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The welded pipeline structure of aircraft fuel is a complex and diverse entity, significantly influenced by fluid–solid coupling. The refined aviation fuel-welded pipeline model plays a pivotal role in the investigation of its fluid–solid coupling mechanical properties. However, the mechanical analyses of pipelines with welded structures frequently simplify or ignore the influence of the weld zone (WZ). Consequently, these analyses fail to reveal the complex interactions between different weld zones in detail. In this study, a comprehensive and precise fuel-welded pipeline refinement model is developed through the acquisition of microstructural dimensions and mechanical parameters of the weld zone via metallographic inspection and microtensile testing. Additionally, the influence of clamps and brackets under airborne conditions is fully considered. Furthermore, the numerical simulation results are compared and verified using modal and random vibration tests. This paper addresses the impact of diverse fluid characteristics on the velocity field, pressure field, and stress in disparate areas, and it also conducts an investigation into the random vibration characteristics of the pipeline. The results demonstrate that the fluid pressure and velocity exert a considerable influence on the fluid flow state and structural stress distribution within the pipeline. An increase in flow velocity and alteration to the pipeline geometry will result in a change to the local velocity distribution, which in turn affects the distribution of the fluid pressure field. The highest stresses are observed in the weld zone, particularly at the junction between the weld zone and the heat-affected zone (HAZ). In contrast, the stresses in the bend region exhibit a corrugated distribution in both the axial and circumferential directions. An increase in fluid pressure has a significant impact on the natural frequency of the pipeline. This study enhances our comprehension of the mechanical properties of aircraft fuel lines with fluid–solid coupling and provides a foundation and guidance for the optimal design of fuel-welded lines.

With the aviation industry facing increasing environmental and energy challenges, there has been a growing demand for sustainable aviation fuel (SAF). Previous studies have shown the role of ice accretion, release and blockage in aviation-related incidents and accidents with conventional jet fuel. However, there is no available data that establishes the magnitude of influence new fuel compositions will pose on ice formation and accretion in aircraft fuel systems. A recirculating fuel test rig capable of cooling fuel from ambient to −30°C within 4h was built by Airbus to simulate conditions in an aircraft wing tank and allow characterisation of ice accretion. The key characteristic was the pressure drop across an inline fuel strainer for the different SAF explored but visual analysis of ice accretion on the strainer mesh (filters used in protecting fuel feed pumps) was also performed for individual experimental runs for comparison. Measurements revealed that 100% conventional fuel exhibited a higher propensity to strainer blockage compared to the SAF tested. However, all SAF blends behaved differently as the blending ratio with Jet A-1 fuel had an impact on the pressure differential at different temperatures. Data from this work are essential to establish confidence in the safe operation of future aircraft fuel systems that will potentially be compatible with 100 % SAF.

In this paper, according to the terminal vibration test method in SAE-AS5692, a ground fault arc test platform was designed to simulate aircraft vibration-induced ground fault arcs in wiring harnesses and fuel lines, and tandem ground fault arc damage tests were carried out under different conditions and parameters, to study the effects of different power supply types and vibration frequencies on arc damage. The results show that: 1) compared with the arc generated by DC 28 V and AC 115 V, the arc generated by DC 28 V is more damaging to the fuel pipeline, and the pipeline vaporization is more serious; 2) as the vibration frequency is increased from 15 Hz to 60 Hz, the duration of the arc is prolonged, and the arc energy is increased, resulting in a positive correlation between the arc damage and the vibration frequency.

In order to overcome the limitation of fuel supply to the nozzle of an aero-engine, a nozzle with two main and secondary fuel paths and accompanied by air-assisted atomization can be used to solve this kind of problem. The two fuel paths make the fuel centrifugal and direct injection respectively, which can achieve the purpose of combining the advantages of centrifugal and direct injection nozzles, thus realizing a wide working range of fuel flow. The results show that when the fuel pressure reach a certain range, the main and secondary fuel lines start to work simultaneously, the atomization cone angle and fuel flow rate increase with the increase of pressure, and when the pressure reaches a certain value, continuing to increase the fuel pressure has little effect on the atomization angle. For the case of air supply and simultaneous operation of the main and secondary fuel lines, with the increase of fuel pressure, the atomization particle size changes gradually and evenly and has a tendency to increase, which is in line with the expected goal.

In order to reduce the wide body aircraft refueling process time-cost and improve the airport operation efficiency, pressure refueling system design strategy was innovated. The shutoff valves’ operation sequence in refueling process was optimized. The diameter of the orifices on the pressure refueling system fuel line was designed. Pressure refueling performance was simulated and analyzed at different scenarios. The results show that it can improve the pressure refueling system performance at different scenarios by optimizing the pressure refueling process strategy design including optimizing the fuel line orifice design and optimizing the wing tank inner side shut-off valve operation sequence.

In order to design the highly integrated fuel jettison system, the hydrodynamic performance design flow chart for the highly integrated fuel system has been proposed, and the 1-D fuel line network performance model has been developed. An innovative fuel jettison system for wide-body aircraft has been designed. The system performance has been simulated and analyzed. The results show that the proposed flow chart can be used for the highly integrated fuel system design, and the fuel jettison performance requirements can be met. The system parameters including the wing tank main pump characteristic, the flow area of the orifice set in the fuel line connecting the feeding line and the refueling line, and the flight height have significant effects on the fuel jettison performance. Besides, the aircraft total fuel jettison performance is also affected by the central tank override pump characteristic, the engine fuel consumption, and the flow resistance of fuel line network.

