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Internal combustion (IC) engines still power most of the vehicles on road and will likely to remain so in the near future, especially for heavy duty applications in which electrification is typically more challenging. Therefore, continued improvements on IC engines in terms of efficiency and longevity are necessary for a more sustainable transportation sector. Two important design objectives for heavy duty engines with wet liners are to reduce friction loss and to lower the risks of cavitation damages, both of which can be greatly influenced by the piston-liner clearance and the design of the piston skirt. However, engine design optimization is difficult due to the nonlinear interactions between the key design variables and the design objectives, as well as the multi-physics and multi-scale nature of the mechanisms that are relevant to the design objectives.

Design, testing, and implementation of new aftertreatment devices under various engine operating conditions is necessary to meet increasingly stringent regulatory mandates. One common aftertreatment device, the catalytic converter, is typically developed at a reduced scale and tested using predefined fluid compositions sourced from bottle gases and can undergo both species and temperature cycling in addition to steady-state testing. However, these bench-top conditions may differ from real-world operation in terms of flow-rates, species composition, and temperatures experienced. Transitioning from small-scale bench-top testing to full-scale engine applications requires larger monoliths that therefore have a significant amount of catalyst slurry to be washcoated, which increases cost and fabrication time.

With reference to present literature, most OEMs are working on reducing product development time by around ~20%, through seamless integration of digital ecosystem and focusing on dynamic customer needs. The Systems Engineering approach focuses on functions & systems rather than components. In this approach, designers (Computer Aided Design) / analysts (Computer Aided Engineering) need to understand program requirements early to enable seamless integration. This approach also reduces the number of iterative loops between cross functions thereby reducing the development cycle time. In this paper, we have attempted to tackle a common challenge faced by Closures (Liftgate) engineering: meeting slam durability fatigue life while replicating customer normal and abusive closing behavior.

Lubricating oil consumption (LOC) is a direct source of hydrocarbon and particulate emissions from internal combustion engines. LOC also inhibits the lifetime of exhaust aftertreatment system components, preventing their ability to effectively filter out other harmful emissions. Due to its influence on piston ring- bore conformability, bore distortion is arguably the most critical parameter for engine designers to consider in prevention of LOC. Bore distortion also has a significant influence on the contact forces between the piston ring and cylinder wall, which determine the wear rate of the ring and cylinder wall and can cause durability issues. Two drivers of bore distortion: thermal expansion and head bolt stresses, are routinely considered in conformability and contact analyses. Separately, bore distortion/vibration due to piston impact and combustion/cylinder pressures has been previously analyzed in wet liner engines for coolant cavitation and noise considerations.

In an engine system, the piston pin is subjected to high loading and severe lubrication conditions, and pin seizures still occur during new engine development. A better understanding of the lubricating oil behavior and the dynamics of the piston pin could lead to cost- effective solutions to mitigate these problems. However, research in this area is still limited due to the complexity of the lubrication and the pin dynamics. In this work, a numerical model that considers structure deformation and oil cavitation was developed to investigate the lubrication and dynamics of the piston pin. The model combines multi-body dynamics and elasto-hydrodynamic lubrication. A routine was established for generating and processing compliance matrices and further optimized to reduce computation time and improve the convergence of the equations. A simple built-in wear model was used to modify the pin bore and small end profiles based on the asperity contact pressures.

The increasing demand for environmentally friendly and fuel-efficient transportation and power generation requires further optimization and minimization of friction power losses. With up to 50% of the overall friction, the piston cylinder unit (PCU) shows most potential within the internal combustion engine (ICE) to increase mechanical efficiency. Calculating friction of internal combustion engines, especially the friction contribution from piston rings and skirt, requires detailed knowledge of the dynamics and lubrication regime of the components being in contact. Part I of this research presents a successful match of simulated and measured piston inter-ring pressures at numerous operation points [1] and constitutes the starting point for the comparison of simulated and measured piston group friction forces as presented in this research.

An analytical mechanics model was employed to predict the delamination of several thermal-barrier-coated pistons that had been previously tested in a high-output, single-cylinder diesel engine. Some of the coatings delaminated during engine operation. Results are presented for two thicknesses of the same coating material, and for two similar coatings with different levels of stiffness. All the coating thermomechanical properties such as thermal conductivity, density, volumetric heat capacity, thickness, elastic modulus, coefficient of thermal expansion, Poisson ratio and toughness, were measured prior to engine testing. Previous measurements of the piston transient heat flux, based on fast-response surface temperature data, in the same engine were used as an input to calculate the multilayer wall temperature distribution. A theoretical methodology was employed to evaluate and predict the coating durability.

