Outer Flame Research Articles

Structure and Laminar Flame Speed of an Ammonia/Methane/Air Premixed Flame under Varying Pressure and Equivalence Ratio.

This paper presents a joint experimental and numerical study on premixed laminar ammonia/methane/air flames, aiming to characterize the flame structures and NO formation and determine the laminar flame speed under different pressure, equivalence ratio, and ammonia fraction in the fuel. The experiments were carried out in a lab-scale pressurized vessel with a Bunsen burner installed with a concentric co-flow of air. Measurements of NH and NO distributions in the flames were made using planar laser-induced fluorescence. A novel method was presented for determination of the laminar flame speed from Bunsen-burner flame measurements, which takes into account the non-uniform flow in the unburned mixture and local flame stretch. NH profiles were chosen as flame front markers. Direct numerical simulation of the flames and one-dimensional chemical kinetic modeling were performed to enhance the understanding of flame structures and evaluate three chemical kinetic mechanisms recently reported in the literature. The stoichiometric and fuel-rich flames exhibit a dual-flame structure, with an inner premixed flame and an outer diffusion flame. The two flames interact, which affects the NO emissions. The impact of the diffusion flame on the laminar flame speed of the inner premixed flame is however minor. At elevated pressures or higher ammonia/methane ratios, the emission of NO is suppressed as a result of the reduced radical mass fraction and promoted NO reduction reactions. It is found that the laminar flame speed measured in the present experiments can be captured by the investigated mechanisms, but quantitative predictions of the NO distribution require further model development.

Effect of enclosure on heat transfer characteristics of dual swirling flame impinging on a flat surface

Experimental investigations have been carried out for impingement heat transfer characteristics of an enclosed dual swirling flame for various enclosure configurations. Effects of the size of the enclosure (DE = 70 mm, 90 mm, 90 mm, 110 mm and 150 mm) and the level of gap between the top of the enclosure and the target surface (G = 12, 16, 20, 24 and 28 mm) have been examined at fixed other operating conditions (Re(o), H/Dh and S). In addition to this, the effects of variation in outer swirling flame Reynolds numbers (Re(o) = 7000–13,000), dimensionless separation distances (H/Dh = 2–5) and the swirl number (S = 0.86, 1.54 and 2.4) have also been examined. Impingement heat transfer characteristics strongly depend on the size of the enclosure (DE) and the level of gap (G). Larger sized enclosures (DE of 110 and 150 mm) with smaller gap levels (G of 12 and 16 mm) perform much better than small sized enclosures (DE of 70 and 80 mm) with larger gap levels (G of 24 and 28 mm). Heat transfer performance continuously increases with an increase in Re(o) in presence of an enclosure in contrast to unenclosed flames where performance deteriorates at high Re(o). The heat transfer enhancement effect in presence of enclosure is more pronounced at larger separation distances (H/Dh of 4 and 5) because of the formation of the outer recirculation zone (ORZ). The effect of the presence of enclosure on impingement heat transfer enhancement becomes more significant at higher levels of swirl.

Combustion behaviour of composite sandwich propellants containing RDX

Addition of nitramine particles (RDX) to composite solid propellants are promoted in advanced propulsion systems for better performances, high energy, high specific impulse, and environmentally benign combustion products. This study is performed for understanding the combustion mechanism of RDX based matrices and sandwich propellants. Four types of fine AP/Al/binder matrix mixtures are considered, two samples contain 5% and 20% RDX while another two mixtures are without RDX, for comparison. Burning rate experiments are carried out on sandwich propellants and matrices in the pressure range of 2–10 MPa. The condensed phase behaviour of RDX decomposition and RDX melt flow, their influence on the matrix flame and interaction with leading edge flames (LEFs) located over lamina interfaces of sandwich propellants are assessed from quenched surface profiles and SEM micrographs. The effect of middle lamina thickness and pressure on burning rates of sandwich propellants are investigated. It is noticed that different levels of addition of RDX to matrix induces either an increase or decrease in burning rates depending upon the composition and fine AP/binder ratio. The binder melt flow effect is reduced in RDX containing matrix lamina due to presence of near-surface premixed flame. The effect of middle lamina thickness on burning rates of RDX containing sandwich propellants is significant. The overall burning rates of RDX sandwich propellants are relatively high when compared to their corresponding non-RDX counterparts. This is due to the existence of RDX assisted matrix flame that re-establishes the interaction between the LEFs anchored over lamina interfaces. Such matrix flames that are located over the regions of matrix in inter-particle spaces of the propellant microstructure would have a positive effect on the LEFs and outer diffusion flames over coarse AP particles.

