Identifying the optimal blade number for an aerodynamic heater using RANS

Aerodynamic heaters are ubiquitous in industrial processes such as preheating, dehumidification and drying. Despite their broad application, the influence of the number of blades mounted on the impeller on thermal performance has not been adequately quantified. This specific concern is addressed here using computational fluid dynamics (CFD) based on Reynolds-Averaged Navier–Stokes (RANS) equations, supported by prototype experiments for model validation. The results reveal that increasing the blade number enhances temperature rise, markedly in the volute region, where the temperature for the 16-blade configuration exceeds the average by more than 10 K. Plane regression visually characterises the intricate interaction between airflow velocity, temperature and turbulence dissipation. The heater’s thermal efficiency and heat flux density peak at 16 blades, achieving a thermal efficiency of 75.85%, representing a 12.59% improvement over the average. Entropy analysis further confirms that the optimal blade configuration minimises thermal losses, offering preferable balance between heating performance and efficiency. A robustness test performed for a slightly modified blade geometry, where the windward sidewall curvature is flattened, verifies that the identified optimal blade count remains valid within the tested design space. The proposed composite performance index, J ( N ) , which integrates multiple performance metrics to identify the optimal blade configuration, offers an extensible framework for performance evaluation in aerodynamic heaters with major geometry changes, supporting energy-efficient design in broader industrial applications.