bluuebunny/crossref_metadata_2025 huggingface dataset:
Effect of Local Ductility of Advanced High Strength Steels in 980MPa and 1180MPa Grades on Crash Performance of Automotive Structures
Authors: Sato Kentaro , Sakaidani Tomohiro , Toji Yuki , Takajo Shigehiro , Paton Adrian , Manuela Irnich , Thiessen Richard
Published: April 2023

A fundamental study on the ductility of high strength steels under impact deformation is carried out to investigate the effect of the local ductility of various materials on crash performance. In this study, newly developed 980 and 1180 MPa grade steels are investigated to clarify their advantages in term of crash performance compared to conventional DP (Dual Phase) steels. The features of the developed steel, named as jetQ are higher yield strength and higher local ductility due to an optimized microstructure by the quenching and partitioning process (QP) [1, 2]. The bending test according to VDA 238-100 is performed while observing the fracture propagation during the bending test. Fracture strain in the tensile tests is evaluated by a three-dimensional shape measurement technique for the fracture surface.

Both three-point bending tests and axial impact tests are performed to evaluate the crashworthiness of different types of steel. The three-point bending test simulates the “structural bending and intrusive deformation” that occur in the automotive side impact test. In the axial impact test, the “folding deformation” and energy absorption during the automotive front crash test are simulated in a laboratory testing machine. In this study, the fracture behavior and energy absorption performance of the high strength steels are investigated under both deformation modes.

Based on the experimental results, the effect of the local ductility of the high strength steel on the risk of material fracture is discussed. The experimental results show that high strength steels with higher ductility of thickness strain can improve crash deformation with lower risk of crash fracture. The jetQ steels of grades over 980 MPa have excellent local ductility compared to conventional DP sheets. The jetQ steel also shows higher crash performance due to its higher yield strength. Considering these advantages, the applicability of the jetQ steel to automobile body structures is discussed from the viewpoint of light weight body structures.
Negative Trends in the Development of Simulation of Real-World Conditions, Testing, and Prediction
Authors: Klyatis Lev
Published: April 2023

This paper reviews the basic negative trends in development of real-world simulation, accelerated testing, and efficiency prediction, including:
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Testing in mobile engineering and negative factors leading to the slow improvement testing, especially reliability and durability testing

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Trends in using physical & virtual technology of simulation attempting to field conditions

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How this influence on inaccurate prediction of product quality, reliability durability, and other components of efficiency

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How current vibration and corrosion simulation differ from real-world vibration & corrosion

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Trends in increasing usage of virtual simulation and decreasing physical simulation

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Negative aspects of trends in publications of testing autonomous vehicles without drivers.
Usefulness and Time Savings Metrics to Evaluate Adoption of Digital Twin Technology
Authors: Eddy Conner , Castanier Matthew , Wagner John , Morris John , Moss Benjamin
Published: April 2023

The application of virtual engineering methods can streamline the product design process through improved collaboration opportunities among the technical staff and facilitate additive manufacturing processes. A product digital twin can be created using the available computer-aided design and analytical mathematical models to numerically explore the current and future system performance based on operating cycles. The strategic decision to implement a digital twin is of interest to companies, whether the required financial and workforce resources will be worthwhile. In this paper, two metrics are introduced to assist management teams in evaluating the technology potential. The usefulness and time savings metrics will be presented with accompanying definitions. A case study highlights the usefulness metric for the “Deep Orange” prototype vehicle, an innovative off-road hybrid vehicle designed and fabricated at Clemson University. Survey responses identified factors including verification/validation and model organization as critical focus areas for future digital twin technology implementation. The results demonstrate how model repertoires can be leveraged to new product cycles and fill the knowledge gaps of new engineers joining the development team. Overall, the metrics establish a basis to generate discussions regarding embracing emerging workplace technology.
Safety Verification and Navigation for Autonomous Vehicles Based on Signal Temporal Logic Constraints
Authors: Parameshwaran Aditya , Wang Yue
Published: April 2023

The software architecture behind modern autonomous vehicles (AV) is becoming more complex steadily. Safety verification is now an imminent task prior to the large-scale deployment of such convoluted models. For safety-critical tasks in navigation, it becomes imperative to perform a verification procedure on the trajectories proposed by the planning algorithm prior to deployment. Signal Temporal Logic (STL) constraints can dictate the safety requirements for an AV. A combination of STL constraints is called a specification. A key difference between STL and other logic constraints is that STL allows us to work on continuous signals. We verify the satisfaction of the STL specifications by calculating the robustness value for each signal within the specification. Higher robustness values indicate a safer system. Model Predictive Control (MPC) is one of the most widely used methods to control the navigation of an AV, with an underlying set of state and input constraints. Our research aims to formulate and test an MPC controller, with STL specifications as constraints, that can safely navigate an AV. The primary goal of the cost function is to minimize the control inputs. STL constraints will act as an additional layer of constraints that would change based on the scenario and task on hand. We propose using sTaliro, a MATLAB-based robustness calculator for STL specifications, formulated in a receding horizon control fashion for an AV navigation task. It inputs a simplified AV state space model and a set of STL specifications, for which it constructs a closed-loop controller. We test out our controller for different test cases/scenarios and verify the safe navigation of our AV model.
Robust Design of Vehicle Suspension with Uncertain Parameters Using a Polynomial Chaos Approach
Authors: Feng Xingxing
Published: April 2023

