Experimental and Numerical Investigation of Swirl Induced Self-Excited Instabilities at the Vicinity of an Airblast Nozzle
Experimental and Numerical Investigation of Swirl Induced Self-Excited Instabilities at the Vicinity of an Airblast Nozzle
复制标题
鼓风喷嘴附近旋流引起的自激不稳定性的实验和数值研究
DOI：
--
复制
发表时间：
2009
期刊：
影响因子：
--
通讯作者：
N. Zarzalis
中科院分区：
文献类型：
--
作者：
P. Fokaides;M. Weiss;M. Kern;N. Zarzalis
本文报道了在空气雾化喷嘴附近以旋进螺旋结构形式出现的旋流诱导自激不稳定性的实验和数值研究。在这项工作的范围内，通过应用双气流Airblast喷嘴，旨在增加对控制旋进涡核现象（PVC）（Gupta等人，1984）的基本因素的了解。本研究集中在燃烧室系统的重要参数对这种不稳定性的性能特性的影响的实验研究。特别是，在这项工作中，PVC的性能是通过应用两种不同的气流雾化器来确定的，其中一种产生附着的旋流火焰，另一种产生提升的旋流火焰。还对受限火焰和非受限火焰进行了测量，旨在确定受限管道对PVC性能的影响。为了获得一些进一步的知识，关于这种空气动力学不稳定性对气体燃料燃烧的影响，PVC的特征在反应条件下实验确定，通过采用激光光片（LLS）测量技术。通过应用LLS测量技术，还试图进一步研究PVC的性质。流场的功率谱密度（PSD）函数的基础上提供的原始数据的三维激光多普勒风速仪（3D-LDA）。为了验证测量技术以及不稳定性的性质，通过采用在12 kHz下执行的高速摄像机来评估流的平面Mie散射。利用三维雷诺应力模型（3D-RSM）对流动进行了数值模拟，证实了流动的旋进特性。数值研究的结果提供了一些有用的信息，关于不稳定的发生在主旋流器以及其大小和振幅。根据该分析，在燃烧器出口下游约一个燃烧器直径的区域内确认了高频不稳定性。最后，在提供准确的（PSD）的情况下的旋流场的（LDA）方法的评价进行。
We report on the experimental and numerical investigation of swirl induced self-excited instabilities in the form of precessing helical structures at the vicinity of an Airblast Atomiser. Within the scope of this work, the increase of the knowledge of the fundamental factors governing the precessing vortex core phenomenon (PVC) (Gupta et al. 1984) by applying dual air-flow Airblast nozzles is aimed. This study concentrates on the experimental investigation of the impact of important parameters of a combustor system on the performance characteristics of this instability. In particular, in terms of this work the properties of the PVC are determined by applying two different Airblast Atomisers, one of them producing an attached swirl flame, and another producing a lifted swirl flame. Measurements are also performed for a confined and a non confined flame, aiming to determine the impact of the confining duct on the performance of the PVC. In order to gain some further knowledge, regarding the impact of this aerodynamic instability on combustion of gaseous fuel, the features of PVC are experimentally identified under reacting conditions, by employing a laser light sheet (LLS) measurement technique. By applying the LLS measurement technique, further investigation on the nature of the PVC is also attempted. The power spectral density (PSD) function of the flow field was determined on the basis of raw data provided by 3D Laser Doppler Anemometry (3D-LDA). In order to validate the measurement technique as well as the nature of the instability, the planar Mie-Scattering of the flow was evaluated by employing a high speed camera performing at 12 kHz. The precessing character of the flow was also confirmed by means of a numerical simulation using the 3D Reynolds Stress Model (3D-RSM). The results of the numerical investigation provided some useful information concerning the onset of the instability within the primary swirler as well as its size and amplitude. According to this analysis, a high frequency instability was confirmed within a region of about one burner diameter downstream of the burner exit. Finally an evaluation of the (LDA) method in terms of providing accurate (PSD) was performed for the case of a swirl flow field.