New Design of the Reversible Jet Fan

Abstract

This paper presents two designs of the axial reversible jet fan, with the special focus on the impeller. The intention was to develop a reversible axial jet fan which operates in the same way in both rotating directions while generating thrust as high as possible. The jet fan model with the outer diameter 499.2 +/- 0.1 mm and ten adjustable blades is the same, while it is in-built in two different casings. The first construction is a cylindrical casing, while the second one is profiled as a nozzle. Thrust, volume flow rate, consumed power and ambient conditions were measured after the international standard ISO 13350. Results for both constructions are presented for three impeller blade angles: 28 degrees, 31 degrees and 35 degrees, and rotation speed in the interval n = 400 to 2600 rpm. The smallest differences in thrust, depending on the fan rotation direction, as well as the highest thrust are achieved for the first design with the cylindrical casing and blade angle at the outer diameter of 35 degrees. Therefore, it was shown that fan casing significantly influences jet fan characteristics. In addition, the maximum thrust value and its independence of the flow direction is experimentally obtained for the angle of 39 degrees in the cylindrical casing.