Vent Diameter Research Articles

Experimental investigation on the vented flame and pressure behaviour of hydrogen-air mixtures

To explore the changes in pressure and flame propagation inside and outside the vessel when the pipe diameter does not match the vent diameter, and to check the conservatism of standards NFPA 68 and EN 14491 for this case, an experimental apparatus was utilized to investigate the influences of static activation pressure (0.7–1.75 bar) and vent diameter (30–70 mm) on the deflagration behavior of hydrogen–air mixtures (Φ: 0.6–1.4). The vented pressure, flame propagation, and pressure–flame interaction characteristics of hydrogen–air mixtures were observed and analyzed. Additionally, the conservatism of the calculated venting area under the experimental conditions of NPFA 68 and EN 14491 was verified. The results indicated that under an equivalence ratio of 0.6, the pressure-time curve inside the container exhibited only one peak (Pmax11). In the stoichiometric and fuel-rich states, the pressure-time curve inside the container exhibited two peaks attributed to the decrease in venting efficiency due to the secondary explosion inside the pipe, increasing the turbulence intensity within the container. When the static activation pressure is 0.7bar, the pressures of the three vent diameters of 30, 50 and 70 dropped by 11.34%, 24.38% and 26.86% respectively. And the Pmax11 at Φ= 1.0 and Φ= 1.4 are similar, while this phenomenon is not observed for other vent diameters. When the vent diameter was inconsistent with the duct diameter. the calculations of both standards were conservative. However, under these testing conditions (vent diameter: 30–70 mm, static activation pressure: 0.7–1.75 bar), the NPFA 68 calculations yield a conservatism range of 3.3 to 11, whereas EN14491 ranges from 1.6 to 15.7. The NPFA 68 results were more stable and concentrated, making these conditions more suitable for industry safety design in hydrogen venting.

Multi-Parameter and Multi-Objective Optimization of Occupant Restraint System in Frontal Collision

To solve the constraints of multi-objective optimization of the driver system and high nonlinear problems, according to the relevant dimensions of a car, we build a simulation model with Hybrid III 50th dummy driver constraint system. The comparison of the driver mechanics index of the experimental data with the simulation data in the frontal crash shows that the accuracy of simulation model meets the requirements. The optimal Latin test design is adopted, and the global sensitivity analysis of the design parameters is carried out based on the Kriging model. The four most sensitive parameters are selected, and the parameters are solved by a multi-island genetic algorithm. And then the nonlinear programming quadratic line (NLPQL) algorithm is used to search for accurate optimization. The optimal parameters of the occupant restraint system are determined: the limiting force value of force limiter 2 985.603 N, belt extension 12.684%, airbag point explosion time 27.585 ms, and airbag vent diameter 27.338 mm, with the weighted injury criterion (WIC) decreased by 12.97%, the head injury decreased by 22.60%, and the chest compression decreased by 7.29%. The results show that the system integration of passive safety devices such as seat belts and airbags can effectively protect the driver.

Study on the influence of barrel venting on the overload waveform of projectile in bore

In order to evaluate the anti shock overload ability of electronic components and parts in explosive device launcher, half sine wave generator with certain amplitude and pulse width is often used to verify it. In this paper, gun launcher is used as the shock wave generator. Different charge structures are studied for the interior ballistics process of barrel with or without venting according to certain requirements of mechanical overload. The influence of different charge structure, chamber volume and vent hole size on the overload waveform of projectile in the process of interior ballistic is studied by numerical simulation. The simulation results show that the larger the vent diameter is, the closer it is to the standard waveform. The research results can provide references for the matching design of projectile and artillery, the research and development of intelligent ammunition and the assessment. The research results can provide for the matching design of new artillery projectile and artillery and the research and development of intelligent ammunition.

