Fractal grid generated turbulence in the low swirl burner

Gas turbine combustion plays an important role in the generation of heat and power. Natural gas is widely used as fuel in gas turbine applications. It is important that the combustion of natural gas in these systems is efficient and environmentally friendly. Especially the emission of NOx is of importance. Low NOx emissions can be achieved by lean combustion. Although it is beneficial for the NOx formation, it also destabilizes the flame. Stable operation is usually achieved by high swirl stabilization in current gas turbines. Low swirl stabilization is a promising new technology that achieves flame stabilization by a diverging flow field. This particular flow field lowers the residence time of gases at high temperature and therefore NOx emissions are reduced. However, low swirl stabilization decreases the mixing near the flame resulting in limited conversion rates. Evidence exists that fractal grids provide an efficient way of enhancing turbulence. In this master assignment the application of fractal grids in low swirl combustion is studied. In an experimental study is found that fractal grids also enhance the turbulence in combination with the low swirl burner. This turbulence interacts with the flame front resulting in significant finer wrinkling. The result is an increase of the reaction rate and a more compact low swirl flame.