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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 examined the entrained mass flow over a range of geometric and flow conditions, including overpressured cases up to an overpressure ratio of 2.83.
Abstract: Particle image velocimetry (PIV) experiments have been conducted to study the velocity flow fields in the developing flow region of high-speed jets. These velocity distributions were examined to determine the entrained mass flow over a range of geometric and flow conditions, including overpressured cases up to an overpressure ratio of 2.83. In the region near the jet exit, all measured flows exhibited the same entrainment up until the location of the first shock when overpressured. Beyond this location, the entrainment was reduced with increasing overpressure ratio, falling to approximately 60% of the magnitudes seen when subsonic. Since entrainment ratios based on lower speed, subsonic results are typically used in one-dimensional volcanological models of plume development, the current analytical methods will underestimate the likelihood of column collapse. In addition, the concept of the entrainment ratio normalization is examined in detail, as several key assumptions in this methodology do not apply when overpressured.
17 citations
Patent•
02 Feb 1995
TL;DR: In this paper, an actuating box with a diaphragm, a spring, and a piston rod was used to adjust the pressure in the actuating chamber of a gas supply pipe.
Abstract: The chamber contains a housing (2), its gas supply pipe (2), pipes (3.1,3.2) integrated in the housing, a pipe coated valve, an actuating box (10) with a diaphragm (11), spring (12), piston rod (13), and pressure connecting union, and a pressure line (6). The actuating box is of overpressure type. The pressure line feeds a gas counter-pressure to the diaphragm overpressure side. The diaphragm low pressure side is engaged by ambient pressure and the spring. The piston rod has a tight seal (14) against the housing.
17 citations
Avco1
TL;DR: In this article, an axisymmetric MPD accelerator is considered, where the self-induced magnetic compression of the plasma in the electrical discharge results, generally, in an overpressure at the cathode tip.
Abstract: An axisymmetric MPD accelerator is considered. The self-induced magnetic compression of the plasma in the electrical discharge results, generally, in an overpressure at the cathode tip. The overpressure, Ap, increases almost linearly with the square of the current / when no external magnetic field B is present. This relationship has been used for the experimental determination of the discharge radius at the cathode. However, when a B field is applied along the axial direction, the overpressure under consideration is drastically reduced and, for sufficiently large #, it becomes negative. In such a case, no simple relationship exists between the discharge current and the cathode-tip overpressure. The reasons for this are discussed and the relevant phenomena are experimentally and analytically examined for a steady-state electrical discharge. The discharge in question (currents up to 2500 amp) takes place between two axisymmetric electrodes, in the presence of an axial B field (0 to 2000 gauss) and a nitrogen flow at rates between 0.10 and 0.40 g/sec. 1325
17 citations
TL;DR: In this article, a correlation of maximum explosion overpressure in LNG tank area was developed based on the momentum conservation equation and the deduced factors in the explosion tests, and the parameters in the correlation were fitted by FLACS simulations of explosions of different LNG storage tank areas.
Abstract: Maximum explosion overpressure is an important index in combustible gas explosions for safety managers and fire rescue commanders. The main factors affecting the maximum explosion overpressure in an LNG tank area were deduced by a series of reduced-scale tests. A correlation of maximum explosion overpressure in LNG tank area was developed based on the momentum conservation equation and the deduced factors in the explosion tests. The parameters in the correlation were fitted by FLACS simulations of explosions of different LNG storage tank areas. Compared with traditional methods such as the TNO Multi-Energy method and Baker-Strehlow method, this correlation is targeted to the scenario of LNG leaking from the joint of a pipeline and the tank top, which may be the most probable type of leak in LNG tank areas. The correlation was verified by five FLACS simulation cases of the LNG tank areas with tank radii of 10 m, 20 m, 30 m, 40 m and 50 m. Comparing the overpressures calculated with FLACS and the correlation, there are fewer relative deviations when the radii of tanks are larger. LNG tanks with a radius greater than 40 m have been widely developed in recent years, and the relative deviation of the correlation and FLACS greater than this size is less than 6.6%. The maximum overpressure of the test scale explosion obtained from the correlation is 326.09 Pa. It is close to 389 Pa, which is the maximum tested overpressure in this paper. This correlation can be used as a reference for LNG tank area safety managers, fire rescue commanders and researchers.
17 citations
01 Jan 2012
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17 citations