Flame Propagation Behavior Research Articles

Experimental study on flame structure transitions of premixed propane/air in micro-scale planar combustors

Flame structure transitions of propane/air premixed combustion in a micro-planar quartz glass combustor in the present study have been extensively investigated using a high-speed digital camera. Six different flame propagation modes, namely, flame repetitive extinction and ignition (FREI), cellular flame, planar flame, U-shaped, inclined and spinning flames, are observed with varying inlet velocity and equivalence ratio. The FREI and cellular flames as well as spinning flames, for the first time, are experimentally discovered in micro-planar straight channel combustor. Based on the upper and lower limit of each flame mode, the flame structure regime diagram is constructed. Experimental observations indicate that different flame propagation modes may coexist during transition due to the hysteresis phenomenon. The effects of equivalence ratio, channel length and channel height on flame characteristics are analyzed. Results show that channel length has minimal effect on flame structure, whereas channel height significantly affects flame propagation behavior. It is also found that the flame dynamics is much more complicated with wider channel height. Furthermore, it is worthy of pointing out that the inclined flames disappears as the channel height is decreased from 3 to 2.5 and 2.0 mm, and the ultimate flame is U-shaped at large inlet velocity.

Dynamic Simulation on Deflagration of LNG Spill

The deflagration characteristics of premixed LNG vapour-air mixtures with different mixing ratios were quantitatively and qualitatively investigated by using CFD (computational fluid dynamics) method. The CFD model was initially established based on theoretical analysis and then validated by a lab-scale deflagration experiment. The flame propagation behaviour, pressure-time history, and flame speed were compared with the experimental data, upon which a good agreement was achieved. A large-scale deflagration fire during LNG bunkering process was conducted using the model to investigate the flame development and overpressure effects. Mesh independence and time scale were tested in order to obtain the suitable grid resolution and time step. Deflagration cases with two different LNG vapour volume fractions, i.e., 10.4% and 15.0%, were simulated and compared. The one with a volume fraction of 10.4% which was around stoichiometric mixing ratio had the highest flame propagating speed. High flame velocity observed in the simulation was coupled with the thin flame front where overpressure occurred. The CFD model could capture the main features of deflagration combustion and account for LNG fire hazard which could provide an in-depth insight when dealing with complicated cases.

A comparative investigation of premixed flame propagation behavior of syngas-air mixtures in closed and half-open ducts

A comparative investigation has been developed in conjunction with high-speed cameras and piezoelectric gauge to gain deep insight into the propagation behavior of premixed syngas-air flames. Experiments were carried out in two constant rectangular ducts, one closed duct (C-D) and one half-open duct (HO-D). One important finding is that the flame behavior in the C-D is different than that in the HO-D. The repeatable distorted tulip flame forms in the C-D while an unrepeatable distorted tulip shape forms in the HO-D. The repeated pressure-flame interactions result in a repetitive process of the tulip distortion. The downstream opening end of the duct has a significant influence on the flame propagation characteristics after the flame surface reaches the lateral walls. The opening end results in a higher maximum flame tip velocity, a lower overpressure and a longer plane formation time in the HO-D. Meanwhile, the position of the plane flame formation decreases as hydrogen fraction increases in the C-D while the opposite is true in the HO-D. Furthermore, the pressure build-up in both ducts are examined, and the maximum flame tip velocity is of importance for distorted tulip flame formation.

Flame Propagation and Combustion Phenomena in a Confined Space with the Perforated Plate at Different Positions

ABSTRACTFlame acceleration and flame–shock interactions are important physical phenomena in combustion science. The primary contribution of this work is to observe different combustion phenomena in the flame acceleration process and during flame–shock interactions in a confined space with a perforated plate. The effect of the perforated plate is to generate a rapidly accelerating flame. The experiment is conducted with an improved experimental apparatus with larger optical windows to observe the complete flame development process and the results are obtained using high-speed Schlieren photography. The complete process is observed clearly, including jet flame formation, turbulent propagation, and shock formation and propagation. Meanwhile, the obvious propagation of the turbulent flame, shock waves and reflected shock waves in burnt and unburnt materials is observed clearly in our experiment in terms of flame–shock interactions. The present results indicate that the perforated plate positions can change the flame propagation as well as the in-cylinder pressure oscillation, and affect the combustion intensity in the confined space significantly. For the middle distance between spark plug and perforated plate (position A), the flame tip velocity after perforated plate increases with increasing hole size. In contrast, the significantly different flame propagation behaviors can be obviously observed for the small distance between the spark plug and perforated plate (position B). The flame tip velocity decreases with increasing hole size initially after the flame passes through the perforated plate. Subsequently, a large hole size results in a turbulent eddy with a larger eddy structure, and consequently the turbulent flame acceleration behavior becomes more obvious for the hole size of 5 mm. Furthermore, a reflected shock wave with a sequence of compression waves with oscillating propagation in the confined space is observed experimentally. The present work could provide valuable insights into super-knocking combustion in gasoline engine, fire-safe fields in mining operations and buildings.

