Perceptible airflow fluctuation frequency and human thermal response

In the past 60–70 years, a lot of thermal comfort studies have examined the effects of air movement on human comfort. Previous research has shown that besides air velocity and turbulence intensity, airflow fluctuation frequency is also important for the perception of thermal environment. In the current study, a dynamic air supply terminal was used to generate sinusoidally varying airflows with different fluctuation frequencies. Subjective climate chamber experiments were carried out at both 28 °C and 30 °C, and the results showed that the perceptible range of fluctuation frequency was between approximately 0.2 and 1.5 Hz. The subjective thermal response results indicated that airflows of 0.5 and 1.0 Hz had a stronger cooling effect on subjects. The air velocity fluctuating frequency identified in the present study confirmed previous findings and was around 0.5 Hz. The results also indicated that proper application of airflow fluctuation frequency could offset the 2 °C temperature increase from 28 °C to 30 °C. So when the air velocity is limited and cannot be elevated, airflow fluctuation frequency can be considered as another control factor to offset increased temperature in warm environment.

► A dynamic air supply terminal was used to generate different airflows.
► Perceptible range of fluctuation frequency was between 0.2 and 1.5 Hz.
► Airflows of 0.5 and 1.0 Hz had stronger cooling effect on subjects.
► Airflow fluctuation frequency can be used to offset increased temperature.