bluuebunny/crossref_metadata_2025 huggingface dataset:
Study on Airbag Concept for Motorcycles Using Opposing Vehicle as Reaction Structure
Authors: Aikyo Yutaka , Kobayashi Yuki , Sato Takashi , Akashi Tomohiko , Ishiwatari Makoto
Published: April 2023

An airbag system for motorcycle applications was developed and commercially released in 2006 based on many research results on that system. In the airbag system, the bag should be supported during the period in a collision. The previously developed system employed a configuration in which the airbag was supported by the structures of the motorcycle, such as the instrument panel and the surrounding structures. These structures receive the reaction force to hold the airbag during a crash to properly absorb the rider's kinetic energy. Meanwhile, the previous system requires a larger area for these reaction structures and is applicable only to the motorcycles that can provide the area. To overcome this limitation, we propose an airbag system employing another concept. In this concept, the airbag does not use its vehicle structures as reaction structures but uses the structures of an opposing vehicle, such as doors and/or pillars. For evaluations of the proposed system, full scale motorcycle-to-car crash tests using 125 cm3 scooter-type models with and without the airbag were conducted in the seven impact configurations specified in ISO13232. Through the crash tests, benefits of protective effects of the airbag system were confirmed in particular impact configurations, and no significant risk for the rider due to the airbag was observed in the all tested impact configurations. It was concluded that the proposed airbag system is feasible for reducing rider's severity of injuries in a collision of a motorcycle not having sufficient reaction structures.
Development of Fracture-Split Connecting Rods Made of Titanium Alloy for Use on Supersport Motorcycles
Authors: Kubota Tsuyoshi , Doi Kosuke , Murakami Takeshi , Kojima Yuuki , Miura Tetsu
Published: April 2023

A connecting rod made of titanium alloy is effective for lower fuel consumption and higher power output comparing to a steel one because the titanium connecting rod enables to reduce the weight of both of reciprocating and rotating parts in an entire engine substantially. But up to now, it has been adopted only to expensive and small-lot production models because a material cost is high, a processing is difficult and a wear on a sliding area should be prevented. In order to adopt the titanium connecting rods into a more types of motorcycles, appropriate materials, processing methods and surface treatment were considered. Hot forging process was applied not only to reduce a machining volume but also to enhance a material strength and stiffness. And the fracture-splitting (FS) method for the big-end of the titanium connecting rod was put into a practical use. The brittle fractured surface of the big-end by FS method is useful for not only cost reduction but also ensuring the stiffness of the connecting rod compensating the low elastic modulus of titanium alloy comparing to that of ferrous alloys. In this study, the evaluation results of materials characteristics related to these processes and functional property of surface treatment is described. From these evaluations, the capabilities of FS titanium connecting rods were quantitatively shown. FS titanium connecting rods have been produced for the supersport motorcycle engines from November 2014.
Motorcycle Stability Control - The Next Generation of Motorcycle Safety and Riding Dynamics
Authors: Lich Thomas , Block Wilko Gordon , Prashanth S N , Heiler Brad
Published: April 2023

Anti-lock Braking Systems (ABS) for motorcycles have already contributed significantly to the safety of powered two-wheelers (PTW) on public roads by improving bike stability and controllability in emergency braking situations.

In order to address further riding situations, another step forward has been achieved with Motorcycle Stability Control (MSC) system. By combining ABS, electronically combined braking system (eCBS), traction control and inertial sensors even in situations like braking and accelerating in corners the riders' safety can be improved. The MSC system controls the distribution of braking and traction forces using an algorithm that takes into account all available vehicle information from wheels, power train and vehicle attitude. With its ability to control fundamental vehicle dynamics, the MSC system will be a basis for further development and integration of comprehensive safety systems.

The contribution of ABS towards motorcycle safety has been confirmed by numerous international research studies, making it the safety technology with the highest possible benefit for motorcycles available today. Recent investigations by Bosch accident researchers show the contribution of the MSC system to further increase the safety benefit for motorcycle riders by extending the acceleration and braking control functions to cover more riding situations. The MSC systems could avoid more than every 3rd accident with casualties involving a motorcycle in Germany.

This paper focuses on these new motorcycle technologies developed with centralized system architecture and their safety benefits in preventing and mitigating motorcycle accidents with injuries and fatalities.
Analysis of Interaction between Autoignition and Strong Pressure Wave Formation during Knock in a Supercharged SI Engine Based on High Speed Photography of the End Gas
Authors: Iijima Akira , Izako Takuya , Ishikawa Takahiro , Yamashita Takahiro , Takahata Shuhei , Kudo Hiroki , Shimizu Kento , Tanabe Mitsuaki , Shoji Hideo
Published: April 2023