The optimum design of suspension system is a subject with great importance as suspension system has a significant role in ride and handling of vehicles. Practical vehicle systems often contain some uncertainties, which should be considered in the optimum design process of suspension. In this study, a quarter-car model is used to investigate and optimize the dynamic response of cars with random uncertainty which comes from the terrain profile and the variable system parameters. In order to achieve an optimum robust design against uncertainty in reality, a new robust design approach is proposed, which is a combination of a multi-objective genetic algorithm and the generalized polynomial chaos theory. Then Pareto optimum robust design is applied to the quarter-car model with three performances criteria, related to ride comfort, suspension travel and road holding. As a result, an optimum robust design point for vehicle model is obtained by using the polynomial chaos approach. In order to validate the polynomial chaos approach, a deterministic optimization is applied for vehicle model without considering any uncertainty, and an optimum deterministic design point is obtained. By the comparison of the optimum robust design point and the optimum deterministic design point, the robust design approach using polynomial chaos is proved to be effective and useful.
A Quasi-Dimensional Burn Rate Model for Pre-Chamber-Initiated Jet Ignition Combustion
Authors: Salerno Francesco , Bargende Michael , Kulzer André , Grill Michael , Burkardt Patrick , Günther Marco , Pischinger Stefan , Villforth Jonas
Published: April 2023

Prospective combustion engine applications require the highest possible energy conversion efficiencies for environmental and economic sustainability. For conventional Spark-Ignition (SI) engines, the quasi-hemispherical flame propagation combustion method can only be significantly optimized in combination with high excess air dilution or increased combustion speed. However, with increasing excess air dilution, this is difficult due to decreasing flame speeds and flammability limits. Pre-Chamber (PC) initiated jet ignition combustion systems significantly shift the flammability and flame stability limits towards higher dilution areas due to high levels of introduced turbulence and a significantly increased flame area in early combustion stages, leading to considerably increased combustion speeds and high efficiencies. By now, vehicle implementations of PC-initiated combustion systems remain niche applications, especially in combination with lean mixtures. This is also due to challenges regarding cold-start, combustion stability at low loads, and emissions. Nevertheless, PC ignition systems allow overall engine efficiencies >45%. Therefore, a market launch of an engine using globally lean mixtures ignited by a PC system is desirable. This requires a fast-running and predictive physical model to conduct robust design studies and complement existing testing methodologies (3D-CFD, experimental). This paper addresses the development of a quasi-dimensional burn rate model for PC ignition combustion systems. The presented modeling approach combines the well-established two-zone entrainment model (main-chamber) with a semi-empirical PC model that aims to detect the PC influence on the main-chamber combustion. Dedicated models predict the impact of the jet-induced turbulence and the increased flame area. The models are integrated into the so-called cylinder module developed at IFS (Institute of Automotive Engineering Stuttgart). For the model validation, measurement data of a single-cylinder research engine using different fuels (E1001, RON95E102), loads (IMEP = 6 − 15 bar), excess air dilutions (λ = 1 − 2) and compression ratios (16.41, 12.62) are used, showing a satisfactory prediction of the burn rate and pressure curve.
Transmission Shifting Analysis and Model Validation for Medium Duty Vehicles
Authors: Kim Namdoo , Islam Ehsan Sabri , Vijayagopal Ram , Pamminger Michael
Published: April 2023

Over the past couple of years, Argonne National Laboratory has tested, analyzed, and validated automobile models for the light duty vehicle class, including several types of powertrains including conventional, hybrid electric, plug-in hybrid electric and battery electric vehicles. Argonne’s previous works focused on the light duty vehicle models, but no work has been done on medium and heavy-duty vehicles. This study focuses on the validation of shifting control in advanced automatic transmission technologies for medium duty vehicles by using Argonne’s model-based high-fidelity, forward-looking, vehicle simulation tool, Autonomie.

Different medium duty vehicles, from Argonne’s own fleet, including the Ram 2500, Ford F-250 and Ford F-350, were tested with the equipment for OBD (on-board diagnostics) signal data record. For the medium duty vehicles, a workflow process was used to import test data. In addition to importing measured test signals into the Autonomie environment, the process also calculated some of the critical missing signals, such as each component effort or flow signal. Numerous analysis functions have been developed to quickly analyze the shifting map, using the integrated test data in Autonomie to generate model parameters. In addition, a set of calibrations for the generic shifting algorithm was developed to match the test data. Finally, we demonstrated the validation of Autonomie transmission component models and shifting control strategy by using medium duty vehicle test data over different driving records.
Thermo-Diffusive Flame Speed Adjustment and its Application to Hydrogen Engines
Authors: Hernandez Ignacio , Turquand d'Auzay Charles , Penning Richard , Shapiro Evgeniy , Hughes John
Published: April 2023

