Fuel Tanks Research Articles

Determination of Fatigue Life and Failure Location of Vehicle Cylindrical LPG Fuel Tanks

Abstract This study addresses the determination of the fatigue life and its failure locations of the vehicle cylindrical LPG fuel tanks using both experimental and finite element analysis (FEA) methods. The experimental investigations performed as an accelerated fatigue tests are carried out using a hydraulics test unit in which the cylinders are internally pressurized by hydraulic oil. The LPG cylinders are subjected to repeated cyclic pressure varying from zero to service pressure of the tank. The FEA modeling of these tanks are developed in three dimensional (3D) using non-uniform geometrical parameters and nonlinear material properties. These models are also subjected to zero-based high cycle fatigue pressure load considering the stress life approach. The FEA modeling process is also simulated in non-homogeneous material conditions. Therefore, the fatigue life performance and failure location of the cylindrical LPG fuel tanks are predicted and compared to the experimental results.

エポキシ樹脂による舶用機器据付とLNG燃料タンクの据付

エポキシ樹脂による舶用機器据付とLNG燃料タンクの据付

Development of an Advanced Extrusion Process for the Reduction of Volatile and Semi-Volatile Organic Compounds of Recycled Hdpe from Fuel Tanks

Development of an Advanced Extrusion Process for the Reduction of Volatile and Semi-Volatile Organic Compounds of Recycled Hdpe from Fuel Tanks

Massive Molecular Gas as a Fuel Tank for Active Galactic Nuclei Feedback In Central Cluster Galaxies

Abstract Massive molecular gas has been discovered in giant elliptical galaxies at the centers of galaxy clusters. To reveal its role in active galactic nucleus (AGN) feedback in those galaxies, we construct a semianalytical model of gas circulation. This model especially focuses on the massive molecular gas (interstellar cold gas on a scale of ∼10 kpc) and the circumnuclear disk (≲0.5 kpc). We consider the destruction of the interstellar cold gas by star formation and the gravitational instability for the circumnuclear disk. Our model can reproduce the basic properties of the interstellar cold gas and the circumnuclear disk, such as their masses. We also find that the circumnuclear disk tends to stay at the boundary between stable and unstable states. This works as an “adjusting valve” that regulates mass accretion toward the supermassive black hole. On the other hand, the interstellar cold gas serves as a “fuel tank” in the AGN feedback. Even if the cooling of the galactic hot gas is prevented, the interstellar cold gas can sustain the AGN activity for ≳0.5 Gyr. We also confirm that the small entropy of hot gas (≲30 keV cm2) or the short cooling time (≲1 Gyr) is a critical condition for the existence of massive amounts of molecular gas in the galaxy. The dissipation time of the interstellar cold gas may be related to the critical cooling time. The galaxy behavior is described by a simple relation among the disk stability, the cloud dissipation time, and the gas cooling rate.

Raw Scanned Point Cloud Registration with Repetition for Aircraft Fuel Tank Inspection

The aircraft fuel tank, as the source of fuel supply, is one of the key components for an aircraft. It is fastened to the fuselage with thousands of rivets, in which each rivet is sealed carefully to prevent the leakage. Thus, the sealing quality of the aircraft fuel tank needs to be precisely measured to ensure its normal function. To achieve the measurement, the complete 3D point clouds captured by 3D scanning are usually utilized. Therefore, it is necessary to align the different views of the aircraft fuel tank point clouds, to obtain the complete data. However, the aircraft fuel tank consists of abundant repetitive structures, such as the regular-distributed rivets, which can lead to mismatches in the aircraft fuel tank point clouds if using the conventional registration methods. In order to address the challenges, we propose a new registration framework, which is able to handle the point cloud match under the repetitive and complex scenes. First, a novel 3D descriptor called LP-PPF is constructed with the point and line features from the aircraft fuel tank point clouds, so as to identify the repetitive structures correctly. Then, according to the proposed descriptor, the accurate registration can be achieved between the neighboring point cloud pairs. Finally, based on the results of pairwise registration, the complete aircraft fuel tank point cloud can be obtained via the multi-view registration method. Experiments demonstrate that our method achieves favorable results on both synthetic and raw scanned point cloud data.

Digital Shape and Geometric Dimension Analysis of Polymer Fuel Tanks

Digital Shape and Geometric Dimension Analysis of Polymer Fuel Tanks

Greenhouse Gas Emission Analysis by LNG Fuel Tank Size through Life Cycle

As greenhouse gas emissions from maritime transport are increasing, the International Maritime Organization is continuously working to strengthen emission regulations. Liquefied natural gas (LNG) fuel is less advantageous as a point of CO2 reduction due to the methane leakage that occurs during the bunkering and operation of marine engines. In this study, greenhouse gas emissions from an LNG-fueled ship were analyzed from the perspective of the life cycle. The amount ofmethane emission during the bunkering and operation procedures with various boil-off gas (BOG) treatment methods and gas engine specifications was analyzed by dynamic simulation. The results were also compared with those of other liquid fuel engines. As a result, small LNG-fueled ships without a BOG treatment facility emitted 32% more greenhouse gas than ships utilizing marine gas oil or heavy fuel oil. To achieve a greenhouse gas reduction via a BOG treatment method, a gas combustion unit or re-liquefaction system must be mounted, which results in a greenhouse gas reduction effect of about 25% and 30%. As a result of comparing the amount of greenhouse gas generated according to the BOG treatment method used with each tank size from the perspective of the operating cycle with the amounts from using existing marine fuels, the BOG treatment method showed superior effects of greenhouse gas reduction.

Crashworthiness of a Composite Bladder Fuel Tank for a Tilt Rotor Aircraft

The fulfilment of the crash is a demanding requirement for a Tiltrotor. Indeed, such a kind of aircraft, being a hybrid between an airplane and a helicopter, inherits the requirements mainly from helicopters (EASA CS 29) due to its hovering ability. In particular, the fuel storage system must be designed in such a manner that it is crash resistant, under prescribed airworthiness requirements, in order to avoid the fuel leakage during such an event, preventing fire and, thus, increasing the survival chances of the crew and the passengers. The present work deals with the evaluation of crashworthiness of the fuel storage system of a Tiltrotor (bladder tank), and, in particular, it aims at describing the adopted numerical approach and some specific results. Crash resistance requirements are considered from the earliest design stages, and for this reason they are mainly addressed from a numerical point of view and by simulations that treat both single components and small/medium size assemblies. The developed numerical models include all the main parts needed for simulating the structural behavior of the investigated wing section: the tank, the structural components of the wing, the fuel sub-systems (fuel lines, probes, etc.) and the fuel itself. During the crash event there are several parts inside the tanks that can come into contact with the tank structure; therefore, it is necessary to evaluate which of these parts can be a damage source for the tank itself and could generate fuel loss. The SPH approach has been adopted to discretise fuel and to estimate the interaction forces with respect to the tank structure. Experimental data were used to calibrate the fuel tank and foam material models and to define the acceleration time-history to be applied. Thanks to the optimized foam’s configuration, the amount of dissipated impact energy is remarkable, and the evaluation of tanks/fuel system stress distribution allows estimating any undesired failure due to a survivable crash event.

Computational Model for Electrochemical Gas Separation and Inerting System

In July 1996, TWA flight 800 crashed into the Atlantic Ocean only 12 minutes after takeoff killing all 230 people on board. After a 4-year investigation into this catastrophe, the National Transportation Safety Board concluded that the accident was probably caused by the explosion of flammable fuel vapor in the Boeing 747’s center fuel tank. Following this landmark incident new regulations for aircraft fuel tank inerting were developed to prevent such explosions. Fuel tank inerting is the process of reducing the flammability of the fuel vapor by restricting the oxygen concentration in the ullage (air volume above the fuel) to a safe value – 12% for commercial aircraft and 9% for military aircraft. Generally, inerting is carried out by driving oxygen out the ullage using an inert gas like nitrogen.Existing inerting technologies include systems like liquid nitrogen, explosion suppressant foam, halon extinguishment, and on-board inert gas generation systems (OBIGGS). Compared to other techniques, OBIGGS is seen as viable option since nitrogen enriched air (NEA) can be produced during flight by supplying pressurized air into separation modules that preferentially retain nitrogen while allowing oxygen to escape. However, such systems are expensive and consume substantial amounts of energy, while also undergoing premature failure. Additionally, the NEA generation rate is fixed in such systems, whereas the actual NEA requirement depends on the aircraft’s flight stage. Thus, incumbent technologies are designed based on the highest demand making them overweight and expensive.Here, we propose a novel on-board electrochemical gas separation and inerting system (EGSIS) to overcome such problems. EGSIS is an electrically powered system that can be used to produce and supply NEA to the fuel tank. It combines a polymer electrolyte membrane (PEM) electrolyzer anode wherein water is dissociated to generate oxygen, and a PEM fuel cell cathode where oxygen from the inlet air inlet is reduced to produce humidified NEA as the output gas. After proper dehumidification, the NEA can be supplied directly to the ullage to reduce its oxygen concentration. Unlike current technologies, the NEA production rate in EGSIS can be easily varied with demand just by controlling the voltage applied to the system. Experimental investigations of EGSIS have been previously conducted by our group. This paper represents the first attempt to model and simulate EGSIS.We present a two-dimensional mathematical model of a single cell EGSIS that provides a foundation for the simulation and analysis of a full-scale EGSIS module. A single phase, two-dimensional, steady state, isothermal model is implemented in an EGSIS cell using COMSOL. Various EGSIS performance parameters such as current densities, reactant concentration distributions, and polarization curves are investigated as a function of operating voltage and temperature. The model involves the material properties of the various components including the polymer electrolyte membrane, the catalyst later and gas diffusion media; the transport of water vapor and air in the anode and cathode flow field channels, respectively; the transport of protons and water in the catalyst layer and the membrane; and the transport of electrical charge in the solid phase. The governing equations include continuity and steady-state incompressible Navier-Stokes equations. Additionally, species transport is modeled using the generalized Stefan-Maxwell equations whereas the Butler-Volmer equation is employed for charge transport. All of these coupled model equations are solved by the finite element method using the COMSOL Multi physics software package. The results from the computational model are then compared and validated with our experimental results for various operating conditions. Different operating strategies are explored with the goal of improving system performance. The simulated results reveal the influence of temperature, reaction flowrate, and optimized material properties on EGSIS performance. This model also provides a base for future research into the effect of alternate catalysts and gas diffusion media. It also serves as a foundation for the analysis of a practical EGSIS stack.

