A SOLUTION FOR EXPERIMENTAL MODELING THE AXIAL FANS WITH HIGH EFFICIENCY AND REDUCED NOISE

Present paper describes some experimental results obtained for modeling an axial fan with newly designed blade profiles, having high efficiency, low vibrations and noise. The axial fan was firstly designed by computational method, during a research project with our industrial partner SAVEB SA. One of the company objectives is represented by the production of the axial industrial fans, dedicated to different users to eliminate the smoke and the air pollutants from industrial halls, according to their specific needs. In the beginning, are presented some aspects of the theoretical aspects used in the numerical modeling for designing the rotor blades. Some considerations concerning the selection of the incidence angles of 10 degrees, 15 degrees, and 20 degrees are mentioned. The profiles were selected from the recommended schemes, for different industrial applications, as the industrial halls for the air or gas circulation without corrosive, abrasive, or toxic agents, metallic dust, or with crowding/sticking suspensions contents. For this type of axial fan, the content of suspensions should not exceed 50 mg/m(3). Further is presented the experimental stand, in conformity with actual standards, STAS 7466-84 and DIN 24163, equipped with a hydrometer with an error less than 3%, barometer with an error less than 1 mm Hg, stroboscope and tachometer with an error less 0,5% from the total rotation velocity, two voltmeters, with an error less 0,5, two wattmeters, etc. For the experimental tests was selected a fan with a diameter of 630 mm, which as standard execution has a maximum efficiency of 56%, in six different constructive variants: a rotor with 12 profiles and directory device with 11 blades, with 6 blades and directory device, etc. As the first variant of the rotor's profiles has been used two solutions for the realization as two technological options, both of them tested in the laboratory. There are detailed some schemes adopted for the measurements and tests, and finally the adopted solution for measuring different characteristic parameters like efficiency, noise, and vibrations produced by the axial fan. Next are illustrated part of the measurement reports and the corresponding charts. Of the total amount of experimental results were selected for measuring scheme III and IV for their optimum energetic characteristics and high efficiency. All four diagrams are presented for both selected solutions used in the realization of the fan rotor blades. Finally, some conclusions and references are presented.