The uniformity of supply airflow is crucial in efficiently transporting fresh air to the target area and establishing a healthy indoor environment. However, connectors such as reducers in front of the air supply terminal disrupt airflow. Adding a rectifier device between the air supply terminal and connector is an effective approach to address this issue within limited installation space. Nevertheless, conventional rectifiers suffer from excessive resistance. This paper innovatively proposes a rectifier topology optimization method utilizing a dual-objective function, and optimally designs a novel low-resistance rectifier to enhance the uniformity of supply air. An experimental comparison between the topology optimization rectifier and traditional rectifier is conducted to validate the effectiveness. Numerical analysis elucidates the mechanism of driving performance enhancement in the topology optimization rectifier. The findings suggest that the topology optimization result is influenced by the number of outlets in the physical model and the weight factor of the dual-objective function. The topology-optimized rectifier improves supply airflow uniformity while reducing resistance, unlike traditional rectifiers that increase resistance. It reduces pressure drop at the inlet and outlet by 23%, enhances outlet uniformity by 59%, and mitigates the axial velocity decay rate compared to the case without a rectifier. Moreover, the rectification mechanism results from the tree-shaped bending structure of the topology-optimized rectifier, which evenly distributes airflow and minimizes reversion zones, thus decreasing energy dissipation. This study provides guidance for designing low-resistance rectifiers to achieve a uniform air supply.

The accumulation of pollutants in the recirculation zone can worsen ventilation. It is critical to reduce recirculation zones to improve the ventilation efficiency of buildings. However, the variation rule of the recirculation zone in a cylindrical confined space (CCS) is unclear, and there are few solutions to suppress or eliminate the recirculation zone at present. In this paper, an annular deflector orifice plate for suppressing the recirculation zone was developed based on the structural characteristics of the CCS. This device is simple in structure and can be used flexibly. Through experiments and numerical simulations, the variation rule of the recirculation zone length and the influence of structural parameters of the device on the vortex suppression were explored. Firstly, empirical formulas for calculating the length of the recirculation zone in the CCS were obtained. In addition, it was proved that placing the annular orifice plate inside the CCS effectively reduced the recirculation zone and improved the ventilation efficiency. Compared to the system without the annular orifice plate, the dimensionless length of the recirculation zone was decreased by 76.3%, and the time to completely discharge the pollutants from the CCS was decreased by 16.7%. Finally, parameters of the annular orifice plate that form the best vortex suppression effect were proposed: the porosity range was 40%–50%, uniform in shape with equal ring spacing, and placed more than one inlet diameter away from the inlet. The results help guide the ventilation design of CCS.