TY - CONF A1 - Askar, Enis A1 - Grunewald, Thomas T1 - Experimental Study on the ignition of hydrogen containing atmospheres by mechanical impacts N2 - In this presentation the results of the Project HySpark are shown. Mechanical impacts are among the important possible ignition sources to be considered in explosion protection. Hydrogen is particularly prone to be ignited by mechanical impacts compared to natural gas. The effectivity of mechanical impacts as ignition source is dependent from different parameters. In this work the effectivity of impacts as an ignition source for hydrogen containing atmospheres was studied experimentally depending on the inhomogeneous material pairing of the impact. Moreover it was studied, how the effectivity of mechanical impacts as ignition source changes when hydrogen is added to natural gas. T2 - International Conference on Hydrogen Safety (ICHS) 2023 CY - Quebec City, Canada DA - 19.09.2023 KW - Explosion protection KW - Ignition sources KW - Natural gas KW - Safety KW - Mechanical sparks PY - 2023 AN - OPUS4-58514 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Mitu, M. A1 - Razus, D. A1 - Schröder, Volkmar T1 - Laminar burning velocities of hydrogen-blended methane-air and natural gas-air mixtures, calculated from the early stage of p(t) records in a spherical vessel N2 - The flammable hydrogen-blended methane–air and natural gas–air mixtures raise specific safety and environmental issues in the industry and transportation; therefore, their explosion characteristics such as the explosion limits, explosion pressures, and rates of pressure rise have significant importance from a safety point of view. At the same time, the laminar burning velocities are the most useful parameters for practical applications and in basic studies for the validation of reaction mechanisms and modeling turbulent combustion. In the present study, an experimental and numerical study of the effect of hydrogen addition on the laminar burning velocity (LBV) of methane–air and natural gas–air mixtures was conducted, using mixtures with equivalence ratios within 0.90 and 1.30 and various hydrogen fractions rH within 0.0 and 0.5. The experiments were performed in a 14 L spherical vessel with central ignition at ambient initial conditions. The LBVs were calculated from p(t) data, determined in accordance with EN 15967, by using only the early stage of flame propagation. The results show that hydrogen addition determines an increase in LBV for all examined binary flammable mixtures. The LBV variation versus the fraction of added hydrogen, rH, follows a linear trend only at moderate hydrogen fractions. The further increase in rH results in a stronger variation in LBV, as shown by both experimental and computed LBVs. Hydrogen addition significantly changes the thermal diffusivity of flammable CH4–air or NG–air mixtures, the rate of heat release, and the concentration of active radical species in the flame front and contribute, thus, to LBV variation. KW - Hydrogen KW - Methane KW - Natural gas KW - Laminar burning velocity (LBV) KW - Closed vessel combustion PY - 2021 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:b43-569083 SN - 1996-1073 VL - 14 IS - 22 SP - 1 EP - 16 PB - MDPI CY - Basel AN - OPUS4-56908 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Lugovtsova, Yevgeniya A1 - Bulling, Jannis A1 - Prager, Jens T1 - Fantastic guided modes and how to find them N2 - Ultrasonic guided waves (UGW) have been shown to be suitable for non-destructive testing (NDT) and structural health monitoring (SHM) of many engineering structures. Development of a technique based on UGWs requires careful understanding obtained through modelling and analysis of wave propagation and mode-damage interaction due to their dispersion and multimodal character. This presentation will provide insights into the Scaled Boundary Finite Element Method and its applicability for tackling wave propagation problems. Features and limitations of the SBFEM will be presented on an example of a multi-layered plate structure consisting of isotropic and anisotropic materials bonded together. You will be guided through the process of picking up the wave modes for your application. Starting from the calculation of dispersion curves and mode shapes to the analysis of wave propagation and mode-damage interaction. The main highlight of the