Simultaneously measuring fluorescence and velocity in turbulent combustion

Detailed understanding of turbulent combustion phenomena is very important for developing high efficiency combustors that may contribute to resolving global environmental issues.

Since turbulent combustion involves strong interactions between fluid turbulence and combustion reactions, highly sophisticated measurement techniques for both fluid motion and flames are required to study the process.

Now, Mamoru Tanahashi and colleagues at Tokyo Institute of Technology have developed a simultaneous measurement technique for multi-radical planar laser-induced fluorescence (PLIF) and three velocity components of fluid in multi dimensions.

In this technique, dual-plane PLIF of CH radicals and single-plane PLIF of OH radicals have been conducted on three different cross-sections. The separation between each plane was very small (around 200 µm). Furthermore, wavelength-based dual-plane stereoscopic particle image velocimetry was performed simultaneously. The velocimetry measurement gives three components of the fluid velocity and nine components of the velocity gradients in a cross-section.

The measurement system developed was used to monitor a methane-air flame in a swirl-stabilized turbulent combustor. Turbulent flame has complicated three-dimensional structures that have not been theoretically predicted. The characteristics of local flame elements are closely related to those of fluid turbulence.

The advanced laser diagnostics used in these measurements will contribute to progress in turbulent combustion research, which will help in the development of high-efficiency combustors.

• Authors: Masayasu Shimura ¹; Takashi Ueda ¹; Gyung-Min Choi ²; Mamoru Tanahashi ¹ and Toshio Miyauchi ¹.
• Title of original paper: Simultaneous dual-plane CH PLIF, single-plane OH PLIF and dual-plane stereoscopic PIV measurements in methane-air turbulent premixed flames.
• Journal, volume, pages and year: Proceedings of the Combustion Institute 33, 775-782 (2011).
• Digital Object Identifier (DOI): 10.1016/j.proci.2010.05.026
• Affiliations: ¹ Department of Mechanical and Aerospace Engineering, Tokyo Institute of Technology. ² School of Mechanical Engineering, Pusan National University.
• Department website: http://www.3mech.titech.ac.jp/index_e.html

Schematic of the developed measurement system.

Three-dimensional flame structure.

Strain-rate effects in turbulent combustion.