Effects of a carbon monoxide-dominant gas mixture on the explosion and flame propagation behaviors of methane in air

This work aimed to experimentally evaluate the effects of a carbon monoxide-dominant gas mixture on the explosion characteristics of methane in air and report the results of an experimental study on explosion pressure measurement in closed vessel deflagration for a carbon monoxide-dominant gas mixture over its entire flammable range. Experiments were performed in a 20-L spherical explosion tank with a quartz glass window 110 mm in diameter using an electric spark (1 J) as the ignition source. All experiments were conducted at room temperature and at ambient pressure, with a relative humidity ranging from 52 to 73%. The peak explosion pressure (Pmax), maximum pressure rise rate ((dp/dt)max), and gas deflagration index (KG) were observed and analyzed. The flame propagation behavior in the initial stage was recorded using a high-speed camera. The spherical outward flame front was determined on the basis of a canny method, from which the maximum flame propagation speed (Sn) was calculated. The results indicated that the existence of the mixture had a significant effect on the flame propagation of CH4-air and increased its explosion risk. As the volume fraction of the mixed gas increases, the Pmax, (dp/dt)max, KG and Sn of the fuel-lean CH4-air mixture (7% CH4-air mixture) increase nonlinearly. In contrast, addition of the mixed gas negatively affected the fuel-rich mixture (11% CH4-air mixture), exhibiting a decreasing trend. Under stoichiometric conditions (9.5% CH4-air mixture), the mixed gas slightly lowered Pmax, (dp/dt)max, KG, and Sn. The Pmax of CH4-air mixtures at volume fractions of 7%, 9.5%, and 11% were 5.4, 6.9, and 6.8 bar, respectively. The Sn of CH4-air mixtures at volume fractions of 7%, 9.5%, and 11% were 1.2 m/s, 2.0 m/s, and 1.8 m/s, respectively. The outcome of the study is comprehensive data that quantify the dependency of explosion severity parameters on the gas concentration. In the storage and transportation of flammable gases, the information is required to quantify the potential severity of an explosion, design vessels able to withstand an explosion and design explosion safety measures for installations handling this gas.

Experimental Study on Multiple Explosions during the Development and Utilization of Oil Shale Dust

Oil shale is a kind of high‐combustion heat mineral; in the process of exploitation, storage, and utilization, oil shale dust has the risk of explosion. The explosion characteristics and flame propagation behavior of oil shale dust are worth studying. The difference between the multiple explosion behaviors of oil shale dust was investigated with the use of a 20 L explosive spherical tank and a dust MIE experimental device. The explosion characteristics and microstructure changes of the explosive products in multiple explosions were examined. The experimental results show that the maximum explosion pressure (Pmax) dropped, and simultaneously, the minimum ignition energy (MIE), the explosion time (t), and the maximum rate of pressure rise ((dp/dt)max) increased as the explosions continued. Furthermore, the oil shale continued exploding until the third explosion. Some original oil shale dust (OOSD) and explosive residues were analyzed using a scanning electron microscope (SEM) and Fourier transform infrared (FT‐IR) spectrometer. The SEM images of the explosive residues indicate a high fragmentation degree and well‐developed pore structure during the entire multiexplosion process. Oxygen‐containing functional groups, the aliphatic C‐H bond, and the aromatic C‐H bond in oil shale dust all participated in the oil shale dust explosion process.

