02. Industrial Aerodynamics

Multi-copters (drones) have been introduced in indoor environments, such as inspections on the building construction site. There are upper walls including ceilings and beams. When a drone approaches the upper wall, a lifting force (thrust) rapidly increases, which is known as the ceiling effect . It can cause the drone to fly unstable or crash by colliding with the upper wall. The mechanism of the ceiling effect on the drone hovers near a fully-covered upper wall has been clarified. When the top surface of the drone's rotor is extremely close to the upper wall, an outward/inward swirling flow and a negative pressure region generates between the top of the rotor and the upper wall. The negative pressure region causes the thrust increase. Based on this thrust increase mechanism, although it has been confirmed that the developed rotor is effective in controlling the thrust increase when the rotor top is fully covered by the upper wall, the partially covered case such as steps has not been investigated. Therefore, we investigated the effectiveness of the developed rotor partially covered by the upper wall in controlling the thrust increase. Mainly, a fixed thrust test was conducted with the gap between the upper wall and the rotor and a cover ratio of the upper wall as parameters, a flow visualization near the rotor and a measurement of the upper wall pressure distribution were conducted. As a result, it is found that the developed rotor suppresses the thrust increase compared to the conventional rotor, even when the rotor is partially covered by the upper wall.