共查询到19条相似文献,搜索用时 593 毫秒
1.
2.
本文通过自行研制的多孔介质燃烧实验系统,研究了液体燃料在热多孔介质中的燃烧可行性及其燃烧特性.燃烧系统包括燃烧室、供气系统、供油系统和测量系统等,该系统分别以气体和液体作为燃料,先通过多孔介质内的预混合燃烧对多孔介质固相进行预热,然后喷入液体燃料,实现燃烧,实验证实了液体燃料在热多孔介质内汽化及自维持燃烧的可行性,并讨论了空气量和喷油量等对燃烧室温度的影响. 相似文献
3.
《工程热物理学报》2015,(10)
本文对积木式结构多孔介质燃烧器稳定燃烧超低热值燃气的功率范围进行了试验研究。用甲烷和氮气配制了试验燃气的热值为1.4~3.0 MJ/m~3,在理论当量比条件下组织了预混燃烧。通过改变甲烷的流量,测试了不同燃烧强度工况下燃烧室壁面的温度分布,进而判定了各工况条件下燃烧室内是否能保持稳定燃烧。结果表明,本文所设计的燃烧器对于超低热值气体有着良好的适应性,对于热值高于1.4 MJ/m~3的气体都有一个稳定燃烧的功率区间,且稳定燃烧的功率范围随着气体热值的增大而增大。在预热温度为1200 K的前提下,燃气热值为1.4 MJ/m~3时,稳定燃烧的燃烧强度范围为30.57~107.01 kW/m~2,而当气体热值为3.0 MJ/m~3时,燃烧极限的近似范围是107.01~229.30 kW/m~2。 相似文献
4.
5.
6.
7.
本文对甲烷预混气在多孔介质中的火焰传播特性进行了实验研究,在开口竖直管中充填多孔介质,通过改变预混气氧含量使火焰在不同多孔介质中传播并测量火焰传播速度。预混气中氧含量最高达到29%。实验结果表明:多孔介质中甲烷可燃预混气火焰传播速度大于其层流火焰传播速度,可达到5倍以上(当量比的甲烷-空气预混气);多孔介质当量孔直径越大,或预混气层流火焰速度越高,则预混气火焰传播速度越高;多孔介质中可燃混气的火焰传播界限变小,当量孔直径大的多孔介质其界限值较大。实验结果与Babkin提出的多孔介质中的火焰传播机理相符。 相似文献
8.
地面常重力(1g)条件下,丙烷/空气预混火焰向上传播的富燃极限为9.2%C_3H_8,而向下传播时的富燃极限仅为6.3%C_3H_8,二者之间存在明显差距。利用微重力条件下的实验,对燃料浓度从6.5%到8.6%(微重力实验中测定的可燃极限)范围内的丙烷/空气预混火焰特性进行了研究。实验发现,重力对近极限丙烷/空气火焰的传播有显著影响,影响程度随着当量比的增加而增大。微重力下丙烷/空气的富燃极限为8.6%C_3H_8(φ=2.24),明显高于1g条件下向下传播火焰的可燃极限,略低于向上传播火焰的可燃极限。随着当量比的增大,根据压力变化曲线计算的火焰层流燃烧速度从8.5cm/s逐渐减小到2.7 cm/s,可燃极限处的层流燃烧速度与前人实验数据一致。 相似文献
9.
10.
11.
12.
13.
Nickolay A. Lutsenko 《Combustion Theory and Modelling》2018,22(2):359-377
A novel mathematical model and original numerical method for investigating the two-dimensional waves of heterogeneous combustion in porous media are proposed and described in detail. The mathematical model is constructed within the framework of the model of interacting interpenetrating continua and includes equations of state, continuity, momentum conservation and energy for solid and gas phases. Combustion, considered in the paper, is due to the exothermic reaction between fuel in the porous solid medium and oxidiser contained in the gas flowing through the porous object. The original numerical method is based on a combination of explicit and implicit finite-difference schemes. A distinctive feature of the proposed model is that the gas velocity at the open boundaries (inlet and outlet) of the porous object is unknown and has to be found from the solution of the problem, i.e. the flow rate of the gas regulates itself. This approach allows processes to be modelled not only under forced filtration, but also under free convection, when there is no forced gas input in porous objects, which is typical for many natural or anthropogenic disasters (burning of peatlands, coal dumps, landfills, grain elevators). Some two-dimensional time-dependent problems of heterogeneous combustion in porous objects have been solved using the proposed numerical method. It is shown that two-dimensional waves of heterogeneous combustion in porous media can propagate in two modes with different characteristics, as in the case of one-dimensional combustion, but the combustion front can move in a complex manner, and gas dynamics within the porous objects can be complicated. When natural convection takes place, self-sustaining combustion waves can go through the all parts of the object regardless of where an ignition zone was located, so the all combustible material in each part of the object is burned out, in contrast to forced filtration. 相似文献
14.