Flame inhibition of aluminum dust explosion by NaHCO3 and NH4H2PO4

To evaluate the inhibition capacity of NaHCO3 and NH4H2PO4 on the flame in aluminum dust explosions, the inhibition of 5 μm and 30 μm aluminum dust explosions by NaHCO3 and NH4H2PO4 has been studied experimentally, using a high-speed camera for measurement of flame propagation behaviors and a thermocouple for measurement of flame temperatures. The mechanism of flame inhibition is further investigated computationally. It is found that the concentration of NH4H2PO4 required to inhibit the aluminum dust explosion is lower in comparison with NaHCO3. The acceleration and the maximum flame speed significantly decrease and the flame morphology becomes irregular and discrete, as the inhibitor concentration increases. The NH4H2PO4 addition exerts a stronger effect on aluminum flame temperature compared to NaHCO3 addition. The chemical kinetic model indicates that the addition of the inhibitor decreases the concentrations of AlO and O in the reaction zone. This reduction becomes larger with increasing the inerting ratio. Na- and P-containing species promote highly reactive O atoms to recombine and form a stable combustion product O2, which leads to less heat release and a lower flame temperature. For Na-containing compounds, NaO ⇔ Na inhibition cycle is effective to reduce O atoms. NH3 that decomposed by NH4H2PO4 could consume O2 and reduce the flame temperature of aluminum in air. In addition, the gas‒phase chemical effect of inhibitors is significant for aluminum particles in the diffusion-controlled regime.

Spontaneous ignition of high-pressure hydrogen during its sudden release into hydrogen/air mixtures

This paper investigates the effects of hydrogen additions on spontaneous ignition of high-pressure hydrogen released into hydrogen-air mixture. Hydrogen and air are premixed with different volume concentrations (0%, 5%, 10%, 15% and 20% H2) in the tube before high-pressure hydrogen is suddenly released. Pressure transducers are employed to detect the shock waves, estimate the mean shock wave speed and record the shock wave overpressure. Light sensors are used to determine the occurrence of high-pressure hydrogen spontaneous ignition in the tube. A high-speed camera is used to capture the flame propagation behavior outside the tube. It is found that only 5% hydrogen addition could decrease the minimum storage pressure required for spontaneous ignition from 4.37 MPa to 2.78 MPa significantly. When 10% or 15% hydrogen is added to the air, the minimum storage pressure decreases to 2.81 MPa and 1.85 MPa, respectively. When hydrogen addition increases to 20%, the spontaneous ignition even takes place at burst pressure as low as 1.79 MPa inside the straight tube.

Ignition sensitivity and flame propagation of zirconium powder clouds.

The ignition sensitivity and flame propagation of zirconium powder clouds are investigated with the influence of initial turbulence. The effect of initial turbulence on the zirconium powder explosion is studied by the change of ignition delay time and dispersion pressure. Hartmann apparatus and Godbert-Greenwald furnace are used to evaluate the minimum ignition energy and minimum ignition temperature, respectively. The high-speed camera is used to analyze the flame propagation behaviors of zirconium powder cloud. The experimental results show that the minimum ignition energy is between 1 mJ and 3 mJ and minimum ignition temperature is 503 K. The ignition energy reaches the minimum value of 30 mJ at the 0.7 MPa. The ignition energy with the effect of ignition delay time has revealed the similar rule. The maximum flame speed increases with the increase of dispersion pressure. Although, the instantaneous flame speed with the lowest dispersion pressure (0.4 MPa) is significantly higher than two others in the early stage of flame propagation.

LES/CMC Modelling of a Gas Turbine Model Combustor with Quick Fuel Mixing

The first-order, single-conditioned sub-grid Conditional Moment Closure (CMC) model for Large Eddy Simulation (LES) is applied to simulate a globally lean swirling methane flame in a gas turbine model combustor that has been studied experimentally. The time-averaged velocity, mixture fraction, temperature, major species and OH mass fractions, and the heat release rate are predicted well for most locations. A transient lift-off and flashback of the flame root due to localized extinction near the burner exit is observed that is qualitatively consistent with the experimental measurements. The time-averaged temperature is over-predicted very close to the fuel injection point, while it is accurately reproduced downstream. Comparisons of instantaneous conditionally-filtered temperature in mixture fraction space shows that the LES/CMC reproduces the large scatter of the experimental data points in temperature–mixture fraction plane that span the full range unburnt to fully burnt, but to a smaller extent, suggesting a minor under-prediction of local extinction or the inaccuracy of the present first-order, coarse-grid CMC formulation to capture locally premixed flame propagation behaviour. Periodic variation of the heat release rate is observed with a frequency close to that of the measured Precessing Vortex Core (PVC). In general, the current LES/CMC model captures most features of this high-mixing-rate nominally non-premixed swirl flame in a gas turbine model combustor in agreement with experimental measurements.

