pressure losses lambda[-]. is presented. The main achievement of the paper is the statement that the lambda coefficient lambda can replace the coefficients zeta(i) for all 79 examined duct cross-sections.