Attenuation corrections for in-cylinder NO LIF measurements in a heavy-duty Diesel engine |
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| Authors: | K Verbiezen RJH Klein-Douwel AP van Vliet AJ Donkerbroek WL Meerts NJ Dam JJ ter Meulen |
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| Institution: | (1) Institute for Molecules and Materials, Applied Physics, Radboud University Nijmegen, Toernooiveld 1, 6525 ED Nijmegen, The Netherlands;(2) Mechanical Engineering, Eindhoven University of Technology, P.O. Box 513, WH 3.143, 5600 MB Eindhoven, The Netherlands |
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| Abstract: | Quantification of the nitric oxide (NO) concentration inside the cylinder of a Diesel engine by means of laser-induced fluorescence
(LIF) measurements requires, amongst others, knowledge of the attenuation of the ultraviolet radiation involved. We present
a number of laser diagnostic techniques to assess this attenuation, enabling a correction for laser intensity and detection
efficiency of the raw NO LIF data. Methods discussed include overall laser beam transmission, bidirectional laser scattering
(bidirectional LIF), spectrally resolved fluorescence imaging, and Raman scattering by N2. A combination of techniques is necessary to obtain the complete attenuation of laser beam and NO fluorescence. The overall
laser beam transmission measurements and bidirectional LIF measurements (the latter yielding spatially resolved transmission)
provide evidence of a non-uniform attenuation distribution, with predominant attenuation within or near the piston bowl. Fluorescence
imaging of multiple vibrational bands through a spectrograph is shown to be a powerful method for obtaining spatially resolved
data on the transmission losses of fluorescence. Special attention is paid to the role of CO2 and O2 as UV light absorbers, and the consequences to different excitation-detection schemes for NO.
PACS 82.33.Vx; 42.62.Fi; 33.20.t |
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