Turbulent Premixed Combustion in a High-Pressure Environment up to 4.0MPa

高达4.0MPa高压环境下的湍流预混燃烧

基本信息

批准号：
08455100
负责人：
KOBAYASHI Hideaki
金额：
$ 2.5万
依托单位：
Tohoku University
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (B)
财政年份：
1996
资助国家：
日本
起止时间：
1996 至 1997
项目状态：
已结题

项目摘要

This research was aimed to conduct precise observations of the flame structure, to elucidate the relationship between ambient pressure and turbulence scale and intensities, and to explore the effects of ambient pressure on turbulent burning velocities. Turbulent premixed flames for CH_4-air, C_2H_4-air, and C_3H_8-air mixtures were stabilized by a nozzle burner installed in a high-pressure. The following results were obtained.1) Measured turbulence characteristics showed that turbulence intensities increatsed with increasing mean velocities. Nevertheless, at ordinary pressure, the increase was small in the region of small mean velocities because of an extensive dumping of turbulence. At high-pressures, turbulence intensity linearly increased with the mean velocities in the entire range of the mean velocities.2) At high-pressures, flame structure becomes fine and complicated. S_T/S_L increased rapidly with increasing u'/S_L particularly for weak turbulence regions (u'/S_L<l), indicating … More effects the hydrodynamic instability becomes extensive in a high-pressure environment. For CH_4-air flames, S_T/S_L increases with u'/S_L, up to 30 at 3. OMPa for the experimental conditions achieved.3) The rate of the increase in S_T/S_L for C_3H_8-air flames was smaller than that for C_2H_4-air flames. This is because the flame area increase due to the hydrodynamic instability at high pressures was restrained by diffusive-thermal effects because the larger Lewis number of C_3H_8-air mixtures.4) The data for awide range of turbulence intensities showed that the u'/S_L dependence of S_T/S_L for C_2H_4-air flames is almost the same as that for CH_4-air flames. Nevertheless, S_T/S_L for C_3H_8-air flame showed smaller S_T/S_L than in the cases of C_2H_4-air and CH_4-air flames.5) The applicability of existent correlation between S_T/S_L, u'/S_L, aud turbulence Reynolds number, R_L, to high-pressure flames were examined, and it was found that the data of our experiments had a similar tendency to the correlation by Abde1-Gayd but had larger S_T/S_L than their correlation. 1/4 power law of R_L was seen for S_T/S_L in the strong turbulence region (u'/SL>l.0), consistent with the fractal flamelet model of turbulent burning velocity proposed by Gouldin.6) The best general correlation which can express the experimental data for a whole range of u'/SL and pressure was in the for of S_T/S_L* [ (P/P_O) (u'/S_<1L>) ]^n and the exponent n was close to 0.4. Less

本研究旨在对火焰结构进行精确观测，阐明环境压力与湍流规模和强度之间的关系，探讨环境压力对CH_4-空气、C_2H_4-空气湍流预混火焰的影响。、和C_3H_8-空气混合物通过安装在高压下的喷嘴燃烧器进行稳定化，得到以下结果。1)测量。湍流特征表明，湍流强度随着平均速度的增加而增加，然而，在常压下，由于湍流的广泛倾倒，在小平均速度区域增加很小，湍流强度随着平均速度线性增加。 2）在高压下，火焰结构变得精细且复杂，S_T/S_L迅速增加。随着 u'/S_L 的增加，特别是对于弱湍流区域 (u'/S_L<l)，表明在高压环境中，流体动力学不稳定性变得广泛，对于 CH_4 空气火焰，S_T/S_L 随着 u'/ 的增加而增加。在实验条件下，S_L在3. OMPa下高达30。3) C_3H_8-空气火焰的S_T/S_L的增加速率小于S_T/S_L的增加速率对于 C_2H_4-空气火焰，这是因为由于 C_3H_8-空气混合物的路易斯数较大，高压下流体动力学不稳定性导致的火焰面积增加受到扩散热效应的抑制。4) 各种湍流强度的数据表明。可以看出，C_2H_4-空气火焰的S_T/S_L对u'/S_L的依赖性与CH_4-空气火焰的u'/S_L依赖性几乎相同。然而，C_3H_8-空气火焰的S_T/S_L表现出比C_2H_4-空气和CH_4-空气火焰更小的S_T/S_L。5) S_T/S_L、u'/S_L、aud湍流雷诺数之间现有相关性的适用性，R_L，对高压火焰进行了检查，发现我们的实验数据与以下相关性具有类似的趋势Abde1-Gayd 但在强湍流区域 (u'/SL>l.0) 中 S_T/S_L 的相关性大于 R_L 的 1/4 幂律，与湍流分形火焰模型一致。 Gouldin 提出的燃烧速度。6) 能够表达 u'/SL 和压力整个范围内的实验数据的最佳一般相关性是 S_T/S_L* [ (P/P_O) (u'/S_<1L>) ]^n 并且指数 n 接近 0.4。