On the effects of oxygen fraction on stability and combustion characteristics of dual-swirl oxy-methane flames: An experimental and numerical study

IF 6.4 2区工程技术 Q1 THERMODYNAMICS Case Studies in Thermal Engineering Pub Date : 2024-11-17 DOI:10.1016/j.csite.2024.105519

Mohamed Hamdy, Mohammed El-Adawy, Ahmed Abdelhalim, Ahmed Abdelhafez, Medhat A. Nemitallah

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Abstract

The effects of oxygen fractions of primary and secondary streams on flow/flame interactions, flame stability and macrostructure, and combustion and emissions characteristics of premixed oxy-methane (CH4/CO2/O2) flames were studied experimentally and numerically in a dual annular counter-rotating swirl (DACRS) burner for applications of clean power production in gas turbines. The primary stream oxygen fractions (OFp) of 34 % and 25 % were paired with secondary stream oxygen fractions (OFs) ranging from 25 % to 39 % at fixed primary stream equivalence ratio (φp = 0.9), fixed velocity ratio of 3.0 by the primary (of 5 m/s) and secondary (of 1.667 m/s) streams, and over ranges of secondary stream equivalence ratios (φs). The results showed that at OFp = 34 % and OFS = 39 %, the pilot flame supports a lean secondary flame down to φs = 0.434 at combustor global equivalence ratio (φg) of 0.467. Flame flashback concerns were not seen in the operative OFs zone until the secondary stream reached stoichiometric operation (φs = 1.0). The widths and forms of the inner and outer recirculation zones (IRZ and ORZ) are not significantly affected by changes in OF. Reducing φg and OFg resulted in decreases in Damköhler number (Da), laminar flame speed, and CO emissions.

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氧分数对双漩涡全氧甲烷火焰稳定性和燃烧特性的影响：实验和数值研究

在用于燃气轮机清洁发电的双环形反向旋转漩涡（DACRS）燃烧器中，实验和数值研究了一次流和二次流的氧分数对预混甲烷（CH4/CO2/O2）火焰的流动/火焰相互作用、火焰稳定性和宏观结构以及燃烧和排放特性的影响。在固定一次流当量比 (φp = 0.9)、一次流（5 m/s）和二次流（1.667 m/s）固定速度比 3.0 以及二次流当量比 (φs)范围内，一次流氧分数 (OFp) 为 34 % 和 25 %，二次流氧分数 (OFs) 为 25 % 至 39 %。结果表明，在 OFp = 34 % 和 OFS = 39 % 的条件下，先导火焰可支持燃烧器全等效比 (φg) 为 0.467 时的φs = 0.434 的贫二级火焰。在二次气流达到化学计量运行（φs = 1.0）之前，运行中的 OFs 区域不会出现火焰回火问题。内再循环区和外再循环区（IRZ 和 ORZ）的宽度和形式受 OF 变化的影响不大。降低 φg 和 OFg 会导致达姆克勒数 (Da)、层流火焰速度和 CO 排放量下降。

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来源期刊

Case Studies in Thermal Engineering Chemical Engineering-Fluid Flow and Transfer Processes

CiteScore

8.60

自引率

11.80%

发文量

812

审稿时长

76 days

期刊介绍： Case Studies in Thermal Engineering provides a forum for the rapid publication of short, structured Case Studies in Thermal Engineering and related Short Communications. It provides an essential compendium of case studies for researchers and practitioners in the field of thermal engineering and others who are interested in aspects of thermal engineering cases that could affect other engineering processes. The journal not only publishes new and novel case studies, but also provides a forum for the publication of high quality descriptions of classic thermal engineering problems. The scope of the journal includes case studies of thermal engineering problems in components, devices and systems using existing experimental and numerical techniques in the areas of mechanical, aerospace, chemical, medical, thermal management for electronics, heat exchangers, regeneration, solar thermal energy, thermal storage, building energy conservation, and power generation. Case studies of thermal problems in other areas will also be considered.