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Technical Paper

Combustion analysis of Hydrogen-DDF mode based on OH* chemiluminescence images

2024-04-09
2024-01-2367
Hydrogen-diesel dual-fuel combustion processes were studied in a rapid compression and expansion engine (RCEM). In the experiments, the combustion processes were visualized using an optically accessible RCEM that can simulate a single compression and expansion stroke of a diesel engine. A small amount of diesel was injected as a pilot ignition for the hydrogen, with injection pressures of 40, 80, and 120 MPa using a common rail injection system. The amount of diesel injected was varied as 3, 6, and 13 mm3. The hydrogen-air mixture was introduced into the combustion chamber through the intake valve. The amount of hydrogen was manipulated by varying the total excess air ratio(λtotal) at 3 and 4. The RCEM was operated at a constant speed of 900 rpm, and the in-cylinder pressure and temperature at TDC were set at 5 MPa and 700 K, respectively.
Technical Paper

Effect of in-cylinder flow motion on fuel-air mixture formation in a medium-duty DI-SI H2 engine: an experimentally supported CFD study

2024-04-09
2024-01-2117
The increased utilization of batteries and fuel-cells for powering electric applications, as well as bio- and e-fuels into internal combustion engines are seen as options to lower the carbon footprint of industry and transportation sectors. When high power outputs and fast refuelling are requisites, H2 ICEs may be a relevant choice. Applications include electricity conversion within a genset or mechanical energy in a vehicle. Within this framework, a John Deere 4045 Diesel engine converted to a H2 single-cylinder is studied at relevant operating conditions for the mentioned use cases, which pose high torque and power output requirements. The modified engine integrates a Phinia DI-CHG 10 outward-opening H2 injector instead of the Diesel unit, as well as a spark-plug rather than the standard glow-plug.
Technical Paper

Benchmarking of Neural Netowrk Methodologies for Piston Thermal Model Calibration

2024-04-09
2024-01-2598
During the design phase of engine components, it is important to have accurate model predictions of the temperature field in order to adequately capture temperature-dependent material behavior and thermal gradients that greatly influence the component fatigue life. In pistons, the heat transfer analysis depends on backside heat transfer boundary conditions (BCs), which are difficult to estimate. One method to circumvent this problem is to collect experimental temperature data and calibrate the backside heat transfer BCs in a computer model to this data. Previously, a traditional Bayesian calibration methodology has been successfully applied to calibrate these backside BCs in piston heat transfer models to experimental data. This method leverages the use of Gaussian process surrogate modeling of the computer model and then performing Bayesian inference on the unknown boundary conditions, which can be computationally expensive.
Technical Paper

Improving the Performance of Diesel Engines by Bore Profile Control under Operating Conditions

2024-04-09
2024-01-2832
A cylinder block involves bore deformation due to assembling stress of cylinder head and thermal stress. This distortion is found to be the cause of the exacerbation of piston skirt friction and piston slap. This article presents a numerical and experimental study of the effect of an optimized bore profile on engine performance. A friction analysis of 3-dimentional elastohydrodynamic was applied for an estimation of the piston skirt friction. A cylinder bore with barrel shape under the part load operation point was assumed as an optimal bore profile in terms of piston skirt friction without compromising piston slap. From the simulation study, it was found that the piston secondary motion just after firing top dead center can be mitigated by narrower piston – bore clearance at upper position of the cylinder.
Technical Paper

Conjugate Heat Transfer Analysis of an i-4 Engine including Pistons, Liners, Block, Heads, Water Cooling Jacket, and Oil Cooling Jets

2024-04-09
2024-01-2696
Internal combustion engine (IC engine) vehicles are commonly used for transportation due to their versatility. Due to this, efficiency in design process of IC engines is critical for the industry. To assess performance capabilities of an IC engine, thermal predictions are of utmost consequence. This study describes a computational method based on unsteady Reynolds-averaged Navier–Stokes equations that resolves the gas–liquid interface to examine the unsteady single phase/multiphase flow and heat transfer in a 4-cylinder Inline (i-4) engine. The study considers all important parts of the engine i.e., pistons, cylinder liners, head, block etc. The study highlights the ease of capturing complex and intricate flow paths with a robust mesh generation tool in combination with a robust high-fidelity interface capturing VOF scheme to resolve the gas-liquid interfaces.
Technical Paper