A study on impingement heat transfer characteristics of partially premixed flames on double-concentric-pipe burner

This paper presents an experimental study of free flame patterns, impinging flame structures and flame impingement heat transfer characteristics of a partially premixed flame. The partially premixed flame is produced on a double-concentric-pipe burner, with both flow strength and mixedness of its inner and outer jets controlled by digital flowmeters. The aim of the study is, through examination of the effects of inner and outer jet Reynolds numbers (Rei, Reo), equivalence ratios (Φi, Φo) and nozzle-to-plate distance (H), to understand the heat transfer behaviors of such partially premixed flame and further identify the best impinging flame to achieve higher energy usage efficiency.A total of twelve different free flame patterns are observed by varying Rei-Reo-Φi-Φo, and W-shaped flame is the most representative flame under the conditions tested. The partially premixed dual flame is higher in stability than any single component of it, i.e. Bunsen flame or annulus flame. Further, leaner flammability limit is achieved by the dual flame due to mutual interaction which effectively supports leaner inner flame. Both inner and outer flames influence the radial heat flux distribution of W flame, while the contribution of inner flame becomes significant only when the difference in two flame heights is large. The outer flame globally dominates the total heat transfer rate, leading to general decay with increasing H. Comparison of W flame with single Bunsen and annulus flame shows that W flame has the favorable structure for higher energy efficiency due to double-pipe configuration and mutual flame interaction.

Tunable adsorption activity of candle soot nanoparticles depending on the flame height* *The maximum adsorption capacity for IFP and OFP as predicted by the Langmuir isotherm showed OFP is better adsorbent than that of IFP.

The candle soot particles were collected from the inner and outer regions of the candle flame and their dye adsorption capacities were compared. The surface area of inner flame particles (IFP) and outer flame particles (OFP) was recorded as 48 and 88 m2 g−1, respectively. The coatings of OFP and IFP were found hydrophobic and hydrophilic, respectively. The adsorptive removal of Methylene blue (MB) (conc. 50 mg l−1) was ∼40% higher with OFP than that of IFP. Similarly, significantly higher adsorption was recorded during the adsorption of ciprofloxacin and detergent for OFP than that of IFP. The pseudo-second-order model is found most suitable to explain the kinetic data of adsorption.

Analysis of flame characteristics of low calorific value gas diffusion combustion under the action of thermal dynamics

In this paper, the flame characteristics of co-axial concomitant flow diffusion combustion of low calorific value gas under the action of thermal dynamics are studied. Based on Fluent software, the combustion process of low calorific value gas is simulated by a finite element volume method. According to different air preheating temperatures , by analyzing the changes of temperature field, velocity field and concentration field during combustion and solving the curve fitting equation of velocity field, the changing trend of the flame core, inner flame and outer flame with air preheating temperature is obtained. The results show that the flame front temperature decreases with the increase of when low calorific value gas is burned; the flame core and the inner flame length shorten with the increase of . When rises from 300 K to 500 K, the flame core and the inner flame shorten by 0.05584 and 0.05867 m respectively, with the increase of , the length of the flame outer flame increases first and then decreases. when , the flame outer flame is the longest with the maximum value of 0.78865 m m. When , The value corresponding to the zero-boundary point position of the equivalence ratio of combustion reaction is the largest, and the maximum value is . Therefore, when , the flame outer flame length is the longest, the mixing area of combustible gas and air is the largest, the flame front temperature is higher during combustion, and the combustion effect is the best.

Experimental study of flame heat transfer in a vertical turbulent wall fire

This paper presents experimental measurements in a vertical turbulent wall fire, with a primary goal of developing a deep understating and database for heat transfer on solid surfaces where fuel pyrolyzes. An enhanced porous-plate vertical wall-fire burner was developed, and experiments were conducted with various mass transfer rates of ethylene to measure flame temperature, radiative power, spectral emission, radiative and convective heat flux. The maximum mean flame temperature is found to decrease with height, and the temperature profile in the outer flame boundary layer to be self-similar. The radiant power and heat flux show a linear increase vertically in the pyrolysis region and the peak shifts to higher evaluation with a greater fuel flow rate. Soot emission contributes a dominant fraction to thermal radiation. On the other hand, the convective heat flux promptly reduces from the flame leading edge in the laminar region at the bottom of the wall-burner and remains relatively steady in the downstream turbulent region. Convective heat flux dominates the heat transfer in the lower height while radiative heat transfer is more prominent in the upper region of the wall.