Engine knock is the one of the main issues to be addressed in developing high-efficiency spark-ignition (SI) engines. In order to improve the thermal efficiency of SI engines, it is necessary to develop effective means of suppressing knock. For that purpose, it is necessary to clarify the mechanism generating pressure waves in the end-gas region. This study examined the mechanism producing pressure waves in the end-gas autoignition process during SI engine knock by using an optically accessible engine. Occurrence of local autoignition and its development process to the generation of pressures waves were analyzed under several levels of knock intensity. The results made the following points clear. It was observed that end-gas autoignition seemingly progressed in a manner resembling propagation due to the temperature distribution that naturally formed in the combustion chamber. Stronger knock tended to occur as the apparent propagation speed of autoignition increased. It is particularly notable that a condition was observed in which the apparent propagation speed of autoignition through the end gas clearly exceeded the speed of sound. Exceptionally strong knock occurred at that time. The measured results for the actual development of autoignition made it clear that extremely strong knock, such as what occurs under high-speed, high-load operation and also that induced by low-speed pre-ignition (LSPI) in a supercharged downsized engine under low-speed, high-load operation (Super-Knock), is presumably caused by such phenomena. In other word, extremely strong knock is caused by detonation phenomena produced in autoignition process.
Development of a Neck Finite Element Model with Active Muscle Force for the THOR-50M Numerical Dummy
Authors: Wu Xiaofan , Jiang Binhui , Bai Zhonghao , Zhang Guanjun
Published: April 2023

With the development of active safety technology, effort has gradually shifted to preventing or minimizing car crashes. Automatic Emergency Braking Technology (AEB) can avoid accidents by warning and even automatic braking, but there is a contradiction between the accompanying occupant out-of-position and traditional passive safety design. In addition, the 2025 version of C-NCAP plans to add neck injury assessment requirements for AEB [1]. In order to study the kinematic response of the occupant's neck under AEB, a neck finite element model with active muscle force is established in this paper. Firstly, the open-source THOR-50M neck geometric model is used for finite element discretization. Secondly, the neck FE model of THOR-50M is verified through the qualification procedure of the NHTSA standard. Thirdly, according to the geometric features of human neck muscles in Zygote Body database, the neck muscle parameters are preliminarily determined. Finally, the neck muscle parameters are corrected based on the occupant out-of-position test under AEB conditions. The benchmarking results show the model can truly reflect the head and neck movements of the occupants under AEB conditions. The neck FE model developed in this work can be used for the development and test evaluation of intelligent occupant restraint systems.
Exploration of Vehicle Body Countermeasures Subjected to High Energy Loading
Authors: Ramachandra Sanketh , Deb Anindya , Chou Clifford
Published: April 2023

Enhanced protection against high speed crashes requires more aggressive passive safety countermeasures as compared to what are provided in vehicle structures today. Apart from such collision-related scenarios, high energy explosions, accidentally caused or otherwise, require superior energy-absorbing capability of vehicle body subsystems. A case in point is a passenger vehicle subjected to an underbody blast emanating shock wave energy of military standards. In the current study, assessment of the behavior of a “hollow” countermeasure in the form of a depressed steel false floor panel attached with spot-welds along flanges to a typical predominantly flat floor panel of a car is initially carried out with an explicit LS-DYNA solver. This is followed up with the evaluation of PU (polyurethane) foam-filled and liquid-filled false floor countermeasures. In all cases, a charge is detonated under the false floor subjecting it to a high-energy shock pressure loading. For the case of the liquid-filled countermeasure, a novel ALE (Arbitrary Lagrangian-Eulerian) formulation for fluid-structure interaction has been adopted with a Hybrid III dummy seating above the flat floor with a modified MIL-LX legform for injury prediction. In order to establish confidence on the ALE model, a drop-weight impact test on a liquid-filled square aluminum tube has been carried out and its behavior predicted, prior to the analysis of the countermeasures mentioned. It appears that the fluid-filled countermeasure is a promising solution in countering the effects of a shock pressure loading by greatly reducing the load transferred to the lower limb of an occupant sitting right above a detonated charge placed under the floor of a car.
An Evaluation of the Performance of the WABCO OnGuardACTIVE Collision Mitigation System in a 2019 Freightliner M2 106
Authors: Harrington Shawn , Ward Bill
Published: April 2023

Testing was conducted in daytime and nighttime conditions at four speeds – 35, 50, 55, and 60 miles per hour (mph) – to evaluate the performance of the audible and visual forward collision warning (FCW) system in a WABCO OnGuardACTIVE collision mitigation system (CMS) while approaching a foam stationary vehicle target (SVT). Testing measured the time to collision (TTC) values utilizing a VBOX data acquisition system as well as an “analog” system utilizing synced cameras and a reference line painted on the test track. WABCO Toolbox was utilized to download OnGuard data from the Freightliner after each test; this data was then compared to the data acquired by the VBOX data acquisition system. The results of the testing provide valuable information to collision investigators on the performance of the WABCO OnGuardACTIVE Collision Mitigation System on stationary vehicles. In addition, a review of the data imaged from the OnGuardACTIVE’s radar using WABCO Toolbox will be compared to the testing data.
An Evaluation of the Performance of the Bendix Wingman Advanced Collision Mitigation System in a 2018 & 2019 International 4300
Authors: Harrington Shawn , Lieber Victoria
Published: April 2023

