원통형 밀폐 용기의 내부 구조에 따른 폭발 압력 특성 연구

손의남,손승민,이선권,강규홍 한국마린엔지니어링학회 2019 한국마린엔지니어링학회지 Vol.43 No.3

Demand for explosion-proof electrical equipment is increasing with the increasing number of gas handling areas. Electric motors, which are essential in industrial fields, also require that they be explosion-proof structures. An explosion-proof motor should be designed such that it is sufficiently strong to withstand internal explosion pressure, and the strength of the casing must be verified using a reference pressure test. It is possible to estimate the internal explosion pressure of a general cylindrical structure using engineering calculations. However, this estimation becomes difficult when the internal structure, such as that of an electric motor, is complicated. In addition, the explosion pressure is confirmed experimentally. In this study, to analyze explosion pressure characteristics based on the internal structure of a cylindrical enclosure, models with different structures were fabricated and the same test environment was set up to perform a reference pressure test. After the cylindrical enclosure was tested, the test was repeated with the stator and rotor components added in sequence, and the explosion pressure characteristics based on the internal structure of the enclosure were analyzed based on the results of the explosion test. In addition, experiments were conducted on the closed vessel by changing the size of the air-gap for the motor, which can accelerate the explosion and produce a pressure piling phenomenon. Finally, the explosion pressure characteristics based on the size of the air-gap were analyzed. 가스 취급 구역의 증가에 따라 방폭형 전기기기의 수요가 증가하고 있으며, 산업현장의 필수품인 전동기도 방폭형구조를 요구하고 있다. 방폭형 전동기의 하우징 설계에는 내부 폭발 압력을 견딜 수 있는 강도를 반영해야하며, 기준압시험으로 케이싱의 강도를 검증하고 있다. 일반적인 원통 구조의 내부 폭발 압력은 추산이 가능하나, 전동기와 같이 내부구조가 복잡한 경우에는 공학적인 계산으로 폭발 압력을 추산하는 것이 어려우며, 시험적으로 폭발 압력을 확인해야 한다. 본 논문에서는 원통형 밀폐 용기의 내부 구조에 따른 폭발 압력 특성을 분석하고자 상이한 구조를 가지는 모델들을제작하였으며, 동일한 시험 환경을 조성하여 기준압 시험을 진행하였다. 원통형 밀폐 용기에 대해 실험을 진행한 후, 고정자와 회전자 형상의 구성품을 내부에 차례로 추가하면서 실험을 진행하였으며, 폭발 시험 결과 값을 바탕으로 원통형 밀폐 용기의 내부 구조에 따른 폭발 압력 특성을 분석하였다. 또한, 폭발을 가속시키며 압력 중첩 현상을 발생시킬 수 있는전동기 공극의 크기를 변경하면서 밀폐 용기에 대해 실험을 진행하여 공극 크기에 따른 폭발 압력 특성을 분석하였다.

Internal Force Model for the Conservation of Linear Momentum in Simulations of an Explosion of a System of Particles

이종완 한국물리학회 2015 새물리 Vol.65 No.12

An explosion is a typical example for explaining the principle of conservation of linear momentum of a system of particles. However, demonstrating visually an explosion to students with computer simulations is not trivial. That the center of mass of the particles from the explosion follows the original parabolic path must be shown. The particles from the explosion seem to move randomly at first sight. However, if random values are used, the conservation of linear momentum is not satisfied. Rather, the explosion must be considered as an expansion of interacting particles under the influence of a repulsive internal force acting on the system of particles. In this work, we propose a simple internal force model to simulate an explosion and to show that the principle of conservation of linear momentum is satisfied. Various forms of possible internal forces have been investigated. This model may help students to understand the meaning of the vanishing of the double summation of the internal force in the dynamics of systems of particles.