Flammability limits and near-limit chemistry controlled flame spread over thermally thin paper under sub-atmospheric pressure

Understanding material flammability properties and flame spread rates are important to mitigate fire hazards in high altitude areas, aircraft and spacecraft. Limiting oxygen concentration (LOC) has been widely studied in these conditions, but flame spread near extinction limits has been rarely reported. In this work, the experimental study of horizontal near-limit flame spread over paper is investigated in a sub-atmospheric chamber. We first quantified LOCs at a pressure range from 4 to 45 kPa. Then, the near-limit flame spread was studied by increasing 1mol% oxygen concentration at each pressure. Flame image, flame spread rate and preheating length are measured in this study. Results show that LOC is independent of paper sample thickness but dependent on sample width due to lateral mass and heat losses. Near-limit flames show a two-zone structure, including inner blue flame and outer red flame. We find that the near-limit flame spread rate is dominated by preheating length, and it does not obey the previously proposed the power law relationship between flame spread rate and oxygen concentration and pressure. This work studies flammability and near-limit flame spread at various pressure and oxygen conditions, contributing to understanding the fire risk in the environments different from standard atmospheric conditions.

Modelling of a turbulent lean premixed combustor using a Reynolds-averaged Navier–Stokes approach

This work aims to characterize lean premixed turbulent swirling flames representative of gas turbines and jet engines via a numerical study of flame topologies in a laboratory-scale burner. The state of the art of the numerical studies concerning these types of flames is first reviewed, with respect to Reynolds-averaged Navier–Stokes and large eddy simulations. Then, a turbulent, isothermal flow study is performed within the radial swirler. The impact of mesh refinement levels and boundary conditions on the swirl number and overall flow structure is investigated. The mesh refinement level and slip wall boundary condition alter the computed swirl number significantly. The computed swirl number converges to a value of 0.7, which is larger than the geometrical one, 0.4. Furthermore, using Reynolds-averaged Navier–Stokes transport equations, closed by the realizable $$k-\epsilon$$ model, coupled with a two-equation premixed combustion model for methane/air mixtures, two combustion regimes are analysed. These regimes correspond to the outer recirculation zone flame and an unstable regime. The flow structure is characterized in terms of velocity fields, turbulence and combustion properties. A reaction progress variable comparison is also performed, using existing experimental results, yielding qualitatively similar structures for both studied regimes. Some discrepancies between numerical and experimental results concerning the stable regime may be observed: The computed progress variable at the outer recirculation zone, 0.5, is smaller than the experimental value, 0.8, and the average flame brush thickness, 1 mm, is found to be smaller than the measured, 3 mm.

Study on the deflagration reaction process of oil gas in long-narrow confined space based on PLIF and flame spectra

Oil gas explosion in long-narrow confined space is a typical unsteady combustion process. To study the reaction process, two experiment techniques are adopted in this research. One is planner laser induced fluorescence, which is used to achieve the transient measurement of free radicals in unsteady premixed combustion field. The other one is the spectral testing technique, which is used to measure the luminescence spectrum characteristics of oil gas combustion flame. The distribution of OH radical and CH radical at different positions in the combustion field, the common partition of deflagration flame structure under different oil gas concentrations, and the main luminescence spectra of radicals such as OH, CH, C2, C3, CO2, H2O and HCO are obtained. By comparing the above three aspects, the combustion reaction process of premixed mixture is revealed, driven by the coupling effect of chemical reaction and fluid flow in the process of explosion propagation. The process can be described briefly as follows. In the “outer flame zone”, large hydrocarbon molecules are mainly transformed to small molecules and free radicals by means of pyrolysis, dehydrogenation and oxidation. In the “inner flame zone”, carbon particles and combustion products produced and gathered after relevant reactions.

