Experimental studies of the turbulence structures of impinging reacting jets using time-resolved particle image velocimetry visualisation, hot wire anemometry and acoustic signal processing

Abstract

In this paper, the turbulence structures of premixed impinging jets are investigated by three different experimental techniques: time-resolved particle image velocimetry (TPIV) visualisation, hot wire anemometry (HWA) and acoustic signal processing. The focus is on the TPIV, with the other two techniques providing supplementary information. The 2-D velocities of the impinging jets were obtained by TPIV. The contour maps of velocity derivatives were computed to facilitate the visualisation of the turbulence structure of the reactant part of turbulent impinging flames. Particular attention was concentrated on the turbulence structures out of the burner nozzle and their interactions with the combustion process. It was found that the contour plots are effective in visualising time-dependent structures. It is demonstrated that the derivatives of the velocity field are able to reveal many otherwise hidden turbulence patterns. Test cases were designed to facilitate easy comparisons and analyses. It is shown that combustion has a strong effect on the reactant part of the flow field. The turbulence substructure is strongly dependent on the turbulence generator installed in the burner nozzle exit. Global statistical analysis reveals that the fuel-to-air equivalence ratio significantly affects the turbulence structure of the reactant flow. HWA measurements under cold flow conditions and the acoustic signal processing of the impinging jets provide further information on the turbulence structure.