Refine Your Search

Topic

Author

Affiliation

Search Results

Technical Paper

Numerical Evaluation of Gasoline Compression Ignition at Cold Conditions in a Heavy-Duty Diesel Engine

2020-04-14
2020-01-0778
Achieving robust ignitability for compression ignition of diesel engines at cold conditions is traditionally challenging due to insufficient fuel vaporization, heavy wall impingement, and thick wall films. Gasoline compression ignition (GCI) has shown good potential to offer enhanced NOx-soot tradeoff with diesel-like fuel efficiency, but it is unknown how the volatility and reactivity of the fuel will affect ignition under very cold conditions. Therefore, it is important to investigate the impact of fuel physical and chemical properties on ignition under pressures and temperatures relevant to practical engine operating conditions during cold weather. In this paper, 0-D and 3-D computational fluid dynamics (CFD) simulations of GCI combustion at cold conditions were performed.
Technical Paper

An analytical energy-budget model for diesel droplet impingement on an inclined solid wall

2020-04-14
2020-01-1158
The study of spray-wall interaction is of great importance to understand the dynamics that occur during fuel impingement onto chamber wall or piston surfaces in internal combustion engines. The maximum spreading length after droplet impingement on wall is approved that it can provide a quantitative estimation of heat transfer and energy transformation for spray-wall interaction and further influence air-fuel mixing and hydrocarbon and particle emissions at combusting conditions. In this paper, an analytical model of a single diesel droplet impinging on the wall with different inclined angle (α) under isothermal conditions (liquid droplet and wall with the same temperature) is developed in terms of β_m (the ratio of maximum spreading length to initial droplet diameter) to understand the detailed impinging dynamic process.
Technical Paper

Numerical Analysis of Fuel Impacts on Advanced Compression Ignition Strategies for Multi-Mode Internal Combustion Engines

2020-04-14
2020-01-1124
Multi-mode combustion strategies may provide a promising pathway to improve thermal efficiency in light-duty spark ignition (SI) engines by enabling switchable combustion modes, wherein an engine may operate under advanced compression ignition (ACI) at low load and spark-assisted ignition at high load. The extension from the SI mode to the ACI mode requires accurate control of intake charge conditions; e.g., pressure, temperature and equivalence ratio, in order to achieve stable combustion phasing and rapid mode-switches. This study presents results from computational fluid dynamics (CFD) analysis to gain physical insights into mixture charge formation and combustion dynamics pertaining to auto-ignition processes.
Technical Paper

Combustion System Optimization of a Light-Duty GCI Engine Using CFD and Machine Learning

2020-04-14
2020-01-1313
In this study, the combustion system of a light-duty compression ignition engine running on a market gasoline fuel with Research Octane Number (RON) of 91 was optimized using computational fluid dynamics (CFD) and Machine Learning (ML). The focus of this study was to optimize the piston bowl geometry at two compression ratios (CR) (17 and 18:1) and this exercise was carried out at full-load conditions (22bar indicated mean effective pressure (IMEP). CAESES, a commercial software tool, was used to automatically perturb key bowl design parameters and CONVERGE software was utilized to perform all CFD simulations. 128 piston bowl designs were evaluated at each compression ratio. Subsequently, a Machine Learning-Grid Gradient Algorithm (ML-GGA) approach was developed to further optimize the piston bowl design. This extensive optimization exercise yielded significant improvements in the engine performance and emissions compared to the baseline piston bowl designs.
Technical Paper

Performance of a Printed Bimetallic (Stainless Steel and Bronze) Engine Head Operating Under Stoichiometric and Lean SI Combustion of Natural Gas

2020-04-14
2020-01-0770
The purpose of this study was to evaluate the durability and operational performance of a bimetallic (stainless steel and bronze) natural gas engine head. The performance was evaluated against a stock cast iron head for comparison. During manufacturing of the printed head, efforts were made to ensure that the internal features, including the fire deck geometry for the two head were identical. The engine was operated under two engine speeds (1200 rpm and 1800 rpm) and two Brake Mean Effective Pressures (6 bar and 10 bar). For each speed and BMEP combination, two equivalence ratios (0.7 and 1.0) were evaluated. In addition to emissions and engine performance data, the research team also took thermal images of both operating heads to ascertain heat transfer and thermal loss differences between the two head materials. The results showed that the brake efficiency, coolant and exhaust temperature were the same for both heads.
Technical Paper