The Bendix Wingman Advanced – a radar-only collision mitigation system (CMS) available on commercial vehicles – was evaluated in two separate test series to determine its performance in simulated stationary vehicle rear collision scenarios. In the first series of tests, evaluations were conducted in daytime and nighttime conditions at two speed ranges – 35 and 45-50 miles per hour (mph) – to evaluate the performance of the audible and visual forward collision warning (FCW) system in a Bendix Wingman Advanced CMS while approaching a stationary vehicle target (SVT) in a 2018 International 4300. Two years later, a second test series was conducted with a 2019 International 4300 traveling between 15 – 55 mph in low light and nighttime conditions approaching the SVT to evaluate the Bendix Wingman Advanced CMS on the truck. Both test series sought to determine the maximum speed the system would warn prior to the test driver swerving around the SVT. The tests utilized a foam stationary vehicle target built using Euro NCAP specifications as a guide. Testing measured the time to collision (TTC) values utilizing VBOX data acquisition equipment as well as an “analog” system utilizing synced cameras and a reference line painted on the test track. The TTC at the left evasive steering maneuver by the test driver to avoid the stationary vehicle target was typically between 1.0 – 1.5 seconds. The results of the two series of tests provide valuable information about the performance of the Bendix Wingman Advanced CMS approaching stationary vehicles in rear collision scenarios.
Real-Time Estimation of Perception Sensor Misalignment in Autonomous Vehicles
Authors: Meyer Richard
Published: April 2023

Autonomous vehicles rely upon accurate information about their surrounding environment to perform safe operational planning. The environment sense and perception system normally produces camera image data and LiDAR point cloud data that are processed and then fused to obtain a better perception of the environment than is possible from either alone. The accuracy of the fused data depends upon knowledge of the position of each sensor on the ego vehicle. Vehicle damage, improper sensor installation, sensor mount deformation, mount movement excited by vehicle motion, and/or other situations can result in an unexpected position of the sensor. This error adds uncertainty into the sensor measurement fusion that is normally not accounted for. LiDAR translational offset and angular orientation misalignment errors are investigated for correction. The correction approach, derived from camera image information, is based upon an error-in-variables recursion that takes into account errors from LiDAR angular and ranging uncertainties that increase with distance due to beam spread. The proposed approach incorporates approximations of these errors to make continuous updates to the estimates of the LiDAR misalignment. The approach, with and without noise included, is compared to recursive least squares and nonlinear least squares in simulated traffic of various speeds and positions relative to the ego vehicle. Results show that nonlinear least squares provides the best overall performance (based upon an error metric) since it utilizes the whole data set at once to produce an estimate. However, the proposed approach without noise gave similar or better misalignment estimates compared to the other recursive methods and is the overall preferred recursive method since it has lower computational complexity than the proposed approach with noise. Further, recursive least squares provides acceptable online misalignment estimates at low computational complexity when the angular error is less than or equal to 10°.
Impact of BEV Introduction in Japan on the Power Generation Mix and CO2 Emission through Demand-Side Optimization by BEV Charging and Discharging
Authors: Honda Atsuo , Ogimoto Kazuhiko , Iwafune Yumiko , Azuma Hitoshi
Published: April 2023

The purpose of this paper is to make quantitative analysis on the effect of demand side optimization, especially on the reduction of CO2 emission realized by optimizing charging and discharging schedule of battery electric vehicles (BEVs), or by optimized Vehicle-to-Grid (V2G) operations. BEV optimization model is incorporated into the existing electricity supply-demand model to study how the introduction of BEVs make differences on a power system operation, composition of power generation and CO2 emission on the power supply side. Three cases of BEV operation are studied, 1) dumb charging without optimization, 2) optimization of charging, 3) optimization of charging and discharging with Vehicle-to-Grid operations. Analysis is also made on how de-carbonization of the supply side will make differences by studying the case of 2035 and 2040 in addition to 2030, the target year of Japan’s new national energy plan.