Demonstrating buoyancy in waterlogged ground

Archimedes’ principle is one of the foundation subjects in physics. Normally the principle is exemplified by reference to floating boats. However, Archimedes’ principle also applies to objects embedded in waterlogged ground, which can lead to the surprising result of an object weighing several tons being lifted. A practical example is presented of a 22 ton concrete water tank being lifted out of waterlogged ground. Fuel tanks embedded in the ground can be crushed by groundwater. Ground water buoyancy can be a serious problem when a large excavation for the foundation of a high-rise building is left empty before building commences. A qualitative classroom demonstration of groundwater buoyancy is described that involves immersing plastic cups in sand and adding water to observe the cups rising out of the sand. Additionally, a quantitative demonstration is described in which an empty beaker is floated on a water-filled container placed on an electronic balance placed on a scissor table. A plank of wood placed across the top of the beaker holds it in place while the scissor table is used to raise the water level around the beaker simulating rising groundwater. In view of the challenges of climate change and increasing frequency and severity of flooding, knowledge of groundwater buoyancy is useful for students.

Deep (Meta)genomics and (Meta)transcriptome Analyses of Fungal and Bacteria Consortia From Aircraft Tanks and Kerosene Identify Key Genes in Fuel and Tank Corrosion.

Microbial contamination of fuels, associated with a wide variety of bacteria and fungi, leads to decreased product quality and can compromise equipment performance by biofouling or microbiologically influenced corrosion. Detection and quantification of microorganisms are critical in monitoring fuel systems for an early detection of microbial contaminations. To address these challenges, we have analyzed six metagenomes, one transcriptome, and more than 1,200 fluid and swab samples taken from fuel tanks or kerosene. Our deep metagenome sequencing and binning approaches in combination with RNA-seq data and qPCR methods implied a metabolic symbiosis between fungi and bacteria. The most abundant bacteria were affiliated with α-, β-, and γ-Proteobacteria and the filamentous fungi Amorphotheca. We identified a high number of genes, which are related to kerosene degradation and biofilm formation. Surprisingly, a large number of genes coded enzymes involved in polymer degradation and potential bio-corrosion processes. Thereby, the transcriptionally most active microorganisms were affiliated with the genera Methylobacteria, Pseudomonas, Kocuria, Amorpotheka, Aspergillus, Fusarium, and Penicillium. Many not yet cultured bacteria and fungi appeared to contribute to the biofilm transcriptional activities. The largest numbers of transcripts were observed for dehydrogenase, oxygenase, and exopolysaccharide production, attachment and pili/flagella-associated proteins, efflux pumps, and secretion systems as well as lipase and esterase activity.

