SAE_WCX19_paper_no_2019-01-0722.pdf (1.57 MB)
Download file

Cycle-to-cycle variation analysis of two-colour PLIF temperature measurements calibrated with laser induced grating spectroscopy in a firing GDI engine

Download (1.57 MB)
journal contribution
posted on 07.05.2020, 14:01 by Christopher Willman, Richard Stone, Martin Davy, Benjamin AO Williams, Paul Ewart, Li Shen, David LS Hung, Mengqi Liu, Joe Camm
In-cylinder temperatures and their cyclic variations strongly influence many aspects of internal combustion engine operation, from chemical reaction rates determining the production of NOx and particulate matter to the tendency for auto-ignition leading to knock in spark ignition engines. Spatially resolved measurements of temperature can provide insights into such processes and enable validation of Computational Fluid Dynamics simulations used to model engine performance and guide engine design. This work uses a combination of Two-Colour Planar Laser Induced Fluorescence (TC-PLIF) and Laser Induced Grating Spectroscopy (LIGS) to measure the in-cylinder temperature distributions of a firing optically accessible spark ignition engine. TC-PLIF performs 2-D temperature measurements using fluorescence emission in two different wavelength bands but requires calibration under conditions of known temperature, pressure and composition. Here the TC-PLIF technique is calibrated in-situ using high precision (<1%) LIGS point measurements. Temperature distributions were recorded during the compression stroke for fired operation with Direct Injection and with Plenum Fuel Injection of three two-component fuels containing toluene and iso-octane. Temperature inhomogeneity was observed for all fuels and injection strategies, with mm-scale regions having temperatures up to 10% higher than the local environment. Charge cooling of 3% due to direct injection was resolved. Proper Orthogonal Decomposition (POD) was used to quantify the cycle-to-cycle variation of the temperature data. Low-order POD modes featured most of the cyclic variation in temperature and the corresponding mode coefficients were used to investigate correlations with combustion analysis, fuel injection strategies and toluene content of the fuel. Additionally, the low-order POD mode coefficients provided an opportunity to identify cycles containing local hotspots or outlier measurements.


Engineering and Physical Science Research Council (EPSRC) UK

BP Formulated Products Technology

Jaguar Land Rover Ltd

Royal Academy of Engineering under the Newton Research Collaboration Programme (Distinguished Visiting Fellowship, DVF1415/2/10)



  • Mechanical, Electrical and Manufacturing Engineering

Published in

SAE International Journal of Advances and Current Practices in Mobility






1404 - 1419


SAE International


AM (Accepted Manuscript)

Rights holder

© SAE International

Publisher statement

This paper was accepted for publication in the journal SAE International Journal of Advances and Current Practices in Mobility and the definitive published version is available at

Acceptance date


Publication date


Copyright date



This article was presented at WCX™19, Detroit, MI, April 9-11, 2019.








Dr Joe Camm. Deposit date: 6 May 2020

Article number