Study on Reduction Effect of Vibration Propagation due to Internal Explosion Using Composite Materials

Sangwoo Park,Jangwoon Beak,Kukjoo Kim,Young?Jun Park 한국콘크리트학회 2021 International Journal of Concrete Structures and M Vol.15 No.4

With the increasing installation cases of underground explosive facilities (e.g., ammunition magazines, hydrogen tanks, etc.) in urban areas in recent years, the risk of internal explosions is also increasing. However, few studies on the measures for reducing damage by the ground vibration have been conducted except for maintaining safety distance. In this study, a method for attenuating the vibration propagated outward by installing a blast-proof panel was numerically and experimentally investigated. Two cubical reinforced concrete structures were manufactured according to the concrete strength and a blast-proof panel was installed on only one side of the structure. Then, acceleration sensors were installed on the external surface to evaluate the propagation of vibration outward depending on the installation of a blast-proof panel. Before a field experiment, a preliminary numerical simulation was performed. The results showed that the acceleration propagated outward could be effectively reduced by installing a blast-proof panel. Even though the performance of a blast-proof panel on vibration reduction was also investigated in the field experiment, significantly larger absolute accelerations were estimated due to the different experimental conditions. Finally, the vibration reduction effect of the blast-proof panel was numerically evaluated according to its thickness and the internal explosion load. A blast-proof panel more effectively reduced the acceleration propagated outward as its thickness increased and the explosion load decreased.

터널 내 폭발에 의한 지표 변위에 관한 수치해석적 연구

박훈 ( Hoon Park ) 대한화약발파공학회 2020 화약발파 Vol.38 No.4

지하공간의 이용범위 확장 및 활용이 증가함에 따라 테러리스트들에 의한 지하 내부 폭발의 발생 가능성이 증가하고 있다. 본 연구에서는 심도 50m의 심도에 굴착된 원형 터널을 모델링한 후, 터널의 내부에 폭발하중을 가하였다. 폭발하중은 ATF(Bureau of Alcohol, Tobacco, and Firearms)에서 제시하는 6종류의 운반용 차량에 대한 최대 폭약량의 폭발하중을 산정하였다. 원형 터널 주변 지반은 국내 터널 설계에서 제시하는 지보패턴에 따른 3종류의 암반등급을 선정하였다. 비선형 동적해석을 수행하여 폭발하중과 지반 특성을 매개변수로 지표 변위를 분석하여 지상 구조물의 영향에 대해 평가하였다. 해석결과, 1등급암에 대해서는 지반의 융기에 대한 영향을 고려해야 하며, 2등급암과 3등급암은 부등침하에 대한 영향을 고려해야 한다. 특히, 3등급암은 40m 이내의 지상 구조물에 대해서는 정밀 분석이 요구된다. 또한 지표 변위는 탄성계수에 의한 영향이 주요인인 것으로 판단된다. With the increase of expansion and use of the underground space, the possibility of an underground explosion by terrorists is increasing. In this study, after modeling a circular tunnel excavated at a depth of 50m, an explosion load was applied to the inside of the tunnel. As for the explosion load, the explosion load of the maximum explosive amount for six types of vehicle booms proposed by ATF (Bureau of Alcohol, Tobacco, and Firearms) was calculated. For the rock mass around the circular tunnel, three types of rock grades were selected according to the support pattern suggested in the domestic tunnel design. Nonlinear dynamic analysis was performed to evaluate the influence of the ground structure by examining the surface displacement using the explosion load and rock mass characteristics as parameters. As a result of the analysis, for grade 1 rock, the influence on the uplift of the surface should be considered, and for grade 2 and 3 rocks, the influence on a differential settlement should be considered. In particular, for grade 3 rocks, detailed analysis is required for ground-structure interaction within 40m. Also, it is considered that the influence of Young’s modulus is the main factor for the surface displacement.

