STUDY REGARDING THE GEOMETRY OF SOME PIECES USED IN FLAT-OVAL DUCTS

Abstract

Nowadays people spend increasingly more time indoors, which has led to higher expectations in terms of comfort and indoor air quality. In this respect, an important role belongs to the ventilation and air conditioning systems, which transport fresh or respectively, treated air. The agent is transported by means of large dimensions tubes, having circular, rectangular and more recently flat oval sections. From technical point of view, the flat-oval sections combine the advantages of the circular and rectangular types. Flat-oval tubes are less widespread in our country, which is the reason why the authors consider important to study the parts necessary for the tubing, such as various fittings and transition pieces. A complete study of these parts requires both fluid flow and geometric analysis. This paper presents geometrical solving of some pieces used for changing the flow direction such as elbows, branches or bifurcations. These parts, if are not suitable selected, can introduce local load losses, having as possible disadvantages increased energy costs and low reliability. Solving these pieces requires knowledge of descriptive geometry regarding cylindrical and conical surfaces, namely, plane sections, developments and intersections between cylinders.