Detailed experimental investigation of air speed field induced by ceiling fans

Comfort cooling by ceiling fans is cost-effective and energy-efficient compared to compressor-based cooling and fans are commonly used in tropical and subtropical countries. There are however limited data and design tools supporting the design of fan systems, especially for situations where there are multiple fans. In this paper, we investigate airflow profiles induced by a single fan and multiple fans using high spatial resolution air speed measurements (5,760 and 20,160 measuring points for the two cases respectively) in a climatic chamber. To authors' knowledge, this is the first time that interaction between multiple fans has been reported. We developed typical airflow patterns from the measurements and further validated them via smoke visualization. The single-fan results are consistent with previous studies of this configuration, providing additional refinements. For the multiple-fan case, both the difference of fan speed levels and the distance between the fans affect the interacting airflow profiles of the fans in complex ways. When fans are close enough, the combined air speed profile cannot be extrapolated from the profile of a single fan. All the measurement results are open sourced: raw data is included in the supplementary materials and can be visualized via an online platform (single fan, multiple fans). The data and the tool can be used to validate CFD models and inform fan layout design.