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Organisationseinheit der BAM
Turning maneuvers of rail vehicles involve demanding situations for the infrastructure because of the steering forces generated and the resultant lateral load transfers. Such forcing situation involves increased tangential forces that consume kinetic energy from the vehicle. While much attention has been paid in the literature to the damage in such infrastructure segments, the energy that is dissipated in these maneuvers, has not been explicitly addressed. In this paper, a specialized scale-down infrastructure is used to characterize the effect of the initial speed of the vehicle and its mass, on the magnitude of both the rail forces developed and the amount of dissipated energy during turning maneuvers. The outputs of the experiments suggest that most of the original kinetic energy is dissipated at the first portion of the turn. Also, that the magnitude of the wheel forces and the amount of dissipated energy, correlate. That is, a greater rail damage would correspond to greater energy dissipation.
Pressurisation of full-containment pressure vessels in fire is known to be driven by thermal stratification. The predominant mode of heat transfer to the contents (convection from the shell to the liquid phase) results in formation of „hot“ boundary layers. Sub-cooled boiling may also be present. The warm layer rises to the surface through buoyancy and bubble flow, increasing the surface of the liquid above that of the bulk temperature, and hence driving a pressure rise.
For reliable prediction of the complex effects governing vessel pressurization a three-dimensional numerical model is required. Work is being undertaken on such a model by other institutions in cooperation with this project.
A new tank design for Hazmat
(2016)
Initial studies have shown pre-deformed honeycomb structure
pressure vessels to have comparable burst pressure to straight steel vessels.
It was shown that honeycomp structured tanks have a higher energy absorption than straight steel tanks.
Future studies will investigate optimization of the deformed plate, to determine if increased payloads or a reduced wall thickness can be achieved.
The arrangement of the measuring sensors allowed the
capture of air flow induced temperatures and material
temperatures on various points of the cylinder body. Four
significant temperature levels could be observed: Inside the cylinder (far from the wall, close to the wall), inside the aluminium liner and outer surface. Figure 5 shows the temperature distribution after a regular filling process with a filling time of ten minutes. The temperature sensors T1 - T9 are marked with different colors. The corresponding measurement points are shown in Figure 4. Due to the high thermal conductivity of the aluminum liner the induced temperature peaks are quickly derived. A flow-induced exceeding of the maximum approval temperature is not expected. Regarding the safety assessement the results show that the pressure and temperature profilesmustbe taken into account.
The vessel wall response shows a good agreement between the numerical predictions of and experimental data using the limit load approach. Further work is continuing to understand the thermohydraulic response and the boundary conditions for material modelling. As shown in figure 2 there was one BLEVE of a bare tank containing a PRV, highlighting the risk of serious consequences if models are inaccurate. The behavior of partly coated tanks were similar to the bare tank.
Gefahrguttanks
(2016)
The results are based on data1. Figure 3 displays temperatures of the tank wall and of the gas phase over testing time. It can be seen that a complete coating strongly delayed the heating of tank wall and gas phase, whereas the partly coated tanks only had a minor influence on temperature development. There was no significant difference between a half coated and a thirdly coated tank measurable. Figure 4 shows the internal pressure of tanks over testing time. Only the fully coated tank enabled a low pressure over 90 min testing time. Hence, a complete coating is necessary to guarantee the fire safety of hazmat tanks and a partly coating is not sufficient.
Commodities and rail damage
(2018)
The normalized contact-mechanics fourth-power law approach for the
dynamic loads, suggest: worst railway use situation (double deck at 65 km/h) is 350 times that of the less rail damage situation (flat car at 45 km/h).
The normalized dispersion approach for the dynamic loads (Dynamic Load Coefficient), suggest that the worst railway use situation (double deck at 65 km/h) is about 4 times that of the less rail damage Situation (flat car at 45 km/h).
The potential effect of the different types of cars on the railway fatigue life could be significant, as a function of the vehicle speed.
The experimental validation of these outputs will be carried out as a continuation of this research effort. In addition to that, it should be mentioned that the associated simplified model could be used to analyze some other situations, related with the transport safety of different products.
It was possible to achieve an error as 9% or even 0% at certain time steps, as shown in the graph above, the usage of UDF code has major importance in achieving the pressure Profile required, and it heat transfer between the bottle itself and the surroundings was taken into consideration which of course had a high influence on how the temperature of the air flask changes.
Liquefied Hydrogen (LH2) or Liquefied Natural Gas (LNG)
establish themselves as important energy carriers in the transport
sector. Its storage requires tanks with Thermal Super Insulations
(TSI) to keep the transported fluid cold. TSI has proven itself in
various applications over a long time, but not in the land
transport sector, where accidents involving collisions, fires, and
their combination are to be expected. The focus of this study is
to investigate the behavior of different types of TSI when
exposed to a heat source that represents a fire. Therefore, a High-
Temperature Thermal Vacuum Chamber (HTTVC) was used that
allows the thermal loading of thermal insulation material in a
vacuum and measuring the heat flow through the TSI in parallel.
Within this study, 5 samples were tested regarding 3 different
types of MLI, rock wool, and perlites. The thermal exposure
caused different effects on the samples. In practice, this can be
connected to the rapid release of flammable gases as well as a
Boiling Liquid Expanding Vapour Explosion (BLEVE). These
results are relevant for the evaluation of accident scenarios, the
improvement of TSI, and the development of emergency
measures.
Biofuels, particularly biodiesel, have gained significant attention as an alternative to traditional fossil fuels in recent years. Unlike diesel, which contains hundreds of compounds, biodiesel only contains a few compounds in the C16-C18 carbon chain. However, the use of biodiesel in automobile and transportation applications can result in problems of degradation or even damage in materials. Among the commonly used polymer materials, fluorocarbon (FKM) shows excellent performance and high stability and compatibility towards oil, diesel, ethanol, and other chemicals. FKM is a family of fluorocarbon-based fluoroelastomer materials, which provide excellent high-temperature and chemical stability compared to other elastomers. As a result, FKM is widely used in chemical processes such as petroleum refining, where it is used for sealings, pumps, and other components.