LES of combustion dynamics in a pulse combustor

Abstract

Simulation of combustion process in a pulse combustor is carried out to understand the dynamics of flameholding, flow-chemistry interaction and the resulting pulsation. To simulate natural pulsation, a characteristic based boundary condition was modified to simulate the behavior of the flapper valve. Large-eddy simulations (LES) in an axisymmetric configuration are carried out for a range of combustor dimensions. The inflow boundary conditions automatically synchronizes with the acoustic mode and results in steady-state pulsation in this device. Results show that strain-induced extinction upstream of the flameholder is critical in achieving oscillation at the expected frequency. A scaling analysis is also carried out whereby the pulse combustor dimensions are reduced from typical systems of the order of 1 meter to as small as 15 cm to determine if the dynamics can be reproduced even in such small devices. Potential application of these small pulse combustors for micro-scale heat transfer is also discussed.

Material Treatment in the Pulsation Reactor—From Flame Spray Pyrolysis to Industrial Scale

“…Therefore, the inlet condition is prescribed explicitly in a majority of the models, which directly defines the pulsation frequency. Only the models by Benelli et al [28], Tajiri and Menon [30], and Zhonghua et al [33,35] treat the inlet condition in a way which allows the formation of oscillations with a frequency corresponding to the combustion kinetics.…”

An experimental study of NOx emissions from a Helmholtz resonator

“…12 Pulsed combustion engines have recently attracted interest because they are characterized by low NO x emissions, high combustion intensity, high heat transfer rates, efficient combustion, and fewer pollutant emissions compared to conventional combustion engines. [12][13][14][15] Pulse combustors have relatively low NO x emissions of 34-46 ppm compared to 58-138 ppm for conventional combustion. 16 Pulse combustion devices can successfully run on conventional fuels such as natural gas, propane, liquefied petroleum gas, and methane.…”

The Influence of Design Geometry on the Operational Performance of Helmholtz Pulse Combustor

“…4 Pulse combustion is distinguished by high combustion intensity, high heat transfer rates, efficient combustion, and less pollutant emissions than conventional combustion. [5][6][7][8] Pulse combustion has a wide variety of uses, from drying systems to propulsion devices. Due to their simplicity, pulsejets offer a good solution to the growing interest in the defense industry for propelling small, lightweight unmanned aerial vehicles (UAV).…”