Numerical Research of Thermal-Flow Channel Performance in Industrial Hot Air Blower
Abstract
This paper presents a systematic numerical investigation of the thermal-flow channel in an industrial hot air blower, focusing on the optimization of the connection structure between the outlet component and the heating component. The original rectangular straight transition connector, which introduces abrupt flow path changes causing flow separation and elevated localized pressure losses, is replaced by a circular-arc cylindrical transition structure (radius of curvature $\mathrm{R} = 300\text{mm}$) that provides smooth, continuous area change. A three-dimensional steady-state CFD model employing the SST k-omega turbulence formulation is developed and validated against the Gnielinski and Petukhov empirical correlations, achieving Nusselt number and friction factor maximum deviations of 5% and 2%, respectively. Further validation against published experimental data yields maximum discrepancies of 14% and 5%, confirming adequate accuracy. Exploiting 6-fold rotational periodicity, a 60-degree periodic sector model with 5,476,477 hexahedral cells and 12 near-wall inflation layers $(\mathrm{y}+<1)$ is constructed. Five inlet velocity conditions-30, 40, 50, 57, and 70 m/s-are systematically evaluated under uniform heating power of 1111 W per wire (3333 W total). Results reveal a characteristic trade-off between temperature rise and outlet velocity: lower inlet velocities (30-40 m/s) yield higher temperature rise (204 K and 154.6 K) but insufficient outlet velocity (34.15 and $41.17 \mathrm{m}/\mathrm{s}$); the $57\mathrm{m}/\mathrm{s}$ condition achieves an outlet velocity of 53.27 m/s, satisfying the 50 m/s target for the first time, with a pressure drop of 2286 Pa within the structural safety margin. The arc transition structure effectively eliminates flow separation and recirculation, reduces localized flow resistance, and enhances overall channel flow uniformity. The 57 m/s inlet velocity with the circular-arc transition is identified as the optimal configuration, providing a reliable basis for hot air blower flow channel engineering.