Experimentelle Untersuchungen laminarer Triplet- und Tripelflammen

Product Description

Due to increasingly scarce resources of fossil fuels and increasingly strict guidelines and regulations prescribed by lawmakers for the sustainable use of energy and environment, there has been a growing interest in recent years in the development of engines and combustion systems with lower emissions and consumption. As a rule, technically relevant combustion processes take place under complex turbulent conditions, whose description has not yet been satisfactorily solved to this day. The goal of scientific investigations is therefore to develop mathematical-physical models with whose help one can approach the description of real combustion processes. A multitude of models developed in recent years are based on the idea that turbulent flames are composed of an ensemble of laminar flamelets (flamelet model). In the formulation of such flamelet models, so-called laminar triple flames play an important role, which occur in many combustion processes as a result of uneven mixing and propagate in so-called mixing layers. Experimentally, such flame structures can be can be realized in both co-flow and counter-flow burners. Within the framework of this work, experimental investigations of the influence of varying mixture gradients and stagnation point parameters on the structure and occurrence of laminar triple and triplet flames were carried out. Triplet flames occur in steady-state operation of counter-flow burners with differently pre-mixed volume flows and have the same structure as triple flames except for the so-called triple point. They consist of three coupled flames, a lean and a rich premixed flame and a diffusion flame embedded between them. The investigations were carried out using laser-optical measurement techniques. In particular, velocity fields were determined using digital Particle Image Velocimetry (DPIV) and OH distributions using planar Laser-Induced Fluorescence (PLIF). Additionally, the propagation behavior of unsteady triple flames shortly after ignition of different mixtures was investigated using digital high-speed recordings.