Practical direct injection hydrogen combustion applications typically require operating the engine in the lean regime. Lean hydrogen flames feature strong thermo-diffusive instability effects making 3D CFD simulations challenging. In particular where the calibrated model is required to operate across a range of equivalence ratios without adjustment and provide accurate results on coarse grids necessitated by the run-times of 3D CFD. In this paper we present a 3D CFD study of a Euro VI HD diesel engine converted to operate on hydrogen gas using direct injection. A scaling methodology recently proposed for conversion from constrained to freely propagating flame based on DNS data is implemented. A laminar flame speed tabulation is developed based on the conversion of 1D results obtained from direct kinetics simulations to freely propagating flame expression considering the behaviour of the thermo-diffusive instability for a wide range of pressures, temperatures and equivalence ratios. The resulting approach is applied to model engine operation under a set of fuelling conditions ranging from λ = 2.5 to λ = 3.5 within the framework of a G-equation/RANS combustion model with tabulated kinetics. Discussion of the meshing requirements is also presented. The resulting model is demonstrated to accurately predict the trends in engine performance and correctly capture the flame acceleration driven by thermo-diffusive effects.
AI Super-Resolution-Based Subfilter Modeling for Finite-Rate-Chemistry Flows: A Jet Flow Case Study
Authors: Bode Mathis
Published: April 2023

Large-eddy simulation (LES) can be a very important tool to support and accelerate the energy transition to green technologies and thus play a significant role in the fight against climate change. However, especially LES of reactive flows is still challenging, e.g., with respect to emission prediction, and perfect subfilter models do not yet exist. Recently, new subfilter models based on physics-informed generative adversarial networks (GANs), called physics-informed enhanced super-resolution GANs (PIESRGANs), have been developed and successfully applied to a wide range of flows, including decaying turbulence, sprays, and finite-rate-chemistry flows. This technique, based on AI super-resolution, allows for the systematic derivation of accurate subfilter models from direct numerical simulation (DNS) data, which is critical, e.g., for the development of efficient energy devices based on advanced fuels. This paper describes a case study demonstrating PIESRGANA for a finite-rate chemical methane jet flow using transfer learning. A priori and a posteriori results are presented and discussed. Since the training process is very crucial for the successful application of this new LES technique, a detailed description of possible strategies is provided.
A Predictive Model for Spark Stretch and Mixture Ignition in SI Engines
Authors: Briggs Thomas , Conway Graham
Published: April 2023

A physics-based spark ignition model was developed and integrated into a commercial CFD code. The model predicted the spark discharge process based on the electrical parameters of the secondary ignition circuit, tracked the spark motion as it was stretched by in-cylinder gas motion, and determined the resulting energy deposition to the gas. In concert with the existing kinetic solver in the CFD code, the resulting ignition and flame propagation processes were simulated. The model results have been validated against both imaging rig experiments of the spark in moving air and against engine experimental data. The model was able to replicate the key features of the spark and to capture the cyclic variability of high-dilution combustion when multiple engine cycles were simulated.
A 3D-CFD Numerical Approach for Combustion Simulations of Spark Ignition Engines Fuelled with Hydrogen: A Preliminary Analysis
Authors: Sfriso Stefano , Berni Fabio , Fontanesi Stefano , D'Adamo Alessandro , Antonelli Marco , Frigo Stefano
Published: April 2023

With growing concern about global warming, alternatives to fossil fuels in internal combustion engines are searched. In this context, hydrogen is one of the most interesting fuels as it shows excellent combustion properties such as laminar flame speed and energy density. In this work a CFD methodology for 3D-CFD in-cylinder simulations of engine combustion is proposed and its predictive capabilities are validated against test-bench data from a direct injection spark-ignition (DISI) prototype. The original engine is a naturally aspirated, single cylinder compression ignition (Diesel fueled) unit. It is modified substituting the Diesel injector with a spark plug, adding two direct gas injectors, and lowering the compression ratio to run with hydrogen fuel. A 3D-CFD model is built, embedding in-house developed ignition and heat transfer models besides G-equation one for combustion. Three different lean-burn conditions are selected among the tested ones for the validation of the numerical framework. The investigated conditions are characterized by the same revving speed (3000 rpm) but different equivalence ratios (0.4, 0.6 and 0.8, respectively). A good agreement with the experimental dataset is observed, confirming the validity of the proposed CFD approach, and opening the possibility of further virtual optimizations of the engine.
Model Based Calibration of a Multi Cylinder Spark Ignition Engine for Idle Speed Control Using PID Control Strategy
Authors: SAHU RAJESH KUMAR , Srivastava Dhananjay Kumar
Published: April 2023