Max A.E. Kokubun Fernando M. Pereira Fernando F. Fachini 《Proceedings of the Combustion Institute》2013,34(1):839-845
It has been shown both theoretically and experimentally that combustion within porous inert media can extend the flammability limits of reactant mixtures for unstretched stationary premixed flames. However little attention has been given to flames within porous media submitted to stretch conditions. This work presents a closed form approximate analytical solution for the problem of ultra-lean premixed flames within porous inert media subjected to small stretch rates in an impinging flow configuration against a constant temperature wall. The solution is obtained using the method of matched asymptotic expansions taking advantage of the large difference between the solid- and gas-phase thermal conductivities. The model allows for thermal nonequilibrium between the phases and is able to predict the flame temperature, velocity and position as function of the stretch rate. The results show that within porous media low stretch rates may increase the flame temperature, further extending the lean flammability limit of the reactant mixture when compared to planar flames. The model is restricted to low porosities, low stretch rates, low heat losses and intense interphase heat transfer. 相似文献
15.
甲烷微尺度催化燃烧的数值模拟 总被引:9,自引:1,他引:9
本文联合使用计算流体力学软件FLUENT和可以计算表面反应的化学反应动力学软件DETCHEM对有逆流换热的微尺度燃烧器进行了数值计算。计算中忽略空间反应。燃料-空气混合物的当量比为0.4,反应器壁面采用等温边界条件。计算结果表明,采用催化燃烧可以实现微尺度下通常情况下无法实现的甲烷稳定燃烧。通过适当设置催化表面,可以实现燃料低温、高效转变。甲烷的总转变率受流动状态、反应温度和催化表面的大小等因素的影响。 相似文献
16.
Nickolay A. Lutsenko 《Proceedings of the Combustion Institute》2013,34(2):2289-2294
A mathematical model and a numerical method, based on the combination of explicit and implicit finite difference schemes, have been developed for investigating the unsteady gas flows in porous objects with zones of heterogeneous combustion when gas pressure at object boundaries is known. Used approach enables to solve problems of filtration combustion for both forced filtration and free convection, so it can be efficiently applied for modeling the combustion zones in porous media, which may arise from natural or man-caused disasters. One-dimensional unsteady processes of heterogeneous combustion in porous object under free convection have been investigated using numerical experiment. Two regimes of combustion wave propagation have been revealed – wave movement up and down in the object – and it is shown that these regimes are significantly different in degree of burn of solid combustible material, the temperature in the combustion zone and propagation velocity of combustion wave. 相似文献
17.
18.
Characteristic regimes of premixed gas combustion in high-porosity micro-fibrous porous media 总被引:1,自引:0,他引:1
R. Fursenko S. Minaev K. Maruta H. Nakamura H. Yang 《Combustion Theory and Modelling》2013,17(4):571-581
Dynamical behaviour of the premixed flame propagating in the inert high-porosity micro-fibrous porous media has been studied numerically. Effects of mixture filtration velocity, equivalence ratio and burner transverse size on the flame structure have been investigated and the regions of existence of different combustion regimes have been determined. It was found that the influence of the hydrodynamic instability on the flame dynamics is significant in the case of the moderate and high filtration velocities and this effect is negligible at the low velocities. At the moderate filtration velocities the effect of hydrodynamic instability manifests in the flame front deformation and in particular in the flame inclination. It was found that the flame can be stabilized within the whole interval of the filtration gas velocity, whereas in the ordinary porous media the standing wave is settled only at fixed value of gas filtration velocity. This finding is in line with recent experimental results on combustion in micro-fibrous porous media (Yang et al., Combust. Sci. Tech. 181 (2009), 1–16). Possible physical interpretation of the flame anchoring effect may be given on the base of present numerical analysis. At the high filtration velocities the hydrodynamic instability manifests itself in periodical appearance of the moving wrinkles on the flame front surface which forms non stationary high temperature trailing spots behind the leading part of the flame front. Such dynamics may be associated with splitting wave structures which were revealed in previous experiments (Yang et al., Combust. Sci. Tech. 181 (2009), 1–16). 相似文献