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Modeling and Identification of Technically Premix Flame Dynamics

技术上预混火焰动力学的建模和识别

基本信息

批准号：
393001638
负责人：
Professor Dr. Michael Pfitzner
金额：
--
依托单位：
Institut für Thermodynamik (LRT-10)
依托单位国家：
德国
项目类别：
Research Grants
财政年份：
2017
资助国家：
德国
起止时间：
2016-12-31 至 2021-12-31
项目状态：
已结题

来源：
https://gepris.dfg.de/gepris/projekt/393001638?language=en
关键词：
Modeling Identification Technically Premix Flame

项目摘要

In order to study self-excited combustion instabilities, it is essential to characterize the response of the flame of interest to relevant flow perturbations. In the proposed study, the dynamic response of technically premixed flames to perturbations of upstream velocity and equivalence ratio will be modelled and quantified simultaneously. This will be achieved by combining validated Large Eddy Simulation (LES) of turbulent, reacting flow with advanced System Identification (SI) in order to generate reduced order models of flame dynamics that properly respect the Multiple-Input / Single-Output (MISO) structure of technically premixed flames. Two main challenges will be addressed: 1) Advanced SI methods, employing Box-Jenkins models with MISO structure, will be used to identify reduced order response functions from LES time series data. Unlike models based on traditional identification schemes, the resulting flame models will be independent of the acoustic properties of the fuel injection system. In addition, combustion noise resulting from resolved turbulent fluctuations will not be disregarded in the advanced SI framework, as was done previously, but instead will be modelled as colored noise. This enhances the quality of the overall identification and allows to quantify uncertainties that result from finite time series length. 2) Reduced order models determined with System Identification (SI) can only be as accurate as the time series data that they are deduced from. Furthermore, MISO identification requires time series of considerable length. Thus a turbulent combustion model for LES of technically premixed flames that is both accurate and efficient must be employed, or developed and validated with respect to mean and fluctuating quantities. Furthermore, the capability of LES combustion models to predict flame dynamics will be validated. The model must be reliable even for coarse meshes and at elevated pressure, where sub-grid flame wrinkling can be considerable. The MISO models determined with validated LES/SI can be combined with acoustic models to study, for example, the impact of location and acoustic impedance of fuel injectors on the thermoacoustic stability of combustors in a flexible and efficient manner.

为了研究自激燃烧不稳定性，必须表征感兴趣的火焰对相关流动扰动的响应。在拟议的研究中，技术预混火焰的上游速度和当量比的扰动的动态响应将建模和量化的同时。这将通过将湍流反应流的有效大涡模拟（LES）与先进的系统识别（SI）相结合来实现，以生成适当尊重技术预混火焰的多输入/单输出（MISO）结构的火焰动力学降阶模型。两个主要的挑战将被解决：1）先进的SI方法，采用Box-Jenkins模型与MISO结构，将被用来识别降阶响应函数从LES时间序列数据。与基于传统识别方案的模型不同，所得到的火焰模型将独立于燃料喷射系统的声学特性。此外，在先进的SI框架中，由解析的湍流波动引起的燃烧噪声将不会被忽略，就像以前所做的那样，而是将被建模为有色噪声。这提高了整体识别的质量，并允许量化有限时间序列长度导致的不确定性。2)用系统识别（SI）确定的降阶模型只能与它们从中推导出的时间序列数据一样准确。此外，MISO识别需要相当长的时间序列。因此，技术预混火焰的LES湍流燃烧模型，这是准确和有效的，必须采用，或开发和验证的平均值和波动量。此外，LES燃烧模型预测火焰动力学的能力将得到验证。该模型必须是可靠的，即使在粗网格和高压，亚网格火焰湍流可以是相当大的。MISO模型确定与验证LES/SI可以与声学模型相结合的研究，例如，位置和声阻抗的燃料喷射器上的燃烧室的热声稳定性的影响，在一个灵活和有效的方式。