Development of a numerical model for obtaining flame transfer function in a simplified slit burner with heat exchanger

The goal of the present work is to develop a model to investigate the interactions between a burner and a heat exchanger, looking from a hydrodynamic and thermoacoustic point of view. Thermoacoustics of laminar premixed flames in open air have been studied by some re-searchers in the past decades. However, a burner in open air may behave differently com-pared to if situated in a combustion chamber enclosure. This could be related to the effect of temperature, the effect of flame shape (e.g. flames impinging on the heat exchanger walls in compact boilers), distribution of the flame on the burner deck, etc. The behavior of a linear array of a multiple Bunsen-type flames is studied on a 2D geometry in a CFD code to simulate the effects of heat exchanger addition on the flames thermoacoustics. The location of the heat exchanger surface is varied for different conditions of power. A step profile velocity perturbation is used for obtaining the response of the flame represented within the flame transfer function approach. The calculated gain and phase of the flame transfer function are compared for different cases as the indicator of the thermoacoustic behavior. Results show that the main parameter having considerable influence is the burner load and flame shape. The setup to experimentally investigate these effects will be constructed in near future.