Detailed Analysis of U.S. Department of Energy Engine Targets Compared To Existing Engine Technologies

2020-04-14
2020-01-0835
The U.S. Department of Energy, Vehicle Technologies Office (U.S. DOE-VTO) has been developing more energy-efficient and environmentally friendly highway transportation technologies that would enable the United States to burn less petroleum on the road. System simulation is an accepted approach to evaluate the fuel economy potential of advanced (future) technology targets. U.S. DOE-VTO defines the targets for advancement in powertrain technologies (e.g., engine efficiency targets, battery energy density, lightweighting, etc.) Vehicle system simulation models based on these targets have been generated in Autonomie, to reflect the different EPA classifications of vehicles for different advanced timeframes as part of DOE Benefits and Scenario Analysis (BaSce). It is also important to evaluate the progress of these component technical targets compared to existing technologies available in the market.
Technical Paper

Potential analysis and virtual development of SI Engines operated with synthetic fuel DMC+

2020-04-14
2020-01-0342
On the way to emission-free mobility, future fuels must be CO2 neutral. To achieve this, synthetic fuels are being developed. In order to better assess the effects of the new fuels on the engine process, simulation models are being developed that reproduce the chemical and physical properties of these fuels. In this paper, the fuel DMC+ is examined. DMC+ (a mixture of DMC and MeFo mainly, characterized by the lack of C-C Bonds and high oxygen content) offers advantages with regard to evaporation heat, demand of oxygen and knock resistance. Furthermore, its combustion is almost particle free. With the aid of modern 0D/1D-Simulation methods, an assessment of the potential of DMC+ can be made.
Technical Paper

Analysis of Drivability Influence on Tailpipe Emissions by Means of Engine-in-the-Loop Test Benches

2020-04-14
2020-01-0373
Due to increasing environmental awareness, standards for pollutant and CO2 emission legislations are getting stricter in most markets around the world. In important markets such as Europe, also the emissions during driving on real roads, the so called “Real Driving Emissions” (RDE), are now a part of the type approval process for passenger cars. In addition to the hybridization and electrification of vehicles, the complexity and degrees of freedom of conventional powertrains with internal combustion engines are continuing to increase in order to comply with stricter exhaust emission standards. Besides the different requirements placed on vehicle emissions, the drivability capabilities of passenger vehicles desired by the costumers, varies within markets.
Technical Paper

Objectified Evaluation and Classification of Passenger Vehicles Longitudinal Drivability Capabilities in Automated Load Change Drive Maneuvers at Engine-in-the-Loop Test Benches

2020-04-14
2020-01-0245
The growing number of passenger car variants and derivatives in all global markets, their high order of software differentiability caused by regionally different legislative regulations, as well as pronounced market-specific customer expectations require a continuous optimization of the entire vehicle development process. Additionally, the continued increasingly stringent emission standards lead to considerable increases in powertrain hardware and control complexity. Also, efforts to achieve global market and brand specific multistep adjustable drivability characteristics as unique selling proposition, rapidly increase the scope for calibration and testing tasks during the development of the powertrain control units. The resulting extent of interdependencies between the drivability calibration and other development and calibration tasks require frontloading of development tasks.
Technical Paper

Hybrid Powertrain Choices for Emerging Engine Technologies

2020-04-14
2020-01-0440
US department of energy estimates the peak efficiency of a modern spark ignited naturally aspirated Otto cycle engine to be 36%. Atkinson cycle engines are estimated to get 40% peak efficiency. Most engines can achieve this peak efficiency only for a limited operating region. Hybrid powertrains enable engine to operate in this efficiently. Overall efficiency is improved by shutting down engine during idle events and by adjusting the operating speed and load on the engine using electric machines. The choice of the powertrain and component sizes depends on the engine characteristics, drive cycles and vehicle technical requirements. This study examines what type of powertrains will be suitable for more efficient engines that are likely to be available in the near future. Some of these technologies achieve higher efficiency with a trade off on power or by accepting a more restrictive operating region.
Technical Paper

