Experimental Investigation on combustion characteristics of DME lean side mixtures under micro-gravity

实验已经被携带出来，以替代二甲醚燃料空气混合物的基本燃烧特性。该研究获得的主要结果如下：对于使用微重力技术对DME燃料空气混合物的燃烧速度的测量，而微重力技术是提取DME燃料空气混合物的基本燃烧特性的最合适的方法，特别是接近混合物的一个非常明显的方面，二甲醚燃料-空气混合物的燃烧速度单方面的退化与Decre 4asing equivalence Ratio的均衡率，这些价值观与所有研究过的甲基-空气混合物中的4个相同，由于燃烧速度的实例为44.2厘米/秒和16.5厘米/秒，因此，在房间温度和大气压力下等于1.1和0.65以下的温度和大气压力，以及二甲醚燃料空气混合物的稀薄方面的燃烧速度的分解大于丰富的混合面，对于基本分析的燃烧行为 ... More DME laminar premixed burner flames，DME premixed flames的燃烧速度接近34 cm/s，平均比率为1.0。将DME与甲烷和丙烷-空气混合物的燃烧速度进行比较，而丙烷-空气混合物的燃烧速度比那些DME-空气混合物和DME-空气混合物的燃烧速度大。因此，DME的波动性和闪烁的波动性总是大于那些甲烷的波动性。火焰的稳定区域很容易通过边界速度梯度（g）进行测试。在Circular Tube Laminar Flow的情况下，边界速度梯度可以表示为g=4V/πR^3。V是音量流动率，R是燃烧器半径。二甲醚燃料-空气混合物的燃烧比甲烷-空气混合物更稳定。在这一研究中，我们已经尝试过使用燃烧器方法来使用燃烧器的历史来获得较低的燃烧能力限制。该方法获得的DME-空气预混合火焰的较低闪光度限制是近似Φ=0.34，而该方法的空气预混合火焰是近似Φ=0.55。从这些数据可以预测，二甲醚发动机燃烧的应用将是未来的一种有效替代燃料，并通过平板火焰传播方法测量二甲醚燃料空气混合物燃烧的距离，（1）二甲醚燃料的混合距离的两者-用Parallel plate和Circular Tube测量空气混合物与退化的均衡率，这些值几乎是确定的，与相应的值是一致的。甲烷-空气和丙烷-空气混合物的价值。□平行板L_q的确定距离之间的关系，以及圆形管d_q可以由L_q =0.65·d_q表示。（3）Buoyancy在向上火焰传播中的速度增加和量化距离衰减的影响。（4）正交距离也取决于表面区域S到内部体积V的圆柱形长管的比率和正交距离成为较小的S/V决定。从这些实验数据中可以预测到应用到DME燃料燃烧的引擎燃烧是不可能的。Less（低）

Experiments have been carried out to elucidate the fundamental combustion characteristics of DME fuel-air mixtures. The main results obtained for the study are as follows that, for the measurement of burning velocity on DME fuel-air mixtures using microgravity technique, □The micro-gravity technique is the most suitable method to extract the essential combustion characteristics of DME fuel-air mixtures, especially, near the very lean side of mixtures, The burning velocity of DME fuel-air mixtures monotonically decreases with decre4asing equivalence ratio and these values are nearly the same with those4 of methane-air mixtures at all the equivalence ratios studied, for instance the burning velocity is 44.2cm/s and 16.5cm/s, respectively, at equivalence of 1.1 and 0.65 under room temperature and atmospheric pressure and □The decrease of burning velocity of lean side of DME fuel-air mixtures is larger than that of rich side of mixtures, for the fundamental analysis an combustion behavior … More of DME laminar premixed burner flames, The burning velocity of DME premixed flames is approximately 34cm/s at 1.0 of equivalence ratio. As comparison of the burning velocity of DME with those of methane and propane-air mixture, the burning velocity of propane-air mixtures are larger than those of DME-air mixture and DME-air mixture are larger than methane-air mixtures. The blow off velocity and flashback velocity of DME are always larger than those of methane. □The stable region of the flame is easily to examine by the boundary velocity gradients(g). In case of circular tube laminar flow, the boundary velocity gradients can be expressed as g=4V/πR^3. Where V is the volume flow rate and R is the burner radius. Combustion of DME fuel-air mixtures is more stable than that of methane-air mixtures. In this study, we have tried to obtain the lower flammability limit using the burner method with the flame histories. The lower flammability limits of DME-air premixed flame obtained by this method are approximately Φ=0.34 and that of methane-air premixed flame are approximately Φ=0.55. From these data it may be predicted that the application to the engine combustion of DME is an effective alternative fuel for the future and, for measurement of quenching distance on combustion of DME fuel-air mixtures by flat flame propagation method, (1) Both of the quenching distance of DME fuel-air mixtures measuring by parallel plate and circular tube increase with decreasing equivalence ratio and these values are almost identical with the corresponding value for methane-air and propane-air mixtures. □The relationship between the quenching distance of parallel plate L_q, and circular tube d_q may be expressed by L_q=0.65・d_q. (3) The effect of buoyancy makes flame propagation speed increase and quenching distance decrease in upward flame propagation. (4) The quenching distance also depends on the ratio of surface area S to internal volume V of cylindrical long tube and the quenching distance becomes smaller as the S/V decreases.From these experimental data it may be predicted that the application to the engine combustion of DME fuel is not impossible. Less