Scaling the performance of a miniature axial flow fan

• Published in: Sadhana (Bangalore) Vol. 48; no. 3
• Main Authors: Hiremath, Soumyashree A, Sivapragasam, M, Umesh, S, Deshpande, M D
• Format: Journal Article
• Language: English
• Published: New Delhi Springer India 19-07-2023
• Subjects: Engineering; Miniature fan; flow rate coefficient; scaling laws; pressure rise coefficient; hydrodynamic efficiency
• ISSN: 0973-7677; 0973-7677
• DOI: 10.1007/s12046-023-02204-1

The performance characteristics of a miniature axial flow fan are studied computationally by solving the Navier–Stokes equations. The fan performance is evaluated in the Reynolds number range
R
e
ϵ
[10
−3
, 10
7
]. It is shown that in the high Reynolds number regime the curves of flow rate coefficient
ϕ
versus the pressure rise coefficient
ψ
, flow rate coefficient
ϕ
versus the torque coefficient
τ
, and the flow rate coefficient
ϕ
versus the fan hydrodynamic efficiency
η
collapse well. In the low Reynolds number regime the pressure rise coefficient and the torque coefficient scaled by the Reynolds number lead to an excellent collapse of the performance curves. Further, from the computational results and enriched with scaling arguments, it is shown that for
Re
→ ∞,
ϕ
max
→ 0.378, and for
Re
→ 0,
ϕ
max
→ 0.083. The asymptotic limits for maximum pressure rise and maximum torque coefficients are also evaluated. Finally, the asymptotic limits for the maximum fan hydrodynamic efficiency
η
are obtained. They are: for
Re
→ ∞,
η
max
→ 0.400, and for
Re
→ 0,
η
max
→ 0.013. An expression for the maximum fan hydrodynamic efficiency in the entire Reynolds number range is presented which is free of Reynolds number as an explicit parameter. The results obtained in the present study will be useful in the scaling, design and testing of miniature axial flow fans.