The jet fan is a sort of axial fan mainly used in a longitudinal ventilation system for road, railway, metro and underground railway tunnel, where it is often hanged up overhead or laterally, needless of occupying traffic area or building an additional ductwork .. This is an economical ventilation means at the lowest installation and operating cost jet can be installed easily and maintained conveniently.
In operation, part of the airflow passing through the tunnel will be sucked in the jet and jetted out at high speed by means of fan impeller. As the jet from the fan diffuses, it transfers energy to the tunnel airflow and creates an increase in static pressure, which causes air to flow ahead. When the airflow velocity slows down to a certain value, the next jet fan unit along the tunnel will work, thus supplying fresh air on one side and extracting polluted air on the other.