Morphometric trends and implications for the formation of araneiform clusters

Araneiforms are an exotic type of feature exclusive to the Martian south polar terrain which have no known direct Earth analog. The dilation and recession of the seasonal CO2 ice deposit has long been hypothesized to be responsible for their gradual formation. However, high south polar latitude araneiforms have not been observed to form or extend in the present day and it is unclear whether they are growing below the limits of high resolution imagery, or whether they formed in a paleoclimate. Furthermore, it is unclear what physical factors govern the distinct araneiform morphologies, which often appear in discrete ‘clusters’, showing non-random spatial distribution. While qualitative observations of morphology have been reported, there has been a paucity of quantitative measurements of the many physical controls that govern araneiform activity and morphology. Here we present the results of a survey designed to initiate a quantitative morphometric approach to exploring some of the factors which may influence araneiform morphologies. We survey distinct clusters within 3 sites in the Martian south polar regions representing unique araneiform morphologies ranging from ‘fat’ to ‘thin’ to starburst' in order to test the relationship between vent spacing and diameter to morphology found in experimental results. Using the diameters of their central pits as proxies for their starting vent diameters, we find that the level of branching of these dendritic features appears to be correlated with (i) inferred vent spacing and (ii) inferred vent diameter. We suggest that the individual araneiforms within such distinct clusters may have formed contemporaneously, and that vent geometry reflects at least one control on their distinct morphologies. We surveyed and measured araneiforms in three HiRISE images and we have observed and characterized new morphologies at eight sites in HiRISE and CTX images between lat=-87.521°N and lon=162.39°E and lat=-74.7°N, lon=168.41°E in order to investigate if there are any trends in araneiform morphology with latitude. For the sites we studied, we find no discernable relationship between morphology and latitude, though we caution that a more extended survey is needed to confirm this observation on the broader scale. Additionally, from this survey, we report six new araneiform morphologies; ‘fan’, ‘linear’, ‘spiky’, ‘segmented’, ‘flowing’ and ‘sunflower’.

Enhanced NOx reduction performance in the I-type radiant tube by combining a novel triple air-staging with flue gas recirculation

In this study, a novel triple air-staged combustion (ASC) with internal flue gas recirculation (FGR) was proposed to further achieve low NOx emissions and high combustion efficiency in the I-type radiant tube (RT). The effects of air vent structural parameters, including secondary air vent gap d (0, 1, 2, 3 mm) and diameter D (2, 4, 6, 8 mm) of tertiary air vents, on NOx emission and thermal efficiency were analyzed by numerical simulation. The results showed that NOx emissions increased from 33.7 to 66.0 mg/m3 as the secondary air vent gap changed from 0 to 3 mm. The thermal efficiency was higher than the original structure only at d=3 mm. When the tertiary air vent diameter increased from 2 to 8 mm, NOx increased from 49.3 to 180.4 mg/m3 and the thermal efficiency changed with a slight variation. On the premise of higher thermal efficiency than the original structure, the NOx at D=2 mm reached the minimum value of 49.3 mg/m3 under all optimized schemes, with a 64.0% reduction.

Configuration influence in relation to fluid flow of venturi system

AbstractDue to its simplicity and accurately measuring the flow rate, the venturi system is a special kind of pipe that is widely used in various applied fluid mixtures. One of the venturi system's important applications is ejectors devices that accurately facilitate adding air to water to sustain oxygen demand target levels in many waterworks engineering systems. This study aims to improve venturi system measurement accuracy through experimental investigation and analytical analysis for the venturi system conditional configuration parameters effect on target aeration operational efficiency. In the experiment work, different runs are implemented to characterize the performance of such aerators by describing the impact of venturi characteristics and configurations, including water flow rate, air inlets orifices diameters, inlet velocities, throat lengths, inlet angles, outlets angles, and outlet diameters on aeration efficiency. Results show that the venturi air vent diameter is an important governing parameter for determining aeration performance value. Additionally, an indicated increase in aeration performance with an increasing throat length to its diameter ratio. Meanwhile, the results revealed a varying noted effect of the venturi system characteristics and configurations on aeration performance. Moreover, the equations that relate venturi system configuration and Reynolds numbers with the aeration operational performance are developed to facilitate the target accurate aeration efficiency estimation.

