Session: 10-01 Experimental Aerodynamics of Fans

Submission Number: 178547

Experimental Investigation of the Solidity Effects on the Aerodynamic and Acoustic Behaviour of a Low-Speed Shrouded Axial Fan 

This work investigates the influence of rotor solidity on leakage flow dynamics and noise generation in a low-speed axial fan equipped with a rotating shroud. The fan, designed for automotive applications, features a variable-geometry rotor that allows varying the blade count while keeping the blade shape and chord unchanged. This configuration enables isolating the effects of solidity under constant global operating conditions, volumetric flow rate and pressure rise, by testing blade numbers from 3 to 9, corresponding to mid-span solidities between 0.144 and 0.432.

The flow field in the tip gap region and its interaction with the main stream were characterized using Laser Doppler Velocimetry (LDV) and Particle Image Velocimetry (PIV), while far-field acoustic measurements were conducted in a hemi-anechoic chamber to evaluate the associated sound radiation.

The results show that varying the blade count modifies the characteristic curve, leading to differences in the maximum achievable pressure rise. Moreover, when scaled by the number of blades, the total-to-total pressure rise increases as solidity decreases. Variations in blade loading distribution significantly affect the leakage flow trajectory and its reingestion process into the rotor passages, resulting in substantial changes to the spectral content of the radiated noise. In particular, the sub-harmonic humps associated with leakage flow–blade interaction exhibit noticeable shifts in amplitude and frequency relative to the blade passing frequency.

Presenting Author: Matteo Dellacasagrande University of Genoa

Presenting Author Biography: Matteo Dellacasagrande is currently employed as research fellow at the University of Genoa in the department of Mechanical, Energy, Management and Transportation Engineering. His actual research activity focuses on turbine and compressor aerodynamics and experimental study of the aeroacustics of axial fans.

Authors:

Matteo Dellacasagrande University of Genoa
Edward Canepa University of Genoa
Andrea Cattanei University of Genoa
Alessandro Nilberto University of Genoa