Characterization of instabilities in a Rotating Detonation Combustor
Characterization of instabilities in a Rotating Detonation Combustor
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DOI：
10.1016/j.ijhydene.2015.09.046
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发表时间：
2015-12
影响因子：
7.2
通讯作者：
V. Anand;A. S. George;R. Driscoll;E. Gutmark
中科院分区：
文献类型：
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作者：
V. Anand;A. S. George;R. Driscoll;E. Gutmark
研究了旋转爆震燃烧室(RDC)在不同空气流量、燃料流量和不同几何形状下的运行情况，揭示了四种根本不同的不稳定性。选择测试点，利用定性和定量工具研究这些不稳定性。首先，对于稀薄极限、亚音速空气喷射或大喷油孔的RDC运行，燃烧室内的爆轰波在燃烧室环空经历了非周期的混沌传播，其特征是压力-时间轨迹不一致。记录到的压力高度不一致，以及随后的压力峰值有相当大的变化，这表明爆轰波多次失败和重新启动。其次，在测试的各种条件下，几乎所有工作点都表现出一定程度的低频正弦振荡，其特征是随后的爆轰峰值压力周期性地变大和变小。对于所研究的操作地图，它发生在200赫兹到500赫兹之间。第三，RDC中的模式切换现象也被定义为不稳定，因为燃烧室中存在的爆轰波数量的突然变化在时间上是不可预测的，并且对于给定的几何形状通常是不可预测的。研究发现，当燃烧室内存在多个爆轰波时，RDC的运行更为稳定。在背压式收敛喷管的作用下，RDC在某些工作点表现出与脉冲爆震燃烧室(PDC)相似的轴对称脉冲工作特性。有重要证据表明，这些纵向脉冲爆轰(LPD)是由于RDC出口的激波反射，然后是新反应物的激波起爆。对于所调查的测试案例，这种不稳定的频率约为3.8千赫。
Rotating Detonation Combustor (RDC) operation is investigated under different air and fuel flow rates, and varied geometries to reveal four fundamentally different instabilities. Select test points are chosen to study these instabilities using qualitative and quantitative tools. First, for RDC operation at lean limits, or with subsonic air injection, or with large fuel injection orifices, the detonation wave inside the combustor undergoes aperiodic chaotic propagation around the combustor annulus characterized by incoherent pressure-time traces. The high incoherence in recorded pressure, along with the considerable variation in subsequent pressure peaks suggests numerous failure and re-initiation of the detonation wave. Second, almost all operating points at the variety of conditions tested exhibit some degree of low frequency sinusoidal oscillations characterized by periodic waxing and waning of subsequent detonation peak pressures. It occurs between 200 Hz and 500 Hz for the operating maps studied. Third, the phenomenon of mode switching in the RDC is also defined as instability since the sudden change in the number of detonation waves existing in the combustor is temporally unpredictable, and often unpredictable for a given geometry. It is found that RDC operation is more stable when there are multiple detonation waves inside the chamber. With a back-pressurizing convergent nozzle, at certain operating points, the RDC exhibits axisymmetric pulsed operation like the Pulsed Detonation Combustor (PDC). There is significant evidence to suggest that these longitudinal pulsed detonations (LPD) are manifested due to shock-reflection from the RDC exit followed by a subsequent shock-initiation of the fresh reactants. The frequency of this instability is around 3.8 kHz for the test case investigated.