YDF2.4-A is a non-inducing fan duct, an air directional device, it is more than can be induced to form a fan spray flow guidance system. Injection nozzle from the induced orientation of fan unit, high-speed airflow, driving around the air flow duct is not needed under the conditions of the formation of an air supply to the exhaust from the directional airflow and ventilation to dilute indoor air pollution candle The purpose of