The analysis showed that, as an important use case of a demand side optimization, BEVs will contribute to the reduction of CO2 emission in Japan by elaborately coordinating the introduction process of BEVs with the de-carbonization of the power supply side and with the degree of development of social environment to realize the demand side optimization.
The Jetq-Family - New Highly Ductile AHSS Steel Grades with Improved Technological Properties
Authors: Irnich Manuela , Thiessen Richard , Paton Adrian , Sato Kentaro , Toji Yuki , Minami Hidekazu
Published: April 2023

New highly ductile AHSS steel grades with tensile strength greater than 980 MPa have been developed with the aim of combining high strength and excellent formability. The new jetQ-Family offers high local and global ductility while still fulfilling standards for resistance towards hydrogen embrittlement and weldability. These improved properties are based on their specifically engineered microstructure, which utilize the TRIP-mechanism in a strengthened matrix. This work shows how the microstructure plays a significant role for the tensile testing as well as hole-expansion. Based on the increased yield strength a better crash performance compared to conventional DP steel grades can be attained. The local ductility is demonstrated with excellent hole expansion ratios and high resistance to sheared edge failure. In combination with improved bending angles and thickness strain at fracture a robust process for manufacturing of components can be achieved. The results are completed by the characterization of resistance spot welding and the resistance towards hydrogen embrittlement. The jetQ-Family with its optimized property profile will contribute to greater safety and efficiency in vehicle bodies.
Study on Local Stress Variable Strength Design Effect of B-Pillar Structure
Authors: Zheng Yuqing , Chen Yanli , Nie Xiaojing , Zhu Xichan
Published: April 2023

In this paper, the principles, advantages and disadvantages of the main technology of variable strength design of automobile B-pillar Based on the finite element simulation technology, the local stress variable strength design effect of Automobile B-pillar structure is simulated, compared and evaluated. The simulation results show that with the same mechanical properties, the overall lightweight degree of B-pillar structure with variable strength design can be reduced by about 8.9%. With the expansion of the strengthening area of variable strength design of parts, the degree of lightweight of parts can be further improved. It can be seen that the local stress variable strength design method provides a new technical option for the lightweight design of automobile parts.
Nested vs. Non-Nested Sampling: Definition of an Infilling Strategy for Multi-Fidelity Bayesian Optimization Based on Data Correlation
Authors: Favaretti Piero
Published: April 2023

The multi-fidelity Bayesian optimization of large models with multiple parameters can be computationally very expensive and thereby the proper choice of the infilling strategy is crucial to minimize the required convergence time. If, on one hand, nested infilling guarantees a better performance of the multi-fidelity Gaussian algorithm, on the other hand the new samples added at every iteration and at all levels represent a non-negligible cost factor. In this paper the two alternative infilling approaches, nested and non-nested sampling, are analyzed for a family of data sets, each one characterized by a different correlation factor. The aim is to establish for each case the best option that minimizes the computational time and thus a connection between correlation level of the data and infilling strategy. Three data sets are investigated: low, medium and highly correlated data in accordance with their correlation matrix calculated ex ante knowing the exact solutions in the entire domain. The total process time is given by the summation for each iteration of the time required for the single acquisition and this variable depends not only on the infilling strategy, single or multilevel, but also on the single level acquisition itself assuming that adding points on the high-fidelity level is more expensive than on the low-fidelity level. For this reason a weighted selection of the acquisition function (AQF) is defined. The exact data correlation factor (DCF) is in real cases unknown but the partial data correlation factor based on the available data can already provide useful information. The present study has general validity but it has been especially designed as preliminary investigation for the optimization of a laser welding process.
Actively Articulated Wheeled Architectures for Autonomous Ground Vehicles - Opportunities and Challenges
Authors: Mehta Dhruv , Kosaraju Krishna Chaitanya , Krovi Venkat N
Published: April 2023

Traditional ground vehicle architectures comprise of a chassis connected via passive, semi-active, or active suspension systems to multiple ground wheels. Current design-optimizations of vehicle architectures for on-road applications have diminished their mobility and maneuverability in off-road settings. Autonomous Ground Vehicles (AGV) traversing off-road environments face numerous challenges concerning terrain roughness, soil hardness, uneven obstacle-filled terrain, and varying traction conditions. Numerous Active Articulated-Wheeled (AAW) vehicle architectures have emerged to permit AGVs to adapt to variable terrain conditions in various off-road application arenas (off-road, construction, mining, and space robotics). However, a comprehensive framework of AAW platforms for exploring various facets of system architecture/design, analysis (kinematics/dynamics), and control (motions/forces) remains challenging. While current literature on the AAW system incorporates modeling and control from the legged and wheeled-legged robots community, it lacks a systematic process of architecture selection and motion control that should be developed around critical quantifiable performance parameters. This paper will: (i) analyze a broad body of literature; and (ii) identify modeling and control techniques that can enable the efficient development of AAW platforms. We then analyze key performance measures with respect to traversability, maneuverability, and terrainability, along with an experimental simulation of an AAW vehicle traversing over uneven terrain and how active articulation could achieve some of the critical performance measures. Against the performance parameters, gaps within the existing literature and opportunities for further research are identified to potentially enhance AAW platforms’ performance.
Formal Verification of Autonomous Vehicles: Bridging the Gap between Model-Based Design and Model Checking
Authors: Rao Ananya , Wang Yue
Published: April 2023

