High precision temperature measurements for reacting flows

反应流的高精度温度测量

基本信息

批准号：
EP/K02924X/1
负责人：
Simone Hochgreb
金额：
$ 54.16万
依托单位：
University of Cambridge
依托单位国家：
英国
项目类别：
Research Grant
财政年份：
2014
资助国家：
英国
起止时间：
2014 至无数据
项目状态：
已结题

来源：
https://gtr.ukri.org/projects?ref=EP%2FK02924X%2F1
关键词：
precision temperature measurements reacting flows

项目摘要

The effective and fast design of low emission gas turbines depends critically on the ability of engineers to make accurate and precise predictions of gas temperatures within the combustion chamber. This project aims to produce instantaneous temperature measurements of the highest accuracy and precision ever in model and industrial scale combustors. These precision measurements aim not only provide the basis for validation of models by industrial and academic users, but also to create a path for development of a lower cost, high precision thermometry technique for deployment in realistic combustors. The two key factors governing the design of continuous flow combustors are maintaining low emissions - particularly nitric oxides - and keeping the system away from thermoacoustic instabilities. The spatial and statistical distribution of burned gas temperatures is the single most important factor governing the formation of nitric oxide (NO): a local change of 50 K can lead to a change of 70% in thermal NO formation rates at typical combustion temperatures. Validation of emission prediction models is hemmed by the lack of availability of statistical and spatial information on temperatures. Thermoacoustic instabilities are created by a feedback effect in which acoustic waves generated by the unsteady acceleration of the flow during combustion in a confined environment lead to further unsteadiness in heat release. Two factors associated with the flame are important: the response of the flame to acoustic perturbation, and the generation of temperature non-uniformities (called entropy spots): the former leads directly to density fluctuations and acoustic waves, and the latter couple the boundary conditions to reflect as pressure waves. The identification of the origin of combustion instabilities is complex, as several factors can contribute fluctuations, yet usually only pressure information is available, sometimes aided by relative total heat release fluctuations via chemiluminescence. Nevertheless, statistical measurements of temperatures in either model or industrial scale gas turbine flames are relatively uncommon, because of difficulties with physical probes or optical methods relying on calibration of signal amplitudes. The proposed measurements do not rely on amplitudes, but on the measurement of signal frequency, which can be made significantly more precisely (down to errors of 0.2%) than comparable techniques. Furthermore, the present measurements will enable the direct simultaneous measurements of NO and temperature with a single laser, thus creating a unique statistical database for model validation. Finally, the technique will enable for the measurement of temperature fluctuations through a nozzle at very high precision, which has not been done previously. The high precision measurements will have a direct impact on assessing the quality of model predictions for NO and instabilities, and when translated into design codes, into the design of cleaner and more stable power and propulsion systems.

低排放燃气轮机的有效和快速设计取决于工程师对燃烧室内气温进行准确和精确预测的能力。该项目旨在在模型和工业规模燃烧器中生成有史以来最高精度和精度的瞬时温度测量。这些精确度量的目的不仅为工业用户和学术用户验证模型的基础，而且还为开发较低成本，高精度调节技术的发展途径，以在现实燃烧器中部署。控制连续流燃烧器设计的两个关键因素是保持低排放量（尤其是一氧化氮），并使系统远离热声不稳定性。燃烧气体温度的空间和统计分布是一氧化氮形成（NO）的最重要因素：50 K的局部变化可能导致在典型燃烧温度下的热无形成速率变化70％。由于缺乏有关温度的统计和空间信息的可用性，对排放预测模型的验证逐渐消失。热声不稳定性是通过反馈效应产生的，在燃烧环境中燃烧过程中流动不稳定的加速产生的声波导致热量释放的进一步不稳定。与火焰相关的两个因素很重要：火焰对声学扰动的响应以及温度不均匀性的产生（称为熵斑）：前者直接导致密度波动和声波，后者夫妇夫妇界线以反射为压力波。燃烧不稳定性起源的鉴定是复杂的，因为几个因素可以造成波动，但通常只有压力信息可用，有时通过化学发光的相对总热释放波动有助于。然而，由于依赖信号振幅校准的物理探针或光学方法的困难，模型或工业规模燃气轮机火焰中温度的统计测量并不常见。所提出的测量不依赖幅度，而是基于信号频率的测量，这可以比可比技术更精确地（误差为0.2％）。此外，当前的测量值将通过单个激光器对NO和温度进行直接同时测量，从而创建一个唯一的统计数据库来进行模型验证。最后，该技术将以非常高的精度通过喷嘴测量温度波动，这是以前尚未进行的。高精度测量结果将直接影响评估NO和不稳定性的模型预测质量，并在将设计代码转换为设计代码时，成为更清洁，更稳定的功率和推进系统的设计。