휴대폰 배터리의 폭발 및 화재 위험성에 관한 실험적 연구

이호성,김시국 한국화재소방학회 2016 한국화재소방학회논문지 Vol.30 No.4

This is an experimental study to analyze the explosion and fire hazards of mobile phone batteries. Using the lithium-ionbatteries currently used on smart phone as the experiment samples, the experiments were conducted by overcharging,internal and external short circuit, and thermal shock with the potential of explosion and fire caused by careless use orabnormal conditions. The experiment results showed that, in the case of overcharging and external short circuit, there wasno explosion and fire hazard in the normal operation of the protection circuit module (PCM), but there were big riskswhen the PCM faulted conditions were assumed. In the case of the experiments by internal short circuit and thermalshock, such risks varied depending on a battery charge state. In other words, it could be verified that there were low risksof explosion and fire in a full discharge state, but there were high risks in a full charge state. These experiment resultssuggest that to minimize the explosion and fire hazards of mobile phone batteries, an alarm device is necessary when thePCM fault occurs. In addition, a solid battery case should be made and safety equipment, such as a cooling device toavoid high temperature, is needed. 본 논문은 휴대폰 배터리의 폭발 및 화재 위험성을 분석하기 위한 실험적 연구로서, 실험은 스마트폰 배터리로 사용되고 있는 리튬-이온 배터리를 대상으로 하여 사용상 부주의 또는 이상상태 등에서 폭발 및 화재가 발생될 가능성이 있는과충전, 내부단락 및 외부단락 그리고 열충격에 의한 실험을 진행하였다. 리튬-이온 배터리는 과충전 및 외부단락 실험의 경우 보호회로가 정상적으로 작동될 때는 폭발 및 화재 위험성이 없었으나, 보호회로가 고장상태를 가정하였을 때 폭발 및 화재 위험성이 크게 나타났다. 내부단락 및 열충격 실험의 경우 충전상태에 따라 위험성에 차이가 나타났다. 즉,완방전 상태에서는 폭발 및 화재 위험성이 낮았으나, 완충전 상태에서는 폭발 및 화재 위험성이 높게 나타나는 것을 확인할 수 있었다. 실험결과 휴대폰 배터리의 폭발 및 화재 위험성을 최소화하기 위해서는 보호회로 고장시 알람장치 및배터리 케이스 강화 그리고 고온방지를 위한 냉각장치 등의 안전장치의 강화가 필요할 것으로 생각된다.

IEC 기술표준의 가스폭발위험범위 연구

정용재,이창준 한국안전학회 2018 한국안전학회지 Vol.33 No.3

The occupational safety and health act defines how to evaluate the explosion hazardous areas according to KS (Korean Industrial Standards). Current KS have to follow IEC (International Electrotechnical Commission) 60079-10-1 1st edition and there has been no change since 2008. And its 2nd edition has been revised in 2015. In this study, IEC 1st Ed. (IEC 60079-10-1 1st edition) is compared with IEC 2nd edition. Total 112 case studies including four materials (methane, propane, benzene, methanol) are selected to test and explosion hazardous ranges evaluated by IEC 1st and 2nd Ed. are analyzed according to various leakage pressures and hole sizes. In order to verify the results calculated by them, PHAST, which is one of the most representative consequence analysis programs, is employed. As a result, it can be concluded that there are many differences between IEC 1st and 2nd Ed. due to the discharge and the ventilation parameters. As comparing with PHAST, it is confirmed that IEC 1st provides more conservative values than PHAST. Even if IEC 2nd Ed. provides more conservative for gases, this fails to provide more conservative values for liquids. Therefore, it is worth to note that a large value between the explosion hazardous ranges value calculated by the IEC 1st Ed. and 2nd Ed. should be selected until further investigation and analysis is made. Morevover, the full consideration for IEC 2nd Ed. have to be needed.

Extent of damage analysis of naval ships subject to internal explosions

곽묘정,윤준영,Park Sayyoon,Kwon Seungmin,신윤호,노유정 대한조선학회 2023 International Journal of Naval Architecture and Oc Vol.15 No.-

A well-balanced naval ship design to enhance the survivability from the initial design stage in parallel with other designs focusing on the major function and its inherent mission is considered as a desirable design trend in ROK navy since Cheonan sinking accident. Because it is difficult to estimate a hit location of a given threat for survivability evaluation, a statistical approach based on multiple-hit scenarios is frequently addressed, and it is necessary to accomplish rapid analyzes considering the tight design schedule. In addition, accurately estimating the extent of damage caused by the given threat is also an important matter to secure the reliability of evaluation. In particular, the empirical formula-based damage extent estimation method, which is frequently used for initial rapid vulnerability analysis, has limitations in not faithfully reflecting the latest technology advances such as hull design changes and diversification of threats, so researches on this have been continuously accomplished. In this study, a method for analyzing the extent of damage was developed considering the structural response of a ship to damage under a blast load. The proposed method quickly and easily calculates the extent of damage using physical design parameters together with the accurate analysis results and is also very effective at the initial design stage of the naval ship (e.g., in evaluating various design candidates for structural configurations). To show the effectiveness of suggested method, FLACS, a well-known commercial program for explosion analysis, is used for the analysis of nine representative scenarios together with the stepwise validations of the suggested procedure; the analysis results are observed the same in most cases with the developed program based on the proposed procedure, with a difference of approximately 15% for one scenario.