presentation lies in the ability to detect damage in a certain layer depending on the mode used. The resulting deeper understanding of the wave propagation in multi-layered structures is the key to further developments of NDT and SHM for engineering structures consisting of multiple layers. T2 - Von CEA Eingeladener Vortrag CY - Saclay, France DA - 07.06.2019 KW - Structural Health Monitoring KW - Pressure tanks KW - Hydrogen storage KW - Natural gas KW - Composites KW - Scaled Boundary Finite Element Method PY - 2019 AN - OPUS4-48375 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Lugovtsova, Yevgeniya A1 - Prager, Jens T1 - Analysis of Guided Wave Propagation in an Aluminium-CFRP Plate N2 - Guided waves cover comparably long distances and thus allow for online structural health monitoring of safety relevant components, e.g. lightweight composite overwrapped pressure vessels (COPV) as used for the transportation of pressurised gases. Reliable non-destructive assessment of COPVs’ condition is not available yet due to their complex composite structure comprising a thin metal liner and a fibre reinforced plastics (FRP) overwrap. The conventional overload hydrostatic pressure testing used for the metal vessels is not suitable for the composite vessels, because it may damage the FRP overwrap reducing the service life of the COPV. Therefore, ISO and CEN defined a maximum service life of composite pressure vessels as of 15 to 20 years. To extend the COPVs’ service life and to ensure a safer usage a structural health monitoring system based on guided ultrasonic waves is to be developed. In this contribution first results of guided waves propagation in a flat composite plate consisting of an aluminium layer firmly bonded to a carbon fibre reinforced plastic laminate are presented. Based on experimental results material properties of FRP are reconstructed by means of the Scaled Boundary Finite Element Method (SBFEM). T2 - ECNDT 2018 CY - Gothenburg, Sweden DA - 11.06.2018 KW - Structural Health Monitoring KW - Pressure tanks KW - Hydrogen storage KW - Natural gas KW - Composites PY - 2018 AN - OPUS4-45210 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Lugovtsova, Yevgeniya A1 - Prager, Jens T1 - Analysis of Guided Wave Propagation in an Aluminium-CFRP Plate N2 - Guided waves cover comparably long distances and thus allow for online structural health monitoring of safety relevant components, e.g. lightweight composite overwrapped pressure vessels (COPV) as used for the transportation of pressurised gases. Reliable non-destructive assessment of COPVs’ condition is not available yet due to their complex composite structure comprising a thin metal liner and a fibre reinforced plastics (FRP) overwrap. The conventional overload hydrostatic pressure testing used for the metal vessels is not suitable for the composite vessels, because it may damage the FRP overwrap reducing the service life of the COPV. Therefore, ISO and CEN defined a maximum service life of composite pressure vessels as of 15 to 20 years. To extend the COPVs’ service life and to ensure a safer usage a structural health monitoring system based on guided ultrasonic waves is to be developed. In this contribution first results of guided waves propagation in a flat composite plate consisting of an aluminium layer firmly bonded to a carbon fibre reinforced plastic laminate are presented. Based on experimental results material properties of FRP are reconstructed by means of the Scaled Boundary Finite Element Method (SBFEM). T2 - ECNDT 2018 CY - Gothenburg, Sweden DA - 11.06.2018 KW - Structural Health Monitoring KW - Pressure tanks KW - Hydrogen storage KW - Natural gas KW - Composites PY - 2018 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:b43-452084 SP - 1 EP - 6 AN - OPUS4-45208 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Lugovtsova, Yevgeniya A1 - Bulling, Jannis A1 - Prager, Jens T1 - Efficient Modelling of Guided Ultrasonic Waves using the Scaled Boundary Finite Element Method with Application to Composite Pressure Vessels N2 - The Scaled Boundary Finite Element Method (SBFEM) is a semi-analytical method that showed promising results in modelling of guided ultrasonic waves. Efficiency and a low computational cost of the method are achieved by the discretisation of the boundary of a computational domain only, whereas for the domain itself the