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The high injection pressure and small cylinder volume of direct injection spark ignition (DISI) engines can result in flat-wall wetness on the surface of the piston, increasing fuel consumption and pollutant emissions. The characteristics of microscopic fuel adhesion are observed using refractive index matching (RIM). Fuel adhesion characteristics after wall impingement are evaluated with various cross-flow velocities under triple stage injection conditions. The results indicate that cross-flow has a beneficial effect on the diffusion of fuel spray. Average fuel adhesion thickness decreases with an increase in cross-flow velocities. Furthermore, cross-flow promotes the evaporation of fuel adhesion, which leads to a reduction in the fuel adhesion mass/mass ratio. The improvement of injection strategy has guidance on low-carbon future.

Engine oil consumption must be reduced because it produces particulate matter in exhaust gases and poisons the catalyst in an aftertreatment system. Oil transport upward via piston ring gaps is one of the factors for oil consumption. It is known that piston rings rotate circumferentially during engine operation, and that oil consumption increases when the ring gaps of multiple piston rings are close to each other. Force acting on a piston ring in the circumferential direction was investigated in a past study [3], and a wave form of the force was measured against the crank angle. Furthermore, the forces were varied according to the measurement position in the circumferential direction. It means that the ring gap tends to stay where the force showed a small value. The force shows a periodic wave form against the crank angle for each cycle, and some parts of the waveform show a correlation with piston slap motion [3].

Future demands for modern emission free drivetrains using hydrogen or liquid e-fuels also necessitate a fundamental reduction in oil emissions. Entry of lubrication oil into the combustion chamber can lead to pre-combustion phenomena (LSPI) in downsizing or hydrogen engines and is a cause of particle emissions, which play a significant role especially if fuel related particle emissions are already low. A fundamental understanding of the oil film behavior on the piston assembly and cylinder liner surface are crucial to avoid oil ingress into the combustion chamber. The processes involved take place mainly around the piston group. In particular, the area of the piston rings with the prevailing pressure and temperature conditions as well as the component geometries has a high influence on the exchange of media between the crankcase and combustion chamber. The objective of this paper is to increase the understanding of the processes leading to oil ingress into the combustion chamber.

Photochromism is a reversible color change phenomenon based on chemical reactions caused by light illumination. In the present study, this technique is applied to visualize the lubricating oil and fuel around the piston rings in the gasoline engine. The oil film was colored with a UV laser and photographed by synchronizing the shutter of a high-speed camera with a flashlight. The color density was evaluated as a value of absorbance, calculated from images taken at two different wavelengths and two different times before and after the coloration. The authors performed photochromism visualization experiments in an engine under motored operation. However, using photochromic dyes that are robust to temperature changes makes it possible to visualize the engine under fired operation. The experiment was conducted mainly by switching to the motored operation for a fixed time between the fired operations.

The mechanism of lubricant dilution by post injection fuel in a diesel engine was investigated. The operating conditions of the engine were changed, and oil was sampled from each part of the piston and the crankcase, and the dilution ratio was analyzed. Also, photochromism was used to visualize the oil and fuel flow. Dilution ratios obtained from oil sampling and photochromism showed the same tendency.

The paper presents a preliminary study on a virtual 2-stroke 3-cylinder 0.9 L DI SI supercharged engine running on Hydrogen (H2), able to meet both high performance targets and ultra-low emissions limits (NOx<20 ppm). Combustion is similar to a conventional 4-stroke H2 DI engine, while the design of the cylinder and the actuation law of both intake and exhaust valves are specifically optimized for the 2-stroke cycle. In comparison to a more conventional 2-stroke loop scavenged engine, with piston-controlled ports, the use of poppet valves enables a more flexible control of the gas exchange process and to maintain the same design of a 4-stroke engine for pistons, cylinders block, crankcase and lubrication system. On the other hand, it is more difficult to avoid the short-circuit of the fresh charge, while permeability of the valves becomes quite critical at high engine speed.

During an exemplary engineering career Charles Matthews Manly (1876-1927), former president of the SAE and one of America's foremost aircraft engine pioneers, contributed greatly to the design and development of the radial piston engine, which came to dominate aircraft propulsion until the 1950s. He is best known for development and refinement of a world-class 52-hp, five-cylinder, water-cooled radial aircraft engine at the Smithsonian Institution. His early academic achievements led to his appointment as chief assistant to Professor S. P. Langley, secretary of the Smithsonian Institution, who was engaged in early aeronautic experiments and, in 1903, racing with the Wright brothers to demonstrate the first manned aeroplane. Easily the most advanced aeronautical engine in the world at the turn of the century, the so-called Manly-Balzer radial powerplant used in Langley's Aerodrome was almost 20 years ahead of its time in terms of specific-weight excellence.

