Fluidic force and wake velocity of 3D body with four limbs in uniform flow

Abstract

Robots that operate at a disaster site have been proposed and the dispatch of rescue robots to such site is required. However, discussion on the transport of these robots is insufficient. One method of transporting such robots is to use an airplane and the parachute. In order to safely drop these robots by parachute, it is important to investigate the aerodynamics characteristics of the robots in free fall before opening of the parachute. In the present study, the fluidic forces that acted on the robot and the wake velocities behind the robot were measured using a load cell and particle image velocimetry (PIV) in uniform flow ranges of 4 to 22 m/s. In addition, the bending angles of 30°, 45° and 60° were evaluated in terms of aerodynamic coefficients, streamlines and vorticity in the wake. As a result, changes in the fluidic forces were obtained due to the number of bending limbs. A vortex pair appeared in the wake, and the recirculation region became smaller as the number of limbs increases. In addition, the aerodynamics coefficient for the fluidic force in the z direction was a maximum at bending angle of 45° for the type-D of robot model with two limbs bent due to the vortex size and position in the bending-limb side.

Keywords

• three-dimensional bluff body
• fluidic force
• wake
• particle image velocimetry(piv)
• flow control
• aerodynamic coefficient