Flame lift-off height control by a combined vane-plasma swirler

Abstract

In this study, a swirler combining the vane swirler and the plasma swirler is designed to control the flame lift-off height. The plasma swirler is located near the rim of the injector and the vane swirler is placed upstream of the plasma swirler. The vane swirler is employed to form a divergent flow to sustain the detached flame and the plasma swirler is adopted to control the flame lift-off height. The ionic wind clinging to the inner wall of the injector tube does not penetrate into the center, leaving the main stream flow in the central region largely undisturbed. Characteristics of the flow field are analyzed from the results of laser Doppler anemometry (LDA) measurement and mechanism of the flame lift-off control by the combined vane-plasma swirler is revealed. The flame lift-off locations calculated from the LDA measurement are consistent with those from direct observation. The dielectric barrier discharge (DBD) voltage influences the height of the flame lift-off with a linear relationship observed, which means the flame lift-off height can be controlled precisely by the DBD voltage without any mechanical movement or changing the mass flow rate. The combined vane-plasma swirler has the potential to improve the fuel flexibility, increase flame stability and attenuate the injector overheating.Highlights1. A combined vane-plasma swirler is designed to control the flame lift-off height.2. Flame lift-off height can be adjusted by changing the voltage of the dielectric barrier discharge.3. A linear relationship between flame lift-off height and the dielectric barrier discharge voltage is observed.4. Flame lift-off control by the combined vane-plasma swirler is mainly associated with the aerodynamic effect.5. The swirler can improve fuel flexibility, increase flame stability and attenuate injector overheating.