Characteristics of reattachment and blowout of laminar lifted flames in partially premixed propane jets

The blowout mechanism of turbulent jet diffusion flames

“…The measured pulsating frequency is also similar to the pulsating frequency of nonpremixed jet flames near extinction proposed by Füri et al [17], but less than the characteristic frequency (10-18 Hz) of buoyancy-induced large toroidal vortices, which is a type of Kelvin-Helmholtz instability [30]. For the current turbulent blowout flames, the thermal-diffusive instabilities may not be as dominant in the blowout process [15] as they are in the laminar flames [31] and may be suppressed by increasing convective velocity of flow [17]. The mechanism for instability as the flame moves downstream of the maximum waist of the stoichiometric contour is still not clear and cannot be given based on current results.…”

Observation of multi-scale oscillation of laminar lifted flames with low-frequency AC electric fields

“…90 mm and 20 cm in length was installed at the exit of the coflow air. The coflow velocity was fixed at V CO = 3.0 cm/s to obtain stable lifted flames, as compared to a free jet case [13][14][15].…”

“…The result shows that the liftoff height H L increases with the jet velocity U 0 . The photo of a typical stationary lifted flame shown as the inset exhibits that the base of the lifted flame has a tribrachial (or triple) edge structure, having a lean and a rich premixed flame wings and a trailing diffusion flame, all extending from the tribrachial point [13][14][15].…”

“…The increase in the propagation speed of tribrachial (or triple) flame under the influence of AC and DC electric fields was also investigated [12]. Note that a tribrachial (or triple) flame plays a crucial role for the stabilization of laminar lifted flames, since the balance mechanism of the propagation speed of a lifted flame edge and local flow velocity stabilizes stationary lifted flames [13][14][15][16][17][18][19].…”

Several applications of laser diagnostics for visualization of combustion phenomena

“…Later, it has been shown that the stabilization point is unstable for Sc < 1 in laminar free jets . Reattachment of lifted flames and blowout phenomena have also been investigated (Lee and Chung, 2001). …”