The Flow Field, Particle Distribution, and Determination of the Optimal Sampling Area around Aircraft
Abstract
Particle trajectories around an aircraft will change during a flight; therefore, analyzing particle distribution around the aircraft is necessary to accurately sample aerosols. Both computational fluid dynamics (CFD) simulations and wind tunnel experiments are employed to optimize the sampling zones around an aircraft. The wind tunnel model is the Harbin Y-12, similar to the Twin Otter and King Air. The aircraft head is taken as the coordinate original point. The coordinate X is parallel to the wings, the coordinate Y is parallel to the fuselage, and the coordinate Z is perpendicular to the fuselage. The results show that the closer the distance to the central line for the X direction is, the greater the velocity error is. A suitable position for sampling is under the fuselage because of low turbulence, convenient connection pipelines, and safety considerations. The shadow and enhancement zone area thicknesses gradually increase with increasing particle size. The shadow zone thickness under the fuselage is approximately 20, 70, 110, and 350 mm for particle sizes of 1, 10, 20, and 50 μm, respectively. The greater the distance from the aircraft head for the Y direction is, the smaller the velocity error is. The attack angle has no obvious effect on the flow speed at different positions. The CFD simulation results are in basic agreement with the wind tunnel experiment results. The optimal sampling zone is approximately 2300–6500 mm for the Y direction for the aircraft head, 250–500 mm for the X direction for the aircraft head, and 490–600 mm for the Z direction under the fuselage of aircraft.
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