An idle speed controller allows the engine to idle at the lowest possible RPM without stalling to support various power-consuming accessories. In this study, an idle speed control system is designed using a PID control strategy based on an engine model. The engine model was developed considering engine dynamics and various cylinder airflow calculation methodologies, such as Speed-density, Alpha-N, and Throttle-flow. The engine model was created in MATLAB Simulink. The model utilizes several calibrated lookup tables that were obtained using the model-based calibration (MBC) technique. A multi-cylinder spark ignition (SI) engine was calibrated using the MATLAB MBC Toolbox to generate real-time maps for idle speed control. This paper aims to investigate the performance of the developed idle speed controller for different cylinder airflow calculation methodologies. The idle speed control system was simulated for various load-torque disturbances to evaluate the controller's performance. The controller responses, such as the settling time and peak speed variation, were analyzed to select a suitable airflow calculation methodology for idle speed control application. The simulated results of the designed controller are compared to the experimental results of the original controller for validation. The simulated results show that the Speed-density method has a higher peak speed variation and a longer settling time than the other two methods for all loading conditions because it considers the intake manifold dynamics. Alpha-N and Throttle-flow methods display similar performance for all tested conditions. Hence, both Alpha-N and Throttle-flow techniques can be considered for idle speed control applications.
Combustion Regimes in the Chrysler Multi-Air Multi-Fuel Engine, Part 1 - Diesel Assisted Spark Ignited
Authors: Church William , McConnell Steven
Published: April 2023

This paper is the first of three papers stemming from a dual fuel Chrysler prototype engine which uses both diesel and gasoline direct injection running at stoichiometric conditions, as part of a project to explore the viability of incorporating an engine platform which utilizes low temperature combustion regimes into a modern automotive application. The combustion system used high rates of EGR while maintaining combustion stability by using high charge motion intake port and a high energy ignition system. The engine ran highly dilute SI combustion at low loads, Diesel Assisted Spark Ignition at medium loads and a transition to Diesel Micro Pilot ignition at medium to high load. This paper explores diesel assisted spark ignited combustion at medium loads 6.5 bar to 12.7 bar BMEP. The second paper will explore the use of diesel micro-pilot ignition at high loads 10.6 bar to 14.5 bar BMEP and the third paper to be published in 2024 will explore fuel property effects (mainly Cetane and Octane) through the use of alternative fuels. In the diesel assisted spark ignited combustion regime combustion is initiated via a spark while using a diesel injection to provide a low octane fuel source early in combustion. Results were obtained at speed/load points ranging from 1500 to 3200 RPM and boost levels ranging from 95 to 200 kPa. Spark timing, diesel injection timing, and exhaust gas recirculation percentage were crucial variables affecting the performance of the engine. Brake thermal efficiency levels above 39% were possible at numerous operating conditions.
Development of 50% Thermal Efficiency S.I. Engine to Contribute Realization of Carbon Neutrality
Authors: Kimura Koshiro , SAKAI Hiroyuki , Omura Tetsuo , Takahashi Daishi
Published: April 2023

To prevent global warming, many countries are making efforts to reduce CO2 emissions toward achieving 2050 carbon neutrality. In order to reduce CO2 concentration quickly, in addition to spread of renewable energy and expansion of BEV, it is also important to reduce CO2 emissions by improving thermal efficiency of ICE (internal combustion engine) and utilizing carbon neutral fuels such as synthetic fuels and biofuels. It is well known that lean burn is an effective technology to increase thermal efficiency of engine highly. However, since NOx emission from lean burn engine cannot be reduced with three-way catalyst, there have been issues such as complicated system configuration due to the addition of NOx reduction catalyst or limiting lean operation to narrow engine speed and load in order to meet emission regulation of each country. This paper introduces super lean burn engine with over lambda 2.5 that achieves both high thermal efficiency and significantly low NOx emission in order to solve the issues of conventional lean burn engine. Key technologies for combustion such as ignition, flame propagation, and unburned HC reduction are described firstly, and then the possibility of further improvement of thermal efficiency and combustion effect by applying ethanol as CN (Carbon neural) fuel to the super lean burn engine is indicated.
Impact of Thermal Barrier Coatings on Intake and Exhaust Valves in a Spark Ignition Engine
Authors: Gandolfo John , Gainey Brian , Jiang Chen , Jordan Eric , Filipi Zoran , Lawler Benjamin
Published: April 2023

Spark ignition knock is highly sensitive to changes in intake air temperature. Hot surface temperatures due to ceramic thermal barrier coatings increase knock propensity by elevating the incoming air temperature, thus mitigating the positive impacts of low heat transfer losses by requiring spark retard to avoid knock. Low thermal inertia coatings (i.e. Temperature swing coatings) have been proposed as a means of reducing or eliminating the open cycle charge heating penalty of traditional TBCs through a combination of low thermal conductivity and low volumetric heat capacity materials. However, in order to achieve a meaningful gain in efficiency, a significant fraction of the combustion chamber must be coated. In this study, a coated piston and intake and exhaust valves with coated combustion faces, backsides, and stems are installed in a single-cylinder research engine to evaluate the effect of high coated fractions of the combustion chamber in a knock-sensitive architecture. Spark timing sweeps demonstrated a small, but notable increase in net thermal efficiency compared to the coated piston by itself. A staged valve removal demonstrated that the coated intake valve prevents heat transfer to the incoming air, reducing knock propensity compared to the coated exhaust valve individually.
Performance, Combustion and Emissions Evaluation of Liquid Phase Port-Injected LPG on a Single Cylinder Heavy-Duty Spark Ignited Engine
Authors: Fosudo Toluwalase , Kar Tanmay , Windom Bret , Schlagel Jacob , Olsen Daniel
Published: April 2023

