A study on the shielding effect of neck fan on air pollutants at the mouth and nose area

Wearable ventilation devices are expected to reduce individuals’ respiratory exposure levels in polluted environments. This study explores the performance of a neck fan equipped with dual vents using Computational Fluid Dynamics (CFD).

The neck fan provides clean air through side vents, which deflect along the face under the Coanda effect and form a clean air layer at the mouth and nose, reducing the impact of polluted air. The study analyzes the impact of different combinations of roll angles, pitch angles, and airflow speeds on protection efficiency. Results show that when the roll angle exceeds 30°, the Coanda effect becomes significant, forming an effective air layer. The pitch angle can change the convergence point of the two airflows from the neck side, thereby affecting the position of the clean air layer.

The airflow speed has a minor impact on the effectiveness of the neck fan when combined with appropriate roll and pitch angles. With a pitch angle of 45° and a roll angle of 30°, pollutant exposure reduction (PER) can reach up to 75.2%. This study provides effective and intuitive guidance for applying neck fans for protection in environments with air pollution or pathogens.