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水雾作用下富燃料甲烷预混火焰化学发光特性 总被引:1,自引:0,他引:1
利用阶梯光栅光谱仪与自行研制的水雾协流管式燃烧器,对富燃料甲烷/空气层流预混火焰化学发光特性进行实验研究.分析了锥形预混火焰燃烧过程中火焰面OH、CH以及C2自由基粒子光谱强度分布规律,以及水雾协流作用下的预混火焰发射光谱特性,探讨了水雾液滴对富燃料甲烷预混火焰发射光谱的影响.实验结果表明:当水雾量充足时,作用于内锥火焰阵面的水雾液滴使得火焰阵面OH、CH以及C2自由基粒子发射光谱强度减弱,抑制预混火焰燃烧;当作用于火焰面的水雾载荷比较小时,富燃料预混火焰的OH、CH的发射光谱强度得到一定程度的增强. 相似文献
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利用低功率电弧放电辅助甲烷燃烧,研究了在不同甲烷/空气比例的情况下,等离子体对甲烷燃烧的影响。采用发射光谱仪进行光谱诊断,比较有/无等离子体辅助甲烷燃烧火焰发射光谱的异同,讨论了等离子体辅助燃烧可能发生的过程和机理。比较有/无等离子体辅助甲烷燃烧火焰温度的变化。利用气相色谱和烟气分析仪对甲烷燃烧产物中的CH4、CO 和O2 进行分析。实验结果表明,加等离子体后,火焰的温度升高,尾气中的可燃性成分减少,氧气含量降低,在很大程度上提高了甲烷的燃烧效率;甲烷/空气的比例越低,燃烧效率的提高越明显;甲烷的富燃燃烧极限从16%调高到21%。 相似文献
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建立了1维非稳腔空间增强探测CARS实验系统,该系统由光源(YAG激光器、染料激光器)、实验光路和信号采集系统组成。分别测量了空气和化学平衡比为1,甲烷流量为0.7 L/min的甲烷-空气预混火焰中的氮气Q支的CARS实验谱。给出了火焰不同高度处小范围内的温度分布结果,并对实验结果进行了分析,结果表明:预混火焰温度随高度的增加呈下降趋势,测量结果的不确定度优于7%。该技术可用于稳态燃烧场温度的测量。 相似文献
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燃油分级多点喷射低污染燃烧室的化学反应网络模型分析 总被引:4,自引:0,他引:4
本文采用基于详细化学反应机理的化学反应网络模型分析了航空发动机燃油径向分级多点喷射低污染燃烧室的NO_x排放特性。该分级燃烧室不同于传统燃烧室,头部由值班区和主燃区两个不同的燃烧区域,根据CFD得到的流场特性和当量比的分布特性对燃烧室进行分区构建化学反应器网络模型,研究了值班级当量比以及值班级和主燃级两级供油比例对排放的影响。同时,还分析了空气进口温度对NO_x排放的影响。得到了较为合理的变化趋势,为低污染燃烧室的初步设计提供了有益的指导。 相似文献
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Sirshendu Mondal Achintya Mukhopadhyay Swarnendu Sen 《Combustion Theory and Modelling》2013,17(1):59-74
To increase the pulse combustor load, a higher amount of fuel-air mixture has to be supplied. This increases the flow rate or equivalently, the flow time is reduced. However, an increase in flow rate leads to an early extinction. This implies that obtaining pulsating combustion is difficult at higher loads. The objective of the present work is to explore the possibility of extending the regime of pulsating combustion at higher flow rates by preheating and diluting the reactants. In this work, the effects of preheating and dilution are examined by varying the inlet temperature and inlet fuel mass fraction. Varying these parameters, a map, presenting regime of pulsating combustion from steady combustion to extinction for each value of flow time considered, has been made. Lastly, Hopf bifurcation points of the system have been investigated by determining the eigenvalues of Jacobian matrix of the coupled non-linear system at the fixed point using a specialised package for bifurcation analysis, MATCONT. It has been found that at higher load, pulsating combustion can be achieved at higher inlet temperature and lower inlet fuel mass fraction. Comparing the Hopf points with mapping, it is found that existence of Hopf bifurcation agrees with the birth and death of pulsating combustion. The results indicate that altering the mixture condition at the inlet can be used for controlling chaos and stabilising periodic solutions in thermal pulse combustors and thus increase the range of pulsating combustion to higher power regimes. 相似文献
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《Combustion Theory and Modelling》2013,17(4):613-635
Hydrodynamic (Landau) instability in combustion is typically associated with the onset of wrinkling of a flame surface, corresponding to the formation of steady cellular structures as the stability threshold is crossed. In the context of liquid-propellant combustion, such instability has recently been shown to occur for critical values of the pressure sensitivity of the burning rate and the disturbance wavenumber, significantly generalizing previous classical results for this problem that assumed a constant normal burning rate. Additionally, however, a pulsating form of hydrodynamic instability has been shown to occur as well, corresponding to the onset of temporal oscillations in the location of the liquid/gas interface. In the present work, we consider the realistic influence of a non-zero temperature sensitivity in the local burning rate on both types of stability thresholds. It is found that for sufficiently small values of this parameter, there exists a stable range of pressure sensitivities for steady, planar burning such that the classical cellular form of hydrodynamic instability and the more recent pulsating form of hydrodynamic instability can each occur as the corresponding stability threshold is crossed. For larger thermal sensitivities, however, the pulsating stability boundary evolves into a C-shaped curve in the (disturbance-wavenumber, pressure-sensitivity) plane, indicating loss of stability to pulsating perturbations for all sufficiently large disturbance wavelengths. It is thus concluded, based on characteristic parameter values, that an equally likely form of hydrodynamic instability in liquid-propellant combustion is of a non-steady, long-wave nature, distinct from the steady, cellular form originally predicted by Landau. 相似文献