Liquefied petroleum gas (LPG), like many other alternative fuels, has witnessed increased adoption in the last decade, and its use is projected to rise as stricter emissions regulations continue to be applied. However, much of its use is limited to dual fuel applications, gaseous phase injection, light-duty passenger vehicle applications, or scenarios that require conversion from gasoline engines. Therefore, to address these limitations and discover the most efficient means of harnessing its full potential, more research is required in the development of optimized fuel injection equipment for liquid port and direct injection, along with the implementation of advanced combustion strategies that will improve its thermal efficiency to the levels of conventional fuels. This paper focuses on the development of a liquid phase port-injection system for LPG, the design of a reference piston, and the baseline evaluation of the performance, combustion, and emissions characteristics of a single cylinder research engine to establish a benchmark comparable to existing LPG engines. A sweep of start of injection (SOI) timing is performed by injecting liquid LPG at several closed and open intake valve timings, which demonstrates no significant variation in engine performance, but accounts for a 10% reduction in bsCO with the optimal SOI timing. Spark timing sweep demonstrates the 50% burn crank angle location related to maximum brake torque (MBT) point with a brake thermal efficiency (BTE) of ~34% for the tested load case. The effect of equivalence ratio is also presented with optimal SOI timing at MBT condition. The engine starts exhibiting knocking combustion at 140kPa intake manifold air pressure (IMAP) with a peak torque of 253Nm and a 5% reduction in brake specific fuel consumption compared to the naturally aspirated scenario.
CFD-Based Assessment of the Effect of End-Gas Temperature Stratification on Acoustic Knock Generation in an Ultra-Lean Burn Spark Ignition Engine
Authors: Strickland Tyler , Sjöberg Magnus , Matsubara Naoyoshi , Kitano Koji , Kaneko Kazuki
Published: April 2023

End-gas temperature stratification has long been studied with respect to its effect on stoichiometric spark-ignition (SI) engine knock. The role of temperature stratification for homogeneous-charge compression ignition (HCCI) engine operation is also reasonably well understood. However, the role of temperature stratification in ultra-lean SI engines has had less coverage. Literature is lacking well-controlled studies of how knock is affected by changes in the full cylinder temperature fields, especially since cycle-to-cycle variability can impede a determination of cause and effect. In this work, the knocking propensity of specific cylinder conditions is investigated via 3D computational fluid dynamics (CFD) simulations utilizing a large eddy simulation (LES) framework. The end-gas temperature stratification is systematically varied such that all other parameters remain relatively constant (including the flow field, thereby avoiding cycle-to-cycle variability) allowing for direct conclusions to be drawn. It is found that a substantial paradigm shift in acoustic knock generation is brought on by having large volumes in the end-gas being under a stratification limit set by the time it takes for an acoustic wave to traverse the cylinder domain. Hence, it is shown that temperature stratification of the end gas plays a key role, enabling the combustion system to accept some degree of end-gas autoignition without inducing unwanted acoustic knock.
Development of a Supercharged Octane Number and a Supercharged Octane Index
Authors: Hoth Alexander , Kolodziej Christopher P. , Waqas Muhammad , Szybist James , Miers Scott A.
Published: April 2023

Gasoline knock resistance is characterized by the Research and Motor Octane Number (RON and MON), which are rated on the CFR octane rating engine at naturally aspirated conditions. However, modern automotive downsized boosted spark ignition (SI) engines generally operate at higher cylinder pressures and lower temperatures relative to the RON and MON tests. Using the naturally aspirated RON and MON ratings, the octane index (OI) characterizes the knock resistance of gasolines under boosted operation by linearly extrapolating into boosted “beyond RON” conditions via RON, MON, and a linear regression K factor. Using OI solely based on naturally aspirated RON and MON tests to extrapolate into boosted conditions can lead to significant errors in predicting boosted knock resistance between gasolines due to non-linear changes in autoignition and knocking characteristics with increasing pressure conditions. A new “Supercharged Octane Number” (SON) method was developed on the CFR engine at increased intake pressures, which improved the correlation to boosted knock-limited automotive SI engine data over RON for several surrogate fuels and gasolines, including five “Co-Optima” RON 98 fuels and an E10 regular grade gasoline. Furthermore, the conventional OI was extended to a newly introduced Supercharged Octane Index (OIS) based on SON and RON, which significantly improved the correlation to fuel knock resistance measurements from modern boosted SI engine knock-limited spark advance tests. This demonstrated the first proof of concept of a SON and OIS to better characterize a fuel’s knock resistance in modern boosted SI engines.
Multiple Spark Ignition Approach to Burn Ammonia in a Spark-Ignition Engine: An Optical Study
Authors: Uddeen Kalim , Tang Qinglong , Shi Hao , Magnotti Gaetano , Turner James
Published: April 2023

