The present subject matter relates an apparatus (120) for distributing polyphasic fluid mixture to a catalyst bed in a downflow reactor (100). The apparatus (120) comprises a distributor tray (140) comprising a plurality of distributor units (150). The distributor unit (150) comprises an inner tube (210), an outer tube (220) disposed outside and concentric to the inner tube (210), a cover (346), a cap plate (350), and a gas inlet (358). The inner tube comprises a first aperture (314) to allow liquid to enter the inner tube (210) and a solid insert (326). The solid insert (326) forms a narrow passage (330). The outer tube (220) comprises a slot (338) to allow liquid from the distributor tray (140) to enter an annular portion (342).