Performance of the University of Denver Low Turbulence, Airborne Aerosol Inlet in PELTI, TexAQS2000 and ITCT

The University of Denver Low Turbulence Inlet (DULTI) was flown on the NOAA P-3 in ITCT, the NCAR C-130 in PELTI and the NCAR Electra in TexAQS2000. This inlet delivered up to 220 lpm of sample flow at velocities of a few meters per second at the exit of the inlet. This flow was slowed from the true air speed of the aircraft (100 to 150 m/s) to a few meters per second in a short diffuser with porous walls. The flow in the diffusing section was laminar. The DULTI permits super micron particles to be sampled and delivered with high efficiency to the interior of the aircraft where they can be measured or collected. Because most of the air entering the inlet is removed through the porous medium, particles in the sample flow are inertially enhanced. Because these enhancements occur in laminar flow, they can be calculated using FLUENT. Enhancement factors are defined as the ratio of the number of particles of a given size per unit mass of air in the sample to the number of particles of that size per unit mass of air in the ambient. The same diffuser was used in PELTI (2000), TexAQS2000 (2000) and ITCT (2002). In this poster, the performance of the inlet in flight is compared with the calculated performance and enhancement factors are presented for flight conditions. The enhancement factors are found to depend upon the Stokes number of particles in the entrance to the inlet and the Reynolds number of the flow at the exit of the diffuser.