A Study on the Factors Influencing Coal Fracturing Range Caused by Liquid Carbon Dioxide Phase Transition

Liquid carbon dioxide phase transition fracturing technology (LCPTF) is an effective method to increase coal seam permeability, but there are many factors that affect the fracturing effect. Blasting pressure, vent diameter, and blasting time are important factors that affect the fracturing effect. However, very limited studies were performed in this regard. Therefore, in this paper, a multifield coupled model for fracturing coal bodies by LCPTF is established; the effect of blasting pressure, vent diameter, and blasting time on blasting effectiveness was studied; a numerical simulation study based on the seepage field and stress field is performed and verified in the field based on the specific geological conditions of Hujiahe mine. Experimental results show that the fracturing radius and the maximum displacement of coal increase with the increase of blasting pressure, and the fracturing radius is 4.875 m when the blasting pressure is 280 MPa, which is 9.6% higher than that of 200 MPa, and the effect is obvious. The fracturing effect improves with the increase of vent diameter but the effect is modest. In general, the fracturing effect increases with the increase of CO2 impact duration, and when there is no gas impact, the fracturing radius basically remains the same. The maximum displacement gradually decreases with time, and its maximum displacement of the coal body decreases by 33.69% at 200 s. After field blasting, the gas flow attenuation coefficient was reduced by up to 85.7% and the effective radius of influence was between 4 and 5 m.

Air-Water Bubbly Flow by Multiple Vents on a Hydrofoil in a Steady Free-Stream

Flow features, due to air injection through multiple vents on the surface of a hydrofoil inclined at an angle with respect to the free-stream in a cavitation tunnel, are presented here. The hydrofoil, with a chord length, c, is oriented at the angle of inclination, α = 3.5°. The Froude number, Fn, based on the free-stream velocity, V∞, and air injection vent diameter, dh, is 30.30, 50.51 and 70.71. Air is injected through multiple vents on the hydrofoil at the non-dimensional air injection coefficient, Cq∼16−8917. The air bubble packing per unit area is quantified using spatial density, SD, at various combinations of Fn,Cq based on a high-speed video from the side view. The time-averaged spatial density, <SD>, is observed to increase in a logarithmic manner with an increase in the air injection rate, Q, at various Froude numbers. There is an increase in the mean spatial density of the bubbles with the increase in Cq at all Fn. A power–law relation is shown to exist between the time-averaged spatial density, <SD>, and the non-dimensional flow variables, Reynolds number, Reair, Fn and Cq based on a regression analysis. By tracking individual finite volume bubbles flowing with the free-stream, the bubble dimensions in pixels are quantified using quantities such as the deformation rate, ϵ, and standardization, ϵS, from the side-view videos. It is observed that ϵ and ϵS change with time, even as they become advected with the free-stream. Through high-speed imaging from the top view, we characterize the bubbly flow features’ time-averaged thickness, t, at various combinations of Fn,Cq at α = 3.5°. We obtain a power-law relation between the non-dimensional time-averaged jet thickness, t/c, and the non-dimensional flow parameters such as, Reair, Fn,Cq and the non-dimensional streamwise distance, x/xref, based on a regression analysis, where xref is a reference distance. The results are relevant to engineering applications where the air–water bubbly flow in a free-stream is important.

Volcanic Vortex Rings: Axial Dynamics, Acoustic Features, and Their Link to Vent Diameter and Supersonic Jet Flow.

