共查询到18条相似文献,搜索用时 437 毫秒
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作者对一种用来计算燃气涡轮燃烧室排气中的氮氧化物(NO_x)的简单模型进行了分析,探讨了它为什么在实际应用中能使计算结果较好地与实验数据相符合的原因。并在此基础上,作者发展了该模型使它能同时计算在燃气涡轮燃烧室排气中两个有代表性的重要污染物——氮氧化物(NO_x)和一氧化碳。 采用了一个CO消失的综合反应速率方程,和作者归纳得到的燃烧初始阶段CO生成量随主燃区当量比变化的经验关系式,用该模型对二种不同燃烧室进行了CO排放量的计算,计算值与实验数据相当一致。 相似文献
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《工程热物理学报》2010,(11)
均质混合气压燃(HCCI)燃烧受爆震和NO_x排放的限制,高负荷拓展是一个难题。本文提出利用理论空燃比SICI组合燃烧作为汽油机中高负荷运行区域的高效低污染燃烧模式。在试验台架上研究了理论空燃比SICI组合燃烧的排放特性及其对三效催化剂(TWC)转换性能的影响。研究发现,通过外部EGR与点火控制相结合,理论空燃比SICI组合燃烧可以在指示平均有效压力(IMEP)0.65~0.82MPa范围内稳定实现;与传统SI燃烧相比,理论空燃比SICI组合燃烧燃油经济性提高近10%,NO_x排放降低80%以上,但HC排放有所增加;SICI组合燃烧与传统SI燃烧类似,TWC空燃比特性的高效区间在理论空燃比附近,但对HC排放的催化能力提出了更高的要求。 相似文献
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燃气轮机燃烧室化学反应器网络模型研究 总被引:3,自引:0,他引:3
本文针对CFD燃烧室设计方法在计算时间以及计算的准确度上的不足,发展了一种计算量较小的、能够快速准确地预测燃气轮机燃烧室污染物排放的化学反应器网络模型方法(CRN).该方法首先根据CFD的计算结果对燃烧室进行分区,不同的区域采用不同的化学反应器模型进行模拟,反应器之间的连接关系以及入口参数都根据CFD的结果确定.本文采用这种方法对某个燃烧富氢合成气的重型燃气轮机燃烧室的NO_x排放随燃料加湿量的变化进行了预测,并与现场测量的结果进行了比较.计算结果与现场试验数据吻合得很好,证明这是一种很好的预测燃烧室NO_x排放的方法,与CFD方法相比预测精度有了很大提高,而且在计算时间上小了几个数量级. 相似文献
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多点喷射燃烧室冷态流场特性研究 总被引:2,自引:0,他引:2
首先用可实现κ-ε湍流模型(RKE)和雷诺应力湍流模型(RSM)对双径向旋流杯下游流场进行数值模拟,并将计算结果与实验值对比.结果显示,在大部分区域计算值与实验值比较一致,RKE模型和RSM模型的最大误差分别为5%和3%,RKE模型可以用于旋流杯燃烧室计算.此后,用RKE模型对单头部燃烧室和多点喷射燃烧室的流场进行数值模拟.对于同样的燃烧室衬套结构,多点喷射燃烧室旋流器出口附近每个旋流器都有各自的回流区,并在下游逐渐融合,在主燃孔附近多点喷射燃烧室和单头部燃烧室的回流区结构类似.对于同样的多点喷射燃烧室头部,没有主燃孔时,回流区在原主燃孔位置前结束,有主燃孔时,单个的回流区在主燃孔附近又形成新的回流区. 相似文献
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燃气轮机合成气双旋流非预混燃烧室的设计及实验测试 总被引:1,自引:0,他引:1
本文针对上海交通大学25 kW燃气轮机性能试验台的合成气燃烧室开展了设计研究,完成了燃烧室样机的加工与实验测试。研究过程中,首先对合成气燃烧室开展了结构设计;采用双旋流结构的燃烧器进行合成气燃烧火焰组织;采用了燃烧室头部贫燃方式(低当量比)设计以保证燃烧室低排放特性;利用双层壁冷却方式进行火焰筒壁面冷却。在燃烧室结构设计的基础上,利用数值方法系统分析了合成气双旋流非预混燃烧室工作特性,完成了合成气非预混母型燃烧室的设计优化。根据优化方案,完成了燃烧室样机的加工、安装,并进行了实验性能测试。实验结果表明实验工况该燃烧室燃烧稳定,NO_x排放小于25 mg/m~3@15%O_2。 相似文献
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Ekenechukwu C. Okafor K.D. Kunkuma A. Somarathne Akihiro Hayakawa Taku Kudo Osamu Kurata Norihiko Iki Hideaki Kobayashi 《Proceedings of the Combustion Institute》2019,37(4):4597-4606
Recent studies have demonstrated stable generation of power from pure ammonia combustion in a micro gas turbine (MGT) with a high combustion efficiency, thus overcoming some of the challenges that discouraged such applications of ammonia in the past. However, achievement of low NOx emission from ammonia combustors remains an important challenge. In this study, combustion techniques and combustor design for efficient combustion and low NOx emission from an ammonia MGT swirl combustor are proposed. The effects of fuel injection angle, combustor inlet temperature, equivalence ratio, and ambient pressure on flame stabilization and emissions were investigated in a laboratory high pressure combustion chamber. An FTIR gas analyser was employed in analysing the exhaust gases. Numerical modeling using OpenFOAM was done to better understand the dependence of NO emissions on the equivalence ratio. The result show that inclined fuel injection as opposed to vertical injection along the combustor central axis resulted to improved flame stability, and lower NH3 and NOx emissions. Numerical and experimental results showed that a control of the equivalence ratio upstream of the combustor is critical for low NOx emission in a rich-lean ammonia combustor. NO emission had a minimum value at an upstream equivalence ratio of 1.10 in the experiments. Furthermore, NO emission was found to decrease with ambient pressure, especially for premixed combustion. For the rich-lean combustion strategy employed in this study, lower NOx emission was recorded in premixed combustion than in non-premixed combustion indicating the importance of mixture uniformity for low NOx emission from ammonia combustion. A prototype liner developed to enhance the control and uniformity of the equivalence ratio upstream of the combustor further improved ammonia combustion. With the proposed liner design, NOx emission of 42?ppmv and ammonia combustion efficiency of 99.5% were achieved at 0.3?MPa for fuel input power of 31.44?kW. 相似文献
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Mitsuhiro Tsue Osamu Imamura Shunsuke Suzuki Koshiro Fukumoto Shunsuke Nishida George Ianus Yasushige Ujiie Michikata Kono 《Proceedings of the Combustion Institute》2011,33(2):2391-2398