Investigation of Reynolds Stress Model for Complex Flow using CONVERGE

2020-04-14
2020-01-1104
The Reynolds Stress turbulence (RSM) model has been developed to go beyond the Boussinesq hypothesis and to improve turbulence modeling of flow with significant mean streamline curvature and secondary flow. In this paper the RSM model in commercial CFD software CONVERGE is tested for its performance and robustness when applying to complex flows such as engine flow. Several validation cases including flow over flat plate, swirling flow in vortex combustor, diesel engine spray and combustion were selected to test the RSM model. The swirling flow in vortex combustor, non-reacting but vaporizing ECN Spray A (free jet) and Sandia small bore diesel engine case which shows spray interaction with piston bowl are used to demonstrate the benefits of the RSM model over the widely used RNG k-epsilon model without model tuning. The vortex combustor case shows the RSM model can provide good prediction for strong swirling flow.
Technical Paper

Analytical approach to characterize the effect of engine control parameters and fuel properties on ACI operation in a GDI engine

2020-04-14
2020-01-1141
Advanced compression ignition (ACI) operation in gasoline direct injection (GDI) engines is a promising concept to reduce fuel consumption and emissions at part load conditions. However, combustion phasing control and the limited operating range in ACI mode are a perennial challenge. In this study the combined impact of fuel properties and engine control strategies are investigated. A design of experiments method was implemented using a three level orthogonal array to determine the sensitivity of five engine control parameters on four engine response variables under low load ACI operation for three 98 RON gasoline fuels, exhibiting disparate chemical composition. Furthermore, the thermodynamic state of the compression histories was studied with the aid of the pressure-temperature framework and correlations were drawn to analogous HCCI experiments conducted in an instrumented CFR engine.
Technical Paper

Improvements to a CFR Engine Three Pressure Analysis GT-Power Model for HCCI and SI Conditions

2020-01-24
2019-32-0608
While experimental data measured directly on the engine are very valuable, there is a limitation of what measurements can be made without modifying the engine or the process that is being investigated, such as cylinder temperature. In order to supplement the experimental results, a Three Pressure Analysis (TPA) GT-Power model of the Cooperative Fuel Research (CFR) engine was previously developed and validated for estimating cylinder temperature and residual fraction. However, this model had only been validated for normal and knocking spark ignition (SI) combustion with RON-like intake conditions (naturally aspirated, <52 °C). This work presents improvements made to the GT-Power model and the expansion of its use for HCCI combustion. The burn rate estimation sub-model was modified to allow for low temperature heat release estimation and compression ignition operation.
Technical Paper

Computational Chemistry Consortium: Surrogate Fuel Mechanism Development, Pollutants Sub-Mechanisms and Components Library

2019-09-09
2019-24-0020
The Computational Chemistry Consortium (C3) is dedicated to leading the advancement of combustion and emissions modeling. The C3 cluster combines the expertise of different groups involved in combustion research aiming to refine existing chemistry models and to develop more efficient tools for the generation of surrogate and multi-fuel mechanisms, and suitable mechanisms for CFD applications. In addition to the development of more accurate kinetic models for different components of interest in real fuel surrogates and for pollutants formation (NOx, PAH, soot), the core activity of C3 is to develop a tool capable of merging high-fidelity kinetics from different partners, resulting in a high-fidelity model for a specific application. A core mechanism forms the basis of a gasoline surrogate model containing larger components including n-heptane, iso-octane, n-dodecane, toluene and other larger hydrocarbons.
Technical Paper

Towards an Integral Combustion Model for Model-Based Control of PCCI Engines

2019-09-09
2019-24-0001
Physics-based models in a closed-loop feedback control of a premixed charge compression ignition (PCCI) engine can improve the combustion efficiency and potentially reduce harmful NOx and soot emissions. A stand-alone multi-zone combustion model has been proposed in the literature using a physics-based mixing approach. The scalar dissipation rate emerged as the determining parameter in the model for mixing among different zones in the mixture fraction space. However, the calculation of the scalar dissipation rate depends on three approaches: three-dimensional computational fluid dynamics (3-D CFD) combustion simulations based on representative interactive flamelet (RIF) model, tabulation, or an empirical algebraic model of the scalar dissipation rate fitted for the given operating conditions of the engine. While the 3-D CFD approach provides accurate results, it is computationally too expensive to use the multi-zone model in closed-loop control.
Technical Paper