Formal verification plays an important role in proving the safety of autonomous vehicles (AV). It is crucial to find errors in the AV system model to ensure safety critical features are not compromised. Model checking is a formal verification method which checks if the finite state machine (FSM) model meets system requirements. These requirements can be expressed as linear Temporal logic (LTL) formulae to describe a sequence of states with linear Temporal properties to be satisfied. NuSMV is a dedicated software for performing model checking based on Temporal logic formulae on FSM models. However, NuSMV does not provide model-based design. On the other hand, Stateflow in MATLAB/SIMULINK is a powerful tool for designing the model and offers an interactive Graphical User Interface (GUI) for the user/verifier but is not as efficient as NuSMV in model checking. Hence, model transformation becomes vital to convert the AV model in Stateflow to an input language of model checking software such as NuSMV. In this paper, we model an AV using Stateflow, which consists of cruise control, lane change/abortion, obstacle avoidance and gap maintenance blocks in the form of FSMs. We design an automatic verification tool to perform model transformation using a C compiler with NuSMV library included. Guard conditions are represented by Boolean expressions to capture the transition sequence between different blocks. LTL specifications of safety critical requirements are verified to guarantee the validity of the AV system design. When guard conditions fail, i.e., system requirements are not met, the verification tool will give a counterexample as the output. A case study is performed to show how this verification tool can help designers to make modifications based on the counterexamples to better meet the system requirements. We also perform a benchmark verification using the design verifier in SIMULINK to compare the performance. 1
Failure Assessment of Electronics Component under Gravel Bombardment Test in Automotive Electronics
Authors: Hande Madhura , Wojcik Marek
Published: April 2023

Exposing sensors to environment without any physical protection introduces risk of failure due to collision with small hard objects like stones. This type of interaction is tested during product validation by usage of gravel bombardment procedures, originally designed for evaluating resistance of surface coating to chipping by gravel impact. While useful for practitioners, this procedure is difficult to be used during product design and virtual validation since it does not provide statistical measures regarding gravel size, mass or velocity distribution of moving gravels. Consequently, computer simulation must assume certain properties of impactors. The following simulation methodology evaluates risks associated with gravel bombardment test. It is based on impact force transmission through interconnects belonging to big and/or critical electronic components.
Study of Vibroacoustics in Fluid-Coupling System
Authors: Krishnan Paranthaman , Yang Zane , Velayudham Vijayakumar , Duraipandi Arumuga Pandian
Published: April 2023

In recent years, the electric vehicle industry has been booming rapidly to decarbonize the world. One of the major concerns in an electric vehicle is the noise emitted from the electric powertrain system, which affects the driving comfort assistance in electric vehicles. Thus, we have to find the methodology to measure the noise level in an automotive transmission system during the design stage itself. This drives us to develop the methodology on a simple design, having a structural and fluid coupling and then followed by an acoustics analysis. A Transient CFD simulation is performed to generate an excitation source for noise; excitation forces observed in the transient simulation are converted into the frequency domain by performing a fast Fourier transform (FFT). To understand this structural behavior, modal analysis is performed for a simple test model to identify the critical modes. Harmonic excitation sources from CFD fluid coupling are imported to a structural model, replicating the transient phenomenon in the frequency domain. Then harmonic velocity calculated from the dynamic responses is fed into the acoustic system where anechoic chambers are modeled to sensitize the different parameters such as radiation boundary and absorption condition. In this paper, we discussed in detail the acoustics methodology by considering the pressure load from the fluid interactions to excite the structural vibration of the system and studying the different acoustic wave absorption conditions that represent the operating environment. Finally, also presented is how the noise level is changed when we change the different design parameters by using the proposed methodology.
Analysis of the Multi-Zone SI-Engine Model for Fuel-Flexible Engine Design Applications
Authors: Zaev Ivan , Smirnov Sergey , Kostukov Andrey
Published: April 2023

Development of fuel-flexible spark-ignition engines, working on CNG, LPG, hydrogen-enriched fuels or with mixtures of gaseous fuel/gasoline requires models for prediction of heat release rate, which can capture the effect of fuel composition and combustion chamber geometry on engine performance and emissions. Multi-zone models with explicit tracking of turbulent flame surface can be used for this purpose. Coupled with detailed chemical kinetic mechanisms, these models can also predict self-ignition of unburned charge ahead of the flame front. When optimizing engine performance and emissions in a fuel-flexible mode, the key question is sensitivity of the multi-zone model parameters to the properties of the fuel. In the present work, the multi-zone model of the CFR engine is developed based on Blizard-Keck eddy burn-up flame propagation approach for prediction of flame propagation and heat release rate. Model parameters are time constant for flame development, eddy entrainment rate constant for unburned mixture, time constant of burn-up in turbulent eddies. The simulations are performed for number of fuels: PRF and LPG components. The set of mentioned parameters is determined for every fuel and corresponding compression ratios used in experiments. It is shown that these parameters demonstrate only a slight sensitivity to fuel selected and can be used for prediction of fuel effects on engine performance. It is identified that for the model parameters to be true constants, the correct selection of turbulence integral length scale is required. Also, it is shown that the accurate correlation for laminar flame speed as function of unburned mixture state is required for the model to provide reasonable accuracy and predictive capability. New laminar flame speed correlations for n-butane, iso-butane and propylene are proposed.
Real-Time Simulation of CNG Engine and After-Treatment System Cold Start Part 1: Transient Engine-Out Emission Prediction Using a Stochastic Reactor Model
Authors: Siddareddy Reddy Babu , Franken Tim , Pasternak Michal , Leon de Syniawa Larisa , Oder Johannes , Rottengruber Hermann , Mauss Fabian
Published: April 2023