By injecting a mixture of gas and pyroclasts into the atmosphere, explosive volcanic eruptions frequently generate vortex rings, which are toroidal vortices formed by the jet's initial momentum. Here, we report high‐speed imaging and acoustic measurements of vortex rings sourcing from gas‐rich eruptive jets at Stromboli volcano (Italy). Volcanic vortex rings (VVRs) form at the vent together with an initial compression acoustic wave, VVRs maximum rise velocity being directly proportional to the amplitude and inversely proportional to the duration of the compression wave. The axial rise and acoustic signature of VVRs match well those predicted by recent fluid‐dynamic experiments. This good match allows using the high‐frequency (80–1,000 Hz) component of the jet sound and the time‐dependent rise of VVRs to retrieve two key eruption parameters: the Mach number of the eruptive jets (<1.5) and vent diameter (∼0.7 m), respectively, the latter being confirmed independently by direct Uncrewed Aerial Vehicle observations.

Numerical analysis of a solar air heater with circular perforated absorber plate

Numerical analysis of a solar air heater with perforated circular absorber plate is carried out to study the effect on the thermo-hydraulic performance due to the elimination of laminar viscous layer that otherwise exist in a conventional solar air heater. The study is conducted for configurations of the absorber plate consisting of 5 mm, 8 mm, 10 mm and 12 mm vent diameters and the number of vents is varied as, 24, 36 and 54. The numerical CFD analysis is conducted for Reynolds numbers ranging from 3000 to 21,000. The CFD analysis is evaluated against the experimental results. The average increase in the thermal efficiency of 23.33% is obtained for the configuration with 8 mm diameter vents and 36 number of vents compared to the base model without the absorber plate. The average increase in thermohydraulic efficiency is 21.78% higher for the configuration with 36 vents and a vent diameter of 8 mm compared to the base model. The highest thermohydraulic efficiency of 72.8% is obtained. The thermohydraulic efficiency of the collector is directly proportional to the increase in vent diameter. The study infers that the circular geometry and vented absorber plate causes vortex formation resulting in increase in turbulence induced heat transfer.

Modelling pyroclastic density currents from a subplinian eruption at La Soufri\xe8re de Guadeloupe (West Indies, France)

We have used a three-dimensional, non-equilibrium multiphase flow numerical model to simulate subplinian eruption scenarios at La Soufrière de Guadeloupe (Lesser Antilles, France). Initial and boundary conditions for computer simulations were set on the basis of independent estimates of eruption source parameters (i.e. mass eruption rate, volatile content, temperature, grain size distribution) from a field reconstruction of the 1530 CE subplinian eruption. This event is here taken as a reference scenario for hazard assessment at La Soufrière de Guadeloupe. A parametric study on eruption source parameters allowed us to quantify their influence on the simulated dynamics and, in particular, the increase of the percentage of column collapse and pyroclastic density current (PDC) intensity, at constant mass eruption rate, with variable vent diameter. Numerical results enabled us to quantify the effects of the proximal morphology on distributing the collapsing mass around the volcano and into deep and long valleys and to estimate the areas invaded by PDCs, their associated temperature and dynamic pressure. Significant impact (temperature > 300 °C and dynamic pressure > 1 kPa) in the inhabited region around the volcano is expected for fully collapsing conditions and mass eruption rates > 2 × 107 kg/s. We thus combine this spatial distribution of temperature and dynamic pressure with an objective consideration of model-related uncertainty to produce preliminary PDC hazard maps for the reference scenario. In such a representation, we identify three areas of varying degree of susceptibility to invasion by PDCs—very likely to be invaded (and highly impacted), susceptible to invasion (and moderately impacted), and unlikely to be invaded (or marginally impacted). The study also raises some key questions about the use of deterministic scenario simulations for hazard assessment, where probability distributions and uncertainties are difficult to estimate. Use of high-performance computing techniques will in part allow us to overcome such difficulties, but the problem remains open in a scientific context where validation of numerical models is still, necessarily, an incomplete and ongoing process. Nevertheless, our findings provide an important contribution to the quantitative assessment of volcanic hazard and risk at La Soufrière de Guadeloupe particularly in the context of the current unrest of the volcano and the need to prepare for a possible future reawakening of the volcano that could culminate in a magmatic explosive eruption.

