Temperature measurements under diesel engine conditions using laser induced grating spectroscopy

Journal article

Crank angle-resolved temperatures have been measured using laser induced grating spectroscopy (LIGS) in a reciprocating rapid compression machine (RCM) to simulate diesel engine operating conditions. A portable LIGS system based on a pulsed Nd:YAG laser, fundamental emission at 1064 nm and the fourth harmonic at 266 nm, was used with a c.w. diode-pumped solid state laser as probe at 660 nm. Laser induced thermal grating scattering (LITGS) using resonant absorption by 1-methylnaphthalene, as a substitute fuel, of the 266 nm pump-radiation was used for temperature measurements during non-combusting cycles. Laser induced electrostrictive grating scattering (LIEGS) using 1064 nm pump-radiation was used to measure temperatures in both combusting and non-combusting cycles with good agreement with the results of LITGS measurements which had a single-shot precision of ± 15 K and standard error of ± 1.5 K. The accuracy was estimated to be ± 3 K based on the uncertainty involved in the modified equation of state used in the derivation from the LIGS measurements of sound speed in the gas. Differences in the in-cylinder bulk gas temperature between combusting and non-combusting cycles were unambiguously resolved and temperatures of 2300 ± 100 K, typical of flames, were recorded in individual cycles. The results confirm the potential for LIGS-based thermometry for high-precision thermometry of combustion under compression-ignition conditions.

Authors: Forster, F; Crua, C; Davy, M; Ewart, P

• Publication status: Published
• Peer review status: Peer reviewed
• Publisher: Elsevier
• Journal: Combustion and Flame
• Publication date: 2018-11-01
• Acceptance date: 2018-10-12
• DOI: 10.1016/j.combustflame.2018.10.017
• EISSN: 1556-2921
• ISSN: 0010-2180
• Keywords: laser induced grating spectroscopy; thermometry; combustion diagnostics; diesel combustion