Search Results (7)

In crude oil storage tank fires, large amounts of firefighting water are used, which may trigger boilover. Variations in oil level affect ullage height, while firefighting water injection alters the water layer thickness, with both processes influencing boilover behavior. This study conducts boilover experiments with 3 types of crude oil to investigate the effects of ullage height and water layer thickness. The results show that the water-cooling effect delays boilover onset time, suppresses intensity, and reduces the mass burning rate, with Jidong crude showing the highest reduction (19.2%). However, the water-cooling effect has a limit, and its influence weakens when the water layer thickness exceeds 6 cm. Ullage height affects flame behavior. A moderate increase enhances combustion and shortens boilover onset time, while further increases cause self-extinction. The oil–water interface temperature varies nonlinearly between approximately 100 and 120 °C with changing ullage height. The variation trends of hot wave propagation rate with water layer thickness and ullage height are consistent with those of the burning rate, and correlation equations between them are established. Additionally, the study shows that light crude oil exhibits a later boilover onset with a longer duration and experiences 2~3 distinct boilover events, whereas high-viscosity Jidong crude oil undergoes a single short and intense boilover. Full article

Large-format additive manufacturing is a candidate for tremendous savings in terms of time and cost while simultaneously enabling higher flexibility, quality, and variability. Most of the design constraints of small-scale polymer 3D printers still apply to large-format additive manufacturing. The paper details both the strengths and deformation-related design considerations for additive manufacturing to gain a better understanding of the material capabilities and limitations, mechanical characteristics, and how to use them for large-format additive manufacturing (LFAM). The results show that the tested materials for additive manufacturing meet the requirements from the stress and deformation points of view. Compared to the steel and composite material, the strength limits are lower, but high enough for the given load. The materials HI TEMP, HI TEMP CF, PA12CF, PA6/66, and PLA seem to be the most promising for LFAM to create a firefighting water tank. The results may be considered as an introduction to further research that should lead to real solutions for the production of atypical tanks. Full article

A structure located in seismic regions must have a resistance capacity based on current seismic design codes and maintain this capacity for its design life. However, the responses of structures to several major earthquakes worldwide over the past decade have demonstrated the inadequacy of current seismic design codes. Thus, there is a need for an accurate method for assessing the strength of structures under seismic loads. Accordingly, this study aimed to numerically review the structural performance of a typical firefighting water tank equipped with an anti-wave plate under seismic loads. Quasi-static and transient structural analysis methods were developed to determine the structural strength of the water tank. In addition, a one-way fluid–structure interaction (FSI) method was developed to analyse the effect of the anti-wave plate on the liquid-sloshing motion in and the structural strength of the water tank. Moreover, convergence tests were performed to aid the development of mesh models and grid models for finite element method and finite volume method analyses, respectively. Subsequently, the structural responses of the water tank were determined via quasi-static, transient, and one-way FSI analyses. Finally, the effectiveness of the anti-wave plate for mitigating the sloshing pressure in the water tank and the structural responses according to the pressure change were analyzed. The commercial software ANSYS Workbench (ver. 2020R2) was used. Full article

Helicopters are more and more widely used for water dumping in fire extinguishing operations nowadays. Increasing attention is being paid to improving helicopter firefighting efficiency. Water distribution onto the ground from the helicopter tank is a key reference target to evaluate firefighting efficiency. Numerical simulations and calculations were carried out concerning water dumping out of the belly tank of a helicopter using the VOF (Volume of Fluent Model) model and mesh adaptation in ANSYS Fluent, and the effects of two parameters, the height of the tank above the ground and the wind speed, on the wake flow and water distribution were discussed. The results showed that for forward flight, the higher the forward flight speed, the less the average water depth on the ground. Similar results were obtained for flight height. The average water depth was one order of magnitude less than in the cases of the corresponding hovering helicopter for a given wind speed. As for hovering flight, the higher the wind speed, the less the average water depth on the ground. The simulation results were basically consistent with the conclusions of water dump tests of fire-fighting equipment carried by helicopters. For example, when the helicopter flew at a forward flight speed of 15 m/s and the tank bottom was 30 m above the ground, the area covered by the dumped water would be 337.5 m², and the average water depth accumulated per square meter would be 0.3 cm. This result was close to the 0.34 cm obtained under Hayden Biggs’s test condition with a forward flight speed of 70 km/h and a height above the ground of 24 m. Full article