The future of the internal combustion (IC) engine relies on carbon-free fuels to mitigate climate change. Ammonia (NH3) is a promising carbon-free fuel, which can be used as an energy carrier for hydrogen (H2) and directly as a combustible fuel inside the engines. However, burning pure ammonia fuel is difficult due to its low flammability, burning velocity, and consequently large cycle-to-cycle variation. This study used a multiple-spark-plug approach to burn pure ammonia gas with reduced combustion duration and higher engine power output. The natural flame luminosity (NFL) imaging method was used to capture the multiple flames initiated by various ignition sites. In order to perform the experiment a customized liner having four spark plugs installed at equal spacing to each other, and to compare the results with conventional spark-ignition (SI) conditions, one spark plug was mounted at the center of the cylinder head. The results show that firing the single central spark plug generated lower in-cylinder pressure and heat release rate (HRR) along with higher combustion duration due to the low flame speed. However, adding more spark plugs increased the cylinder pressure generation and HRR along with creating shorter combustion duration for the same operating conditions. In addition, multiple flames produced by multiple plugs increased the engine power output and reduced the cyclic variation significantly due to higher-pressure generation. Additionally, NFL imaging was used to evaluate the flame intensity and flame area proportion for various ignition cases, and it was found that multiple spark plugs burned the air-fuel mixture more quickly with faster flame area proportion along with higher flame intensity. Furthermore, firing multiple spark plugs produced higher NOx emissions than the single spark plug case due to higher in-cylinder temperatures generated by multiple flame kernels.
Soot and Gaseous Emissions Characterization of Butyl-Acetate/Diesel Blend in a Heavy-Duty Engine
Authors: Hall Spencer L. , Bittle Joshua A.
Published: April 2023

Significant effort has been put toward developing future-generation biofuels aimed at either spark-ignition or compression-ignition engines. Butyl-Acetate (BA), C6H12O2, is one such fuel that may be viable as a soot reduction drop-in blend candidate without significant impact on performance or efficiency. Though BA does have a low CN (≈ 20) and heating value (27 MJ/kg), it offers promise as a drop in blend-candidate with pump diesel due to its improved cold weather performance, high flash point, and potential for high volume renewable production capacity.

This work investigated the impacts of 5% by volume blend of BA and standard pump diesel (DF2) on overall performance and with a particular focus on soot behavior. Tests were completed at 13 operating points spanning the operating map including full power. Results show a significant reduction in soot without significant impact on NOx emissions and minimal impact on thermal efficiency. Of course, BSFC increases due to the reduced heating value but does not have a noticeable impact on ECU operating set-points or resulting in-cylinder combustion-related parameters. Ultimately, despite decrease in global oxygen-to-fuel ratio with BA blend and no clear changes to combustion or control behavior, soot concentration is reduced by an average of 30%. The potential impact on regeneration cycles for the soot particulate filter enabled by this soot reduction represent clear opportunity for corresponding reduction in total fuel consumption for operators.
Engine and Emissions Performance of Renewable Diesel in a Heavy-Duty Diesel Engine: A Single-cylinder Engine Experiment
Authors: Cung Khanh , Buffaloe Gina , Briggs Thomas , Bitsis Chris , Smith Edward , Khalek Imad , Michlberger Alexander
Published: April 2023

As an alternative fuel, renewable diesel (RD) could improve the performance of conventional internal combustion engines (ICE) because of its difference in fuel properties. With almost no aromatic content in the fuel, RD produces less soot emissions than diesel. The higher cetane number (CN) of RD also promotes ignition of the fuel, which is critical, especially under low load, and low reactivity conditions. This study tested RD fuel in a heavy-duty single-cylinder engine (SCE) under compression-ignition (CI) operation. Test condition includes low and high load points with change in exhaust gas recirculation (EGR) and start of injection (SOI). Measurements and analysis are provided to study combustion and emissions, including particulate matters (PM) mass and particle number (PN). It was found that while the combustion of RD and diesel are very similar, PM and PN emissions of RD were reduced substantially compared to diesel. Indicated thermal efficiency or fuel consumption were also improved slightly with RD. This study suggests that alternative fuels such as RD can contribute toward a pathway of achieving higher efficiency and lower emissions ICEs.
Numerical Simulations of Pre-Chamber Induced HCCI Combustion (PC-HCCI)
Authors: Krajnovic Josip , Dilber Viktor , Tomic Rudolf , Sjeric Momir , Ilincic Petar , Kozarac Darko
Published: April 2023