An experimental investigation into the behavior of premixed flames of hydrogen/carbon monoxide/air mixtures in a half-open duct

In this paper, the premixed flame behavior of hydrogen/carbon monoxide/air mixtures is investigated experimentally in a half-open duct with a large aspect ratio (L/D = 20), employing a high-speed camera and a pressure transducer. The flame front structure, flame tip position, and flame tip velocity of the mixtures are obtained by analysing the high-speed images. Meanwhile, the overpressure history is obtained and analysed to examine their effects on the flame propagation behaviour. Additionally, the effects of the PVC membrane on the flame propagation behaviour is specifically scrutinized. The experimental results indicate that the effects of the PVC membrane on the flame front shape are negligible, but they can affect the flame tip and overpressure dynamics more or less in some specific conditions. When the flame propagates along the half-open duct, four stages of the tulip flame formation can be obtained in all cases. Additionally, the tulip distortion phenomenon occurs in most of the cases. This indicates that the distorted tulip flame may be an intrinsic and universal phenomenon. The most interesting phenomenon is that there is a flame front stretch process in the stage where the flame’s skirt touches the sidewalls. This stretched process cannot affect the flame front inversion and tulip distortion. In this work, an observable oscillation in the overpressure history results from the changes in the flame’s surface area. In addition, the flame stretch process indicates that the pressure waves cannot change the flame front structure. This is evidence that the pressure waves are not the incitation factor for the flame inversion and tulip distortion in the half-open duct.

Spherical turbulent flame propagation of pulverized coal particle clouds in an O2/N2 atmosphere

The present study aims to clarify the effects of turbulence intensity and coal concentration on the spherical turbulent flame propagation of a pulverized coal particle cloud. A unique experimental apparatus was developed in which coal particles can be dispersed homogeneously in a turbulent flow field generated by two fans. Experiments on spherical turbulent flame propagation of pulverized coal particle clouds in a constant volume spherical chamber in various turbulence intensities and coal concentrations were conducted. A common bituminous coal was used in the present study. The flame propagation velocity was obtained from an analysis of flame propagation images taken using a high-speed camera. It was found that the flame propagation velocity increased with increasing flame radius. The flame propagation velocity increases as the turbulence intensity increases. Similar trends were observed in spherical flames using gaseous fuel. The coal concentration has a weak effect on the flame propagation velocity, which is unique to pulverized coal combustions in a turbulent field. These are the first reports of experimental results for the spherical turbulent flame propagation behavior of pulverized coal particle clouds. The results obtained in the present study are obviously different from those of previous pulverized coal combustion studies and any other results of gaseous fuel combustion research.

Flame propagation behaviors and influential factors of TiH2 dust explosions at a constant pressure

The flame propagation through TiH2 dust cloud at near constant pressure condition is studied in a series of experiments using an apparatus with transparent latex balloons. The influential factors for the combustion performance of TiH2 dust cloud, including dust concentration, particle size, scale of isobaric space and oxygen content are investigated. Results show that the burning velocity increases with dust concentration in the fuel-lean mixtures, and then plateaus after crossing the stoichiometric condition, while the trend of flame speed changing with dust concentration varies for different mean particle sizes (D50) of 48 and 106 μm. The flame propagation speed of dust cloud is positively correlated to the isobaric space scale and oxygen content. The burning mechanism of TiH2 dust is thought to be mainly controlled by diffusion regime, the appearance of hydrogen gas accelerates the combustion rate of TiH2 particles and also makes the TiH2 dust changed from a discrete media to a continuum, which may account for the phenomenon that the flame speed in dust cloud of TiH2 is larger than that of Ti at the same concentration no matter in air or oxygen atmosphere.

