Session: 10-03 Design and optimization

Paper Number: 82245

82245 - Effect of Solidity and Aspect Ratio on the Aerodynamic Performance of Axial-Flow Fans With 0.2 Hub-to-Tip Ratio 

Aspect ratio and solidity play a complimentary role in the aerodynamic design of axial fan rotors blading. In fact, they quantify the distribution and volume of blade solid material which occupies the space enclosing a blade row. There are rather abundant references about the effect of solidity on the aerodynamic performance of low-speed axial fans, but most of them focuses on medium to high hub-to-tip ratio designs. Regardless the hub-to-tip ratio, there are very few references in the low-speed axial fan literature focusing on the effect of the aspect ratio and its interaction with blade solidity in terms of the fan aerodynamic performance. The paper deals with the selection of solidity and blade aspect ratio in the preliminary design of low-pressure industrial fans with minimum hub-to-tip ratio. The aim of the paper is to make available to the fan community experimental data that allow the extracting the optimum aspect ratio as a function of the blade solidity value.

To this end, the performance of three 315mm propeller fans designed according to a practical method suggested by the authors for very low hub-to-tip ratio tube-axial fans have been compared. In particular, the three industrial fans feature hub-to-tip ratio equal to 0.2 and were designed to match the same best efficiency operation with 4, 5, and 6 blades, respectively. Since the rotor blade solidity has been kept unchanged, three values of the aspect ratio were obtained. In addition, the prototypes’ assembly was conceived to allow operation with different blades count, i.e., with different rotor solidity at fixed blade aspect ratio. The aerodynamic performance measured in accordance with the ISO-5801 standard has been rearranged to extract the sensitivity and trend of the fan pressure and aeraulic efficiency against blade aspect ratio and solidity. The measured effect of blade aspect ratio has been compared to the findings available in the literature for higher hub-to-tip ratio fans and compressors.

Presenting Author: Piero Danieli University of Padova

Presenting Author Biography: ----

Authors:

Massimo Masi University of Padova
Piero Danieli University of Padova
Andrea Lazzaretto University of Padova