Design and Development of Nested Inlet for Sampling Stratospheric Aerosol (NISSA) for Effective Reduction of Turbulence in Aircraft Aerosol Measurements

NAGARAJAN RADHAKRISHNAN, Sreekesh Kookkal, Suresh Dhaniyala, Clarkson university

     Abstract Number: 184
     Working Group: Planetary Aerosols: From Earth to Exoplanets

Abstract
The sampling of aerosol particles in the stratosphere for studying size distribution, concentration, and chemical composition often encounters challenges related to turbulence during aircraft-based measurements. This study proposes a design and development of a Nested Inlet for Sampling Stratospheric Aerosol (NISSA) aimed at mitigating turbulence effects for more accurate aerosol sampling. NISSA utilizes a nested mechanism incorporating two distinct inlet sizes to efficiently reduce turbulence during aircraft aerosol sampling. The first section of NISSA acts as a shroud and ensures that sampled flow is unaffected by the aircraft angle of attack. The second section acts to isokinetically sample flow and the reduce its speed without increasing flow turbulence. The final sample section is designed to sub-sample isokinetically from the slowed down flow and enable turning of the sample flow and bring it into the aircraft plumbing. The inlet design was partially based on previous inlet geometries, including the NCAR HIMIL inlet and the final geometry was established based on results of parametric modeling of inlet sampling performance. The parametric computational fluid dynamics (CFD) modeling of this inlet was performed using the K-omega turbulence model in ANSYS FLUENT and integrating the flow modeling results with a new turbulent particle trajectory model developed in our group. We will present final inlet design, details of inlet modeling, and predicted performance characteristics of NISSA under a range of aircraft sampling conditions in the stratosphere.