Engine Crank Stop Position Control to Reduce Starting Vibration of a Parallel Hybrid Vehicle

2024-04-09
2024-01-2784
Engine off control is conducted on parallel hybrid vehicles in order to reduce fuel consumption. It is efficient in terms of fuel economy, however, noise and vibration is generated on engine cranking and transferred through engine mount on every mode transition from EV to HEV. Engine crank position control has been studied in this paper in order to reduce vibration when next cranking starts. System modeling of an architecture composed of an engine, P1 and P2 motors has been conducted. According to the prior studies, there exists correlation between crank vibration level and the crank angle. Thus a method to put pistons on a specific crank angle which results in a local minimum of vibration magnitude could be considered. The P1 motor mounted on a crankshaft facilitates this crank position control when engine turns off, and its location allows the system model to obtain more precise crank position estimation and improved linearity in torque control as well.
Technical Paper

Combustion Chamber Development for Flat Firedeck Heavy-Duty Natural Gas Engines

2024-04-09
2024-01-2115
The widely accepted best practice for spark-ignition combustion is the four-valve pent-roof chamber using a central sparkplug and incorporating tumble flow during the intake event. The bulk tumble flow readily breaks up during the compression stroke to fine-scale turbulent kinetic energy desired for rapid, robust combustion. The natural gas engines used in medium- and heavy-truck applications would benefit from a similar, high-tumble pent-roof combustion chamber. However, these engines are invariably derived from their higher-volume diesel counterparts, and the production volumes are insufficient to justify the amount of modification required to incorporate a pent-roof system. The objective of this multi-dimensional computational study was to develop a combustion chamber addressing the objectives of a pent-roof chamber while maintaining the flat firedeck and vertical valve orientation of the diesel engine.
Technical Paper

Ducted Fuel Injection: Confirmed re-entrainment hypothesis

2024-04-09
2024-01-2885
Testing of ducted fuel injection (DFI) in a single-cylinder engine with production-like hardware previously showed that simply adding a duct structure increased soot emissions at the full load, rated speed operating point. In the authors’ 2021 SAE paper, which reported these findings, it was hypothesized that the DFI flame, which is faster than a conventional diesel combustion (CDC) flame, and has a shorter distance to travel, was being re-entrained into the on-going injection around the lift-off length, thus reducing air entrainment into the on-going injection. The engine operating condition and the engine combustion chamber geometry were duplicated in a constant pressure vessel. The experimental setup used a 3D piston section combined with a glass fire deck allowing for a comparison between a CDC flame and a DFI flame via high-speed imaging. Testing clearly confirmed the detrimental effect of the DFI flame re-entrainment hypothesis presented in the previous on-engine work.
Technical Paper

Elucidation of Deteriorating Oil Consumption Mechanism due to Piston Top Ring Groove Wear

2024-04-09
2024-01-2269
During engine durability testing, the piston and piston ring are used in harsh contact environments, causing the piston ring groove to experience significant wear, leading to significant development costs for countermeasures. To ensure functional feasibility due to wear on the piston top ring groove (hereinafter referred to as the ring groove), traditional methods of evaluating function through practical engine durability tests were the only option, presenting challenges in determining the wear limit value itself. Therefore, the judgment criteria had to have a margin for functional assurance purposes, although the mechanism of ring groove wear has been revealed in past research. To establish judgment criteria for optimal design, it was necessary to understand the effects and mechanism of ring groove wear. This study clarified the functional impact and occurrence mechanism of upper-surface wear on the ring groove through two experiments.
Technical Paper

The Development and Validation of a Novel Two-Parameter Controlled Tribometer for Durability Analysis of the Piston Ring-Cylinder Tribopair in IC Engines

2024-04-09
2024-01-2067
The wear of the piston ring-cylinder liner system in gasoline engines is inevitable and significantly impacts fuel economy. Utilizing a custom-built linear reciprocating tribometer, this study assesses the wear resistance of newly developed engine cylinder coatings. The custom device offers a cost-effective means for tribological evaluation, optimizing coating process parameters with precise control over critical operational factors such as normal load and sliding frequency. Unlike conventional commercial tribometers, it ensures a more accurate simulation of the engine cylinder system. However, existing research lacks a comprehensive comparative analysis and procedure to establish precision limits for such modified devices. This study evaluates the custom tribometer's repeatability compared to a commercial wear-testing instrument, confirming its potential as a valuable tool for advanced wear testing on engine cylinder samples.
Technical Paper

