Multipoint temperature measurements in gas flows using 1-D laser-induced grating scattering

• Published in: Experiments in fluids Vol. 57; no. 12; pp. 1 - 9
• Main Authors: Willman, Christopher, Ewart, Paul
• Format: Journal Article
• Language: English
• Published: Berlin/Heidelberg Springer Berlin Heidelberg 01.12.2016; Springer Nature B.V
• Subjects: Arrays; Engineering; Engineering Fluid Dynamics; Engineering Thermodynamics; Fiber optics; Fluid- and Aerodynamics; Gas flow; Heat and Mass Transfer; Optical fibers; Photodiodes; Pressure effects; Research Article; Scattering; Spatial resolution; Temperature gradient; Thermocouples; Probe Beam; Internal Combustion Engine; Pump Beam; Pump Pulse; Nozzle Exit
• ISSN: 0723-4864; 1432-1114
• DOI: 10.1007/s00348-016-2282-x

A technique is reported for simultaneous, time- and space-resolved measurements of temperature using laser-induced thermal grating scattering, LITGS, from four points on a 1-D line. Signals from four separate points on the line, separated by 1 mm, in toluene-seeded nitrogen flows, were imaged onto a fibre-optic array and delivered to separate photodiode detectors to record their temporal evolution from which the temperatures at each point were derived with a spatial resolution of 1 mm and a precision of 0.7% at atmospheric pressure. Effects of variation of composition on the accuracy of the measurements were compensated by a calibration method providing good agreement with values inferred from thermocouple measurements. Temperature gradients at the boundary between parallel gas flows and at the surface of hot and cold surfaces were measured with a resolution of 5 K mm −1 . Extension of the technique to more measurement points and improvements in spatial resolution are briefly discussed.