Visualization of dilute hydrogen jet flame in air flow

Abstract

The structure of hydrogen jet flame diluted by CO2 in air flow is studied by various visualization techniques, such as schlieren, direct photograph, tracer injection and reactive Mie scattering method, which allow understanding of the influence of CO2 on the characteristics of the hydrogen jet flame. The experimental result indicates that the flame structure consists of laminar fuel jet and surrounding reaction zone near the nozzle exit. When the CO2 fraction is increased, the width of the fuel jet grows and the reaction zone is reduced in size. These observations are further confirmed by quantitative measurements of temperature and velocity fields in the flame, which are evaluated by thermocouple and particle image velocimetry (PIV), respectively. These results indicate that the flame temperature is decreased and the flow rate of the fuel jet is increased by the influence of diluents, which are due to the reduced calorific value and larger density of fuel, respectively.

Simultaneous measurement of three-dimensional flame contour and velocity field for characterizing the flickering motion of a dilute hydrogen flame

“…Such recirculation is also useful for the design of a high performance burner for application to a reformer. Therefore, the effect of diluents on the combustion characteristics of a hydrogen flame has been studied by Chinone and Fujisawa (2004), who found the influences of diluents on the flame contour, temperature and velocity field by planar measurements. With increase in diluent fraction, the fuel flow grows in width and the flame temperature decreases.…”

“…As the target flame of butane is well visible by direct observation due to the luminous nature of the flame, direct imaging by three CCD cameras allows quantitative visualization of the three-dimensional flame geometry. This technique can be applied to the target flame of dilute hydrogen in the present study, which is combined with the flow visualization technique with a reactive Mie scattering technique (Chen and Roquemore 1986, Chung 2003, Chinone and Fujisawa 2004. Although flickering motion can be considered as an axisymmetrical phenomenon theoretically, the real flame suffers from minor disturbances of the fuel flow upstream, surrounding co-air flow and so on.…”

Temperature measurement of dilute hydrogen flame by digital laser-speckle technique

“…The influences of diluents on NOx formation of hydrogen flame has been studied by Feese and Turns (1998), Barlow et al (1999), Rortveit et al (2002), because they are useful for the design of combustor having flue-gas recirculation system. It is generally known that the hydrogen flame becomes more inactive to the chemical reactions at higher fraction of diluents, which is due to the reduction in the calorific value of the fuel and the reduced buoyancy of the flame (Chinone and Fujisawa 2004).…”

Performance of a PIV system for a combusting flow and its application to a spray combustor model

“…Such combustion flow has been measured by using Laser Doppler Anemometry (LDA) and Particle Image Velocimetry (PIV). The latter technique is becoming more important for velocity measurement, because it allows whole-flow measurement of instantaneous velocity field in the combustion flow (Kawanabe et al, 2000, Stella et al, 2001and Chinone and Fujisawa, 2004.…”

“…Therefore, the light emitted from the luminous flame has to be removed in order to capture clear images of the tracers necessary for PIV processing. In order to overcome this difficulty, the imaging technique by the standard PIV system has been improved by using the high-speed shutters (Shioji et al, 1997), band-pass filers (Ikeda et al, 2000, Palero and Ikeda, 2002, Chinone and Fujisawa, 2004 and combined use of rotary shutters and band-pass filters (Willert and Jarius 2002. By weakening the influence of the high-intensity luminous flame by these additions, it is made possible to evaluate the velocity field by PIV.…”