HITEMP derived spectral database for the prediction of jet engine exhaust infrared emission using a statistical band model

Abstract

The spectroscopic database HITEMP 2010 is used to upgrade the parameters of the statistical molecular band model which is part of the infrared signature prediction code NIRATAM (NATO InfraRed Air TArget Model). This band model was recommended by NASA and is applied in several codes that determine the infrared emission of combustion gases. The upgrade regards spectral absorption coefficients and line densities of the gases H2O, CO2, and CO in the spectral region 400–5000 cm^-1 (2-25 um) with a spectral resolution of 5 cm^-1. The temperature range 100–3000 K is covered. Two methods to update the database are presented: the usually applied method as provided in the literature and an alternative, more laborious procedure that employs least squares fitting. The achieved improvements resulting from both methods are demonstrated by comparisons of radiance spectra obtained from the band model to line-by-line results. The performance in a realistic scenario is investigated on the basis of measured and predicted spectra of a jet aircraft plume in afterburner mode.