Effect of Nozzle Inclination Angle on Fuel-Air Mixing and Combustion in a Heavy Fuel Engine

Heavy-fuel engines are widely used in UAVs(Unmanned Autonomous Vehicles)because of their reliability and high-power density.In this study,a combustion model for an in-cylinder direct injection engine has been imple-mented using the AVL FIRE software.The effects of the angle of nozzle inclination on fuel evaporation,mixture distribution,and combustion in the engine cylinder have been systematically studied at 5500 r/min and consider-ing full load cruise conditions.According to the results,as the angle of nozzle inclination increases,the maximum combustion explosion pressure in the cylinderfirst increases and then it decreases.When the angle of nozzle incli-nation is less than 45°,the quality of the mixture in the cylinder and the combustion performance can be improved by increasing the angle.When the angle of nozzle inclination is greater than 45°,however,the mixture unevenness increases slightly with the angle,leading to a deterioration of the combustion performances.When the angle of nozzle inclination is between 35°and 55°,the overall combustion performance of the engine is rela-tively good.When the angle of nozzle inclination is 45°,the combustion chamber’s geometry and the cylinder’s airflow are well matched with the fuel spray,and the mixture quality is the best.Compared with 25°,the peak heat release rate increases by 20%,and the maximum combustion burst pressure increases by 5.5%.

Thermomechanical and Hydrous Effect of Heavy Fuel Oil in a Building Material Based on Silty Clayey Soil

This study focuses on the use of heavy fuel oil in construction in Burkina Faso.Mixed with silty and/or clay soil,it is used as a coating to reinforce the walls of raw soil constructions which are very sensitive to water.The interest of this paper is to shed light on the thermomechanical and above all water effects of heavy fuel oil on a sample of silty clayey soil.To achieve this,we used heavy fuel oil added in different proportions to silty clayey soil,to make sample of bricks on which tests were carried out.At the end of the experimental tests carried out on materials made(bricks)with our soil sample,it appears that heavy fuel oil moderately reduces the mechanical resistance of bricks and slightly increases thermal diffusion through them.On the contrary,we note a very good water resistance of the bricks thanks to the heavy fuel oil,in particular their water absorption by capillarity.This confirms that the mixture of heavy fuel oil and a silty-clayey soil used as a coating makes it possible to prevent the infiltration of water into the walls of raw soil constructions.However,its use as a construction material does not guarantee very good mechanical resistance,and slightly increases thermal diffusion.

Numerical simulation of heavy fuel oil atomization using a pulsed pressure-swirl injector

It is known that increasing the injection pressure reduces the breakup length and the droplet size.Adding pulses,on the other hand,helps to atomize the liquid into finer droplets,similar to airassisted injectors but without altering the airtofuel concentration.To further reduce the droplet size and breakup length,a novel injector type,called''Pulsed PressureSwirl"(PPS),is introduced in this work,which is a combination of pressureswirl and ultrasonic pulsed injectors.A pressureswirl atomizer was designed and fabricated specifically for Mazut HFO(Heavy Fuel Oil).The droplet formation process and droplet size distribution have been studied experimentally(by shadowgraphy high speed imaging)and numerically(with the opensource VolumeofFluid code Gerris).Changing liquid injection pressure effect on the spray angle and film thickness has been quantified.These simulations have been used to study the primary breakup process and quantify the droplet size distributions,using different injection pulse frequencies and pressures.The numerical results have revealed that the new injector concept successfully produces finer droplets and results in a decrease in the breakup length,especially when applying high pulse frequencies,with no significant changes in the spray angle.

Recent Progress in Heavy Fuel Aviation Piston Engine

Heavy fuel aviation piston engines(HF-APEs)refer to the engine using fuels with high flash point,such as kerosene or light diesel.Here technique specifications of some classical foreign HF-APEs(Hirth3503,Zanzottera 498)are introduced.Recent progress and trend of fuel injection,fuel ignition,working cycle,intake charging,thermal management and electronic control of HF-APE are compared and summarized.Emphases are put on the technological difficulties,solutions and development tendency in the design,retrofitting and manufacturing of HF-APE aiming to provide references for the research of related area and the development of prototype HF-APE in China.