This study explores the feasibility of using a sustainable lignin-based fuel, consisting of 44 % lignin, 50 % ethanol, and 6 % water, in conventional compression ignition (CI) marine engines. Through experimental evaluations on a modified small-bore CI engine, we identified the primary challenges associated with lignin-based fuel, including engine startup and shutdown issues due to solvent evaporation and lignin solidification inside the fuel system, and deposit formation on cylinder walls leading to piston ring seizure. To address these issues, we developed a fuel switching system transitioning from lignin-based fuel to cleaning fuel with 85 vol% of acetone, 10 vol% of water and 5 vol% of ignition improving additive, effectively preventing system clogs.

Combustion characteristics of a hydrogen (H2) direct-injected (DI) pre-chamber (PC)-assisted opposed piston two-stroke (OP2S) engine are investigated by 3D computational fluid dynamics (CFD) simulations. The architecture of the OP2S engine has potential features for reducing wall heat losses, as the DI H2 jets are not directed towards the piston face. To overcome the high resistance to autoignition of H2, a PC technology was implemented in order to enhance the ignition of the mixture by the multiple hot reactive jets. To further investigate the interaction between the H2 plume and the chamber walls, three different piston bowl designs were evaluated and ranked based on a merit function. For the cases under study, the flat piston design was found to be most favorable (compared to the narrow and wide pistons) due to its reduced surface area for lower wall heat losses.

Gasoline engines achieve maximum efficiency when operated at the knock limit. Knock control ignition systems enable an engine to operate in either continuous or intermittent light knock. Laboratory research has indicated it is harmless to run an engine within this range. Experience with knock control engines in passenger cars has shown erosion damage on pistons. Typical examples of knock erosion damage and ways of influencing severity of damage are discussed. Nickel coating has been developed as an effective and reliable technique to protect pistons from combustion knock erosion. Additional benefits of nickel coated pistons include: Reduced piston deposits Increased wear resistance in the top ring groove. Reduced cylinder head temperatures Engine text results and an analysis of engine efficiency increase due to nickel piston coatings is also presented.

Recent literature published by Toyota Motor Company[1] and Musashi Institute of Technology[2] have found that an offset crankshaft design has the potential for reducing friction and possibly increasing thermodynamic efficiency. In an effort to further evaluate this potential, a single-cylinder variant of a production GM 4.2L I6 engine was designed and tested. Cylinder pressure acquisition equipment and dynamometer torque measurements were used to quantify differences in combustion performance and firing friction between an offset crankshaft design and a standard baseline configuration. Extensive testing on the single-cylinder engine in both configurations found no significant frictional or thermodynamic differences to exist. Multiple tests of both design configurations were run in an effort to increase statistical confidence and test data showed good repeatability and precision.

Reactivity Controlled Compression Ignition (RCCI) is an engine combustion strategy that produces low NO and PM emissions with high thermal efficiency. Previous RCCI research has been investigated in single-cylinder heavy-duty engines. The current study investigates RCCI operation in a light-duty multi-cylinder engine at 3 operating points. These operating points were chosen to cover a range of conditions seen in the US EPA light-duty FTP test. The operating points were chosen by the Ad Hoc working group to simulate operation in the FTP test. The fueling strategy for the engine experiments consisted of in-cylinder fuel blending using port fuel-injection (PFI) of gasoline and early-cycle, direct-injection (DI) of diesel fuel. At these 3 points, the stock engine configuration is compared to operation with both the original equipment manufacturer (OEM) and custom-machined pistons designed for RCCI operation.

Brake caliper commonly utilizes rubber or spring components to maintain specific clearance range for sliding characteristics, rendering them susceptible to rattle noise. The Electro-Mechanical Brake (EMB) caliper has attracted attention for its advantageous features such as reduced brake drag, optimized vehicle layout, and precise brake control. However, the inclusion of additional components related to the dry-type pressurizing system results in increased caliper weight and susceptibility to rattle noise. This study thoroughly examines rattle noise characteristics in our prototype EMB caliper, identifying primary noise sources on the piston and guide-pin sides. Implementing piston seals and guide-pin boots tightening force proves the effectiveness in improving rattle noise characteristics. Collisions between the piston and ball-screw head can be mitigated by piston inner seal, significantly reducing rattle noise.