Propagation and extinction behavior of methane/air premixed flames through straight and converging-diverging microchannels

Propagation and extinction behavior of a CH4/air premixed flame passing through straight and converging-diverging (C-D) microchannels (diameters ranging from 1 to 10 mm) were investigated both experimentally and numerically. The dynamic behavior of flame propagation inside the channels was experimentally studied by using CH∗ chemiluminescence and direct imaging. Three patterns of flame propagation were observed, i.e., the flame can survive, partially extinguish and then re-ignite downstream, or completely extinguish. Regime diagrams showing these different patterns as functions of channel geometry and equivalence ratio were generated for both the straight and C-D channels. Numerical simulations were carried out to explain the experimentally observed flame dynamics inside the channels using detailed CH4/air chemistry. In general, flames were easier to extinguish in C-D channels than in straight channels for a fixed channel diameter and equivalence ratio. Additionally, flames were harder to survive in C-D channels with larger exit-to-throat area ratios. Both heat loss and flame stretch were key factors that can generally cause flame extinction in narrow C-D channels. Heat loss was found to be the primary reason for flame extinction inside the microchannel in comparison with the stretch effect.

Experimental study of premixed syngas/air flame deflagration in a closed duct

The propagation behaviour of a deflagration premixed syngas/air flame over a wide range of equivalence ratios is investigated experimentally in a closed rectangular duct using a high-speed camera and pressure transducer. The syngas hydrogen volume fraction, φ, ranges from 0.1 to 0.9. The flame propagation parameters such as flame structure, propagation time, velocity and overpressure are obtained from the experiment. The effects of the equivalence ratio and hydrogen fraction on flame propagation behaviour are examined. The results indicate that the hydrogen fraction in a syngas mixture greatly influences the flame propagation behaviour. When φ, the hydrogen fraction, is ≥0.5, the prominently distorted tulip flame can be formed in all equivalence ratios, and the minimum propagation time can be obtained at an equivalence ratio of 2.0. When φ < 0.5, the tulip flame distortion only occurs in a hydrogen fraction of φ = 0.3 with an equivalence ratio of 1.5 and above. The minimum flame propagation time can be acquired at an equivalence ratio of 1.5. The distortion occurs when the maximum flame propagation velocity is larger than 31.27 m s−1. The observable oscillation and stepped rise in the overpressure trajectory indicate that the pressure wave plays an important role in the syngas/air deflagration. The initial tulip distortion time and the plane flame formation time share the same tendency in all equivalence ratios, and the time interval between them is nearly constant, 4.03 ms. This parameter is important for exploring the quantitative theory or models of distorted tulip flames.

Effects of reduced oxygen levels on flame propagation behaviors of starch dust deflagration

An experimental investigation of reduced oxygen levels on flame behaviors of starch dust deflagration is studied in a half-closed dust explosion tube. Six kinds of nitrogen/air ratio mixtures are prepared as the experimental atmosphere for flame propagation. A high-speed photography is used to record flame propagation behaviors and luminous features. The characteristics of flame temperature and deflagration pressure are measured by fine thermocouple and pressure sensor, respectively. The influence of reduced oxygen concentration on flame propagation characteristics are discussed in different conditions. The results show that reducing the oxygen content can effectively retard the flame propagation process and weaken the dust combustion reaction. Compared with air atmosphere, flame acceleration process under reduced oxygen atmosphere is suppressed and the luminous intensity of flame post-combustion zone is greatly diminished. The characteristic parameters of flame velocity, flame temperature and deflagration pressure are all influenced by the reduction in oxygen concentration. Furthermore, effective partial inerting suppression can be achieved for starch deflagration flame, when the oxygen concentration is lower than 18.90%. This study is helpful for dust explosion prevention and mitigation. Additionally, the dust cloud concentration changes the flame velocity characteristic at low oxygen levels and higher dust concentration is more limited the flame acceleration.

Study on flame propagation of premixed N2O–NH3/N2O–NH3–C3H8 in cylindrical vessels

ABSTRACTThe flame propagation behavior of premixed N2O–NH3/N2O–NH3–C3H8 was experimentally investigated in elongated vented cylindrical vessels with central ignition. The effect of vessel diameter and propane concentration ([C3H8] = 1.96–7.41 wt.%) on the process of flame acceleration was studied and discussed. The results revealed that the maximum value of flame acceleration rate was found in the cylindrical vessel with an inner diameter of 7 mm, followed by 5 mm, 10 mm, and 15 mm. At a constant vessel diameter, the rate of flame acceleration was noticeably improved by adding propane ([C3H8] = 1.96–3.85 wt.%) to the premixed N2O–NH3. However, a further increase in the propane fraction up to 5.66%, caused a decline in the flame acceleration rate, probably as a consequence of a combined effect between the reduction of oxygen and greater dilution of the ammonia in the total concentration.