Combustion characteristics of liquid hydrocarbon fuels are studied in a model combustor of SCRAM jet engines. The Mach number and total pressure of main flow in the combustor are 2.0 and 0.38 MPa, respectively, and the total temperature is varied from 1800 to 2400 K. Five kinds of n-alkane fuels such as n-heptane, n-octane, n-decane, n-tridecane and n-hexadecane are employed in experiments. Fuels are injected with a carrier nitrogen gas perpendicular to the mail flow in the combustor and the self-ignition behavior is investigated. The results show that the liquid fuels with lower carbon number have better self-ignition performance. This suggests that physical properties of liquid fuels such as volatility have a dominant effect on the self-ignition. The flame-holding behavior is investigated with the addition of pilot hydrogen to carrier nitrogen gas. The critical equivalence ratio at which the stable combustion keeps after cut-off of the pilot hydrogen is obtained. The relationship between the critical equivalence ratio and carbon number of fuel shows that fuels with the carbon numbers from 8 to 10 have the best flame-holding performance among the tested fuels. These experimental results can be expressed qualitatively by the simplified analysis with the concept of physical and chemical induction times. 相似文献
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《Proceedings of the Combustion Institute》2023,39(3):3107-3116
The combustion instability in a laboratory-scale direct-connect hydrogen-fueled scramjet combustor is investigated numerically. The numerical simulation has been carried out using a delayed detached eddy simulation (DDES) with a detailed reaction mechanism. The computational framework has high fidelity by applying multi-dimensional high order accurate schemes for handling convective and viscous fluxes. The field data were accumulated up to 100 milliseconds on each case to capture sufficiently the repetitive behavior of low-frequency instability of order of 100 Hz. The numerical results exhibit the formation/dissipation of pressure and shock wave induced by continuous heat release in the combustor. This motion of pressure/shock wave, so-called upstream-traveling shock wave, presents repeated dynamics between isolator and combustor with a period of several milliseconds. With this periodic hydrodynamic characteristic, the upstream-traveling shock wave interacts with the boundary layer and injected fuel stream affecting fuel/air mixing and burning, and finally inducing the combustion instability in a scramjet combustor. Frequency analysis derived major instability frequencies of 190 Hz and 450 Hz in the isolator and combustor for low and high equivalence ratios, respectively. Current numerical results present the underlying flow physics on the shifting of the instability frequency by changing the equivalence ratio observed by the previous experimental studies. The fact that an instability frequency exists homogeneously from isolator to combustor informs that the combustion instability of scramjet engine is the fully coupled flow/combustion dynamics throughout the engine on a macroscopic scale. 相似文献
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《Proceedings of the Combustion Institute》2023,39(3):3117-3126
Effects of fuel jet penetration height on supersonic combustion behaviors were investigated experimentally in a supersonic combustion ramjet model combustor at a Mach speed of 2 and at a stagnation temperature of 1900 K. The jet-to-crossflow momentum flux ratio was varied to control the fuel-jet penetration height, using several injectors with different orifice diameters: 2, 3, and 4 mm. First, transverse nitrogen jets were observed to identify a relationship between the fuel jet penetration height and the momentum flux ratio by focusing Schlieren photography. Then, supersonic combustion behaviors of ethylene were investigated through combustion pressure measurements. Simultaneously, time-resolved images of CH* chemiluminescence and shadowgraphs were recorded with high-speed video cameras. Furthermore, a morphology of supersonic combustion modes was investigated for various equivalence ratios and fuel penetration heights in a two-dimensional latent space trained by the shared Gaussian process latent variable models (SGPLVM), considering CH* chemiluminescence images and the shock parameters. The results indicated that the penetration height of nitrogen jets was a function of the jet momentum flux ratio; this function was expressed by a fitting curve. Five typical combustion modes were identified based on time-resolved CH* chemiluminescence images, shadowgraphs, and pressure profiles. Even for a given equivalence ratio, different combustion modes were observed depending on the fuel penetration height. For an injection diameter of 3 and 4 mm, cavity shear-layer and jet-wake stabilized combustions were observed as the scram modes. On the other hand, although the cavity shear-layer and lifted-shear-layer stabilized combustions were observed, no jet-wake stabilized combustion was observed for an orifice diameter of 2 mm. Fuel penetration heights above the cavity aft wall were expected to affect the combustion behavior. Finally, a morphology of the supersonic combustion modes was clearly shown in the two-dimensional latent space of the SGPVLM. 相似文献