Flame Edge Dynamics and Interaction in a Multinozzle Can Combustor With Fuel Staging

The characterization and mitigation of thermoacoustic combustion instabilities in gas turbine engines are necessary to reduce pollutant emissions, premature wear, and component failure associated with unstable flames. Fuel staging, a technique in which the fuel flow to a multinozzle combustor is unevenly distributed between the nozzles, has been shown to mitigate the intensity of self-excited combustion instabilities in multiple nozzle combustors. In our previous work, we hypothesized that staging suppresses instability through a phase-cancelation effect in which the heat release rate from the staged nozzle oscillates out of phase with that of the other nozzles, leading to destructive interference that suppresses the instability. This previous theory, however, was based on chemiluminescence imaging, which is a line-of-sight integrated technique. In this work, we use high-speed laser-induced fluorescence to further investigate instability suppression in two staging configurations: center-nozzle and outer-nozzle staging. An edge-tracking algorithm is used to compute local flame edge displacement as a function of time, allowing instability-driven edge oscillation phase coherence and other instantaneous flame dynamics to be spectrally and spatially resolved. Analysis of flame edge oscillations shows the presence of convecting coherent fluctuations of the flame edge caused by periodic vortex shedding. When the system is unstable, these two flame edges oscillate together as a result of high-intensity longitudinal-mode acoustic oscillations in the combustor that drive periodic vortex shedding at each of the nozzle exits. In the stable cases, however, the phase between the oscillations of the center and outer flame edges is greater than 90 deg (∼114 deg), suggesting that the phase-cancelation hypothesis may be valid. This analysis allows a better understanding of the instantaneous flame dynamics behind flame edge oscillation phase offset and fuel staging-based instability suppression.

Resilient, fire-retardant and mechanically strong polyimide-polyvinylpolymethylsiloxane composite aerogel prepared via stepwise chemical liquid deposition

Resilient, fire-retardant and mechanically strong polyimide-polyvinylpolymethylsiloxane (PI-PVPMS) composite aerogels have been prepared via stepwise chemical liquid deposition (SCLD). The synthesis is based on the formation of PI-PVPMS crosslinked network structure with (3-aminopropyl)trimethoxysilane (APTMS) as a coupling agent to provide reactive sites on the backbone. We successfully realize the PI in-situ growth on the whole super-flexible PVPMS gel skeleton with this simple method. The effect of APTMS amount and deposition time on the properties of final samples is deeply investigated. The resultant PI-PVPMS composite aerogels show excellent mechanical and thermal properties. They can support at least 10,000 times of their own weight and can recover 20% from a 60% of compressive strain, with an elastic modulus of 32 MPa. For thermal performance, they can maintain their structural integrity after being subjected to the alcohol lamp outer flame of around 650 °C for 30 min. These results together with the simple synthesis process demonstrate the potential for construction materials using PI-PVPMS composite aerogels. Furthermore, the SCLD synthesis method could also be applied to prepare other composite aerogels, especially for those containing complex polymer.

Instantaneous planar measurements of nitric oxide concentration in a turbulent n-heptane spray flame

Instantaneous and mean nitric oxide (NO) concentrations are measured in a turbulent, lifted, n-heptane jet spray flame at an atmospheric pressure using planar laser-induced fluorescence (PLIF). The flame-front is simultaneously located using OH-PLIF. The NO excitation line with the least temperature-quenching dependence is selected, and the associated NO-LIF dependence is corrected. LIF optimization and data reduction are based on previous work [Mulla et al. Combust. Flame 203 (2019) 217–229] where the NO-LIF signal was simulated at the spray flame condition (temperature and gas composition from LES) using a spectroscopic model. In the present work, to reduce interferences from polycyclic aromatic hydrocarbons (PAH) and soot, the detection bandwidth is progressively reduced from broadband (F6), intermediate (F3), to narrowband (F1). F6 results in a significant interference, while F1 contains the least interference. Instantaneous NO mole fraction (χNO) is deduced from F1 dataset using a novel instant-wise mapped interference subtraction approach (F1-Inst). The conditional mean NO concentrations derived from F6, F3, F1, and F1-Inst are in agreement (within uncertainty limits); however, F1-Inst appears to be the most reliable. Instantaneous flame-structure (OH) and NO concentration fields are analyzed. The spray flame structure consists of the inner (B1) and outer (B2) flame branches. Local extinctions are observed along B1. Small-scale (<1 mm) extinctions do not alter the NO concentration, whereas large-scale extinctions result in a sharp (50–100%) χNO drop, possibly due to a reduced temperature. Instantaneous χNO along B2 shows a sharp growth until 55 mm height above burner (HAB), beyond which the growth saturates. The deceleration of NO growth and χNO reduction near the sooting region is most likely due to the soot-radiation induced temperature drop. Mean χNO along B1 measures ∼ 25 ppm with a small axial variation (20–30 ppm). Expected lower temperature and nearly constant χNO with residence time suggest the nitrous oxide and prompt NO formations routes. Mean χNO in the outer diffusion branch (B2) increases from 35 ppm at the flame-base to 75 ppm at 60 mm HAB. The NO growth and potentially high temperature in B2 indicate the thermal route of NO formation.

