Blowoff hysteresis, flame morphology and the effect of plasma in a swirling flow
Blowoff hysteresis, flame morphology and the effect of plasma in a swirling flow
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DOI：
10.1088/1361-6463/aad4dc
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发表时间：
2018-08
期刊：
影响因子：
--
通讯作者：
Jinhoon Choe;Wenting Sun
中科院分区：
文献类型：
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作者：
Jinhoon Choe;Wenting Sun
研究了纳秒脉冲等离子体对环形旋流燃气轮机模型燃烧室火焰稳定的影响。与通常认为稀薄放空极限是一个单一值相反，在给定条件下，观察到放空的滞后现象，因此稀薄放空极限不是唯一定义的。这种迟滞现象取决于火焰被点燃时等效比的初始值和空气流速。根据等效比和火焰稳定区域的不同，还观察到不同的火焰形态。在燃烧室喷嘴出口处施加纳秒脉冲等离子体，总能观察到稳定的内剪切层火焰。火焰形态和稳定性对流量和当量比均不敏感。等离子体激活后，稀薄放空极限明显延长，迟滞现象消失。这表明等离子体为火焰稳定提供了一种额外的机制。研究了放电电压和重复频率对排气极限的影响。通过排放分析发现，等离子体活化提高了NOx浓度，降低了CO浓度。利用气体分析仪对不同放电条件下的氮氧化物进行了测量，以了解氮氧化物形成的主要因素。
This study focuses on the effect of a nanosecond pulsed plasma on flame stabilization in a model gas turbine dump combustor with an annular swirling flow. Contrary to the common belief that the lean blowoff limit is a single value at a given condition a hysteresis phenomenon on blowoff was observed, therefore the lean blowoff limit is not uniquely defined. This hysteresis phenomenon depends on the initial value of the equivalence ratio at which the flame was ignited and the air flow rate. Different flame morphologies were also observed depending on the equivalence ratio and the region where the flame was stabilized. If a nanosecond pulsed plasma was applied at the combustor nozzle exit a stable inner shear layer flame was always observed. The flame morphology and stability presented no sensitivity to either flow rates or the equivalence ratio. With plasma activation, the lean blowoff limit was significantly extended and the hysteresis phenomenon disappeared. This indicates that the plasma provided an additional mechanism for flame stabilization. The effect of discharge voltage and repetition frequency on the lean blowoff limit was investigated accordingly. It was found that plasma activation increased NOx concentration and decreased CO concentration through emission analysis. Measurement of NOx using a gas analyzer at different discharge conditions was conducted to understand the dominant factor in NOx formation.