Design and Experimental Validation of a Ducted Counter-rotating Axial-flow Fans System

TL;DR

This study designs and tests a ducted counter-rotating axial-flow fans system, demonstrating significant efficiency improvements and flexible operation through experimental validation of various configurations.

Contribution

It introduces a novel design method for counter-rotating axial fans with pure axial discharge, validated through experiments showing enhanced efficiency and operational flexibility.

Findings

Efficiency is significantly higher than conventional fans.

System maintains high efficiency across a wide range of configurations.

Axial spacing has minimal impact on efficiency.

Abstract

An experimental study on the design of counter-rotating axial-flow fans was carried out. The fans were designed using an inverse method. In particular, the system is designed to have a pure axial discharge flow. The counter-rotating fans operate in a ducted-flow configuration and the overall performances are measured in a normalized test bench. The rotation rate of each fan is independently controlled. The relative axial spacing between fans can vary from 17% to 310%. The results show that the efficiency is strongly increased compared to a conventional rotor or to a rotor-stator stage. The effects of varying the rotation rates ratio on the overall performances are studied and show that the system has a very flexible use, with a large patch of high efficient operating points in the parameter space. The increase of axial spacing causes only a small decrease of the efficiency