Experimental and numerical simulation study on polyurea-coated fuel tank subjected to combined action of blast shock waves and fragments

Fuel tanks, as core fuel components of many types of mechanical equipment, are highly vulnerable to strong dynamic loads, such as those from explosions and fragments. In this paper, two types of polyurea materials (AMMT-53 and AMMT-55) were designed to enhance the damage resistance of fuel tanks. The mechanical parameters and performance differences of the two polyurea materials were first obtained. On this basis, a series of experiments study on fuel tanks coated with different thicknesses polyurea subjected to a combination of blast waves and fragments were performed. The results showed that these two types of polyurea materials had different protective abilities. The AMMT-53 polyurea could effectively reduce the perforation rate but could not prevent the liquid leakage, while the AMMT-55 polyurea could not significantly reduce the perforation rate, but the self-healing property could effectively prevent the leakage of liquid. The whole process of the shock wave and the fragments acting on the fuel tank was revealed by numerical simulations. From the change of the fragment velocity, the strength of the shock wave in the liquid, and the energy change of the polyurea layer, it was proven that the coated polyurea layers had good protective effects on the fuel tank.

Analytical Algorithm for Oxygen Concentration of Aircraft Fuel Tank in Various Inerting Stages

Ullage washing is an efficient inerting method to keep the ullage oxygen concentration under the safe value, thus reducing the hazard and loss of fire and explosion of aircraft fuel tanks. In the conventional model of ullage washing, the initial derivatives of oxygen concentration that are used to solve the differential equations are selected subjectively by researchers and the empirical select influences the accuracy of the result. Therefore, this paper proposes an analytical algorithm that can calculate the ullage oxygen concentration without selecting any initial derivative value. The algorithm is based on a fuel tank ullage washing model regarding various inerting stages. It has been experimentally validated with an average relative error of 5.781%. Moreover, sensitive analyses carried out on the proposed model show that ground-based inerting can effectively reduce the ullage oxygen, concentration in the climb phase. Increasing 5 min of pre-takeoff inerting duration can shorten the time of decreasing the ullage oxygen concentration to 9% after takeoff by 2.1 min.

Experimental analysis of evaporative emissions of ethanol-blended gasoline in automotive tanks at different temperature conditions

Automobiles are major sources of Volatile Organic Compounds (VOCs) and Very Volatile Organic Compounds (VVOCs), which are emitted not only from their tailpipes while running but also as evaporative emissions from gasoline fueled vehicle tanks and supply systems; these emissions are the main source of pollution for both standard and hybrid vehicles. VOCs and VVOCs can have significant effects on human health and environment, so emissions are subject to many regulations, both European and international, that are becoming increasingly stringent every year. In this paper, an experimental activity has been carried out to evaluate the fuel vapor generation from gasoline-filled fuel tanks. These experimental tests have been conducted by means of a Variable Temperature mini-SHED in Stellantis N.V. laboratories, at the Pomigliano Technical Center, in Italy. Different conditions of temperature and filling levels have been analyzed by monitoring the fuel vapors coming from the tank to the carbon canister. Tests have been divided in two groups with both constant and variable temperatures, by following standard temperature cycles, defined by regulations. Results are presented in terms of vapor temperature profiles and canister mass variation; they demonstrate the high influence of the environment temperature and of the filling levels on the emission.

Requirements for Designing A Robotic System for Aircraft Wing Fuel Tank Inspection

An aircraft wing is built up of complex subassemblies including rib and spar structures, fuel transfer holes, piping and electronical wiring bundles. The wing structure is also used as storage space for the jet fuel in the ‘wet wing’ configuration. Vigorous inspection procedures are in place to detect defects such as fuel leaks, microbiological initiated corrosion and impact damages. Inspection inside the wing is significantly challenging due to the physical complexity, restricted accessibility and presence of fuel vapour. Current literature has highlighted opportunities for a novel aircraft fuel tank inspection robotic system. This paper starts with an overview of existing maintenance practices with the use of Remote Visual Inspection (RVI) equipment for fuel tank inspection, highlighting the implications and challenges of these methods.
 Their limitations inspire the development of novel robotics to achieve detailed internal inspection of an aircraft wing fuel tank. This research investigates the challenging case of fighter aircraft wing tank inspection. The wing shape geometry is highly irregular with very few fixed cartesian reference points. The internal structure is congested with many systems and difficult to manoeuvre within. This paper summarises the key requirements for inspection robotics for this particular case study.
 The requirements are presented in three categories; Robotic locomotion and navigation imposed by the complex and confined space inside the wing structure, secondly the materials, mechanisms and power sources imposed by the hazardous and potentially explosive environment inside the wing tank and lastly, the inspection sensors and assessment algorithms imposed by fuel tank defect and degradation features. The authors focus on the robotic system flexibility and mobility challenges to overcome the numerous obstacles within the confined space whilst effectively integrating a visual inspection technique to capture defined defects. This paper builds on the limitations of current inspection methods to elaborate the requirements for a robotic system to carry out inspection of fighter aircraft wing fuel tank, typical of challenging harsh environment.