A closed-cycle computational model of a non-Wankel rotary engine was thoroughly investigated to achieve optimal efficiencies, in a multitude of loading conditions relevant to automotive and aeronautical applications. Computational fluid dynamics (CFD) modeling was conducted in CONVERGE CFD, targeting the operation of a single pre-chamber and downstream main chamber engine system, roughly from 100 crank angle degrees (CAD) before top dead center (bTDC) to 100 CAD after top dead center (aTDC). In the developed framework, optimization studies involved main decision variables, including the engine’s compression ratio (CR), the injector’s position within the pre-chamber, the injector’s nozzle hole count and nozzle hole diameters. Traditional and split-injection strategies for the introduction of diesel fuel into the pre-chamber were evaluated by varying spray-related parameters including total injected mass, injection pressure, start of injection(s), and injection duration(s).

Knock in gasoline engines at higher loads is a significant constraint on torque and efficiency. The anti-knock property of a fuel is closely related to its research octane number (RON). Ethanol has superior RON compared to gasoline and thus has been commonly used to blend with gasoline in commercial gasolines. However, as the RON of a fuel is constant, it has not been used as needed in a vehicle. To wisely use the RON, an On-Board Separation (OBS) unit that separates commercial gasoline with ethanol content into high-octane fuel with high ethanol fraction and a lower octane remainder has been developed. Then an onboard Octane-on-demand (OOD) concept uses both fuels in varying proportion to provide to the engine a fuel blend with just enough RON to meet the ever changing octane requirement that depends on driving pattern.

Many efforts have been made in recent years to find renewable replacements for fossil fuels that can reduce the carbon footprint without compromising combustion performance. Bio-blendstock oil developed from woody biomass using a reliable thermochemical conversion method known as catalytic fast pyrolysis (CFP), along with hydrotreating upgrading has the potential to deliver on this renewable promise. To further our understanding of naphthenic-rich bio-blendstock oils, an improved formulation surrogate fuel (SF), SF1.01, featuring decalin and butylcyclohexane naphthenic content was devised and blended with research-grade No.2 diesel (DF2) at various volume percentages. The blends were experimentally evaluated in a single-cylinder Ricardo Hydra compression ignition engine to quantify engine and emissions performance of SF1.01/DF2 blends. Injection timing events were varied from knock limit to misfire limit at the same operating conditions for all blends.

Gear profile deviation is the difference in gear tooth profile from the ideal involute geometry. There are many causes that result in the deviation. Deflection under load, manufacturing, and thermal effects are some of the well-known causes that have been reported to cause deviation of the gear tooth profile. The profile deviation caused by gear tooth profile deformation due to interference-fit assembly has not been discussed previously. Engine timing gear trains, transmission gearboxes, and wind turbine gearboxes are known to use interference-fit to attach the gear to the rotating shaft. This paper discusses the interference-fit joint design and the mechanism of tooth profile deformation due to the interference-fit assembly in gear trains. A new analytical method to calculate the profile slope deviation change due to interference-assembly of parallel axis spur gears is presented.

As the piston pin works under significant mechanical load, it is susceptible to wear, seizure, and structural failure, especially in heavy duty internal combustion engines. It has been found that the friction loss associated with the pin is comparable to that of the piston, and can be reduced when the interface geometry is properly modified. However, the mechanism that leads to such friction reduction, as well as the approaches towards further improvement, remain unknown. This work develops a piston pin lubrication model capable of simulating the interaction between the pin, the piston, and the connecting rod. The model integrates dynamics, solid contact, oil transport, and lubrication theory, and applies an efficient numerical scheme with second order accuracy to solve the highly stiff equations. As a first approach, the current model assumes every component to be rigid.

Hybridizing Solid Oxide Fuel Cells (SOFCs) with internal combustion engines is an attractive solution for power generation at high electrical conversion efficiency while emitting significantly reduced emissions than conventional fossil fueled plants. The gas that exits the anode of an SOFC operating on natural gas is a mixture of H2, CO, CO2, and H2O vapor, which are the products of the fuel reforming and the electrochemical process in the stack. In this study, experiments were conducted on a single-cylinder, spark-ignited Cooperative Fuel Research Engine using the anode off-gas as the fuel, at compression ratio of 11:1 and 13:1, engine speed of 1200 rev/min and intake pressure of 75 kPa, to investigate the combustion characteristics and emissions formation. A comparison was drawn with combustion with Compressed Natural Gas (CNG) at the same engine operating conditions.

