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

这项研究的目的是对火焰结构进行精确的观察，以阐明环境压力与湍流量表与强度之间的关系，并探索环境压力对湍流燃烧速度的影响。 CH_4-Air，C_2H_4-Air和C_3H_8-Air混合物的湍流预防火焰通过在高压中安装的喷嘴燃烧器稳定。获得以下结果。1）测量的湍流特征表明，湍流强度随平均速度的增加而增加。然而，在普通压力下，由于广泛的湍流倾倒，平均速度的较小区域的增加很小。在高压下，湍流强度随着平均速度的整个范围内的平均速度线性增加。2）在高压下，火焰结构变得精细而复杂。 S_T/S_L随着U'/S_L的增加而迅速增加，特别是对于弱湍流区域（U'/S_L <L），表明……在高压环境中，流体动力不稳定的影响更大。对于Ch_4-air火焰，S_T/S_L随U'/s_l增加，在实验条件下最多30。这是因为由于高压下的流体动力学不稳定，火焰区域增加了不同的效果，因为C_3H_8-Air混合物的较大的刘易斯数量。4）湍流强度的数据范围表明，S_T/S_L的u'/s_l依赖性s_t/s_l s_l s_l for C_2H_4-Air SASSAir sAssAir SASSASSASSASSASSASSASSASSASSASSASSASSASSASSASSASSASSASSASSASSASSASASASASASASASASASASASASASASASASASASASASASASASASASASASASASASAS_L。尽管如此，与C_2H_4-Air和CH_4-Air火焰相比，S_T/S_L显示S_T/S_L的S_T/S_L小于S_T/S_L。 ABDE1-GAYD与相关性的趋势类似，但S_T/S_L的相关性比它们的相关性大。在强湍流区域（U'/SL> L.0）中可以看到R_L的1/4功率定律，与Gouldin提出的湍流燃烧速度的分形火焰模型一致。（u'/s_ <1l>）]^n，指数n接近0.4。较少的