NINTH INTERNATIONAL CONGRESS ON SOUND AND VIBRATION, ICSV9 MODELLING OF COMPLEX THERMOACOUSTIC SYSTEMS: A STATE-SPACE APPROACH

摘要

A method for modeling of complex thermoacoustic systems is presented. The system is modeled as a modular network, the input-output relation of the modules can be based on analytic models, experimental data or on numerical analysis. A modal expansion technique is used to obtain a state-space representation of the acoustic propagation through complex 3-dimensional geometries. The modal expansion can be based on an analytic model (for relatively simple volumes), or on a finite element analysis (for geometries of any complexity). Modules that are difficult to model analytically, such as the acoustic behavior of the combustion process itself, are modeled using a combined experimental/analytic approach. All modules are represented as state-space systems and interconnected by making use of linear fractional transforms. Advantages of this approach are: the analysis of the models is very time-efficient, the stability of the system can easily be analyzed, it is a perfect basis for the development of active control systems and time simulations of the system allow for analysis of non-linear limit cycles. Validation of the model is successfully performed by comparing the state space model of a simplified representation of a multi-burner annular combustor to finite element analysis.