Numerical Simulation and Optimization of Airflow Distribution Characteristics in the Air Distribution Chamber of a Needle-type Forage Dryer

To address uneven air supply among multiple needle tubes during the drying of high-density forage bales, this study investigated the airflow characteristics and structural optimization of the upper and lower air distribution chambers of a needle-type forage dryer. A three-dimensional CFD model was established, and airflow performance was evaluated using the velocity non-uniformity coefficient M and the inlet-to-outlet total pressure drop Δp. Response surface methodology was used to optimize the key structural parameters. For the upper chamber, installation of a T-shaped baffle and optimization of the cavity height Hc, diffuser angle α, and top-plate opening area ratio Ra yielded an optimal combination of Hc = ۱۳۳.۲۹ mm, α = ۱۲.۵۱°, and Ra = ۱.۱۲, reducing M from ۱۱.۲۲۶۴% to ۳.۳۸۸۶%. For the lower chamber, a strip-perforated airflow equalizing plate with Hb = ۷۴.۸۲ mm, D = ۲۳.۷۹ mm, and W = ۲۵.۰۳ mm reduced M from ۹.۸۷۷۲% to ۱.۵۴۸۴%, with Δp of approximately ۱۳۰ Pa. Mesh-refinement and turbulence-model sensitivity analyses supported the robustness of the numerical predictions. Repeated outlet-velocity measurements yielded mean absolute relative errors of ۳.۰۹%–۴.۵۸%. Smoke visualization and grayscale analysis further indicated that the optimized structures enhanced airflow diffusion and redistribution. The results provide guidance for air distribution chamber design in needle-type forage dryers.

کلیدواژه ها:

Forage drying ، Airflow redistribution ، Plenum optimization ، Computational fluid dynamics ، Response surface methodology ، Smoke visualization