Application of the Runge Kutta Discontinuous Galerkin-Direct Ghost Fluid Method to internal explosion inside a water-filled tube

Park, Jinwon The Society of Naval Architects of Korea 2019 International Journal of Naval Architecture and Oc Vol.11 No.1

This paper aims to assess the applicability of the Runge Kutta Discontinuous Galerkin-Direct Ghost Fluid Method to the internal explosion inside a water-filled tube, which previously was studied by many researchers in separate works. Once the explosive charge located at the inner center of the water-filled tube explodes, the tube wall is subjected to an extremely high intensity fluid loading and deformed. The deformation causes a modification of the field of fluid flow in the region near the water-structure interface so that has substantial influence on the response of the structure. To connect the structure and the fluid, valid data exchanges along the interface are essential. Classical fluid structure interaction simulations usually employ a matched meshing scheme which discretizes the fluid and structure domains using a single mesh density. The computational cost of fluid structure interaction simulations is usually governed by the structure because the size of time step may be determined by the density of structure mesh. The finer mesh density, the better solution, but more expensive computational cost. To reduce such computational cost, a non-matched meshing scheme which allows for different mesh densities is employed. The coupled numerical approach of this paper has fewer difficulties in the implementation and computation, compared to gas dynamics based approach which requires complicated analytical manipulations. It can also be applied to wider compressible, inviscid fluid flow analyses often found in underwater explosion events.

Application of the Runge Kutta Discontinuous Galerkin-Direct Ghost Fluid Method to internal explosion inside a water-filled tube

Jinwon Park 대한조선학회 2019 International Journal of Naval Architecture and Oc Vol.11 No.1

This paper aims to assess the applicability of the Runge Kutta Discontinuous Galerkin-Direct Ghost Fluid Method to the internal explosion inside a water-filled tube, which previously was studied by many researchers in separate works. Once the explosive charge located at the inner center of the water-filled tube explodes, the tube wall is subjected to an extremely high intensity fluid loading and deformed. The deformation causes a modification of the field of fluid flow in the region near the water-structure interface so that has substantial influence on the response of the structure. To connect the structure and the fluid, valid data exchanges along the interface are essential. Classical fluid structure interaction simulations usually employ a matched meshing scheme which discretizes the fluid and structure domains using a single mesh density. The computational cost of fluid structure interaction simulations is usually governed by the structure because the size of time step may be determined by the density of structure mesh. The finer mesh density, the better solution, but more expensive computational cost. To reduce such computational cost, a non-matched meshing scheme which allows for different mesh densities is employed. The coupled numerical approach of this paper has fewer difficulties in the implementation and computation, compared to gas dynamics based approach which requires complicated analytical manipulations. It can also be applied to wider compressible, inviscid fluid flow analyses often found in underwater explosion events.

화약류 간이저장소의 우발적 폭발을 고려한 안전설계 방법 연구

김정규,정승원,김준하,최병희 대한화약발파공학회 2022 화약발파 Vol.40 No.4

화약류 간이저장소에 대한 현재의 규정이 적정한지를 검토할 목적으로 내부 폭발이 표준적인 저장소의 구조적 안정성에 미치는 영향을 FEM 해석과 현장 실험을 통해 분석하였다. 연구 결과, 에멀젼 계열 폭약 15 kg에대한 기존 저장소 구조물의 방폭 성능이 충분하지 않은 것으로 나타났다. 따라서 여기에 대한 하나의 대안으로서폭약을 분할하는 방법을 상정하고 순폭실험을 수행하였다. 실험을 수행한 결과, 폭약을 분할하는 방법이 예상대로 잘 작동하는 것을 확인하였으며, 시험 결과에 근거하여 적정한 분할 폭약량도 결정하였다. 또한, 저장소 구조물 상부를 개방하는 방법을 시험한 결과, 폭발압력이 신속하게 배출되어 구조물 손상이 크게 저감되는 것을 확인하였다. 이러한 구조물 형태는 화약류 간이저장소에 대한 새로운 설계기준으로 사용될 수 있을 것이다.