A Low-Turbulence Inlet (LTI) for Sampling Aerosols from Aboard Aircraft

Bernard Lafleur

Aerosol Research Group

Department of Engineering

University of Denver

Addressing global climate issues requires accurate in situ aerosol measurements by instruments flown on research aircraft, and the sampling of aerosols from aircraft is difficult primarily because of large differences between the respective airspeeds of the aircraft and the aerosol collection and measurement devices. Most inlets for aerosol sampling from aircraft use conical diffusers to achieve the required velocity reductions; however deposition of aerosols in conical diffusers was observed and attributed to strong flow turbulence.

Boundary-layer suction was applied to conical diffusers as a turbulence mitigation technique. The experimental results from laboratory tests of conical diffusers will be presented. Boundary-layer suction applied to a conical diffuser produces a strongly diverging laminar flow field and causes larger particles in the flow field to deviate from the streamlines. Therefore, Computational Fluid Dynamics is used to predict the changes in the ambient and measured particle distributions. Additionally, the engineering challenges of adapting the LTI for aircraft use will be covered.