analytical solution is used. By means of the SBFEM different types of defects, e.g. fatigue cracks, pores, delamination, corrosion, integrated into a structure consisting of anisotropic and isotropic materials can be modelled. In this contribution, the SBFEM is used to analyse the propagation of guided waves in a structure consisting of an isotropic metal bonded to anisotropic carbon fibre reinforced material. The method allowed to identify appropriate wave types (modes) and to analyse their interaction with different defects. Obtained results will be used to develop a structural health monitoring system for composite pressure vessels used in automotive industry. T2 - InnoTesting 2018 CY - Wildau, Germany DA - 22.02.2018 KW - Structural Health Monitoring KW - Defect-mode Interaction KW - Hydrogen storage KW - Natural gas PY - 2018 AN - OPUS4-44289 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Mishra, Kirti Bhushan A1 - Wehrstedt, Klaus-Dieter T1 - Underground gas pipeline explosion and fire: CFD based assessment of foreseeability N2 - Scenarios of underground gas pipeline failure, crater formation, dispersion of gas, explosion and subsequent fires are investigated with semi-empirical and with CFD (Computational Fluid Dynamics) modelling. In order to strengthen the accident based learning approaches present investigations are performed in the context of recent GAIL (Gas Authority of India Limited) natural gas pipeline incident occurred in India. The foreseeability of damages to lives of people and assets due to explosion overpressure and thermal radiation are assessed. The released gas is considered as slightly dense-than-air i.e. 1.5 times. Depending on the LFL (Lower Flammability Limit) of gas the dispersion diameter and heights are predicted which followed the visual evidences appropriately. The model was furthermore tested with an even denser medium and was found to be worked well there too. The estimated explosion overpressures with the standard methods and also with CFD reproduced the scenario nicely. The effects of congestion VBR (Volume Blockage Ratio) in form of vegetation on stable atmospheric boundary layer flow is analysed and its contribution towards turbulence and hazard enhancement is studied. It is found that the major source of fatalities was higher thermal radiation emitted by pool fires of methane. The estimated thermal safety distances clearly demonstrate the ignorance/under estimation of likelihood and consequence of such hazardous events. For such incidents CFD demonstrated a strong capability to assess the pre or/and post events foreseeabilities within a reasonable amount of time and with an acceptable level of accuracy meeting the industrial needs for risk analysis. KW - Natural gas KW - Underground pipeline KW - Dense gas dispersion KW - Explosion and fire KW - CFD KW - Safety distance PY - 2015 U6 - https://doi.org/10.1016/j.jngse.2015.04.010 SN - 1875-5100 VL - 24 SP - 526 EP - 542 PB - Elsevier CY - Amsterdam [u.a.] AN - OPUS4-33671 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Brown, A. S. A1 - Milton, M. J. T. A1 - Cowper, C. J. A1 - Squire, G. D. A1 - Bremser, Wolfram A1 - Branch, R. W. T1 - Analysis of natural gas by gas chromatography Reduction of correlated uncertainties by normalisation N2 - The results of gas chromatographic analysis of natural gas mixtures reveal strong correlations (Pearson correlation coefficient of >0.96) between the uncertainty of each component and variations in the ambient pressure. Although correction for ambient pressure variations can reduce this variability, normalisation of the results of each analysis using the assumption that the sum of all component amount fractions is unity provides significantly greater reductions in the uncertainty of each measured component. We show that the uncertainty in normalised components can be estimated approximately using the correlation coefficient as a measure of the correlation present in the measurements, or exactly using a full calculation of the variance/covariance (V/C) structure of the data. KW - Uncertainty KW - Normalisation KW - Variance KW - Covariance KW - Natural gas KW - Gases KW - Alkanes PY - 2004 U6 - https://doi.org/10.1016/j.chroma.2004.04.007 SN - 0021-9673 VL - 1040 IS - 2 SP - 215 EP - 225 PB - Elsevier CY - Amsterdam AN - OPUS4-3732 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER -