Airflow and Water-Drop Trajectories at Instrument Sampling Points around the Beechcraft King Air and Lockheed Electra

Abstract

Due to distortion of airflow streamlines, flow velocities and droplet size distributions measured around a moving aircraft can differ from freestream conditions. This can complicate measurements made from aircraft platforms. Potential flow calculations were used to predict airflow characteristics and the spatial distribution of different-sized droplets around the Lockheed Electra L-188 and Beechcraft King Air-200 aircraft at a variety of instrument mounting locations. Large deviations from freestream conditions were found to occur at certain locations on both aircraft near the fuselage and in regions of strong curvature. The number concentration of droplets 100?200 µm in diameter is most seriously affected by flow distortion effects. Calculation results were in reasonable agreement with measurements at a forward mounting location on the King Air.