AAAR 31st Annual Conference
October 8-12, 2012
Hyatt Regency Minneapolis
Minneapolis, Minnesota, USA
Abstract View
Computational Fluid Dynamics Analysis of High-Volume Inlets for Atmospheric Aerosol Sampling Application
IGOR NOVOSSELOV, Riley Gorder, Anna Gannet Hallar, Enertechnix Inc
Abstract Number: 479 Working Group: Instrumentation and Methods
Abstract A comparative analysis of five high-volume omni-directional inlets was performed using transient 3D Computational Fluid Dynamics simulations. The modeled inlets included:
1. Enertechnix size-controlled inlet
2. DOE Atmospheric System Research program inlet
3. Sphinx Observatory located in Jungfraujoch, Switzerland inlet
5. Original Storm Peak Laboratory inlet
5. Modified Storm Peak Laboratory inlet
Each of the inlets was placed in a numerical wind tunnel with varied wind speeds from 2.5-15 m/s. The sampling rate was set at 1000 lpm, which is typical for atmospheric aerosol sampling applications. The transmission efficiencies were evaluated for particles in the 10 nm to 20 µm range. Two different turbulence models (k-ε and detached eddy simulations) were used and the effect of particle – turbulence coupling on the transmission efficiency was examined. The modeling results show that for all investigated inlets the particle transmission decreases with the increase of particle size. This is due to particle inertial impaction on the inner walls of the inlets. Additionally the transmission efficiency decreases at higher wind speeds due to the formation of strong recirculation zones and unstable flow behavior inside the inlet geometry. The "Random Walk" turbulent dispersion model was used in the wind tunnel CFD simulations. The model has been previously validated for external flow application against experimental wind tunnel data for one of the modeled inlets and has shown good agreement, especially at wind speeds above 10 m/s. The turbulent dispersion model significantly influences transmission efficiency, especially for the larger internal volume geometries.