Extinction limits and flame bifurcation of lean premixed dimethyl ether-air flames are investigated numerically using the counterflow flame with a reduced chemistry. Emphasis is paid to the combined effect of radiation and flame stretch on the extinction and flammability limits. A method based on the reaction front is presented to predict the Markstein length. The predicted positive Markstein l...

High-speed planar laser-induced fluorescence (PLIF) and 3-D large eddy simulations (LES) are used to study turbulent flame kernel growth, wrinkling and the formation of separated flame pockets in methane/air mixtures. Turbulence was effected by a set of rotary fans situated in a cylindrical enclosure. Flame wrinkling was followed on sequential 2-D OH images captured at kHz repetition rates. Und...

A method of video flame detection based on multi-feature fusion is presented in this paper. Physical characteristics of flame, including color clues, flame movement and flame flicker are incorporated into the scheme to detect fires in color video frames. Firstly, mean filtering was used to smooth the video frames and a flame color filtering algorithm was adopted to extract flame candidate regio...

Premixed laminar flame speed determination is a crucial point since its values are used for the sizing of every combustion systems. In order to measure this parameter, an isochoric method can be used. It consists in measuring pressure (and possibly other parameters) spherical expanding flame. This allows get data large scope important pressures and temperatures supposing isentropic compression....

Turbulent jet ignition technology can significantly improve lean combustion stability and suppress engine knocking. However, the narrow channel between pre-chamber main chamber leads to some difficulties in heat exchange, which affects performance mechanical component lifetime. To clarify effect of temperature conditions on evolutions turbulent ignition, direct numerical simulations with detail...

We present a study of the flame-embedding concept, introduced in [1] as an efficient approach for large-eddy simulation of turbulent combustion at high Reynolds and Damköhler numbers. In flame embedding, the combustion zone is modeled as an unsteady flame modified by the local tangential strain rate, with the latter extracted every time step from the flow field simulations. The flame structure ...

We explore the detailed structure of heat release and the energy budget for a freely-propagating lean, premixed hydrogen flame. At lean conditions, the flame is thermodiffusively unstable and spontaneously develops the cellular burning structures, characteristic of this type of flame. The instabilities in the system saturate quickly, resulting in robust, slowly evolving cellular burning feature...

background: radioactive yttrium glass microspheres are used for liver cancer treatment. these yttrium aluminum silicate microspheres are synthesized from yttrium, aluminum and silicone oxides by melting. there are two known processes used to transform irregular shaped glass particles into microspheres, these ‘spheroidization by flame’ and ‘spheroidization by gravitational fall in a tubular furn...