Abstract:
A multiple-disk Tesla type fan has been designed, tested and analyzed two-dimensionally using the conservation of angular momentum principle. Experimental results showed that such multiple-disk fans exhibited exceptionally low performance characteristics, which could be attributed to the low viscosity, tangential nature of the flow, and large mechanical energy losses at both suction and discharge sections that are comparable to the total input power. By means of theoretical analysis, local and overall shearing stresses on the disk surfaces have been determined based on tangential and radial velocity distributions of the air flow of different volume flow rates at prescribed disk spaces and rotational speeds. Then the total power transmitted by rotating disks to air flow, and the power acquired by the air flow in the gap due to transfer of angular momentum have been obtained by numerically integrating shearing stresses over the disk surfaces. Using the measured shaft and hydraulic powers, these quantities were utilized to evaluate mechanical energy losses associated with the suction and discharge sections of the fan. (c) 2009 Elsevier Inc. All rights reserved.