Combustion behaviors and temperature characteristics in pulverized biomass dust explosions

Abstract Flame propagation behaviors and temperature characteristics of four types of biomass with two different particle size distributions were studied experimentally. Results show that the flame front of a 50–70 μm biomass is nearly spherical and smooth, the flame zone is characterized by yellow or dark red spotted flames, and luminous flames are present behind it. The flame morphology of 100–200 μm biomass dust is irregular and discrete. The average flame propagation velocity and the amplitude of the velocity fluctuation are functions of the mass density of the biomass particles and depend on the particle size distributions. The flame-speed oscillation of biomass particles is caused by the velocity slip between the volatile gases and particles. Flame temperatures of 50–70 μm and 100–200 μm biomass dust reach the maximum value at 1000 g/m3, and show a slight dependence on the particle size distribution. An analysis of the Knudsen number indicates that the combustion characteristics of biomass particles with particle size distributions within the range studied are characterized by a continuum regime. It is indicated that 100–200 μm poplar sawdust will be the “best” option as a biomass replacement feedstock for coal powered plants.

Flame propagation behaviors and temperature characteristics in polyethylene dust explosions

To reveal the flame propagation mechanism in polyethylene (PE) dust explosions, the flame propagation behaviors and temperature characteristics of polyethylene dust clouds were experimentally studied in an open duct. Flame propagations in polyethylene dust clouds with different concentrations and particle size distributions were recorded using high-speed photography. The flame temperatures were measured using two fine thermocouples comprising Pt–Pt/Rh13% wires of diameter 25 μm. Because of severe agglomeration, the minimum explosible concentration of polyethylene particles with diameter < 75 μm was higher than that of the particles with diameter 75–100 μm. It was observed that the flame front gradually became continuous as the particle size increased with the same polyethylene dust concentration of 300 g/m3. With higher polyethylene dust concentration, the flame front of the polyethylene particles of size <75 μm could quickly become discrete, and the floating flame appeared early, while the flame front of the 100–212 μm polyethylene particles transformed from a continuous flame into several independent diffusion flames. It was demonstrated that the flame propagation velocities were not constant, and that they fluctuated owing to the turbulence and expansion of the combustion products. The average flame propagation velocity increased initially, and then decreased with increasing dust concentration. The peak velocity of the polyethylene particles of size <75 μm was 4.79 m/s at a mass density of 300 g/m3, while the peak velocity of the 75–100 μm particles was 4.55 m/s at a mass density of 400 g/m3, and that of the 100–212 μm particles was 2.67 m/s at a mass density of 500 g/m3. In addition, it was found that the maximum flame temperatures of the different polyethylene particles were approximately the same; the temperatures were 1585.4 °C, 1511.8 °C, and 1508.4 °C for the polyethylene particles of sizes of 100–200 μm, <75 μm, and 75–100 μm, respectively. This phenomenon may be caused by the combustion behavior of the molten polyethylene particles. When the dust concentration is increased within the optimum concentration, flame temperature increased with the increase in flame propagation velocity. The flame temperature of the polyethylene particles of size <75 μm decreased as the flame propagation velocity decreased, while the flame temperature of the 75–100 μm polyethylene particles did not change significantly.

Experimental Investigation of the Flame Propagation and Flashback Behavior of a Green Propellant Consisting of N2O and C2H4

Regarding the research on alternatives for monopropellant hydrazine, several so called green propellants are currently under investigation or qualification. Aside others, the DLR Institute of Space Propulsion investigates a N2O/C2H4 premixed green propellant. During the research activities, flashback from the rocket combustion chamber into the feeding system has been identified as a major challenge when using the propellant mixture. This paper shows the results of ignition experiments conducted in a cylindrical, optical accessible ignition chamber. During the ignition and flame propagation process, pressure, temperature and high-speed video data were collected. The high speed video data were used to analyze the flame propagation speed. The obtained propagation speed was about 20 m/s at ignition, while during further propagation of the flame speeds of up to 120 m/s were measured. Additionally, two different porous materials as flame arresting elements were tested: Porous stainless steel and porous bronze material. For both materials Peclet numbers for flashback were derived. The critical Peclet number for the sintered bronze material was around 20, while for the sintered stainless steel the critical Peclet number seems to be larger than 40. Due to the test results, sintered porous materials seem to be suitable as flashback arresters.