An Experimental and Numerical Study on Supported Ultra-Lean Methane Combustion

With a much larger global warming potential (GWP) and much shorter lifespan, the reduction of methane emissions offers an additional opportunity and a relatively quick way of mitigating climate change in the near future. However, the emissions from coal mining in the form of ventilation air methane (VAM), usually in ultra-lean concentration, pose the most significant technical challenge to the mitigation of methane emission. Therefore, a better understanding of ultra-lean methane combustion is essential. With three 5 mm × 50 mm rectangle cross-section slot jets, a novel sandwich-type triple-jet burner is proposed to provide stable combustion of an ultra-lean methane–air mixture with equivalence ratios from 0.3 to 0.88, and 0.22 in extreme conditions. The ultra-lean methane flame in the center of the triple-jet burner is supported by the two lean outer flames at an equivalence ratio φ = 0.88. The flow field and combustion chemical reactions are predicted by detailed numerical simulation with GRI-Mech 3.0 reaction mechanisms. Two-dimensional numerical results are validated with those obtained by experimental particle image velocimetry (PIV), as well as visual flame height and temperature measurements. An ultra-lean methane–air mixture has to burn with external support. In addition, the ultra-lean flame is non-propagating with a relatively low temperature. The ultra-lean center flame is seen to start from the outer flame and incline perfectly to the post-flame temperature and OH concentration profiles of the outer lean flame. The adjacent stronger flame provides heat and active radicals, such as OH and HO2, from the post-flame region and in the wall proximity of the gap between the adjacent flame and the central ultra-lean jet to initiate and maintain the combustion of the central ultra-lean flame. The outstanding wall-proximity radical of HO2 is found to be the main contributor to the initiation and stabilization of the central ultra-lean flame by providing a low-temperature oxidation of fuel through the following reaction: HO2 + CH3 ⇔ OH + CH3O. The major chemical reaction paths contributing to fuel decomposition and oxidation of the supported ultra-lean center flame are also identified and delineated.

Low NOX - LPG staged combustion double swirl flames

As a clean, abundant energy source with demonstrated methodologies for producing liquid petroleum gas (LPG) from renewable feedstocks, the growing availability of LPG motivates this study to investigate the utilization of LPG in a staged swirl burner. The burner has an outer and annular swirlers concentric with a central jet, where the flame stability, NO emissions, and flame structure were investigated. The burner allows controlling the degree of mixing by varying swirl angles (θan, θout), and the equivalence ratios of the annular/outer streams (Φan/Φout). The stability mapping showed that the LPG admitted via the annular mixture improves the flame stability more than the outer mixture, and the central fuel injection further improves the flame’s stability. Less segregation between Φan and Φout leads to low NO emissions. Three distinct zones have featured the flame; the recirculation zone (RZ), the reaction zone; and the outer flame zone. High NO concentration was limited to the RZ, so the RZ residence time, mixture strength and temperature at the RZ boundaries are the controlling parameters for NO emissions. The largest θan together with a small θout has a significant effect on reducing the flame temperature and residence time, and thus produces low NO emissions.

Large Eddy Simulation of a spray jet flame using Doubly Conditional Moment Closure

A spray jet flame is modelled using Large Eddy Simulation (LES) with Doubly Conditional Moment Closure (DCMC). Since turbulent spray flames may include multiple combustion modes, the DCMC model uses both mixture fraction and reaction progress variable as conditioning variables. Conditional spray terms were included in the DCMC model to consider the coupling between evaporation and the flame structure. In the case of spatial homogeneity and in the limit of negligible mixture fraction scalar dissipation rate (SDR), the DCMC equation is shown to reproduce the flame structure of freely propagating laminar flames. For the spray jet flame, a good agreement between the simulation results and the experiments is achieved, in terms of the spray statistics, as well as the instantaneous and mean flame shape. The simulation shows important differences in the flame structure between the turbulent inner and the quasi-laminar outer flame branch. The doubly-conditional parametrisation appears to be advantageous for resolving small scale effects related to droplet evaporation. Analysis of the DCMC equation suggests that the behaviour of the flame at its anchoring point is strongly influenced by non-premixed burning modes. The solution appears to be weakly affected by terms of convective transport in the DCMC equation, but significant spatial variations and temporal fluctuations of the conditional reaction rate, around 10% of the time-based mean, persist.

