甲烷掺氢旋流预混燃烧回火特性研究

Flashback Characteristics in CH_(4)/H_(2)-air Premixed Swirl-stabilized Combustio

在节能减排与碳中和大背景下,燃气轮机燃烧室燃料逐渐向富氢方向发展。燃料掺氢后,燃烧过程更容易发生回火现象,需要对掺氢燃烧回火规律进行探究。本文选取了带钝体旋流预混燃烧室开展甲烷掺氢–空气的预混燃烧数值模拟研究,湍流模型采用SST k-ω模型,湍流燃烧模型采用火焰面生成模型(FGM);准确地计算湍流火焰速度对回火现象的预测非常重要,因此对进度变量输运方程中源项的封闭考虑了掺氢对层流火焰传播速度的影响。数值模型与方法得到了实验验证,并进一步探究了当量比、入口平均轴向速度、钝体壁面热边界条件对回火现象的影响。结果表明降低当量比、提高入口平均轴向速度以及增强壁面换热对回火现象具有抑制作用。本文所总结的回火规律对于掺氢燃烧室设计具有指导意义。

In the context of stringent requirement of energy eficiency and carbon neutrality,there is an increasingly growing trend towards utilizing hydrogen-enriched fuel blend in gas turbine combus-tors.Introducing hydrogen into the fuel increases the likelihood of fashback during the combustion process,necessitating further investigation.In this research,a premixed bluff-body swirl burner is chosen for numerical simulations of premixed CH_(4)/H_(2)-air combustion under various operating con-ditions.SST k-w model and Flamelet-Generated Manifold(FGM)are employed,respectively,as turbulence model and combustion model.It is of great importance to accurately calculate turbu-lent fame speed in order to predict fashback,thus the influence of hydrogen addition on laminar fame speed is considered when concerning the closure of the source term in the transport equation of the progress variable.The numerical models and methods are verified against experimental re-sults.Furthermore,the impact of three key factors on fashback are investigated:equivalence ratio,inlet velocity,and thermal boundary conditions of the bluff-body.Results show that decreasing equivalence ratio,increasing inlet velocity,or enhancing heat transfer at bluff-body wall tend to alleviate the occurrence of fashback.The obtained insight could potentially guide the design of hydrogen-enriched gas turbine combustor.