Temperature measurements in flames

A non-invasive infrared (IK) method has been developed for the measurement of temperatures of small moving fuel droplets in combustion chambers. 7111 The IR system is composed of two coupled off-axis parabolic mirrors and a MCT LWIR detector. The system was used to measure the temperature variations in a chain of monosized droplets generated with equal spacing and diameter (200 pm), moving at a velocity of >5 m/s and evaporating in ambient air. The system was also evaluated for droplet temperature measurements in flames under combustion conditions. 

Hughes, P. M., Parameswaran, T, and Lacelle, R. J. "CARS Temperature Measurements in Flames in Industrial Burners." In Industrial Combustion Testing, edited by C. E. Baukal. Boca Raton, FL Taylor Francis, 2010. 

CARS Temperature Measurements in Flames in Industrial Burners... 

This chapter describes the use of the CARS technique for gas temperature measurements in flames. The description includes the optical arrangement, a brief summary of the theory of CARS signal generation, data acquisition, and analysis. The establishment of a CARS measurement system for practical flames can be challenging and it is hoped that the practical information included in this chapter will be of assistance to a novice attempting to get measurable and accurate CARS temperatures in large flames. Since the establishment of CARS as a practical measurement technique for temperature measurements in flames, literature shows that a lot has been learned about this non-linear interaction resulting... 

R.G. Jolik, J.W. Daily Two-line atomic fluorescence temperature measurements in flames An experimental study. Appl. Opt. 21, 4158 (1982)... 

Kamphus, M. et al., REMPI temperature measurement in molecular beam sampled low-pressure flames, Proc. Combust. Inst., 29,2627, 2002. 

HartHeb, A.T, Atakan, B., and Kohse-Hoinghaus, K., Temperature measurement in fuel-rich non-sooting low-pressure hydrocarbon flames, Appl. Phys. B, 70, 435, 2000. 

One of the most challenging aspects of modeling turbulent combustion is the accurate prediction of finite-rate chemistry effects. In highly turbulent flames, the local transport rates for the removal of combustion radicals and heat may be comparable to or larger than the production rates of radicals and heat from combustion reactions. As a result, the chemistry cannot keep up with the transport and the flame is quenched. To illustrate these finite-rate chemistry effects, we compare temperature measurements in two piloted, partially premixed CH4/air (1/3 by vol.) jet flames with different turbulence levels. Figure 7.2.4 shows scatter plots of temperature as a function of mixture fraction for a fully burning flame (Flame C) and a flame with significant local extinction (Flame F) at a downstream location of xld = 15 [16]. These scatter plots provide a qualitative indication of the probability of local extinction, which is characterized... 

The figure shows U >. S L in this region and Da is predominantly small. At the highest Reynolds numbers the region is entered only for very intense turbulence, U > SL. The region has been considered a distributed reaction zone in which reactants and products are somewhat uniformly dispersed throughout the flame front. Reactions are still fast everywhere, so that unbumed mixture near the burned gas side of the flame is completely burned before it leaves what would be considered the flame front. An instantaneous temperature measurement in this flame would yield a normal probability density function—more importantly, one that is not bimodal. 

Schoenung, S. M., and R. K. Hanson. 1981. CO and temperature measurements in a flat flame by laser absorption spectroscopy and probe techniques. Combustion Science Technology 24 227-37. 

Flame Tests. See Flame, Length and Duration of , Flame Photometry , Flame Propagation and Velocity and Flame Temperature Measurements , in (his Vol Also in Vol 1 Flame Test , p XII ... 

Flow of Suspended Particles. Small particles suspended in the combustible stream have been used for the study of Bunsen flames. Andersen and Fein 2P) use strobo-scopically illuminated particle tracks for the determination of normal burning velocities and flame temperatures. Flame studies using similar techniques are reported by Fristrom, Avery, Prescott, and Mattuck (3P). Wolfhard and Parker 10P) have made temperature measurements of flames containing incandescent particles. The acceleration of flow through a flame front causes particles greater than about 2 microns to lag. Thus, the particles may not follow the flow streamlines. Gilbert, Davis, and Altman (4P) discuss the corrections which must be applied to obtain accurate results. 

Figure 10. Temperature measurements in flat Ht-air diffusion flame. The exit of the flat flame burner is shown schematically (O), radiation-corrected thermocouple measurements (A) Ht CARS temperatures (A), Ot CARS temperatures.

Temperature Measurement in Turbulent Flames Via Rayleigh Scattering... 

Rambach, G. D., Dibble, R. W., Hollenbach, R. E., "Velocity and Temperature Measurements in Turbulent Diffusion Flames," paper no. 79-51 Fall Meeting of Western States Section of the Combusion Institute, Berkeley, CA, 1979. 

Special problems arise in measuring local temperature within spray flames. Liquid and solid particles cause deposits and blockage of orifices in instruments. High-temperature conditions, with particles having high emissivity, result in complex radiative heat transfer which affects the accuracy of temperature measurement. In industrial furnaces and gas turbine combustion chambers, suction pyrometers have been used for... 

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