Evaluating the effects of an Electrically Assisted Turbocharger on scavenging control for an Opposed Piston Two Stroke (OP2S) compression ignition engine

2024-04-09
2024-01-2388
Opposed piston two-stroke (OP2S) diesel engines have demonstrated a reduction in engine-out emissions and increased efficiency compared to conventional four-stroke diesel engines. Due to the higher thermal efficiency and absence of a cylinder head, the heat transfer loss to the coolant is lower near the ‘Top Dead Center’. The selection and design of the airpath are pivotal in realizing the benefits of the OP2S engine architecture. Like any two-stroke diesel engine, the scavenging process and the composition of the internal residuals are predominantly governed by the pressure differential between the intake and the exhaust ports. Moreover, a significant portion of the work involved in pumping air is carried out externally to the engine cylinder which needs to be accounted for when calculating brake efficiencies.
Technical Paper

Piston geometries impact on Spark-Ignition light-duty hydrogen engine

2024-04-09
2024-01-2613
The European Union aims to be climate neutral by 2050 and requires the transportation sector to reduce their emissions by 90%. The deployment of H2ICE to power vehicles is one of the solutions proposed. Indeed, H2ICEs in vehicles can reduce local pollution, reduce global emissions of CO2 and increase efficiency. Although H2ICEs could be rapidly introduced, investigations on hydrogen combustion in internal combustion engines are still required. This paper aims to experimentally compare a flat piston and a bowl piston in terms of performances and emissions. For the performances, experiments were performed with the help of a single cylinder Diesel engine which has been modified. In particular, a center direct injector dedicated to H2 injection and a side-mounted spark plug were installed, and the compression ratio was reduced to 12.7:1. For the emissions, several exhaust gas measurement systems were used to monitor NO, NO2, N2O and H2.
Standard

Internal Combustion Engines - Piston Ring-Grooves

2024-02-16
CURRENT
J2275_202402
There is no ISO standard equivalent to this SAE Standard. This SAE Standard identifies and defines the most commonly used terms for piston ring-groove characteristics, specifies dimensioning for groove widths, and demonstrates the methodology for calculation of piston groove root diameter. The requirements of this document apply to pistons and rings of reciprocating internal combustion engines and compressors working under analogous conditions, up to and including 200 mm diameter and 4.5 mm width for compression rings and 8.0 mm width for oil rings. The specifications in this document assume that components are measured at an ambient temperature of 20 °C (68 °F). Tolerances specified in this document represent practical functional limits and do not imply process capabilities.
Journal Article

Modal Analysis of Combustion Chamber Acoustic Resonance to Reduce High-Frequency Combustion Noise in Pre-Chamber Jet Ignition Combustion Engines

2024-01-31
Abstract The notable increase in combustion noise in the 7–10 kHz band has become an issue in the development of pre-chamber jet ignition combustion gasoline engines that aim for enhanced thermal efficiency. Combustion noise in such a high-frequency band is often an issue in diesel engine development and is known to be due to resonance in the combustion chamber. However, there are few cases of it becoming a serious issue in gasoline engines, and effective countermeasures have not been established. The authors therefore decided to elucidate the mechanism of high-frequency combustion noise generation specific to this engine, and to investigate effective countermeasures. As the first step, in order to analyze the combustion chamber resonance modes of this engine in detail, calculation analysis using a finite element model and experimental modal analysis using an acoustic excitation speaker were conducted.
Technical Paper

Oil Aerosol Emission Optimization Using Deflectors in Turbo Charger Oil Drain Circuit

2024-01-16
2024-26-0047
Closed crankcase ventilation prevent harmful gases from entering atmosphere thereby reducing hydrocarbon emissions. Ventilation system usually carries blowby gases along with oil mist generated from Engine to Air intake system. Major sources of blowby occurs from leak in combustion chamber through piston rings, leakage from turbocharger shafts & leakage from valve guides. Oil mist carried by these blowby gases gets separated using separation media before passing to Air Intake. Fleece separation media has high separation efficiency with lower pressure loss for oil aerosol particles having size above 10 microns. However, efficiency of fleece media drops drastically if size of aerosol particles are below 10 microns. Aerosol mist of lower particle size (>10 microns) generally forms due to flash boiling on piston under crown area and from shafts of turbo charger due to high speeds combined with elevated temperatures. High power density diesel engine is taken for our study.
Technical Paper

