Aerodynamic blockage is a comparatively simple parameter to measure and reveals important aerodynamic performance data. Aerodynamic blockage is directly related to the displacement thickness concept of boundary layers. It represents the fraction by which a flow passage is effectively “blocked” by the presence of the low momentum boundary layer regions. If an analyst knows the aerodynamic blockage, the boundary layer displacement thickness can be directly computed, and vice versa, if the boundary layers are uniform across the passage cross section.