in this paper, free convection in an inclined stepped chamber has been studied. one wall of this enclosure is kept cold and the opposite wall equipped with constant heat source. the remaining walls are maintained adiabatic. there is one adiabatic step on the bottom wall. the aim of the present study is to forecast the effect of raleigh number, slope of enclosure, step dimension, and heat source...

Compared with conventional camera, the light field camera takes the advantage of being capable of recording the direction and intensity information of each ray projected onto the CCD (charge couple device) sensor simultaneously. In this paper, a novel method is proposed for reconstructing three-dimensional (3-D) temperature field of a flame based on a single light field camera. A radiative imag...

Melt flow and dripping of the pyrolysing polymer melt can be both a benefit and a detriment during a fire. In several small-scale fire tests addressing the ignition of a defined specimen with a small ignition source, well-adjusted melt flow and dripping are usually beneficial to pass the test. The presence of flame retardants often changes the melt viscosity crucially. The influence of certain ...

The development of flame ionization detection took place on an empirical basis without a clear understanding of the 1 mechanism. The study of flames by mass spectrometry showed that the all-important ion was the formylium ion CHO . The pre-combustion degradation was thought to be a pyrolytic degradation and hydrogenation at the high temperatures obtained close to the combustion zone. Using a ca...

A computational study was conducted on expanding spherical premixed flames to investigate the dynamics of flame-ball formation at elevated temperatures and pressures. Lean H2/air mixtures were investigated using a time-dependent, spherically symmetric code with detailed chemistry, transport, and radiation submodels. Results show that, with increasing pressure, both the steady-state flame-ball r...

Study of gas fuel temperature influence on combustion performance by means of numerical modeling is a main objective of this work. Combustion of a single jet of propane in a cross-flowing stream of preheated and oxygen deficient air is analyzed. Both Eddy-Break-Up and PDF/mixture fraction combustion models coupled with RNG k-ε turbulent model were applied and compared. Thermal and prompt NOx mo...

Combustion instabilities in gas turbine engines often give rise to acoustic resonances. These resonances occur as manifestations of different acoustic modes, of which a single or multiple modes may be present. In this work, the acoustic behavior of a model gas turbine combustor, developed at DLR Stuttgart by Meier, was investigated using both syn(thetic) gas and standard hydrocarbon fuels. Syng...

The effects of channel width, wall temperature, and flow rate on the dynamics of non-premix flames in a mesoscale combustor were studied in methane and propane–air mixing layers. A flame street structure which consists of multiple triple flamelets in the mixing layer of the reactants was observed experimentally for the first time. Depending on the flow rate, it was found that there are two diff...

Combustion under high-pressure conditions holds the potential for improved thermodynamic efficiency, enhanced power generation, and reduced emission of some pollutants. It underlies the technology of internal combustion engines such as the automotive engine, the gas turbine, and the rocket engine, for which the operating pressure can reach as high as 100s atm. At such high-pressure conditions, ...

The present protocol presents a laboratory technique designed to study chaparral crown fire ignition and spread. Experiments were conducted in a low velocity fire wind tunnel where two distinct layers of fuel were constructed to represent surface and crown fuels in chaparral. Chamise, a common chaparral shrub, comprised the live crown layer. The dead fuel surface layer was constructed with exce...