Combustion dynamics of turbulent swirl flames with hydrogen addition

加氢湍流旋流火焰的燃烧动力学

基本信息

批准号：
EP/G063788/1
负责人：
Ramanarayanan Balachandran
金额：
$ 35.2万
依托单位：
University College London
依托单位国家：
英国
项目类别：
Research Grant
财政年份：
2010
资助国家：
英国
起止时间：
2010 至无数据
项目状态：
已结题

来源：
https://gtr.ukri.org/projects?ref=EP%2FG063788%2F1
关键词：
Combustion dynamics turbulent swirl flames

项目摘要

Combustion instabilities represent one of the most serious problems hindering the development of low-emission aero- and industrial- gas turbine combustors. In order to achieve efficient, low-emissions performance fuel-lean and preferably premixed operating conditions are necessary. However, these lean combustors have the drawback of being particularly susceptible to thermo-acoustic instability. These instabilities are characterised by strong pressure oscillations in the combustion chamber due to a complex interaction between thermo-acoustic and fluid-dynamic processes. When the pressure or velocity oscillations couple favourably with the unsteady heat release, large-amplitude self-sustained oscillation may result. These high amplitude oscillations can have a detrimental effect on combustor performance and may cause catastrophic failure of the system. Lean premix concept is increasingly adopted by gas turbine engine manufacturers to reduce emissions and increase fuel economy. Although fuel lean conditions reduce NOx emissions by decreasing the flame temperature, lean flames are particularly susceptible to combustion oscillations and blow-off. Hydrogen enrichment is one of the promising methods that can be used to improve the stable operation of the combustor under extremely lean conditions. Hydrogen enrichment also improves the ignitability and the response of the flame to strain and curvature. These benefits suggest a promising role for hydrogen enrichment in the development of low-emission gas turbine combustion technology. However, the response of the hydrogen enriched flames in the context of combustion instability is not fully understood. Thus, the primary motivation of this study is to understand and underpin the mechanisms of heat release modulation with hydrogen addition in the context of combustion oscillations. There are several well known mechanisms that can promote fluctuations in the heat release in lean flames; namely, variations in mixture ratio, sensitivity of the flames to pressure/velocity oscillations, and the formation and shedding of vortices. Any of these mechanisms can cause combustion oscillations to grow in amplitude through positive feedback until a self-sustaining limit-cycle amplitude is reached. However, there is often a clear distinction between the mechanisms driving linear growth of instability and those which cause the heat release oscillations to saturate to limit-cycle conditions. In order to predict and control combustion instabilities effectively the transition from linear growth to non-linear saturation and the mechanisms governing this transition has to be better understood, especially in industrial type non-/partially premixed flames with hydrogen addition. This proposal aims: a) to study and compare mechanisms of heat release oscillations in bluff-body and swirl stabilised turbulent flames, b) to investigate the effect of flame anchoring and that of spatial and temporal mixture variation, which are relevant to limit-cycle oscillation in practical combustors, and c) to assess and understand the role of hydrogen addition in improving the dynamic stability of the combustor, using simultaneous measurements of flow and heat release via advanced laser diagnostic techniques. The expected outcome of this project is to underpin the mechanisms of combustion oscillations in turbulent flames relevant to practical combustors. In particular, the proposed experiments will highlight the role of flame stabilisation, equivalence ratio variation and hydrogen addition on the non-linear flame response, which is of significant importance for improving the fundamental understanding and prediction of the limit-cycle oscillations in practical combustion systems. This research will lead to development of non-linear flame models for acoustic analysis and also aid the development of new control strategies for elimination of combustion oscillations in industrial combustors.

燃烧不稳定性代表了阻碍低排放航空和工业燃气轮机燃烧器发展的最严重问题之一。为了实现高效，低排放性能的燃油液和优选的预混合操作条件。但是，这些精益燃烧器的缺点特别容易受到热声不稳定性的影响。这些不稳定性的特征是由于热声和流体动力学过程之间的复杂相互作用，燃烧室中的强压振荡。当压力或速度振荡与不稳定的热量释放相当有利时，可能会导致大振幅自我维持的振荡。这些高振幅振荡可能对燃烧器的性能产生不利影响，并可能导致系统灾难性失败。燃气轮机发动机制造商越来越多地采用精益预兆概念，以减少排放并增加燃油经济性。尽管燃料稀疏条件通过降低火焰温度来减少NOx排放，但倾斜火焰特别容易受到燃烧振荡和吹风。氢富集是一种有前途的方法之一，可用于在极度瘦弱的条件下改善燃烧器的稳定操作。氢富集还改善了火焰对应变和曲率的响应。这些好处表明，氢在低发射燃气轮机燃烧技术的发展中起着有希望的作用。但是，在燃烧不稳定性的情况下，富含氢的火焰的反应尚不完全了解。因此，这项研究的主要动机是在燃烧振荡的背景下使用氢添加氢调制的机理和支撑。有几种众所周知的机制可以促进瘦火中的热量释放中的波动。也就是说，混合比例的变化，火焰对压力/速度振荡的敏感性以及涡流的形成和脱落。这些机制中的任何一种都会导致燃烧振荡通过正反馈振幅增长，直到达到自我维持的极限周期振幅为止。但是，驱动不稳定性线性生长的机制与导致热释放振荡饱和至限制周期条件的机制通常存在明显的区别。为了有效地预测和控制燃烧不稳定性，必须更好地理解从线性生长到非线性饱和度到非线性饱和的过渡，并且必须更好地理解管理此转变的机制，尤其是在氢加氢的非工业类型非/部分预混合的火焰中。该提案的目的是：a）研究和比较悬崖体和漩涡状稳定的湍流火焰中热释放的机制，b）研究火焰锚定的效果以及空间和时间混合物的变化的效果，这些变化与限制周期振荡在实践燃烧器中的限制型振荡有关，以及在实践燃烧方面的作用，以及c）的作用，并理解了动态的作用。通过高级激光诊断技术测量流量和热量。该项目的预期结果是支持与实用燃烧器有关的湍流火焰中燃烧振荡的机制。尤其是，提出的实验将突出火焰稳定，等效比变化和氢在非线性火焰响应中的作用，这对于改善对实际燃烧系统中极限周期振荡的基本理解和预测至关重要。这项研究将导致开发用于声学分析的非线性火焰模型，并有助于开发新的控制策略，以消除工业燃烧器中的燃烧振荡。

项目成果

期刊论文数量（10）

专著数量（0）

科研奖励数量（0）

会议论文数量（0）

专利数量（0）

Heat release rate estimation in laminar premixed flames using laser-induced fluorescence of CH2O and H-atom

DOI：
10.1016/j.combustflame.2015.12.023
发表时间：
2016-03
期刊：
Combustion and Flame
影响因子：
4.4
作者：
I. Mulla;A. Dowlut;T. Hussain;Z. Nikolaou;S. Chakravarthy;N. Swaminathan;R. Balachandran
通讯作者：
I. Mulla;A. Dowlut;T. Hussain;Z. Nikolaou;S. Chakravarthy;N. Swaminathan;R. Balachandran

19th International Congress on Sound & Vibration

第十九届国际声音大会