• 主题
高级搜索  >
历史搜索 清空历史
首页> 外文学位 >Two-point high repetition rate measurement of temperature and thermal dissipation in a turbulent non-premixed jet flame.
【24h】

Two-point high repetition rate measurement of temperature and thermal dissipation in a turbulent non-premixed jet flame.

机译：湍流非预混射流火焰中温度和散热的两点高重复率测量。

获取原文
获取原文并翻译 | 示例
页面导航
  • 摘要
  • 著录项
  • 相似文献
  • 相关主题

摘要

A high-repetition rate (10 kHz) laser Rayleigh scattering facility was developed and used to study the temperature fluctuations, power spectra, gradients and thermal dissipation rate characteristics of a nonpremixed turbulent jet flame at a Reynolds number of 15,200. The flame studied here is similar to the Turbulent Nonpremixed Flame Workshop simple jet flame (DLR_A flame). The radial temperature gradient was measured by a two-point technique, whereas the axial gradient was inferred from temperature time-series measurements combined with Taylor's hypothesis.; Resolution and noise can greatly affect such measurements, and thus a model is proposed to account for the effects of resolution, noise, filtering and data processing on the measured dissipation. The model clearly shows the interplay between resolution and noise, and that noise will create an apparent dissipation (or bias), which will be more significant at high spatial resolution. Techniques to correct the measured mean dissipation for this bias are discussed for the two-point time-series thermal dissipation measurements reported here. A general technique to estimate the noise level for scalar dissipation measurements is also proposed.; The resulting two-point time-resolved measurements in a turbulent flame show that the temperature power spectra along the jet centerline exhibit only a small inertial subrange due to the low local Reynolds number of the flow (Redelta ∼ 2,500), although a larger inertial subrange is present in the spectra at offcenterline locations. Furthermore, the power spectra collapse in the dissipation range when the frequencies are normalized by the Batchelor frequency. Probability density functions of the thermal dissipation are shown to deviate from lognormal in the low-dissipation portion of the distribution when only one component of the gradient is used; however, nearly lognormal distributions are obtained along the centerline when both axial and radial components are included. A procedure is developed for correcting the thermal dissipation for the apparent dissipation introduced by noise. This procedure uses redundant measurements, either temporally or spatially, to quantify the noise contribution on the mean dissipation. This analysis shows that noise has a dominating effect on the dissipation as the apparent dissipation can be as large as five times the actual dissipation on centerline. The corrected dissipation measurements show that the radial profile of the mean thermal dissipation exhibits a peak off centerline at all downstream locations. These results indicate that the underlying turbulence, as inferred from the temperature fluctuations, is in large part similar to that of nonreacting jet flows, provided the Reynolds number is properly modified to account for heat release.
机译：开发了一种高重复频率（10 kHz）的激光瑞利散射设备，用于研究雷诺数为15,200的非预混湍流射流火焰的温度波动，功率谱，梯度和热耗散率特性。这里研究的火焰类似于湍流非预混火焰车间简单喷射火焰（DLR_A火焰）。径向温度梯度是通过两点技术测量的，而轴向梯度是根据温度时间序列测量结果和泰勒假设得出的。分辨率和噪声会极大地影响此类测量，因此，提出了一个模型来考虑分辨率，噪声，滤波和数据处理对所测耗散的影响。该模型清楚地显示了分辨率和噪声之间的相互作用，并且噪声会产生明显的耗散（或偏差），在高空间分辨率下，这种耗散会更大。对于此处报告的两点时间序列热耗散测量，讨论了针对该偏差校正测量的平均耗散的技术。还提出了一种用于标量耗散测量的估计噪声电平的通用技术。在湍流火焰中产生的两点时间分辨测量结果表明，由于射流的局部雷诺数较低（Redelta〜2500），因此沿射流中心线的温度功率谱仅表现出较小的惯性子范围（尽管惯性子范围较大）在谱线中偏心位置。此外，当通过Batchelor频率归一化频率时，功率谱在耗散范围内崩溃。当仅使用梯度的一个分量时，散热的概率密度函数显示为在分布的低散热部分偏离对数正态。但是，当同时包含轴向和径向分量时，沿中心线可获得几乎对数正态分布。开发了一种程序来校正由噪声引入的视在散热的散热。该过程使用时间或空间上的冗余测量来量化噪声对平均耗散的贡献。该分析表明，噪声对耗散具有主要影响，因为视在耗散可能是中心线上实际耗散的五倍。校正后的散热测量结果表明，平均散热的径向分布在所有下游位置均出现偏离中心线的峰值。这些结果表明，根据温度波动推断出的基本湍流在很大程度上类似于未反应的射流，但前提是适当修改雷诺数以考虑热量释放。

著录项

  • 作者

    Wang, Guanghua.;

  • 作者单位

    The University of Texas at Austin.;

  • 授予单位 The University of Texas at Austin.;
  • 学科 Engineering Aerospace.
  • 学位 Ph.D.
  • 年度 2004
  • 页码 211 p.
  • 总页数 211
  • 原文格式 PDF
  • 正文语种 eng
  • 中图分类 航空、航天技术的研究与探索;
  • 关键词

相似文献

  • 外文文献
  • 中文文献
  • 专利
获取原文

客服邮箱：kefu@zhangqiaokeyan.com

京公网安备：11010802029741号 ICP备案号：京ICP备15016152号-6 六维联合信息科技 (北京) 有限公司©版权所有

  • 客服微信

  • 服务号