Topic
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 pressure modulation of a weak shock wave induced by a Nd:YAG laser pulse when passing across a turbulent slit jet was experimentally investigated, and clear relationships were obtained between the overpressure history and the experimentally observed shock front deformation, which was visualized as differential schlieren images.
Abstract: The pressure modulation of a weak shock wave induced by a Nd:YAG laser pulse when passing across a turbulent slit jet was experimentally investigated. With the slit jet the peak overpressure became smaller by an average of 12%, with a standard deviation of 27%. Clear relationships were obtained between the overpressure history and the experimentally observed shock front deformation, which was visualized as differential schlieren images. The peak overpressure was increased when the originally spherical blast wave front was locally flattened, whereas it was decreased when a hump in the shock wave front was formed.
18 citations
TL;DR: In this paper, a semi-confined transparent explosion vessel was used to investigate synergistic inhibition effects by CO2 and ultrafine water mist on a methane/air explosion, and it was found that the CO2 had a better synergistic inhibiting effect with the ultra fine water mist than the N2.
Abstract: Experiments of synergistic inhibition effects by N2 or CO2, and ultrafine water mist on methane/air explosion were carried out in a semi-confined transparent explosion vessel. The maximum flame propagation speed, maximum temperature, and maximum overpressure were found to be significantly decreased in the presence of a lower amount of gas-liquid two phase medium. It was also found that the CO2 had a better synergistic inhibiting effect with the ultrafine water mist than the N2. In the present study, 14% N2 or CO2 and 2 min mist spraying time were necessary to achieve better inhibition effects, such as declines of the maximum overpressure were 69.8% and 74.4%; and the declines of the maximum temperature were 43.4% and 51.9%; and the maximum flame propagation speed was between 2.13 m.s−1 and 3.6 m.s−1, respectively. The experimental results obtained from the present study could potentially facilitate the designs of explosion suppression engineering using water mist inerting systems.
18 citations
TL;DR: In this article, an empirical model is presented for explosion wave propagation, which demonstrates that pressure amplitude is inversely proportional to distance raised to the 1.2 power of a nuclear explosion, and this model resulted from recordings of vertical propagation, essentially unrefracted by the horizontally stratified atmosphere, and by comparison of amplitudes from different yields after nearly simultaneous propagation along more complex atmospheric paths.
Abstract: An empirical model is presented for explosion wave propagation, which demonstrates that pressure amplitude is inversely proportional to distance raised to the 1.2 power. This model resulted from recordings of vertical propagations, essentially unrefracted by the horizontally stratified atmosphere, and by comparison of amplitudes from different yields after nearly simultaneous propagation along more complex atmospheric paths. Recent NASA rocket grenade experiments provide basis for extending the scaled range of applicability to 8000 km from a 1-kt nuclear explosion.
18 citations
12 Jun 2006
TL;DR: In this paper, a novel flight demonstration technique that generates low overpressure N−waves using conventional military aircraft is outlined, in addition to initial quantitative flight data also will be recorded.
Abstract: The recent flight demonstration of shaped sonic booms shows the potential for quiet overland supersonic flight, which could revolutionize air transport. To successfully design quiet supersonic aircraft, the upper limit of an acceptable noise level must be determined through quantitative recording and subjective human response measurements. Past efforts have concentrated on the use of sonic boom simulators to assess human response, but simulators often cannot reproduce a realistic sonic boom sound. Until now, molecular relaxation effects on low overpressure rise time had never been compared with flight data. Supersonic flight slower than the cutoff Mach number, which generates evanescent waves, also prevents loud sonic booms from impacting the ground. The loudness of these evanescent waves can be computed, but flight measurement validation is needed. A novel flight demonstration technique that generates low overpressure N‐waves using conventional military aircraft is outlined, in addition to initial quantitative flight data. As part of this demonstration, evanescent waves also will be recorded.
18 citations
TL;DR: In this article, a semi-confined pipe with a cross-section area of 0.08×-0.08m 2 and a length of 21m was simulated and the multiparameter acceleration characteristics of a methane/air mixture with a fuel concentration of 9.5% and a filling ratio of 100% were simulated.
Abstract: After a semi-confined pipe with a cross-section area of 0.08 × 0.08 m 2 and a length of 21 m, the multiparameter acceleration characteristics of a methane/air mixture with a fuel concentration of 9.5% and a filling ratio of 100% were simulated. The results show that a shock wave and a sonic compression wave produce two peak overpressures after 4.16 m away from the ignition source. The maximum overpressure presents a changing trend of decreasing and increasing with increasing distance. With increasing distance from the ignition source, the peak overpressure formed by shock wave, the flame propagation speed, the maximum combustion rate, the maximum density, and the maximum gas velocity increased gradually, but the peak overpressure formed by sonic compression wave and the maximum temperature decreased gradually. This will provide a basis of gas explosion control research.
18 citations