Experimental investigation of the internal flow field of a meso-scale whirl combustor

In the last decade the interest towards the development of small-scale power generation and propulsion systems based on combustion has grew up. One of the essential requirement to succeed in the development of such micro-power systems is the capability to design very efficient small-scale combustion chamber. At the Politecnico di Milano a research work on a non-premixed centimeter scale (meso-scale) swirl combustor delivering about 100 W of thermal power has been carried out. The use of a tangential air injection along with a 90° impinging fuel jet has been used to achieve good combustion efficiency and flame stabilization over a wide range of operating parameter. The whirl motion should induce a recirculation zone which improve combustor performances, nevertheless actually no experimental data are available about the internal flow field and its relationship with the combustor performances. The experimental investigation of the internal flow field of the combustor has been carried out by means of laser Doppler velocimetry (LDV). Due to limitation in optical access only the radial and tangential component have been measured. Results evidenced that the vortex core is displaced from the geometrical axis and a quite quiescent low velocity region exists in the center of the combustor chamber.