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佐藤, 博之 ; 天谷, 賢児 ; 新井, 雅隆
概要:
application/pdf<br />Journal Article<br />Flame lengths of gas jet diffusion flames were measured under various gravity
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evels. A spin tester was used to obtain a high gravity field which level was changed from normal gravity (G=1) to G-20. In order to investigate the fuel density effect on flame structure at high gravity level, two kinds of fuels (methane and propanw) and further methane-propane mixture fuel whose density was equivalent to the surrounding air were used. As the results, flame length decreased with an increase of gravity level regardless of the positive and negative buoyancy effect between the fuel and surroundings. To investigate the gravity effect on flame structure, length of blue flame which appeared at anchor portion of the flame was measured under various gravity levels. It was confirmed that the blue flame was expanded with an increase of the gravity level. This result was explained by the enhancement of the air entrainment at the anchor portion of the flame. Evaluation of flame length which was obtained by Altenkirch considering the relationship of fuel and required oxygen were used to evaluate the experimental data of flame length under the various gravity level. From this method the following empirical correlation was proposed : L_f/γ_o=1.72Re^<0.667>Fγ^<0.0846>, where L_f is a flame length, γ_o is a nozzle radius, Re is the Reynolds number based on nozzle radius and Fγ is the Froude number.
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林田, 和宏 ; 天谷, 賢児 ; 新井, 雅隆
概要:
application/pdf<br />Journal Article<br />Laser induced fluorescence was applied for the measurement of OH concentration
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in the propane diffusion flames. A tunable, narrow band KrF excimer laser was used to excite the A(ν'=3)←X(ν""=0) band of OH radical. An emission spectrum of the induced light from the flames was measured by a spectroscope. An OH fluorescence component was picked up from the emission spectrum in order to obtain the accurate distribution of OH fluorescence in the flames. We call this method for spectrum-LIF (S-LIF). The spectrum of the induced light from the diffusion flames was compared with that of the premixed flames. Although the spectrum had only OH fluorescence components in the case of premixed flames, high intensity emission from the yellow flame appeared on the LlF image in the case of diffusion flames. To remove the high intensity emission from the LIF image, off resonance image was deducted from the OH resonance image as the background image. Using this deduction method, a planer laser induced fluorescence (P-LIF) was tried to measure the distribution of OH fluorescence. OH fluorescence distribution measured by P-LIF was compared with that of S-LIF. As the result, the P-LIF image qualitatively agreed with the data of S-LIF.
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新居, 利洋 ; 斉藤, 正浩 ; 新井, 雅隆
概要:
application/pdf<br />Journal Article<br />This paper reports the suppression of soot emission from acetylene diffusion flame by applying electric field. The effects of applied voltage, polarity and spacing of electrodes on soot emission
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were investigated experimentally. The results showed that the shape of flame changed and the soot emission decreased with increasing the applied voltage. The polarity of applied voltage influenced to the shape of flame and the soot emission. When positive voltage was applied to the nozzle electrode, the flame length became short and the width at the flame tip was spread. And, more than 90% of soot emission was suppressed at over 200 kV/m of the intensity of electric field. The surface temperature of flame increased with increasing the applied voltage. Thus, it was considered that the increase of flame surface temperature promoted the soot oxidation. When negative voltage was applied to the nozzle electrode, on the contrary, only the 70% of soot emission was suppressed, because the flame temperature was comparable to that for non-applied voltage.
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新井, 雅隆 ; 天谷, 賢児 ; 長倉, 邦仁
概要:
application/pdf<br />Journal Article<br />Laser induced fluorescence method was applied for the measurement of NO concen
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tration in the propane and methane diffusion flames. A tunable, narrow band ArF excimer laser was used to excite the D (υ′=0) ←X (υ″=1) band of NO molecule. Emission spectrum of the induced light by a laser beam was measured by a spectroscope. Spectrum of the induced light from the diffusion flame was compared with that of the premixed flame. Although the spectrum had only NO fluorescence components on premixed flame, a lot of strong spectrum components related to the laser induced incandescence of the soot and laser induced breakdown appeared in the spectrum from the diffusion flame. NO fluorescence component was picked out from the emission spectrum with traversing the irradiate position of laser beam in order to obtain the accurate distribution of NO fluorescence on the flame axis. In this paper this method was named as S-LIF method. A planer laser induced fluorescence (P-LIF) method was tried to measure the distribution of NO fluorescence on the flame axis. In the P-LIF method, an interference filter was used to remove the obstructive light component from the LIF image. NO fluorescence distribution measured by P-LIF method was compared with that of S-LIF method. As the result, the P-LIF image qualitatively agreed with the data of S-LIF. It was confirmed that the interference filter did not remove completely the obstructive light components.
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