Mathematical characteristics of the airflow through vents in porous exterior building shading board

ABSTRACT The shading board has a negative influence on window ventilation while it is blocking direct sunlight. Circle vents are designed in the shading board to decrease the negative ventilation effect because air can flow through vents to compensate for the obstruction effect of shading board in this study. The thickness and the diameter of vents are calculated precisely and the optimum size is obtained. Mathematical analysis and ANSYS simulation analysis of the micro ventilation in vents are performed at the same time. From the comparison and validation of this analysis, the relationship beyond air velocity, shading board thickness and vent diameter is concluded to supply reliable basis and good reference for shading design and window ventilation analysis in the building.

Effect of CO2/N2 on explosion vent behavior of lycopodium/air mixtures in a 20-L sphere

To investigate the inerting effect of CO2/N2 on the explosion venting behaviors of lycopodium/air, a standard 20 L spherical chamber, with a thermo-gravimetric analyzer TGA Q500 was adopted to determine the explosion severity and mechanism of inhibition. In the heat flow of the N2 atmosphere and CO2 atmosphere, the pyrolysis processes of lycopodium powder show obvious differences from 370°C approximately. Through the whole explosion process, CO2 plays a key role and it can effectively cut off the contact between dust and oxygen. The particles with free radicals decomposed from heat lycopodium powder such as nitrogen and carbon will react lowly under the blocking effect of CO2. Meanwhile, carbon, nitrogen and other atoms can participate in chain reaction and react with active groups, which greatly reduces the risk of powder explosion. The explosion pressure Pex and the maximum reduced pressure Pred were obtained with lycopodium powder explosion under a wide range of CO2 concentrations. Compared with the pure physical suppression principle of N2 in the explosion process, CO2 can participate in the explosive reaction more effectively, and hence has a better suppression effect of the explosion than N2. An unexpected behavior has been found in relation to the explosion venting behavior. Under the smaller vent diameter or at higher static activation overpressures, the suppressive effects of carbon dioxide to lycopodium/air venting explosion are better than those of nitrogen.

Numerical Simulation of the Influence of Vent Conditions on Hydrogen Flame Propagation

ABSTRACT In order to reduce the damage caused by a gas explosion in a ventilation duct, a Large Eddy Simulation (LES) model was used to simulate the hydrogen/air explosion process in the ventilation duct under different side vent. The results show that in the process of flame propagation, the large size side vent near the ignition end produces a larger discharge effect, which causes more serious distortion and longer time for the flame front passing through the side vents. The influence mechanism of the side vent on the flame propagation is different at different stages of flame propagation. When the flame front is behind the side vent, the positive flow field traction on the flame front increases the contact area between the flame front and unburned gas, and thus accelerates the flame propagation. When the side vent is 1 m away from the ignition end, with the side vent diameter increasing from 40 mm to 80 mm, the peak flame propagation speed increases by 19.02% before the flame reaches the vent. When the flame front passes through the side vent, the exhaust of the side vent and the disturbance of the vertical flow field can restrain the flame propagation. However, when the flame front is in front of the vent, the synergistic effect between turbulent vortex and reverse flow field causes the flame propagation speed to fluctuate greatly. The influence of the side vent size on the explosion relief effect is restricted by the side vent position. When the side vent is located in the pressure rising section, the pressure relief effect of the side vents with different sizes is very great and is almost unaffected by the size of the side vent. When the side vent is 1 m away from the ignition end, the peak overpressure in the tube decreased by 50.75%, 52.88% and 55.43%, respectively, when the diameter of the side vent was 40 mm, 60 mm and 80 mm. On the contrary, when the side vent is outside the pressure rising section, the pressure relief effect of the side vent will be weakened, and vents with different sizes have a great alteration to pressure relief effect. For the side vent being 5 m from the ignition end, the peak overpressure in the tube decreased by 4.49%, 13.41%, and 35.51%, respectively, when the diameter of the side vent was 40 mm, 60 mm, and 80 mm.

