Aerodynamic performance comparison of wind-driven turbine ventilators: A numerical investigation

Abstract

Wind-driven roof ventilator is a cost-effective and environmentally sustainable solution for improving indoor ventilation and reducing energy use. This study aims to compare the ventilation performance of turbine ventilators with curved and straight blades of various sizes, utilizing both computational fluid dynamics (CFD) methods and experimental validation. Additionally, a mathematical expression is derived based on the aerodynamic principles of turbomachinery. The results indicate that both types of ventilators exhibit two streams of rotating airflow and an upward airflow. The angular velocity and ventilation rate demonstrate an approximately linear increase with higher wind speeds, and ventilators with smaller outer diameters experience a greater rate of increase in angular velocity. Larger-sized ventilators, despite having lower angular velocities, achieve higher ventilation rates for geometries of similar proportions. However, it should be noted that reducing the throat diameter may result in inadequate ventilation rates. In general, straight blade ventilators outperform curved blade ventilators, yielding 10%–38% higher ventilation rates due to their lower flow resistance. The discharge coefficients for the former and the latter are 0.32–0.37 and 0.25–0.32, respectively. The derived mathematical expression based on aerodynamics agrees well with the simulation results, providing a means for predicting ventilator performance. The objectives of this study are to enhance understanding of the ventilation performance of two types of turbine ventilators, aid in the selection and design of wind-driven roof ventilators, and promote improved indoor ventilation and energy efficiency.