AAAR 31st Annual Conference
October 8-12, 2012
Hyatt Regency Minneapolis
Minneapolis, Minnesota, USA
Abstract View
Characterization of Soot Particle Deposition Rates and Optical Effects
DE-LING LIU, Stephen Didziulis, Jesse Fowler, The Aerospace Corporation
Abstract Number: 755 Working Group: Combustion
Abstract Concerns were raised for potential spacecraft contamination inside a launch vehicle payload faring (PLF) from soot particles created in the rocket ignition plume. Soot particles could be ingested through the leak paths in PLF envelope, which in turn poses contamination risk to spacecraft optics, solar cells, and thermal control surfaces. To gain a good understanding regarding the potential risk due to soot particle ingestion, analyses and laboratory experiments were performed to determine soot deposition rates onto surfaces and the light absorbing characteristics of the deposited species.
A test setup consisting of a cylindrical chamber as a PLF simulator was constructed to examine the behavior of soot particle deposition. Soot particles were generated and introduced into the chamber. After the soot generation source ceased, the particle size distribution as a function of time was determined using an aerodynamic particle sizer (APS) and a scanning mobility particle sizer (SMPS). Light weight fused silica substrates were placed inside the chamber for soot particle deposition, and their light transmission spectra from 200 nm to 2000 nm were characterized ex situ as a function of deposited soot mass. The measured particle deposition rates spanned from 0.03 h-1 to 0.2 h-1 for particles of 0.04 to 2.5 micron, in agreement with the literature data. Soot particles were found to cause significant light absorption in the wavelength region of 200 to 300 nm, likely attributed to semi-volatile organic compounds adsorption/condensation on the surfaces of soot particles. The experimentally determined deposition rates in comparison of the time scale of launch ascent, and optical effects of soot particles provide some insights into the potential impact of soot particle contamination as a result of launch plume ingestion.