Cost Effective Pathways toward Highly Efficient and Ultra-Clean CI Engines, Part I: Combustion System Optimization

2024-01-16
2024-26-0037
Following global trends of increasingly stringent greenhouse gas (GHG) and criteria pollutant regulations, India will likely introduce within the next decade equivalent Bharat Stage (BS) regulations for Diesel engines requiring simultaneous reduction in CO2 emissions and up to 90% reduction in NOx emission from current BS-VI levels. Consequently, automakers are likely to face tremendous challenges in meeting such emission reduction requirements while maintaining performance and vehicle total cost of ownership (TCO), especially in the Indian market, which has experienced significant tightening of emission regulation during the past decade. Therefore, it is conceivable that cost effective approaches for improving existing diesel engines platforms for future regulations would be of high strategic importance for automakers.
Technical Paper

Integrated Simulation Methodology to Predict Engine Head, Block, and Piston Temperatures

2024-01-16
2024-26-0315
With the constant strive towards increase in performance and corresponding stringent emission standards of modern IC engine, engine components such as the head, block and piston are subjected to higher thermal loads. An integrated simulation methodology is proposed where the head, the block and the piston are integral part of the analysis. The CFD – CHT methodology is used to simulate and predict the temperature of these engine components. The head and block are run in a steady-state conjugate heat transfer framework while the transient multiphase volume of fluid approach is used to determine piston temperatures. Combustion surfaces boundary conditions are derived from 3D CFD open-loop combustion simulation, while cooling and lubrication surface boundary condition are mapped from 1D system simulation or experimental data. The heat transfer boundary conditions are exchanged between the two simulations.
Technical Paper

Experimental Study of Piston Temperature Profile with Respect to Varying Engine Parameters – Using Telemetry Method

2024-01-16
2024-26-0341
As emissions standards become more stringent, OEMs are pushing engines to run on leaner fuel mixtures, which puts increased thermal stress on components, particularly pistons, causing them to operate at higher temperatures. This requires more robust design and rigorous testing of components. Telemetry methods offer accurate and real-time feedback, allowing designers to test components at various operating conditions, providing more flexibility than other traditional methods. Piston temperature measurement is a critical aspect of engine development because it directly affects engine performance and durability. Among the various techniques available for this purpose, telemetry methods have gained considerable attention in recent years. This method involves integrating temperature sensors and transmitter on the piston, which transmit temperature data wirelessly to a receiver outside the engine.
Technical Paper

Effect of Piston Secondary Motion on Lubricating Oil Consumption, Blow-by and Friction

2024-01-16
2024-26-0259
As per pieces of literature, 40 to 60 % of friction losses of Internal combustion engines occur in their piston-piston rings-liner assemblies and, there is a significant supportive role of simulation in improving this assembly. Literature is also available which tells, how changes in pistons affect oil consumption. Thus, piston dynamics is also important for oil consumption. Furthermore, the results from the simulation module of piston movement also serve as a significant input for postprocessing to calculate piston ring dynamics. This research is conducted to understand the piston secondary motion effect on oil consumption, friction, and blow-by. In this work, the results of ring dynamics and oil consumption simulation modules are studied with consideration and non-consideration of piston secondary motion results. The results like minimum oil film thickness, lubricating oil consumption, friction, friction power loss, and blow-by are investigated.
Journal Article

Research on the Secondary Motion of Engine Piston Considering the Transport of Lubricating Oil

2023-11-21
Abstract At present, it is generally considered in the analysis of the secondary motion of engine piston that the piston skirt–cylinder liner friction pair is fully lubricated in an engine operating cycle. However, in practice, when the piston moves upward, the amount of lubricating oil at the inlet may not ensure that the friction pair is fully lubricated. In this article, the secondary motion of piston is studied when the transport of lubricating oil is considered to determine the lubrication condition of piston skirt–cylinder liner friction pair. The secondary motion of piston is solved based on the combined piston motion model, hydrodynamic lubrication model, asperity contact model, and lubricating oil flow model. The secondary motion equation of piston is solved by the Broyden method. The hydrodynamic lubrication equation is solved by the finite difference method. The asperity contact between piston skirt and cylinder liner is calculated by the Greenwood model.
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