Numerical simulation of hydrocarbon fuel combustion processes in a burner with axial injection of steam jet

A pilot 10 kW burner of novel design using a concept of hydrocarbon fuel combustion enhancement by axial injection of superheated water steam jet is considered. Numerical simulation of turbulent reacting flow and heat transfer, including the radiative heat transfer, soot and NOx formation processes, during combustion of vaporized diesel fuel in this burner has been performed in 2D axisymmetric formulation. As a combustion model, the conserved scalar approach with constrained-equilibrium chemistry model has been used with account for 3 inlet streams and 32 species. The field distributions of velocity, temperature, concentrations of gas species and soot have been obtained from numerical predictions. The numerical results allow to conclude that the effect of combustion intensification, observed in the burner outer flame, arises from the fuel gasification process enhanced by the influence of steam jet.

The role of flow interaction in flame–flame interaction events in a dual burner experiment

A dual burner experiment is used to investigate how flow interactions affect local flame-flame interaction in turbulent premixed flames. The presence of adjacent flows influences the local structure of these flames and understanding the sensitivity of these flames to adjacent flows is essential for multi-nozzle combustion devices. To study this sensitivity, a high-aspect-ratio Bunsen flame operating at a constant flow velocity is placed adjacent to an identical burner with non-reacting flow at varying velocities. High-speed OH-planar laser induced fluorescence and stereoscopic-particle image velocimetry measurements are performed to capture flame-front locations and velocity fields. A non-rigid image registration technique is used to calculate the local flame-area variations that occur due to topological differences, and conditional statistics are extracted to relate the local behavior to changes observed in the global behavior of the flames. Extracted flame curvatures and time-averaged progress variables conditioned on flame-flame interactions show differences existing in the inner and outer flame branches near the flame-attachment region. Statistics of these results are presented and compared for all test cases.

Effect of Wall Temperature on Acetylene Diffusion Flame–Wall Interaction Based on Optical Diagnostics and CFD Simulation

In order to elucidate the effect of wall temperature on a diffusion flame–wall interaction, an acetylene diffusion flame in a head-on quenching type was investigated. Direct photography, two-color thermometry, soot-LII (laser-induced incandescence), OH-LIF (laser-induced fluorescence) and numerical simulation with detailed reaction mechanisms were employed to find out the influence mechanism of wall temperature on near-wall combustion performance and emission characteristics. It is clearly shown through optical diagnostics and computation fluid dynamics (CFD) simulation that, compared with cold wall, the high temperature zone for hot wall becomes wider, and the smaller quenching layer is formed due to the higher wall heat flux. High-concentration soot emission is formed primarily near the outer flame far from the wall. CH2O, CO and HC emissions are decreased as wall temperature rises, while the formation of soot and A4 is increased. A diffusion flame–wall interaction structure is proposed to reveal the influence mechanism of wall temperature.

Local extinction mechanisms analysis of spray jet flame using high speed diagnostics

This paper reports an experimental study where flame structure, flow topology and local extinction mechanisms of n-heptane spray flames are investigated. The burner consists of an annular non-swirling co-flow of air that surrounds a central hollow-cone spray injector, leading to a lifted spray flame. The experiments include measurements of droplet size and velocity by Phase Doppler Anemometry (PDA), flame structure by High-Speed Planar Laser Induced Fluorescence of OH radical (HS-OH-PLIF) simultaneously recorded with the velocity fields of the reactive flow obtained by High-Speed Particle Image Velocimetry (HS-PIV). The poly-disperse spray distribution yields small droplets along the centerline axis while the majority of the mass is located as large droplets along the spray borders. These large droplets associated with high velocities have ballistic trajectories and strongly interact with the inner wrinkled partially premixed flame front and the outer diffusion flame front. Simultaneous HS-OH-PLIF and HS-PIV images characterize the dynamics of extinction events in the spray jet flame. In the inner reaction zone, local flame extinctions are mainly controlled by the shear layer induced by the co-flow and the fuel–air heterogeneities due to the evaporation of small droplets in the vicinity of the flame front. The large scales of turbulence in the shear layer play a significant role in the dynamics of these extinctions. It is also found that the large inertial droplets penetrate the lower part of the inner front reaching the burned gases, where they evaporate rapidly. They also disturb the outer reaction zone due to the low droplets temperature and the rich mixture in the wake of droplet. These new results on local extinction of spray flames and droplet–flame interactions will also strengthen the CORIA Rouen Spray Burner (CRSB) database for the improvement of evaporation and combustion models for reacting sprays.