A unique single cylinder engine was used to assess engine performance and combustion characteristics at three different strokes, with all other variables held constant. The engine utilized a production four-valve, pentroof cylinder head with an 86mm bore. The stock piston was used, and a variable deck height design allowed three crankshafts with strokes of 86, 98, and 115mm to be tested. The compression ratio was also held constant. The engine was run with a controlled boost-to-backpressure ratio to simulate turbocharged operation, and the valve events were optimized for each operating condition using intake and exhaust cam phasers. EGR rates were swept from zero to twenty percent under low and high speed conditions, at MBT and maximum retard ignition timings. The increased stroke engines demonstrated efficiency gains under all operating conditions, as well as measurably reduced 10-to-90 percent burn durations.

The friction reducing capability of engine oils in the piston ring/cylinder bore contact was investigated under fully-flooded and starved lubrication conditions at 100° C using a laboratory piston ring/cylinder bore friction rig. The rig is designed to acquire instantaneous transient measurements of applied loads and friction forces at the ring/bore interface in reciprocating motion over a 50.8 mm stroke. The effects of increasing load and speed on the friction coefficient have been compared with new and used engine oils of different viscosity that were formulated with and without friction modifying additives. Test results with fully formulated engine oils containing molybdenum dithiocarbamate (MoDTC) show that friction is always lower than that obtained with non-friction modified oils but in regions of persistent starvation the coefficient of friction can increase significantly, approaching levels equivalent to fully-flooded non-friction modified formulations.

This paper presents a numerical study of the combustion chamber design influence on the performance of racing engines. The analysis has been applied to the Ferrari 10 cylinder 3.0 liter S.I. engine adopted in Formula One racing. The numerical investigation aimed to asses the influence of stroke-to-bore ratio changes on engine performance within real life design constraints. The effects of the stroke-to-bore ratio on both the volumetric efficiency and the thermal conversion efficiency have been investigated. Flame front area maps, wall areas wetted by burned gases, mean flow field patterns and main turbulent parameters have been compared for two different S/B ratios. Since higher intake and exhaust valve areas per unit displaced volume result in a higher volume of piston bowls, a lower S/B ratio leads to a lower compression ratio, which strongly limits the indicated mean effective pressure.

This paper describes a new 4.5-liter V8 engine, VH45DE, which was developed for use in the INFINITI Q45 sporty luxury sedan that was released in the U.S. and Japanese markets in November 1989. The many V8 engines in use around the world can be broadly devided into two categories. One category is characterized by ample torque at low engine speed and relatively large engine displacement. The other category is characterized by enhanced performance at relatively high engine speeds. The VH45DE engine is a new-generation V8 powerplant that delivers smooth power output at top-end speed and also generates ample torque at low engine speed to maintain good idle stability, and accomplishes it all with the smallest possible displacement. Development efforts were focused on two main goals. The first was to achieve efficient intake air charging. This has been accomplished the intake air resonant point at a relatively high engine speed through appropriate intake branch and collector tuning.

A computer model was used to study the impingement of sprays on walls. The spray model accounts for the effects of drop breakup, drop collision and coalescence, and the effect of drops on the gas turbulence. These effects have been shown to be important in high-pressure sprays where breakup of the liquid yields a core region near the nozzle containing large drops. A new submodel was developed to describe the spray/wall interaction process. The model uses an analogy with the oblique impact on a wall of liquid jets. Following impact, the trajectory of a drop is specified to be tangent to the wall surface. The computations were compared with recent endoscope pictures of engine sprays impinging on a piston bowl and also with constant-volume-bomb measurements of spray shape and penetration. Predictions of the effect of engine swirl, ambient gas pressure (density), wall inclination angle and the distance from the nozzle to the wall, were in good qualitative agreement with the experiments.

Hydraulic piston pump failures may be related to either hardware or fluid problems. In some cases, apparent hardware failures have been traced to various fluid problems. In this paper, selected examples of pump failures will be provided to illustrate some common modes of axial piston pump failures. In most cases, these will represent actual failures including: misalignment, insufficient fluid lubrication, particle contamination, brinelling, corrosion, and cavitation. Various examples of these and other pump failure modes are provided.

In the context of energy conservation and emission reduction, high power density(HPD) and low fuel consumption are the consistent pursuit of diesel engine development. Among the small-bore diesel, the limited space in the cylinder poses higher challenges and requirements for the arrangement of sprays.The high injection pressure results in a greater impulse when the spray impinges chamber, which allows the combustibles to develop along the chamber wall. Based on these characteristics of small-bore HPD diesel, a reasonable injection scheme is proposed to help flame diffusion surface increasing and thermal efficiency enhancing. This work proposes an optimization path to increase the flame diffusion surface, then improve thermal efficiency. It can be achieved with matching between the injector extension length and the spray spray angle.