experimental study on stall cell formation in high-wing commercial jet under take-off conditions

This study investigates the flow physics of a high-wing regional jet aircraft under stall conditions. the main aim of this research is to study the effects of nacelle-pylon configuration and trailing edge control surfaces on flow characteristics, particularly the formation of stall cells, during the takeoff and landing phases of the flight envelope. oil flow visualization techniques were employed to conduct experiments in a low-speed subsonic wind-tunnel at low reynolds numbers, with angles of attack ranging from 0° to 20°. the study also explored the influence of forced transition achieved by using trip strips, flow physics at different angles of attack, and two slotted trailing edge flaps with deflection angles of 15° and 40° on flow separation. results from multiple wind-tunnel tests revealed the existence of mushroom-shaped structures, knowns as stall cells, on the wing surfaces of the typical jet aircraft. the size and strength of these structures increased by increment of the angles of attack. additionally, the slotted flap effectively mitigated stall cell formation by injecting high-pressure flow through the slot and modifying the wing's effective camber line.