During cold start of natural gas engines, increased methane and formaldehyde emissions can be released due to flame quenching on cold cylinder walls, misfiring and the catalyst not being fully active at low temperatures. Euro 6 legislation does not regulate methane and formaldehyde emissions. New limits for these two pollutants have been proposed by CLOVE consortium for Euro 7 scenarios. These proposals indicate tougher requirements for aftertreatment systems of natural gas engines.

In the present study, a zero-dimensional model for real-time engine-out emission prediction for transient engine cold start is presented. The model incorporates the stochastic reactor model for spark ignition engines and tabulated chemistry. The tabulated chemistry approach allows to account for the physical and chemical properties of natural gas fuels in detail by using a-priori generated laminar flame speed and combustion chemistry look-up tables. The turbulence-chemistry interaction within the combustion chamber is predicted using a K-k turbulence model. The optimum turbulence model parameters are trained by matching the experimental cylinder pressure and engine-out emissions of nine steady-state operating points.

Subsequently, the trained engine model is applied for predicting engine-out emissions of a WLTP passenger car engine cold start. The predicted engine-out emissions comprise nitrogen oxide, carbon monoxide, carbon dioxide, unburnt methane, formaldehyde, and hydrogen. The simulation results are validated by comparing to transient engine measurements at different ambient temperatures (-7°C, 0°C, 8°C and 20°C). Additionally, the sensitivity of engine-out emissions towards air-fuel-ratio (λ=1.0 and λ=1.3) and natural gas quality (H-Gas and L-Gas) is investigated.
Experimental and Numerical Analysis of an Active Pre-Chamber Engine Fuelled with Natural Gas
Authors: Riccardi Marco , De Bellis Vincenzo , Sforza Lorenzo , Tunestal Per , Bozza Fabio , Beatrice Carlo , Lucchini Tommaso
Published: April 2023

Increasingly stringent pollutant and CO2 emission standards require the car manufacturers to investigate innovative solutions to further improve the fuel economy and environmental impact of their fleets. Nowadays, NOx emissions standards are stringent for spark-ignition (SI) internal combustion engines (ICEs) and many techniques are investigated to limit these emissions. Among these, an extremely lean combustion has a large potential to simultaneously reduce the NOx raw emissions and the fuel consumption of SI ICEs. Engines with pre-chamber ignition system are promising solutions for realizing a high air-fuel ratio which is both ignitable and with an adequate combustion speed.

In this work, the combustion characteristics of an active pre-chamber system are experimentally investigated using a single-cylinder research engine. The engine under exam is a large bore heavy-duty unit with an active pre-chamber fuelled with compressed natural gas.

In first stage, an experimental campaign was carried out for four different conditions of load and air/fuel ratio, at the same engine speed, then a 3D CFD analysis was realised to evaluate the in-cylinder turbulence and pre-chamber pressure traces. Global engine operating parameters as well as cylinder pressure traces, inside main combustion chamber and pre-chamber, were recorded and analysed. Based on the available 3D and experimental data, a phenomenological model of this unconventional combustion system is developed and validated.

The model is implemented in a commercial 1D code. The proposed numerical approach shows the ability to simulate the experimental data with good accuracy, with no case-dependent tuning. The model demonstrates to correctly describe the behaviour of a pre-chamber combustion system under the four operating conditions and to capture the physics behind such an innovative combustion system concept.
Effect of Fuel and Driving Conditions on Pollutant Emissions from a Diesel Vehicle – A Simulation Study
Authors: Cuaical Víctor , Dominguez Sara , Valencia Ana María , Ramírez Ricardo , Botero Maria Luisa , Bustamante Felipe
Published: April 2023

Pollutant emissions from vehicles depend on both fuel and driving conditions. This work investigates the impact of using a 20% (V/V) biodiesel blend (B20) on the CO2, NOx, and particle number emissions of a light-duty diesel vehicle, using GT-Suite® software. Combustion parameters and emissions were experimentally measured in a Cummins ISF 2.8 L diesel engine and used as inputs for the model. Vehicle simulations using ULSD and B20 were performed for the standard WLTC driving cycle as well as driving cycles representative of Andean cities, that include steep road slopes and heavy traffic. Additionally, simulations considered three gear-shifting strategies, one based on dynamic gear selection and two on imposed-speed thresholds for each gear shift.