An experimental study was conducted on a Ricardo Hydra single-cylinder light-duty diesel research engine. Start of Injection (SOI) timing sweeps from -350 deg aTDC to -210 deg aTDC were performed on a total number of five pistons including two baseline metal pistons and three coated pistons to investigate the effects of thick thermal barrier coatings (TBCs) on the efficiency and emissions of low-temperature combustion (LTC). A fuel with a high latent heat of vaporization, wet ethanol, was chosen to eliminate the undesired effects of thick TBCs on volumetric efficiency. Additionally, the higher surface temperatures of the TBCs can be used to help vaporize the high heat of vaporization fuel and avoid excessive wall wetting. A specialized injector with a 60° included angle was used to target the fuel spray at the surface of the coated piston.

In internal combustion engines, the majority of the friction loss associated with the piston takes place on the thrust side in early expansion stroke. Research has shown that the Friction Mean Effective Pressure (FMEP) of the engine can be reduced if proper modifications to the piston skirt, which is traditionally barrel-shaped, are made. In this research, an existing model was applied for the first time to study the effects of different oil supply strategies for the piston assembly. The model is capable of tracking lubricating oil with the consideration of oil film separation from full film to partial film. It is then used to analyze how the optimized piston skirt profile investigated in a previous study reduces friction.

Topology of liner finish is critical to the performance of internal combustion engines. Proper liner finish simulation processes lead to efficient engine design and research. Fourier methods have been well studied to numerically generate liner topology. However, three major issues wait to be addressed to make the generation processes feasible and reliable. First, in order to simulate real plateau honed liners, approaches should be developed to calculate accurate liner geometric parameters. These parameters are served as the input of the generation algorithm. Material ratio curve, the common geometry calculation method, should be modified so that accurate root mean square of plateau height distribution could be obtained. Second, the set of geometric parameters used in generating liner finish (ISO 13565-2) is different from the set of parameters used in manufacturing industry (ISO 13565-3). Quantitative relations between these two sets should be studied.

This paper describes a post-race analysis of team KOMMIT EVT’s electric motorcycle data collected during the 2016 Pikes Peak International Hill Climb (PPIHC). The motorcycle consumed approximately 4 kWh of battery energy with an average and maximum speed of 107 km/h and 149 km/h, respectively. It was the second fastest electric motorcycle with a finishing time of 11:10.480. Data was logged of the motorcycle’s speed, acceleration, motor speed, power, currents, voltages, temperatures, throttle position, GPS position, rider’s heart rate and the ambient environment (air temperature, pressure and humidity). The data was used to understand the following factors that may have prevented a faster time: physical fitness of the rider, thermal limits of the motor and controller, available battery energy and the sprocket ratio between the motor and rear wheel.

Homogeneous Charge Compression Ignition (HCCI) enables combustion with high efficiency and low emissions. Control over the combustion process and its narrow operating range are still the biggest challenges associated with HCCI. To expand the operable load ranges of HCCI, this paper explores the effects of single versus two-stage ignition fuels by studying the Primary Reference Fuels (PRF) in a variable compression ratio Cooperative Fuel Research (CFR) engine. The PRF fuels, iso-octane and n-heptane, are blended together at various concentrations to create fuel blends with different autoignition characteristics. Experiments were conducted using these PRF blends to explore the extent to which the load range can be extended with two-stage ignition fuels at various compression ratios and intake temperatures. The reactivity of the PRF blends increases with the fraction of n-heptane and so does the amount of low temperature heat release (LTHR).

Homogeneous Charge Compression Ignition (HCCI) is a combustion concept with the potential for future clean and efficient automotive powertrains. In HCCI, the thermal stratification has been proven to play an important role in dictating the combustion process, mainly caused by heat transfer to the wall during compression. In this study, a multi-zone, control-mass model with thermal stratification and chemical kinetics was developed to simulate HCCI combustion. In this kind of model, the initial conditions and the zonal heat transfer fraction distribution are critical for the modeling accuracy and usually require case-by-case tuning. Instead, in this study, the Thermal Stratification Analysis (TSA) methodology is used to generate the zonal heat transfer fraction distribution from experimental HCCI data collected on a fired, metal engine.

Thermally Stratified Compressions Ignition (TSCI) is a new advanced, low temperature combustion concept that aims to control the thermal stratification in the cylinder in order to control the heat release process in a lean, compression-ignition combustion mode. This work uses “wet ethanol”, a mixture of 80% ethanol and 20% water by mass, to increase thermal stratification beyond what naturally occurs, via evaporative cooling of a split direct injection. TSCI with wet ethanol has previously shown the potential to increase the high-load limit when compared to HCCI. The experiments conducted in this paper aim to fundamentally understand the effect that injection strategy has on the heat release process in TSCI. TSCI employs a split-injection strategy in which an injection during the intake stroke allows the majority of the fuel to premix with the air and an injection during the compression stroke introduces the desired level of thermal stratification to control the heat release rate.