Integrating a remote microphone with hearing-aid processing

A remote microphone (RM) links a talker's microphone to a listener's hearing aids (HAs). The RM improves intelligibility in noise and reverberation, but the binaural cues necessary for externalization are lost. Augmenting the RM signal with synthesized binaural cues and early reflections enhances externalization, but interactions of the RM signal with the HA processing could reduce its effectiveness. These potential interactions were evaluated using RM plus HA processing in a realistic listening simulation. The HA input was the RM alone, the augmented RM signal, the acoustic inputs at the HA microphones, including reverberation measured using a dummy head, or a mixture of the augmented RM and acoustic input signals. The HA simulation implemented linear amplification or independent dynamic-range compression at the two ears and incorporated the acoustic effects of vented earmolds. Hearing-impaired listeners scored sentence stimuli for intelligibility and rated clarity, overall quality, externalization, and apparent source width. Using the RM improved intelligibility but reduced the spatial impression. Increasing the vent diameter reduced clarity and increased the spatial impression. Listener ratings reflect a trade-off between the attributes of clarity and overall quality and the attributes of externalization and source width that can be explained using the interaural cross correlation.

Models and Analysis of the Pressure Field for a Hybrid Electric Vehicle With a Fuel Vapor-Containment System in a Refueling Process

Abstract In order to ensure and improve the performance of the fuel vapor-containment system (FVS) on a hybrid electric vehicle (HEV), the vapor pressure field of the evaporative (EVAP) system in the refueling process was analyzed. Numerical models were established to describe the pressure change in the EVAP system. Based on these numerical models, the influences of refueling speed, filler pipe diameter, vent pipe diameter, and fuel vapor-containment valve (FVV) port diameter on pressure change were discussed. The numerical models and the influences of aforementioned effects were validated by experiments. Simulation and experimental results indicated that the vapor pressure field in the EVAP system is more susceptible to the change of refueling speed and FVV port diameter. If the refueling speed increased and the FVV port diameter decreased, the vapor pressure in the EVAP system strongly fluctuated. Furthermore, results also show that the FVV port diameter should be as large as possible but less than 20 mm, while refueling speed should be 50 l/min. The filler pipe diameter can be chosen in the range of 23–28 mm.

Flow behaviour of the exchange flow through a ceiling vent in natural convection: A numerical approach using CALIF3S-ISIS CFD software

In the fire safety context, the exchange flow through a horizontal opening connecting two superposed zones receives a particular interest for developing predictive models and validation of computational codes. Its random behaviour over time could influence the fire source and the vertical spread of the fire smoke. This work is part of a research program developed at the French “Institut de Radioprotection et de Sûreté Nucléaire” (IRSN), and its main objective is to bring new knowledge on this subject by carrying out a numerical study with the computational open-source software named CALIF3S-ISIS developed by IRSN. The configuration of the simulations is that of an experimental reduced-scale set-up, on which data have been obtained and could be used for validation. Large Eddy Simulation (LES) were performed (variation of wall boundary conditions, air injection temperatures, vent diameter and vent mesh refinement), and the bidirectional flow is properly estimated in comparison with the experiment. Particularly, it was determined that the increment of the geometric ratio L/D of the vent of diameter D and thickness L, also leads to an increment of a dimensionless exchange flow rate Froude number at the vent. However, a discrepancy was observed with the model proposed by Epstein based on his experiments in natural convection. The disagreement between the simulation results and the experiments is attributed principally to differences on the vertical temperature stratification of the lower room. Finally, it was investigated the influence of the vertical location within the vent over the mean flow behaviour through different levels of the vent, specifically an exchange of the downward and upward flow organization within the opening.