Results show that using B20 decreases the particle number emissions in 39 – 79% for the tested driving cycles and gear-shifting strategies. Meanwhile, fuel change showed no significant effect on CO2, and NOx emissions were slightly increased between 3 and 11% in the studied cases. Higher emission factors for all pollutants were found with the Andean driving cycles when compared to WLTC, increasing up to 204% in the scenario that included road slope. Regarding the gear-shifting strategies, imposed-speed strategy NEDC led to the lowest fuel consumption and PN emissions, and NBR led to the lowest NOx emissions, while the dynamic strategy led to the highest NOx emissions, with a fuel consumption very similar to NBR strategy.
Zero Dimension Heat Release Modeling for Gasoline, Ethanol, Isobutanol and Diisobutylene Operating in Compression Ignition with Varying Injection Strategies
Authors: Peng Qian , Rockstroh Toby , Hall Carrie , Pamminger Michael
Published: April 2023

Gasoline compression ignition shows great potential in reducing NOx and soot emissions with competitive thermal efficiency by leveraging the properties of gasoline fuels and the high compression ratio of compression ignition engines operating air-dilute. Meanwhile, its control becomes challenging due to not only the properties of different gasoline-type fuels but also the impacts of injection strategies on the in-cylinder reactivity. As such, a computationally efficient zero-dimension combustion model can significantly reduce the cost of control development. In this study, a previously developed zero-dimension combustion model for gasoline compression ignition was extended to multiple gasoline-type fuel blends and a port fuel injection/direct fuel injection strategy. Tests were conducted on a 12.4-liter heavy-duty engine with five fuel blends. A modification was made to the functional ignition delay model to cover the significantly different ignition delay behavior between conventional and oxygenated fuel blends. The parameters in the model were calibrated with only gasoline data at a load of 14 bar brake mean effective pressure. The results showed that this physics-based model can be applied to the other four fuel blends at three different pilot injection strategies without recalibration. For all tests, the error of the maximum pressure is within 14 bar, and that of combustion phasing and indicated mean effective pressure is within 2 CAD and 1.1 bar, respectively. In addition, the model was validated with 7 bar BMEP data and had the same level of accuracy as the 14 bar cases.
Model Based Development for Super Lean Burn Gasoline Engine Using Kolmogorov Microscales
Authors: SAKAI Hiroyuki , Kimura Koshiro , Omura Tetsuo , Takahashi Daishi
Published: April 2023

Combustion in a lean atmosphere diluted with a large amount of air can greatly improve fuel efficiency by reducing cooling loss [1, 2]. On the other hand, when air-fuel mixture in cylinder becomes lean, the turbulent combustion speed will decrease, resulting in problems such as the generation of unburned hydrocarbon (HC) and combustion instability [3, 4]. In order to solve these problems, it is important to increase the turbulence intensity and combustion speed [5, 6, 7, 8, 9, 10].

When designing combustion in cylinder by using Computational Fluid Dynamics (CFD), K-epsilon model is widely used for a turbulence model, and the calculated turbulence energy k or turbulence intensity u’ have been used as important indices of combustion velocity [11, 12]. However, it has been confirmed by measurements that the flow will conversely weaken near the top dead center and the combustion duration will become longer when the air flow in the cylinder is extremely strengthened by improved intake port. This phenomenon can be expressed by using Large Eddy Simulation (LES) instead of K-epsilon model as a turbulence model, so K-epsilon model cannot be used for future combustion development including lean burn, and LES is critical. This paper proposes a model-based development method for designing engine combustion by using LES and Kolmogorov scale.
CFD Modeling of a DME CI Engine in Late-PCCI Operating Conditions
Authors: Schirru Andrea , Hardy Gilles , Wright Yuri M. , Lucchini Tommaso , D'Errico Gianluca , Soltic Patrik , Hilfiker Thomas
Published: April 2023

Predictive combustion models are useful tools towards the development of clean and efficient engines operating with alternative fuels. This work intends to validate two different combustion models on compression-ignition engines fueled with Dimethyl Ether. Both approaches give a detailed characterization of the combustion kinetics, but they substantially differ in how the interaction between fluid-dynamics and chemistry is treated. The first one is single-flamelet Representative Interactive Flamelet, which considers turbulence-kinetic interaction but cannot correctly describe the stabilization of the flame. The second, named Tabulated Well Mixed, correctly accounts for local flow and mixture conditions but does not consider interaction between turbulence and chemistry. An experimental campaign was carried out on a heavy-duty truck engine running on DME at a constant load considering trade-off of EGR and SOI. Simulations results of 10 operating conditions show that both models can be successfully employed to predict cylinder pressure, heat release rate and pollutant emissions.
Multi-Dimensional Spark Ignition Model for Arc Propagation and Thermal Energy Deposition with Crossflow
Authors: Hall Matthew , Kim Kyeongmin , Tambasco Corey , Matthews Ron
Published: April 2023

