A new pattern of flame/flow dynamics for lean-premixed, low-swirl hydrogen turbulent jet flames under thermoacoustic instability
A new pattern of flame/flow dynamics for lean-premixed, low-swirl hydrogen turbulent jet flames under thermoacoustic instability
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热声不稳定下稀薄预混、低旋氢湍流射流火焰的火焰/流动动力学新模式
DOI：
10.1016/j.proci.2020.05.040
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发表时间：
2021
影响因子：
3.4
通讯作者：
Yokomori Takeshi
中科院分区：
文献类型：
--
作者：
Shoji Takeshi;Tachibana Shigeru;Suzuki Terukazu;Nakazumi Yoshihiro;Yokomori Takeshi
本文介绍了一种新的贫预混氢火焰和热声不稳定性下的流场动力学的现象学研究在低旋流燃烧室（LSC）内观察到的两个燃烧室长度为300和500 mm。在这项研究中，初始整体进口速度被设置为Vm = 15 m/s。当空气流量保持恒定时，燃料流量线性增加，导致从稳定操作过渡到TI。同时进行时间分辨的电子激发的羟基自由基（OH*）化学发光成像和二维粒子图像测速仪沿着压力波动测量，以研究波动量，即OH* 化学发光，速度场和压力之间的时空关系，之前和之后TI发病。在长燃烧室中观察到一个典型的TI型，其特征是由喷射器出口附近的发散、减速流引起的抬升、倒置的锥形火焰。相比之下，在短燃烧室TI下的火焰/流动动力学模式具有强烈的压力振荡和异常的LSC火焰结构，其特征在于径向平坦的火焰区域和反向旋转涡对（CVP）火焰结构。在这种情况下，轴向速度的径向轮廓呈现出非典型的礼帽状形状。这一特点导致热声耦合，满足瑞利准则在一个几乎完全平坦的火焰区域，并进一步加强了TI。CVP结构的热膨胀充当收缩中心流动区域的“收敛喷嘴”。这种文丘里效应的周期性出现造成了交替的发散（减速）和收敛（加速）流场，具有15 m/s的显著峰-峰速度振荡幅度，相当于V m。这些关于LSC的开创性观察为氢燃料燃气涡轮机燃烧室中的TI机制提供了进一步的见解。
This paper presents a phenomenological investigation of a new pattern of lean-premixed hydrogen-flame and flowfield dynamics under thermoacoustic instabilities (TIs) observed inside a low-swirl combustor (LSC) with two combustion chamber lengths of 300 and 500 mm. In this study, the initial bulk inlet velocity was set to V m= 15 m/s. The fuel flow rate was linearly increased while the air flow rate was kept constant, causing a transition from stable operation to TI. Simultaneous time-resolved electronically excited hydroxyl radical (OH*) chemiluminescence imaging and two-dimensional particle image velocimetry were performed along with pressure-fluctuation measurements to investigate spatiotemporal relationships between fluctuating quantities, ie, OH* chemiluminescence, velocity fields, and pressure, before and after TI onset. A typical TI pattern characterized by a lifted, inverted conical flame caused by diverging, decelerating flow near the injector exit was observed in the long combustor. In contrast, the flame/flow dynamics pattern under TI in the short combustor had strong pressure oscillations and anomalous LSC flame structures which were characterized by a radially flat flame region and counter-rotating vortex pair (CVP) flame structures. In this case, the radial profile of the axial velocity assumed an atypical top-hat-like shape. This feature resulted in thermoacoustic coupling that satisfied the Rayleigh criterion over an almost entirely flat flame region and further strengthened the TI. Thermal expansions of CVP structures served as “converging nozzles” constricting the central flow region. Periodic appearances of this Venturi-like effect caused an alternating diverging (decelerating) and converging (accelerating) flowfield, with a significant peak-to-peak velocity-oscillation amplitude of 15 m/s, equivalent to V m. These pioneering observations regarding LSCs provide further insights into TI mechanisms in hydrogen-fueled gas turbine combustors.
安装在边界层的双引擎风力涡轮机模型尾流的彩色 PIV
DOI：
--
发表时间：
2016
期刊：
影响因子：
--
作者：
T.Nakashima;T.Shiratori;Y.Murai;Y.Tasaka;Y.Takeda;E.J.Windhab;大友衆示，村井祐一，田坂裕司，Petr Denissenko;磯田 龍，大須賀 侑，小林寛尭，田坂裕司，村井祐一
通讯作者：
磯田 龍，大須賀 侑，小林寛尭，田坂裕司，村井祐一