Advanced combustion concepts that rely on the lean-burn approach are a proven solution for increasing the efficiency and reducing the harmful emissions of SI engines. The pre-chamber spark ignited (PCSI) engines utilize high ignition energy of the multiple jets penetrating from the pre-chamber, to enable fast and stable combustion of lean mixture in the main chamber. The combustion is still governed by the flame propagation, so the dilution level and efficiency benefits are highly restricted by strong decrease of laminar flame speeds. Homogeneous charge compression ignition (HCCI) combustion allows a higher dilution level due to rapid chemically driven combustion, however the inability to directly control the ignition timing has proven to be a major setback in HCCI deployment. The addition of the spark plug, to improve the controllability and widen the operating range, resulted in a combustion concept known as spark-assisted compression ignition (SACI), however spark ignition of lean mixtures is very difficult even at close to HCCI conditions. Since one of the features of active pre-chamber is the ability to control mixture dilution at the spark plug location, a combustion concept called pre-chamber induced HCCI combustion (PC-HCCI) that combines pre-chamber ignition and HCCI combustion is proposed. In this concept a near stoichiometric mixture in the pre-chamber is spark ignited and the combustion in pre-chamber triggers kinetically controlled combustion of lean main combustion chamber mixture. As a first step of the research, numerical modelling of the proposed combustion concept is made by employing 3D-CFD and 1D/0D simulation models. The main purpose of the modelling is to define main geometrical and operating parameters required for achieving a pre-chamber induced HCCI combustion and to predict possible benefits of employing such combustion concept.
Development of a Multiple Injection Strategy for Heated Gasoline Compression Ignition (HGCI)
Authors: Zoldak Philip , Zyada Antowan
Published: April 2023

A multiple-injection combustion strategy has been developed for heated gasoline direct injection compression ignition (HGCI). Gasoline was injected into a 0.4L single cylinder engine at a fuel pressure of 300bar. Fuel temperature was increased from 25degC to a temperature of 280degC by means of electric injector heater. This approach has the potential of improving fuel efficiency, reducing harmful CO and UHC as well as particulate emissions, and reducing pressure rise rates. Moreover, the approach has the potential of reducing fuel system cost compared to high pressure (>500bar) gasoline direct injection fuel systems available in the market for GDI SI engines that are used to reduce particulate matter.

In this study, a multiple injection strategy was developed using electric heating of the fuel prior to direct fuel injection at engine speed of 1500rpm and load of 12.3bar IMEP. The effect of fuel temperature, fuel pressure and start of injection timing are reported for single injection strategy with impact on smoke and pressure rise rates. Double and Triple injection strategies were developed and utilized to maintain the indicated thermal efficiency and NOx emissions, while improving HC, CO, smoke emissions, as well as reducing pressure rise rates to less than 10bar/deg. The HGCI multiple injection strategy was attempted at higher load of 15bar IMEP to demonstrate the potential for low emissions, and high thermal efficiency, with reasonable pressure rise rates and suggest the strategy is scalable to higher speeds and loads.
Experimental Study on Ammonia/OME Combustion in a Dual-Fuel Engine with Emphasis on Highly Diluted Intake Air Conditions
Authors: Untheim Thomas , Großmann Fabian , Tatucu-Ertel Paul , Jochem Marius , Weigand Peter , Bikas Georgios
Published: April 2023

Ammonia, which is considered as an excellent hydrogen carrier, could potentially become a clean fuel for direct use in ICE.

An experimental setup with a strongly modified inline four-cylinder (I4) heavy duty Diesel engine was used to study different combustion modes of ammonia in ICE. The fourth cylinder of that engine was operated in a monovalent mode using either OME or Diesel fuel. Its complete exhaust stream was fed into the first cylinder of the same engine, which was operated on a dual-fuel mode by utilizing ammonia port injection and OME or Diesel pilot injection to ignite the mixture. The fourth cylinder of the I4 heavy duty engine can be operated at conditions between idle and full load and at different stoichiometries (λ) to impact both the temperature and the oxygen concentration at the exhaust of that cylinder. Since the first cylinder is fed by the complete exhaust stream of the fourth, the intake conditions of the first cylinder can be controlled appropriately and various ammonia combustion modes can be realized.

Emissions measurements at the intake and the exhaust of the first cylinder at different speeds and loads show the impact of the different combustion modes, especially due to temperature and oxygen content variations, on NOx and combustion efficiency. Chemical kinetics calculations have been elaborated to explain some of the main observations.
Innovative Piston Design Performance for High Efficiency Stoichiometric Heavy Duty Natural Gas Engine
Authors: rodriguez Juan Felipe , Xu Hui , Hampson Gregory , Bestel Diego , Windom Bret , Olsen Daniel
Published: April 2023

Internal combustion engines will continue to be the leading power-train in the heavy-duty, on-highway sector as technologies like hydrogen, fuel cells, and electrification face challenges. Natural gas (NG) engines offer several advantages over diesel engines including near zero particle matter (PM) emissions, lower NOx emissions, lower capital and operating costs, availability of vast domestic NG resources, and lower CO2 emissions being the cleanest burning of all hydrocarbons (HC). The main limitation of this type of engine is the lower efficiency compared to diesel counterparts. Addressing the limitations (knock and misfire) for achieving diesel-like efficiencies is key to accomplishing widespread adoption, especially for the US market.