A multi-dimensional model of the spark ignition process for SI engines was developed as a user defined function (UDF) integrated into the commercial engine simulation software CONVERGE CFD. The model simulates spark plasma movement in an inert flow environment without combustion. The UT model results were compared with experiments for arc movement in a crossflow and also compared with calorimeter measurements of thermal energy deposition under quiescent conditions. The arc motion simulation is based on a mean-free-path physical model to predict the arc movement given the contours of the crossflow velocity through the gap and the interaction of the spatially resolved electric field with the electrons making up the arc. A further development is the inclusion of a model for the thermal energy deposition of the arc as it is stretched by the interaction of the flow and the electric field. A novel feature of this model is that the thermal energy delivered to the gap at the start of the simulation is distributed uniformly along the arc rather than at discrete points along the arc, as is the case with the default CONVERGE CFD ignition models. This feature was found to greatly reduce the tendency of the arc to distort its shape and tangle itself in a non-physical way, as is the tendency when discrete energy input is used. It was found that the tangled distortion of the arc when using discrete energy input was due to perturbations along the arc caused by differential expansion of the gas along groups of adjacent mesh cells that either had energy input or did not. The distributed energy feature also gave arc temperature distributions that were more spatially uniform and had steeper temperature gradients, consistent with experimental arc images. The results are compared with experimental high-speed video images of arc movement for a spark plug of similar geometry and taken over a range of pressures and crossflow velocities in a high-pressure constant volume vessel. There is good agreement between the simulations and experimental images for the arc stretch distance in response to a crossflow. The simulations did not display as much lateral arc dispersion as seen in the experimental results, however, that were perhaps associated with flow recirculation zones downstream of the gap, present in the experiments. The influence of the electric field was shown by turning off the electric field effect in the simulations such that the arc movement was influenced by the flow field alone. The effect of the electric field was found to be more pronounced at lower crossflow velocities of 5 m/s and at lower pressures.
Turbogenerator Transient Energy Recovery Model
Authors: Petrovich Simon , Ebrahimi Kambiz , Watson Andrew , Mason Byron
Published: April 2023

Significant exhaust enthalpy is wasted in gasoline turbocharged direct injection (GTDI) engines; even at moderate loads the WG (Wastegate) starts to open. This action is required to reduce EBP (Exhaust Back Pressure). Another factor is catalyst protection, placed downstream turbine. Lambda enrichment is used to perform this. However, the conventional turbine has a temperature drop across it when used for energy recovery.

Catalyst performance is critical for emissions, therefore the only location for any additional device is downstream of it. This is a challenge for any additional energy recovery, but a smaller turbine is a design requirement, optimised to work at lower operating pressure ratios.

A WAVE model of the 2.0L GTDI engine was adapted to include a TG (Turbogenerator) and TBV (Turbine Bypass Valve) with the TG in a mechanical turbocompounding configuration, calibrated with steady state dynamometer data to estimate drive cycle benefit. The model derived is used in the development of more advanced control system algorithms. Furthermore, transient verification with WAVE-RT in co-simulation is performed on drive cycles (NEDC, WLTP).

Analysis includes power and fuel consumption, and an additional knock impact assessment. It is shown on the WLTP that, depending on the calibration, up to 9% FC (Fuel Consumption) reduction is achievable with a 0.03kW thermodynamic power recovery, for a similar controller performance. Hints are given for further controller enhancements.

Prototype dynamometer testing or vehicle could be performed to verify design assumptions and simulation results. Electrical turbo-compounding, interfacing to the power-grid, and calibration optimisation, with combined WG and TBV settings is feasible based on this initial work.
Analysis of Cycle-to-Cycle Variation in In-Cylinder Flow and Combustion by Using Simultaneous PIV Measurements on Two Sections
Authors: Moriyoshi Yasuo , Hokimoto Satoshi , Kuboyama Tatsuya , kaneko Makoto
Published: April 2023

To realize stable combustion in lean or diluted conditions, reducing cycle-to-cycle variations of flow and fuel distribution is important. In this study, the effect of initial flow field was examined by simultaneous Time-Resolved PIV and visualization on two cross-sections in a fully optical-access engine under motoring and firing conditions with homogeneous pre-mixture. As a result, Omega index was defined and plotted on the correlation map between turbulence kinetic energy and CA10 (duration from ignition timing to 10% to the total accumulated heat). The omega index describes the strength of a horizontal flow field that resembles the shape of the Greek letter Omega. The plots with high Omega index were found frequently in the CA10 retarded cycles. On the other hand, the plots with low Omega index have simple tumble flows and the correlation was clearly found. This means that not only turbulence but also mean velocity’s pattern are important for the estimation parameter of cycle-to-cycle variation. As a result, it was found that the initial tumble should be given as “outside-fast” and then, a nearly homogeneous tumble was formed near spark timing without an Omega flow.