In the present study, a high-viscous biofuel, namely wheat germ oil (WGO), and a low-viscous biofuel, namely pine oil (PO), are used in a twin-cylinder diesel engine. The fuel ionization filter is fitted with a permanent magnet, an electromagnet, and the combination of permanent magnet and electromagnet, and their effect on the engine performance, emission, and combustion is studied. A fuel ionization filter placed in the fuel line, before the injection pump, ionizes the fuel molecules and increases the rate of disintegration of droplets due to a decrease in viscosity and surface tension. The tests are performed at a constant engine speed of 1500 rpm with loads varying from no load to full load at intervals of 25%. As compared to diesel, the engine operation with ionization filter increased brake thermal efficiency and reduced the fuel consumption for both PO and WGO. The increase in brake thermal efficiency is in the order: permanent magnet, electromagnet, and combination of electromagnet and permanent magnet. The magnetic field strength of electromagnet is higher than permanent magnet which tends to increase the ionization of the fuel. When both the magnets are combined, the magnetic field strength further increases resulting in more ionization of the fuel. It is also perceived that magnetic effect reduces the viscosity of the fuel. Regulated emissions, namely unburned hydrocarbons (HC), carbon monoxide (CO), and smoke emissions, reduced, whereas NOx emissions increased with WGO and ionization filter. With pine oil and ionization filter, all the regulated emissions decreased as compared to neat pine oil. The reduction in HC, CO, and smoke emissions was highest for combination of electromagnet and permanent magnet followed by electromagnet and permanent magnet. The study shows that combination of permanent magnet and electromagnet resulted in the best engine performance and emission characteristics.

Many countries are developing strategies to curb the consumption of fossil fuels, and to increase the share of alternative fuels such as alcohols, natural gas, fuel cell and electricity in the energy pool in order to improve energy security and reduce atmospheric pollution. Alcohol fuels are promising one and it has been widely used in many countries as blending component for gasoline. Ethanol has a high-octane number but it has a lower calorific value than gasoline. The performance of engine may be affected with higher percentage of ethanol in gasoline due to demand for larger quantity of fuel that could not be supplied by vehicles which are tuned to run on gasoline only. In this study, a second electronic control unit (ECU) was installed in series with the existing commercial or primary ECU and an ethanol sensor was installed in the fuel line. This secondary ECU modulates the fuel injection pulse width of the primary ECU depending on ethanol concentration in the fuel. The vehicle studies were carried out using Indian automotive gasoline meeting IS:2796 specification and 85% ethanol blended gasoline (E85) in a climatically controlled chassis dynamometer lab in which test cell temperature maintained at 25±1 °C throughout the test. Modified Indian Driving Cycle tests (MIDC) and constant speed tests were carried out using E85 and commercial gasoline to investigate the fuel economy, gaseous mass emissions, particulate emission in terms number and size characteristics. Gaseous emission was reduced up to 30% with the penalty of reduction in fuel economy by approximately 30% over the MIDC. The vehicle power was maintained while using both fuels at respective constant speeds during the road load simulation cycles however an increase in fuel consumption was observed with E85. The tailpipe exhaust particle emission measurement had shown up to 50% reduction in exhaust particulate emissions with E85. This study demonstrates the potential of using higher blends of ethanol up to E85 and meeting power or speed demand at constant speeds and driving cycle tests.

This study aims to obtain the spray and flame characteristics of biodiesel blend fuel used in the ignition system of a Circulating Fluidized Bed (CFB) coal-fired steam power plant. Characterization of the chemical composition, physics of fuel, handling of biodiesel in handling system to the burner, and the characterization of combustion in the burner simulator are studied. The primary data in this study is the data from the combustion trial results in the burner simulator, while the secondary data is in the form of operation data and power plant design data. Biodiesel has properties close to diesel oil and allows use in blending to a specific ratio. The result shows that the spraying angle of biodiesel and blends are narrower than the B0 condition, and the distance of flame become shorter along with the increase in biodiesel content. These phenomena can cause the burner difficult to ignite, which can be overcome by adjusting the igniter position into the fuel spray distribution zone. Because biodiesel is easily oxidized, it is necessary to maintain the fuel lines kept clean, primarily when the system is not operating for a long time. Biodiesel has a higher viscosity and density than petroleum diesel which can cause problems with the injection start-up burner. The use of biodiesel fuel requires more stringent handling, adding filters, isolating fuel oil tanks from rainwater and humid air, and replacing materials that are not compatible with biodiesel in pipe fittings and gasket.

Density wave oscillations (DWO) are one of the most common instability types in flow boiling systems. In liquid hydrogen (LH2) pipe flow with heat ingress, DWO can cause large fluctuations of temperature, pressure, void fraction, and flow rate in liquid hydrogen (LH2) pipe flow with heat ingress. Large fluctuations increase strain on systems and lead to unstable flow. Predicting the onset of these oscillations and their magnitudes is important for designing robust liquid hydrogen fuel lines. In this study, lumped-element modeling of density wave oscillations in two-phase hydrogen flow is undertaken to evaluate the instability threshold and limit-cycle oscillations in a single heated channel with different orientations. Nonlinear time-domain simulations are employed. The variable parameters include inlet liquid sub-cooling, flow rate, mean pressure, minor losses, and heat supplied to the channel wall. Non-dimensional stability plots using non-dimensional groups relating the variable parameters are presented to show examples of stable and unstable behavior. The results can assist designers and operators of liquid hydrogen transfer systems.