With the aim to achieve high brake thermal efficiency (BTE), three (3) computational fluid dynamics (CFD) optimized pistons with three different compression ratios (CR) have been tested. Tests were carried out using a Cummins ISX-based 2.5-liter single-cylinder heavy-duty engine. A custom exhaust gas recirculation (EGR) system that simulates a high-pressure EGR loop was used to achieve EGR rates from 0 to 35%. The measurements were performed with variable EGR rate, IMEP, and rate of combustion.

Limitations on combustion control and high knock tendency were found on the highest CR piston, as limited heat transfer led to overheating of the piston crown. Higher BTE was achieved for two of the pistons tested, with peak values above 44%, the baseline efficiency of the diesel engine platform used. Controlled end-gas autoignition was achieved, contributing to the increase in peak BTE and expanding the engine load range. The positive results obtained with the CFD-optimized piston designs encourage the continued development of heavy-duty NG engines as feasible alternatives to reduce CO2 and NOx emissions, PM, and diesel fuel dependency.
Experimental Investigations of Methane-Hydrogen Blended Combustion in a Heavy-Duty Optical Diesel Engine Converted to Spark Ignition Operation
Authors: Panthi Niraj , Chang Junseok , AlRamadan Abdullah , Magnotti Gaetano
Published: April 2023

The global need for de-carbonization and stringent emission regulations are pushing the current engine research toward alternative fuels. Previous studies have shown that the uHC, CO, and CO2 emissions are greatly reduced and brake thermal efficiency increases with an increase in hydrogen concentration in methane-hydrogen blends for the richer mixture compositions. However, the combustion suffers from high NOx emissions. While these trends are well established, there is limited information on a detailed optical study on the effect of air-excess ratio for different methane-hydrogen mixtures. In the present study, experimental investigations of different methane-hydrogen blends between 0 and 100% hydrogen concentration by volume for the air-excess ratio of 1, 1.4, 1.8, and 2.2 were conducted in a heavy-duty optical diesel engine converted to spark-ignition operation. The engine was equipped with a flat-shaped optical piston to allow bottom-view imaging of the combustion chamber. High-speed natural combustion luminosity images were recorded at a frame rate of 7.2 kHz for all cases, together with in-cylinder pressure measurements. Results showed that the increase in hydrogen concentration has shifted the CA50 towards TDC thus increasing the peak combustion pressure. Methane combustion shows the lean limit at lambda 1.4 and extension of the lean limit requires at least 20% of hydrogen addition while maintaining the COV of IMEP below 5%. However, at lambda 1.8 case, 60% of hydrogen enhancement was needed to achieve stable combustion. Overall, with higher hydrogen concentration, there is an improvement in the combustion stability irrespective of the air-excess ratio. Image analysis was performed on the high-speed natural combustion luminosity images to obtain quantitative information on the flame front propagation speed for the tested methane-hydrogen blends. Hydrogen addition results in an increase in flame front propagation speed. When the hydrogen concentration in methane-hydrogen blends is about 50% by volume and more, the flame kernel propagates rapidly at the onset of combustion and decreases, resulting in a shorter combustion duration.
Development of a Novel Drop-in Naphthenic Spark Ignition Biofuel by Means of a Fuel Blend Calculator and a Simplified Octane Number Verification Method
Authors: Robeyn Tom , Larsson Tara , Demeersseman Jonathan , Van Biesen Jonas , Verhelst Sebastian
Published: April 2023

In the search for sustainable transportation fuels that are not in competition with food production, considerable efforts are made in the development of so-called second-generation (2G) biofuels. This paper looks into the results of a novel 2G biofuel production technique that is based on a catalytic process that operates at low temperature and that converts woody biomass feedstock into a stable light naphtha. The process development is integrated in the Belgian federal government funded Ad-Libio project and the process outcome is mainly consisting of hydrocarbons containing five to six carbon atoms. Their composition can be altered, resulting in a large amount of different possible fuel blends. The ultimate goal is to produce a drop-in fuel that can be fully interchanged with the gasoline fuels in use today. This is a challenge, since the Ad-Libio fuel components differ significantly from gasoline fuel components. For an initial assessment of the suitability of a novel blend, a fuel blend calculator with integrated fuel database has been developed. This tool enables fast SI fuel property calculations, so quick decisions can be made on the fuel production process outcome. The blend’s research octane number (RON) is one of the important properties to be checked for a blend’s suitability as a spark ignition engine fuel. After a first screening with the calculator, the average peak pressure pulsation (APPP) method was used on a CFR engine to evaluate the octane number of the blends, enabling quick in-house experimental octane number verification of the calculations before the blends can ultimately be sent to an ASTM-compliant testing laboratory.

This article describes the calculation and verification methodology of the first blends that have been used to design a new and fully sustainable SI engine fuel blend, ultimately aiming for a sustainable second-generation drop-in gasoline fuel replacement.