The Biomarker Changes of a Heavy Fuel Oil After Different Weathering Times

This paper presents the experimental results of composition changes of heavy fuel oil by stmulating weathering in static seawater under natural environmental conditions. The results indicate： n-C10 to n-C15 were lost gradually in 24 weeks and the relative abundance of alkanes with long chains （〉n-C19） increased markedly. The aromatic compounds with less than two tings （except C4N） were completely lost in 24 weeks and CnP and CnD became the main aromatics in the heavy fuel oil after 24 weeks. The ratios of n- C1/Pristane （Pr） and n-C18 Phytane （Ph） were suitable for identifying lightly weathered （3 weeks） heavy fuel oil. The ratios of n-ClT/n-C18 and Pr/Ph were suitable for identifying moderately weathered heavy fuel oil （12 weeks）; the ratios of C2D/C2P and C3D/C3P did not change significantly in 24 weeks and were more suitable for identifying moderately weathered heavy fuel oil （24 weeks）.

Characteristics of Particulate Matter Emissions for Low-Sulfur Heavy Oil Used in Low-Speed Two-Stroke Diesel Engines of Ocean-Going Ships

In this work,particulate matter(PM) emissions from a large two-stroke,low-speed marine diesel engine were investigated when the engine was operated with low-sulfur heavy fuel oil(HFO) at various loads.Particle samples were collected in situ from the engine exhaust to determine the detailed physical and chemical properties.The nanostructure and morphology of the nanoparticles were analyzed using transmission electron microscopy images(TEM).The results show that volatile organic carbon(OC) accounts for more than 80% in the HFO particles and leads to an increase in particle size.The thermodynamic conditions of a low-speed engine favor the behavior of capturing the soluble organic components.A large number of spherical char HFO particles with aerodynamic diameters of 0.2 μm-0.5 μm and a suspected inner metal core were detected.The two peak aerodynamic diameters of the HFO nanoparticles are 15 nm and 86 nm.The morphological differences among the HFO nanoparticles in varied engine conditions represent the formation process from primary nascent particles to mature graphitized particles caused by thermodynamics.The above study will be valuable for understanding the characteristics of PM emissions from low-sulfur HFO to achieve the ship PM emissions reduction target.

Gas exchange optimization in aircraft engines using sustainable aviation fuel:A design of experiment and genetic algorithm approach

The poppet valves two-stroke(PV2S)aircraft engine fueled with sustainable aviation fuel is a promising option for general aviation and unmanned aerial vehicle propulsion due to its high power-to-weight ratio,uniform torque output,and flexible valve timings.However,its high-altitude gas exchange performance remains unexplored,presenting new opportunities for optimization through artificial intelligence(AI)technology.This study uses validated 1D+3D models to evaluate the high-altitude gas exchange performance of PV2S aircraft engines.The valve timings of the PV2S engine exhibit considerable flexibility,thus the Latin hypercube design of experiments(DoE)methodology is employed to fit a response surface model.A genetic algorithm(GA)is applied to iteratively optimize valve timings for varying altitudes.The optimization process reveals that increasing the intake duration while decreasing the exhaust duration and valve overlap angles can significantly enhance high-altitude gas exchange performance.The optimal valve overlap angle emerged as 93°CA at sea level and 82°CA at 4000 m altitude.The effects of operating parameters,including engine speed,load,and exhaust back pressure,on the gas exchange process at varying altitudes are further investigated.The higher engine speed increases trapping efficiency but decreases the delivery ratio and charging efficiency at various altitudes.This effect is especially pronounced at elevated altitudes.The increase in exhaust back pressure will significantly reduce the delivery ratio and increase the trapping efficiency.This study demonstrates that integrating DoE with AI algorithms can enhance the high-altitude performance of aircraft engines,serving as a valuable reference for further optimization efforts.

Research on governance of HFO use and carriage on ships in accordance with the Polar Code

In this paper, we discuss the environmental damages caused by the use and carriage of Heavy Fuel Oil(HFO) by ships in Arctic waters. We also review efforts made by major international and regional organizations in governing the use and carriage of HFO by ships in Arctic waters after implementation of the Polar Code, and analyze the obstacles and difficulties that lie ahead. By illustrating the features of the Arctic Council and the International Maritime Organization(IMO), which govern Arctic waters, we examine measures taken by these two organizations in tackling HFO issues. These include: assessing indigenous and local community’s reliance on HFO transportation in the Arctic, developing risk prevention measures for ships operating in Arctic waters, seeking economic alternatives to HFO that contribute to a greener economy, developing a package of HFO governance measures, strengthening cooperation between relevant international and regional organizations that govern HFO to provide suggestions for follow-up discussions on HFOs, and optimize governance by relevant organizations and determine a better global solution to governing the use and carriage of HFO by ships. In addition, we discuss the feasibility of an IMO-imposed HFO ban from the perspective of the Arctic governance to clearly grasp the path of its future development.