掺氢功率比对富氢甲烷燃烧振荡特性的影响

Effects of Hydrogen Power Ratio on Combustion Oscillation Characteristics of Hydrogen-Enriched Methane

关键词:  富氢甲烷  燃烧振荡  分层旋流火焰  贫油燃烧  掺氢功率比

Key words:  Hydrogen-enriched methane  Combustion oscillation  Stratified swirl flame  Lean combustion  Hydrogen power ratio

摘要:

为探究工程应用中富氢甲烷对燃烧振荡的影响，在北航BASIS燃烧器上针对富氢甲烷的中心分层火焰展开实验研究。分析主燃级当量比、预燃级当量比、主燃级掺氢功率比（氢气功率与主燃级燃料功率的比值）对燃烧振荡的影响。保持预燃级空气流量为2g/s，主燃级空气流量为10g/s，围绕主燃级当量比、预燃级当量比、主燃级掺氢功率比进行24个工况下的128组试验。试验对火焰压力脉动的振幅与频率进行测量，并结合火焰宏观形状进行分析研究，发现对于大多数当量比的工况，富氢甲烷火焰都处于同一模态，出现火焰分层现象但不产生燃烧振荡。主燃级当量比?_main=0.6与0.55时，富氢甲烷火焰脉动振幅随掺氢比加大，先增后减，分别有42%和32%的工况发生燃烧振荡。?_main=0.5时，燃烧振荡只在高预燃级当量比（?_pilot）、高掺氢比时发生，仅有7%的工况出现燃烧振荡。因此，为实现更大的减碳比例，在不改变燃烧器构型的情况下，大掺氢功率比燃烧需要工作在主燃级和预燃级非常贫油的条件下。在部分工况中，掺加氢气可以在一定程度上减弱热声振荡的强度。

Abstract:

In order to explore the impact of hydrogen-rich methane on combustion oscillations in engineering applications， experimental research was carried out around the centrally-staged flame of hydrogen-rich methane on the BASIS burner. The effects of main stage equivalent ratio， pilot stage equivalent ratio， and the hydrogen power ratio of main stage on combustion oscillation are conducted and analyzed. In this study， the air flow of pilot stage is 2g/s and that of main stage is 10g/s. 128 groups of tests under 24 working conditions are carried out with three major varying parameters： equivalence ratio of main stage， equivalence ratio of pilot stage and hydrogen power ratio. The pressure fluctuation is measured and analysed combining with the flame macrostructure. It is found that under most of the equivalence ratio conditions， hydrogen-enriched flame occurs in the same thermos-acoustic mode， and the flame stratification is obvious with no combustion instability. When ?_main=0.6 and 0.55， the pulsation amplitude of hydrogen rich methane flame increases first and then decreases with the increase of hydrogen power ratio. Combustion oscillation occurs under 42% and 32% working conditions respectively. When ?_main=0.5， combustion oscillation occurs only under high ?_pilot and high hydrogen power ratio， and combustion oscillation occurs only under 7% working conditions. In order to achieve higher carbon reduction ratio， the combustor should be carried out under very lean combustion conditions of the main and pilot stage to avoid strong combustion instabilities. And in some working conditions， adding hydrogen can weaken the intensity of thermoacoustic oscillation.