The article is focused on the static stability of a vehicle with a 2000-liter water tank behind the rear axle. The purpose of the research is to evaluate the influence of the tank on stability. The vehicle is composed of a forestry skidder, a water tank, and equipment. To equilibrate the tank a ballast weight of 500 kg in front of the skidder is used. The influence of various combinations of the full water tank, half-filled water tank, and ballast weight is evaluated. The stability is determined as the distances of vectors of a stability triangle and a gravity vector, that is placed in a center of gravity of the whole vehicle. A Python programming language is used to implement the solution. The results are displayed in form of heatmaps. For the analyses, a slope angle of ${18}^{\circ }$ is used. The results show that the longitudinal stability is decreased and lateral stability is increased. The tank also makes the vehicle unstable in some positions. Full article

The presented article presents an innovative solution of a fire-fighting adapter based on the basic hypothesis: to provide sufficient technical support in difficult terrain conditions for water transport logistics in order to quickly prevent the spread and destruction of forest fire. At present, when forest fires begin, it is often quite complicated to provide sufficient technical support for the quick prevention and elimination of fires. This fact is largely eliminated by the designed fire-fighting adapter. The mentioned fire-fighting adapter can be used as a fire-fighting mobile device with a base machine of a forest wheeled skidder (LKT), part of the long-distance transport of water in difficult terrain (lake system), a water tank in difficult terrain with the possibility of filling the Bambi bag with a helicopter, part of the long-distance transport of water in the case of a difficult water source without a forest access road network, and a mobile device for emergency transportation of materials in difficult terrain. In addition to the use for fighting forest fires, the fire adapter can also be used to provide for transport of water for forest nurseries (irrigation), freshly planted areas in the event of prolonged drought, the filling of watering-places for forest animals and filling puddles in the dry season. When designing the supporting frame, we used and imitated the evolutionary approach of nature in the form of generative design. The presented paper deals with the use of modern composite materials in the design of superstructures for base machines, which gradually acquire meaning. The main reason for the increasing use of fiberglass is to achieve higher strength and safer weight reduction. This adapter is designed for forest wheel tractors that reach 40% slope availability, are able to work on the stand area, overcome obstacles and are available in sufficient quantities in all Slovak forest areas. Full article

The paper analyses the anthropogenic change in water bodies in the southern part of the Silesian Upland as exemplified by the town of Knurów. The assessment was based on topographic maps from the years 1827–1828, 1928–1936, 1960 and 1993, and on a 2011 orthophotomap. The cartographic materials used were processed as required for analysis purposes. Maps were calibrated in the Quantum GIS program on the basis of map corner coordinates and using the common points method. In Knurów, four main types of water bodies were distinguished with respect to their origins: reservoirs impounded by dams, flooded mineral workings, industrial water bodies and water bodies in subsidence basins and hollows. Historically, the first water bodies to appear were reservoirs impounded by dams, which dominated until the 1930s. They later fell into disuse and were completely dismantled. Water bodies in mineral workings formed in the early 20th century and were associated with the excavation of raw materials for producing bricks. The period of their greatest significance were the 1960s, when they constituted slightly more than 46% of water bodies in total and accounted for nearly 40% of overall surface area. At the end of the 19th and at the beginning of the 20th century, industrial reservoirs began to appear. Within the town of Knurów, those were sedimentation tanks that held mine water, washery effluent, backfill and cooling water, fire-fighting water pools and tanks, tanks at sewage treatment plants, industrial water tanks and others. Presently, these account for 41.4% (29) of the total number of water bodies and have a total surface area of 32.0 ha (25.2%). Within the study area, water bodies in subsidence basins and hollows only began to form in the second half of the 20th century. In 2011, such water bodies numbered 38 (54.3%) and occupied an area of 90.4 ha (71.2%). Full article