报告摘要：

The formation of combustion-driven instabilities in modern low-NOx combustors is still a problem. Therefore, there is an extensive research to develop a reduced physical model, which allows - without time-consuming measurements - to calculate the resonance characteristics of a combustion system consist of Helmholtz-resonator-type components (burner plenum, combustion chamber). For the formulation of this model numerical investigations by means of compressible large eddy simulation (LES) are carried out. In these investigations the flow in the combustion chamber is isotherm, non-reacting and excited with a sinusoidal mass flow rate. The investigations concentrated firstly on the single combustion chamber as a single resonator. The results gave a good prediction of the resonant characteristics and enabled to identify the mean damping mechanism.

In this seminar the investigations of a coupled system will be presented. In order to understand the mechanisms related to pulsations in complex combustion systems it is necessary but not sufficient to predict the resonant characteristics of the single components only. The reduced physical model was extended for the coupled system of burner and combustion chamber. This is an indispensable step to enable the prediction of the resonance characteristic of combustion systems existing of numerous different volumes like mixing unit, air/fuel supply, burner plenum, combustion chamber and the exhaust gas system. By means of numerical simulation and the physical model the resonance characteristics of a combustion system can be predicted already during the design phase. The main goal of the numerical investigation is to predict the damping coefficient of the system which is an important input for the physical model. In order to predict the resonant characteristics of the coupled system and to provide an insight into the flow mechanics 10 compressible LES were carried out. The results are in very good agreement with the experimental investigations.

报告人简历:

Dr. Franco Magagnato是卡尔斯鲁厄大学流体机械研究所计算流体动力学研究所的主任。其主要研究方向为开发应用于不同领域（如涡轮机、汽车、航空动力学和内燃机等）中的新的物理模型和数值模型。以Dr. Franco Magagnato为主开发的CFD程序SPARC，目前在世界上10多个国家的20多个科研机构（包括MIT、加拿大皇家研究院等）得到了应用和开发。