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Overpressure
About: Overpressure is a research topic. Over the lifetime, 3236 publications have been published within this topic receiving 34648 citations.
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TL;DR: In this article, the authors explore the influences of the spatial pore pressure distribution on Sh/Pp coupling and then on failure pressure predictions and trap integrity evaluation, and show that hydraulic fracturing and seal breach occur for fluid pressure greater than it would be expected from conventional retention capacity.
43 citations
TL;DR: In this paper, a 10m3 vessel with a high-speed camera and pressure gauges was used to record the pressure trajectories and flame propagation process of ignition growth, and the experimental results showed that the maximum value of overpressure and the maximum rate of the explosion pressure rise are 0.596 MPa and 1.82 MPa/s for the methane (9.5% in volume)/air mixture at atmospheric conditions, respectively.
Abstract: In this study, experiments of explosions and flame characteristics in methane/air mixtures are performed in a 10-m3 vessel. Pressure gauges and a high-speed camera are utilized to record the pressure trajectories and the flame propagation process of ignition growth. The experimental results show that the maximum value of overpressure and the maximum rate of the explosion pressure rise are 0.596 MPa and 1.82 MPa/s for the methane (9.5% in volume)/air mixture at atmospheric conditions, respectively. Both values are higher than for other mixtures with different compositions. The results also indicate that the overpressure from the large-scale vessel in this study is lower than that of a smaller apparatus (e.g., 5-L closed cylindrical vessel). This difference occurs due to the cooling effect and because the reflected sonic disturbances by the vessel wall affect the explosion process and weaken the energy during the pressure attenuation stage, thus rendering the value of overpressure in the large-scale apparatus lower than in the tiny cylindrical vessels. The maximum overpressure is observed at 0.75 m for C = 7% (“C” means the methane concentration) and 9.5% but at 1.3 m for C = 5%, 6.5%, 11.2%, and 13%. These results indicate that methane/air is an easier means to generate overpressure and that the overpressure is higher near the stoichiometric condition. Based on the analysis of the flame propagation process, the mean value of the flame speed of methane (C = 9.5%)/air is calculated to be approximately 2.43 m/s because the nonuniformity of the chemical reaction at the flame front results in a maximum fluctuation of flame speed of approximately 28.5%. The flame thickness (θ) of methane (C = 9.5%)/air fluctuates between 9.84 and 10.95 mm, with a mean value of 10.53 mm. © 2014 American Institute of Chemical Engineers Process Saf Prog 33: 362–368, 2014
42 citations
TL;DR: In this article, two types of vertical overpressure configuration can be identified by electronic logs and mud pressure, based on the calibration with the test pressure, and some important implications for hydrocarbon exploration can be drawn.
42 citations
TL;DR: In this paper, the authors explore the sustainability of urban utility tunnel and the possibility for methane/hydrogen mixture transportation, FLACS, the gas explosion simulation software, was used to study the explosion in gas compartment in utility tunnel.
42 citations
TL;DR: In this article, several existing empirical equations proposed by various researchers for blast peak positive overpressure of spherical free-air and hemispherical surfacebursts, the arrival time of air-blast shockwave, and positive phase duration of the blast are presented and compared with the available experimental results and predictions of blast design manuals UFC 3-340-02(2008) and IS 4991:1968 for a span of scaled distances.
Abstract: The blast-induced impulsive loads due to unabated accidental and man-made explosions on structures are receiving attention from structural designers. Recent devastating Beirut ammonium nitrate explosion and very recent blast at a chemical factory on the outskirts of Bangkok are examples of the accidental explosions. Such loading applies a high-intensity pressure over a very short duration (microsecond to the millisecond), is generally more damaging than quasi-static and other less intense dynamic loadings induced by wind, wave, or earthquake. The positive phase of the blast load is generally considered in the analysis neglecting the negative phase being less impulsive to cause significant damage to the structure. A number of available empirical relations predict blast wave parameters and each relation validates its experimental results, however, the proposed relations had not been vetted with different available experimental data. In this paper, several existing empirical equations proposed by various researchers for blast peak positive overpressure of spherical free-air and hemispherical surface-bursts, the arrival time of air-blast shockwave, and positive phase duration of the blast are presented and compared with the available experimental results and predictions of blast design manuals UFC 3–340-02(2008) and IS 4991:1968 for a span of scaled distances. The phenomenon of the blast is explained and a list of technical documents and required accessories to measure the experimental response is provided. The limitations of the empirical relationships are explored. This study is useful to structural engineers and researchers for the blast-resistant design of structures.
42 citations