Blockage Effects on the Aerodynamics of a Pitching Wing

The blockage effects on the aerodynamic characteristics of stationary wings have been extensively studied, both numerically and experimentally. However, the effects on flapping wing aerodynamics have not been fully explored. In this paper, the blockage effects on the aerodynamics of a pitching wing are investigated using a numerical approach. The flowfield is described by solving the Navier-Stokes equations on an overlapping grid. The wing motion is handled by a moving overlapping grid method. Force histories at different blockage ratios and reduced pitching frequencies are compared. Simulations show that the pitching motion can mitigate the blockage effects: the higher the reduced frequency, the more minimal the blockage effects. In addition, the sidewall effects are studied. It is demonstrated that sidewalls can lead to a strong spanwise variation in the flowfield, and the variation is further extenuated by the existence of a leading-edge vortex.