Travelling Waves Approach in a Parabolic Coupled System for Modelling the Behaviour of Substances in a Fuel Tank

The aim of this work was to provide a formulation of a non-linear diffusion model with forced convection in the form of a reaction–absorption system. The model was studied with analytical and numerical approaches in the frame of the parabolic operators theory. In addition, the solutions are applied to a gas interaction phenomenon with the intention of producing an inerted ullage in an Airbus A320 aircraft centre fuel tank. We made use of the travelling wave (TW) solutions approach to study the existence of solutions, stability and the precise evolution of profiles. The application exercise sought to answer a key question for aerospace sciences which can be formulated as the time required to ensure an aircraft fuel tank is safe (inerted) to prevent explosion due to the presence of oxygen in the tank ullage.

Environmental Risk Assessment of a Diesel Fuel Tank: A Case Study

The article deals with the application of the environmental damage assessment procedure and H&V index II method to the diesel fuel tank storage facility in a sand mining company using a case study. The procedures enabled the researchers to semi-quantitatively assess the operated diesel fuel tank’s impact on the selected environmental components and the possible damage risk by the leakage of stored fuel. It was discovered, by assessing the operating conditions, the state of the environment at the mining facility, and the risk of a diesel fuel leakage accident, that it is not necessary for the company to implement further steps in the field of environmental damage minimization. The H&V index II method examined both the impacts of diesel fuel leakage on soil, biotic component, groundwater, surface water, and the impact of flammable substances on the biotic environmental component in six steps. Slight or significant impacts were identified depending on the environmental component during the determination of the accident severity. The accident severity, together with the estimated probability, was plotted in the risk matrix which resulted in acceptable risks for all affected environmental components. The results of both approaches showed that the diesel fuel leakage in the mining company represents an acceptable environmental risk in relation to the countermeasures implemented so far.

Intelligent System for Measuring the Level and Mass of Liquid in Fuel Reservoirs and Tanks During Pitching and Tilting

Intelligent System for Measuring the Level and Mass of Liquid in Fuel Reservoirs and Tanks During Pitching and Tilting

LNG Bunkering Technologies in Ports: An Empirical Application of the SWOT Analysis

Liquefied Natural Gas (LNG) as a marine fuel constitutes a valuable technological solution for making the maritime and port industry more sustainable. However, the progressive diffusion of LNG requires huge investments for bunkering and storage facilities in the port domain to develop an LNG supply chain capable to satisfy the demand of LNG-propelled ships. Although this topic is attracting increasing attention from both academics and practitioners, no prior scientific contributions have provided a holistic and structured conceptual framework to disentangle the main pros and cons related to the diverse LNG bunkering and storage solutions. This study investigates the four most promising LNG bunkering technologies (i.e., Truck-to-Ship, Ship-to-Ship, Port-to-Ship and Terminal-to-Ship, and Mobile Fuel Tanks) by applying the SWOT analysis methodology to the Mediterranean port context. The analysis focuses on relevant technical and managerial, including storage capacity, bunkering efficiency, plant scalability, operational flexibility, economic and financial performances, social and environmental impacts. The outcomes unveil the managerial strengths, weaknesses, opportunities, and threats of each technological solution, feeding the academic debate on this topic. Moreover, the paper provides empirical implications for public authorities and port managers improving the knowledge concerning LNG bunkering and storage solutions available in the maritime and port domain.

Electrochemical gas separation and inerting system

Following the TWA 800 flight disaster in 1996 which was attributed to an explosion in the fuel tank, inerting of the ullage (air volume above the fuel in the tank) has gained prominence. Fuel tank inerting is the process of reducing the flammability of the ullage by supplying it with an inert gas like nitrogen. Current inerting techniques are expensive, consume large amounts of energy, and fail prematurely. Here, we propose a novel in-flight electrochemical gas separation and inerting system (EGSIS) to produce and supply nitrogen-enriched air (NEA). EGSIS combines a polymer electrolyte membrane (PEM) fuel cell cathode with a PEM electrolyzer anode to generate humidified NEA as the cathode output which can be dehumidified and supplied directly to the fuel tank. The required rate of NEA varies during a typical flight and a major advantage of EGSIS is that the rate of NEA generation can be conveniently controlled by varying the voltage applied to the system. Here, we report on the performance of a single-cell EGSIS apparatus and evaluate its suitability for aircraft fuel tank inerting.