A New Practical Approach to the Design of Industrial Axial Fans: Tube-Axial Fans With Very Low Hub-to-Tip Ratio

Abstract

This paper presents a simple but complete design method to obtain arbitrary vortex design tube-axial fans starting from fixed size and rotational speed. The method couples the preliminary design method previously suggested by the authors with an original revised version of well-known blade design methods taken from the literature. The aim of this work is to verify the effectiveness of the method in obtaining high-efficiency industrial fans. To this end, the method has been applied to a 315 mm rotor-only tube-axial fan having the same size and rotational speed, and a slightly higher flow rate coefficient, as another prototype previously designed by the authors, which was demonstrated experimentally to noticeably increase the pressure coefficient of an actual 560 mm industrial fan. In contrast, no constraints are imposed on the hub-to-tip ratio and pressure coefficient. The new design features a hub-to-tip ratio equal to 0.28 and radially stacked blades with aerodynamic load distribution corresponding to a roughly constant swirl at rotor exit. The ISO-5801 experimental tests showed fan efficiency equal to 0.68, which is 6% higher than that of the previous prototype. The pressure coefficient is lower, but still 12% higher than that of the benchmark 560 mm industrial fan.

Computational Fluid Dynamics Simulations of Aerodynamic Performance of Low-Pressure Axial Fans With Small Hub-to-Tip Diameter Ratio

“…The CFD predictions for the aerodynamic performance characteristics for this fan are shown in Figure 20. The predictions with both turbulence models show good agreement with measurements.…”

“…For fans with small κ, design approaches based on cascade analyses break down due to the significant radial redistribution of fluid. Design methods for fans with small hub-to-tip ratio κ are presented in [19,20].…”

Preliminary Design Guidelines for Considering the Vibration and Noise of Low-Speed Axial Fans Due to Profile Vortex Shedding

“…These parameters are typical for propeller-type fans [21]. Such propeller-type fans, where low-solidity is characteristic over a significant portion of the span, have been designed, for instance, by [22,23].…”

Design for high efficiency of low-pressure axial fans: Use of blade sweep and vortex distribution

“…Fairly good agreement was found between predictions and design expectations. Masi and Lazzaretto [123] in 2019 described design approach, integrating design ideas reported by Wallis et al [21,121] and Vad [122] for design of axial fans with high total-to-total efficiency η tt , where a mean-line model, described in Ref. [124], was applied to estimate the η tt of axial fans having constant swirl blade loading.…”

“…Design methods for fans with small hub-to-tip ratio κ are presented in Refs. [123,135]. For fans with a fairly large hub-to-tip ratio κ = 0.6 (and including diffuser blades) the influence of forward skewed blades with a prescribed vortex distribution on the aerodynamic performance of axial fans has been investigated in Refs.…”