Analysis of the Emission Conversion Performance of Gasoline Particulate Filters Over Lifetime

2019-09-09
2019-24-0156
Gasoline particulate filters (GPF) recently entered the market, and are already regarded a state-of-the-art solution for gasoline exhaust aftertreatment systems to enable EU6d-TEMP fulfilment and beyond. Especially for coated GPF applications, the prognosis of the emission conversion performance over lifetime poses an ambitious challenge, which significantly influences future catalyst diagnosis calibrations. The paper presents key-findings for the different GPF application variants. In the first part, experimental GPF ash loading results are presented. Ash accumulates as thin wall layers and short plugs, but does not penetrate into the wall. However, it suppresses deep bed filtration of soot, initially decreasing the soot-loaded backpressure. For the emission calibration, the non-linear backpressure development complicates the soot load monitoring, eventually leading to compromises between high safety against soot overloading and a low number of active regenerations.
Technical Paper

Zero-Dimensional Heat Release Modeling Framework for Gasoline Compression-Ignition Engines with Multiple Injection Events

2019-09-09
2019-24-0083
A zero-dimensional heat release model was developed for compression ignition engines. This type of model can be utilized for parametric studies, off-line optimization to reduce experimental efforts as well as model-based control strategies. In this particular case, the combustion model, in a simpler form, will be used in future efforts to control the combustion in compression ignition engines operating on gasoline-like fuels. To allow for a realistic representation of the in-cylinder combustion process, a spray model has been employed to allow for the quantification of fuel distribution as well as turbulent kinetic energy within the injection spray. The combustion model framework is capable of reflecting premixed as well as mixing controlled combustion. Fuel is assigned to various combustion events based on the air-fuel mixture within the spray.
Technical Paper

Efficient Test Bench Operation with Early Damage Detection Systems

2019-09-09
2019-24-0192
The efficient operation of powertrain test benches in research and development is strongly influenced by the state of “health” of the functional test object. Hence, the use of Early Damage Detection Systems (EDDS) with Unit Under Test (UUT) monitoring is becoming increasingly popular. An EDDS should primarily avoid total loss of the test object and ensure that damaged parts are not completely destroyed, and can still be inspected. Therefore, any abnormality from the standard test object behavior, such as an exceeding of predefined limits, must be recognized at an early testing time, and must lead to a shutdown of the test bench operation. With sensors mounted on the test object, it is possible to isolate the damage cause in the event of its detection. Advanced EDDS configurations also optimize the predefined limits by learning new shutdown values according to the test object behavior within a very short time.
Technical Paper

Ultra-Lean Pre-Chamber Gasoline Engine for Future Hybrid Powertrains

2019-09-09
2019-24-0104
Lean burn gasoline spark-ignition engines can support the reduction of CO2 emissions for future hybrid passenger cars. Very high efficiencies and very low NOx raw emissions can be achieved, if relative air/fuel ratios λ of 2 and above can be reached. The biggest challenge here is to assure a reliable ignition process and to enhance the fuel oxidation in order to achieve a short burn duration and a good combustion stability. This article aims at introducing an innovative combustion system fully optimized for ultra-lean operation and very high efficiency. Thereto, a new cylinder head concept has been realized with high peak firing pressure capability and with a low surface-to-volume ratio at high compression ratios. 1D and 3D simulations have been performed to optimize the compression ratio, charge motion and intake valve lift. Numerical calculations also supported the development of the ignition system.
Technical Paper

Separation, Allocation and Psychoacoustic Evaluation of Vehicle Interior Noise

2019-06-05
2019-01-1518
Besides optical and haptic criteria, the interior noise especially influences the quality impression of a vehicle. Separately audible disturbing noises are usually perceived as inadequate product quality. As a result, the reduction of disturbing noise components is a key factor for the overall product quality. Since the acoustic optimization is a complex and time consuming process, the need for an analysis tool which identifies automatically disturbing engine noise components within the vehicle interior noise is high. For this reason, a novel analysis tool has been developed which extracts tonal and impulsive engine noise components from the overall engine noise, and evaluates the annoyance of each noticeable engine component automatically. In addition, each disturbing noise is allocated to the emitting engine component. It is then possible to listen to each engine component noise individually and synthesize a target noise by superimposing manually weighted component noises.
X