Explosion venting of hybrid mixtures: A comparison of standards NFPA 68 and EN 14491

Simple venting experiments of hybrid explosions were performed in a 20-L spherical vessel with length-to-diameter L/D of 1. Three vent diameters of 28, 40, and 60 mm were chosen to carry out the venting experiments at static activation pressures ranging from 0.66 to 2.80 bar. The experimental results were compared with the calculated results according to NFPA 68 and EN 14491 with the aim of examining the applicability of the two standards for the venting of hybrid explosions. The comparative results show that the vent areas obtained following the criteria of EN 14491 are always greater than those obtained with NFPA 68. For a hybrid mixture with a high concentration of methane, the predictive results given by NFPA 68 tend to be conservative, but reverse for EN 14491. However, the predictive results calculated according to both NFPA 68 and EN 14491 tend to be conservative as the vent diameter decreases and the static activation pressure increases. Although the predictive results obtained with both NFPA 68 and EN 14491 are conservative, only NFPA 68 gives a good prediction for hybrid explosion venting with vent diameters of 60 and 40 mm.

A study on the parameter ranges of the locally supplied air in a task ambient conditioning system with chest exposure

The benefits of task ambient conditioning in improving thermal comfort and indoor air quality have been demonstrated in recent studies. The potential use of task ambient conditioning for improving thermal comfort when the room air temperature is beyond the suggested range in mixing ventilation; however, has not been fully explored. A newly developed task ambient conditioning with chest exposure was, therefore, suggested at the room air temperature of 28°C (82.4°F), which is higher than the normally set temperature under cooling conditions in mixing ventilation. The present study aims to explore the appropriate air parameter ranges of the local airflow, but not to develop the practical system. Assessments of the thermal environment were performed by subjective questionnaires under nine distinct conditions with task ambient conditioning with chest exposure as well as the ambient environment in a climate chamber. The thermal sensations under the nine conditions with task ambient conditioning with chest exposure were nearly thermal neutral or slightly cool, while a slightly warm sensation was experienced in an ambient environment. Thermal sensation votes indicated cooler sensations with a decrease in the temperature of the locally supplied air, and with an increase in the velocity of locally supplied air, as well as in the vent diameter. The locally supplied airflow of task ambient conditioning with chest exposure obviously improved thermal comfort, the percentage of discomfort was reduced to 20% or less. Furthermore, the appropriate ranges of airflow parameters (air temperature, air velocity, and vent diameter) of task ambient conditioning with chest exposure were demonstrated, to aid the practical development of task ambient conditioning with chest exposure systems.

Integrating puffing and explosions in a general scheme for Strombolian‐style activity

AbstractStrombolian eruptions are among the most common subaerial styles of explosive volcanism worldwide. Distinctive features of each volcano lead to a correspondingly wide range of variations of magnitude and erupted products, but most papers focus on a single type of event at a single volcano. Here, in order to emphasize the common features underlying this diversity of styles, we scrutinize a database from 35 different erupting vents, including 21 thermal infrared videos from Stromboli (Italy), Etna (Italy), Yasur (Vanuatu), and Batu Tara (Indonesia), from puffing, through rapid explosions to normal explosions, with variable ejection parameters and relative abundance of gas, ash, and bombs. Using field observations and high‐speed thermal infrared videos processed by a new algorithm, we identify the distinguishing characteristics of each type of activity and how they may relate and interact. In particular, we record that ash‐poor normal explosions may be preceded and followed by the onset or the increase of the puffing activity, while ash‐rich explosions are emergent, i.e., with inflation of the free surface followed directly by emission of increasingly large gas pockets. Overall, we see that all Strombolian activities form a continuum arising from a common mechanism and are modulated by the combination of two well‐established controls: (1) the length of the bursting gas pocket with respect to the vent diameter and (2) the presence and thickness of a high‐viscosity layer in the uppermost part of the volcanic conduit.