Overpressure

About: Overpressure is a research topic. Over the lifetime, 3236 publications have been published within this topic receiving 34648 citations.

CFD Simulations to Study Parameters Affecting Gas Explosion Venting in Compressor Compartments

Abstract: In this work, a series of vented explosions in a typical compressor compartment are simulated using FLACS code to analyze the explosion venting characteristics. The effects of relevant parameters on the pressure peaks (i.e., overpressure and negative pressure) are also numerically investigated, including vent area ratio of the compressor compartment, vent activation pressure, mass per unit area of vent panels, and volume blockage ratio of obstacles. In addition, the orthogonal experiment design and improved grey relational analysis are implemented to evaluate the impact degree of these relevant parameters. The results show that the pressure peaks decrease with the increase of vent area ratio. There is an approximately linearly increasing relationship between the pressure peaks and the vent activation pressure. The pressure peaks increase with the mass per unit area of vent panels. The pressure peaks increase with the volume blockage ratio of obstacles. Based on the grey relational grade values, the effects of these relevant parameters on the overpressure peak are ranked as follows: volume blockage ratio of obstacles > vent activation pressure > vent area ratio > mass per unit area of vent panels. These achievements provide effective guidance for the venting safety design of gas compressor compartments.

Starbursts Triggered by Central Overpressure. II. A Parameter Study

Abstract: A parameter study is made of the radiative shock compression of a disk molecular cloud due to the high pressure of the central molecular intercloud medium, after the cloud has fallen into the central region of a galaxy following a galaxy interaction. The dependence of the compression on the disk cloud and central gas parameters has been studied. We show that fshell, the fraction of cloud mass compressed in the outer shell that becomes unstable, is a function of only the external pressure, the cloud radius, and the cloud density. We find that for a wide range of values for the input parameters, fshell is high and lies between 0.75 to 0.90. The fraction fshell is not sensitively dependent on the value of the central gas pressure because the initial inward shock velocity is proportional to the square root of the central pressure, and at later stages it is determined mainly by the self-gravity of the shocked shell. Thus, star formation triggered in disk clouds by compression by the central overpressure, as proposed by Jog & Das, is a general triggering mechanism and is valid as long as the central gas has an overpressure of even a factor of a few higher than that of the incoming disk molecular clouds.We apply the mechanism to the galaxies for which the central gas parameters are known; for example, IC 342 and NGC 1808. We find that in both cases a large fraction of the cloud mass will be compressed. Hence, these galaxies should show a central starburst, provided that there is a substantial gas infall rate from the disk to the central region. This agrees with observations, in that NGC 1808 with gas infall due to galaxy interaction has a central starburst, while IC 342 does not.

Attenuation properties of blast wave through porous layer

Abstract: The propagation and attenuation of blast waves through porous layers is one of the important research topics related to safety assessment and prevention from explosion hazards. This study is a part of series of research on shock in complex media. Blast waves passing through porous layer such as polyurethane foam with high-porosities(≈ 98%) and low densities(≈ 28kg/m3) ; and sand layer having low-porosities(≈ 45%) and high densities (≈1500kg/m3) are tested. Peak overpressures in polyurethane foam and sand layer decrease quickly than that in air, as the blast wave is degenerated into compression waves due to its interaction with three-dimensional porosity distribution. Pressure attenuation caused in present complex media are in between 10 to 40% of the peak overpressure value in air.