权益分类	功能权益	普通用户	{{item.name}}会员
{{category.name}}	{{benefitItem.name}}

Detailed Image Analysis of Vortex-Flame Interaction under Acoustic Excitation of Coherent Structure Characterized by Geometrical Configuration

几何构型相干结构声激励下涡旋-火焰相互作用的详细图像分析

基本信息

批准号：
18560197
负责人：
OHIWA Norio
金额：
$ 2.43万
依托单位：
Nagoya Institute of Technology
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
2006
资助国家：
日本
起止时间：
2006 至 2007
项目状态：
已结题

项目摘要

Depending on their own geometric configurations, many types of coherent structures exist in the practical turbulent flow fields, such as jets, wakes and plane shear layers. Since these flow fields are employed as fundamental flow fields for practical turbulent combustion, detailed optical observations and image processing of vortex-flame interaction in the turbulent combustion enable modeling of basic flame structure. To make the latter possible, a variety of devices is necessary concerning optical observations and image processing. During the first term of this investigation, 2006, acoustic excitation of coherent structure has been introduced to make it conspicuous and to make optical observation easy, whereas detailed PIV measurements and their image processing are made to estimate the effects of baroclinic torque on the vorticity conservation equation. In the final term of this investigation, 2007, the concrete roles of baroclinic torque in the flame-flow interaction have been studi … More ed using an incompressible two-dimensional jet, being most simple among the above-mentioned flows. By means of PIV velocimeter using titanium-oxide powder and smoke of an joss stick of about 1 μm diameter as tracking particles, the behaviors of a single two-dimensional vortex ejected into both uniform and non-uniform density fields under micro-gravity of 0.1 m/s2 have been tracked and analyzed, as well as those under normal gravity. Some devices and improvements have been made, such as a tower system to realize the condition of micro-gravity in the normal room situation and an original PIV-imaging system for making clear the weak effects of baroclinic torque on vortex-flame interaction.It was found that, due to the combined influence of density-gradient and pressure-gradient, a symmetric vorticity is clearly generated along the boundary region of the vortex, and that the flow velocity within the vortex decreases discontinuously across the boundary region of vorticity generation. Also found was that, finally, the effects of baroclinic torque on vortex-flame interaction are selectively enhanced in the flame zone where a steep density gradient inevitably is produced Less

实际湍流流场中存在着许多类型的拟序结构，如射流、尾迹和平面剪切层，这取决于它们各自的几何构型。由于这些流场被用作实际湍流燃烧的基本流场，对湍流燃烧中涡流-火焰相互作用的详细光学观测和图像处理使基本火焰结构的模拟成为可能。为了使后者成为可能，在光学观测和图像处理方面需要各种设备。在2006年的第一期研究中，引入了相干结构的声激励，以使其更明显，并使光学观测变得容易，而详细的PIV测量及其图像处理被用来估计斜压力矩对涡度守恒方程的影响。在这项研究的最后一期，2007年，斜压力矩在火焰-流动相互作用中的具体作用已经被研究i…更多的是使用不可压缩的二维射流，这是上述流动中最简单的。利用PIV测速仪，以二氧化钛粉末和直径约1μm的香棒烟雾为示踪粒子，跟踪和分析了0.1m/s2微重力和正常重力条件下，单个二维涡喷射到均匀和非均匀密度场中的行为。并对其进行了一些改进和改进，如在正常房间条件下实现微重力的塔式系统，以及用于阐明斜压力矩对涡焰相互作用的微弱影响的原始PIV成像系统。研究发现，由于密度梯度和压力梯度的共同影响，涡旋的边界区域明显地产生了对称的涡量，涡旋内部的流速在涡量产生的边界区域不连续地下降。最后还发现，斜压力矩对旋涡-火焰相互作用的影响在火焰区选择性地增强，在那里必然产生较少的陡峭密度梯度。