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Influence of port water injection on the combustion characteristics and exhaust emissions in a spark-ignition direct-injection engine

Shanghai Jiao Tong University-Yadong Fan, Tianbao Wu, Xuesong Li, Min Xu, David Hung
  • Technical Paper
  • 2020-01-0294
To be published on 2020-04-14 by SAE International in United States
It is well known that spark-ignition direct-injection (SIDI) gasoline engines have a huge advantage in fuel economy due to their good anti-knock performance compared to port fuel injection engines. However, higher particle number (PN) emissions associated with fuel impingement make the SIDI engines have additional difficulties to meet the upcoming China VI emission standards. In this study, the port water injection (PWI) techniques on a 1.0-L turbocharged, three cylinder, SIDI engine were investigated. PWI strategies were optimized to quantify port water injection as a means of mitigating the knock and improving the combustion performance by sweeping water-fuel mass ratios and PWI timing at different operating conditions. Measurements indicate that regardless of engine load, PWI induced a worsening of the maximum in-cylinder pressure (P-Max) and cycle-to-cycle variations (IMEPN-COV ) , which mainly due to the effects of water dilution and slower burning velocities. But by the advance of spark timing with knock mitigation, we find that the improvement of combustion phasing finally makes it possible to eliminate fuel enrichment, which bring the potential advantages on the…
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Transient thermal behavior of dry clutch under non-uniform pressure condition

Shanghai Jiao Tong University-Yongchun Jin, Li Chen, Cheng Cheng
  • Technical Paper
  • 2020-01-1418
To be published on 2020-04-14 by SAE International in United States
Accuracy of thermal models is critical to clutch design in case of excessive temperatures due to large amounts of friction heat generated in the narrow space. Pressure distribution on the clutch friction interface is an important factor affecting heat flux distribution, thus affecting temperature distribution. But no previous literature reported how the pressure is distributed on dry clutches. This study conducts an experiment to obtain the pressure distribution for one typical dry clutch equipped with a set of diaphragm spring. Considering that the frictional interface is in contact, ordinary pressure sensors are not applicable because they have to separate the interface for a certain distance. Addressing this difficulty, this study makes use of pressure sensitive film and acquires data based on image processing techniques. Thereafter, a polynomial model with dimensionless parameters is developed to fit the pressure distribution. Thus, the non-uniform pressure model is worked out. After that, the proposed pressure model is applied to a thermal model based on finite element method. In addition, two conventional thermal models, which use uniform pressure and uniform…
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Combustion Characterization of Neat n-Butanol in an SI Engine

Shanghai Jiao Tong University-Tie Li
University of Windsor-Navjot Singh Sandhu, Xiao Yu, Simon Leblanc, Ming Zheng, David Ting
  • Technical Paper
  • 2020-01-0334
To be published on 2020-04-14 by SAE International in United States
Increasingly stringent emission standards have promoted the interest in alternative fuel sources. Because of the comparable energy density to the existing fossil fuels and renewable production, alcohol fuels may be a suitable replacement or an additive to the gasoline/diesel fuels to meet the future emission standards with minimal modification to current engine geometry. Extensive research is published on n-Butanol and gasoline fuel blends in a spark-ignition (SI) engine operation. In this research, the combustion characteristics of neat n-Butanol are analyzed under spark ignition operation using a single cylinder SI engine. The fuel is injected into the intake manifold using a port-fuel injector. Two modes of charge dilution were used in this investigation to test the limits of stable engine operation, namely lean burn using excess fresh air and exhaust gas regeneration (EGR). The in-cylinder pressure measurement and subsequently, heat release analysis are used to investigate the combustion characteristics of the fuel under low load SI engine operation. Additionally, a comprehensive emission analysis is performed using the Fourier transform infrared (FTIR) spectroscopy technique to study the…
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Control Model of Automated Driving Systems based on SOTIF Evaluation

Shanghai Jiao Tong University-Kaijiong Zhang, Weishun Deng, Xi Zhang, Fan Yu
PATAC-Mengge Guo, Shiliang Shang, Cui Haifeng
  • Technical Paper
  • 2020-01-1214
To be published on 2020-04-14 by SAE International in United States
In partially automated and conditionally automated vehicles, part of the work of human drivers is replaced by the system, and the main source of safety risks is no longer system failures, but non-failure risks caused by insufficient system function design. The absence of unreasonable risk due to hazards resulting from functional insufficiencies of the intended functionality or by reasonably foreseeable misuse by persons, is referred to as the Safety Of The Intended Functionality (SOTIF). Drivers have the responsibility to supervise the automated driving system. When they don't agree with the operation behavior of the system, they will interfere with the instructions. However, this may lead to potential risks. In order to discover the causes of human misuse, this paper takes the trust feeling between the driver and the automated driving system as the starting point, and based on the collected data of track test, establishes the evaluation index -- confidence degree to show the trust feeling between the driver and the automated system. Confidence degree is a comprehensive interpretation of the driver's physiological and psychological…
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Computational modeling of Diesel spray combustion with multiple injections

Shanghai Jiao Tong University-Xing-cai Lu
Eindhoven University of Technology-Noud Maes, Bart Somers
  • Technical Paper
  • 2020-01-1155
To be published on 2020-04-14 by SAE International in United States
Multiple injection strategies are commonly used in conventional Diesel engines due to the flexibility for optimizing heat-release timing with a consequent improvement in fuel economy and engine-out emissions, which is also desirable in low temperature combustion (LTC) engine since it offers the potential to reduce UHC and CO emissions. To better utilize these benefits and find optima calibrations of split strategies, it is imperative that the fundamental processes of multiple injection combustion are understood and CFD models accurately describe the flow dynamics and combustion characteristics between different injection events. To this end, this work is dedicated to the identification of suitable methodologies to predict the multiple injection combustion process. Two different approaches: Representative Interactive Flamelet model (RIF) employing different numbers of flamelets and Tabulated Flamelet Progress Variable (TFPV) are compared and Spray A conditions with multiple injections of Engine Combustion Network are simulated using the RANS methods with both standard k-ε and k-ω SST models. Evaluations of different turbulence and combustion models are carried out by comparing computed and measured data in terms of the…
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Numerical Investigation of the Effects of Port Water Injection Timing on Performance and Emissions in a Gasoline Direct Injection Engine

Shanghai Jiao Tong University-Peng Yin, Xuesong Li, David Hung, Yadong Fan, Min Xu
  • Technical Paper
  • 2020-01-0287
To be published on 2020-04-14 by SAE International in United States
Port water injection is considered as a promising strategy to further improve the combustion performance of internal combustion engines for its benefit in knock resistance by reducing the cylinder temperature. A thorough investigation of the port water injection technique is required to fully understand its effects on the engine combustion process. This study explores the potential of the port water injection technique in improving the performance of a turbo-charged Gasoline Direct Injection engine. A 3D computational fluid dynamics model was applied to simulate the in-cylinder mixing and combustion for this engine both with and without water injection. Comparison have been given between the original engine and the water injection one and the results show that the water injection can reduce the cylinder temperature both in the compressing and combustion strokes. The pressure oscillation is also suppressed which indicates a better knocking resistance for water injection strategy. Different water injection timings are also investigated and it is found that the injection timing is important to determine the trapped amount of the water steam in the combustion…
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Internal Model Control During Mode Transition Subject To Time Delay For Hybrid Electric Vehicles

Shanghai Jiao Tong University-Dongxiao Miao, Li Chen, Ping Yi
  • Technical Paper
  • 2020-01-0961
To be published on 2020-04-14 by SAE International in United States
With the rapid development of series-parallel hybrid electric vehicles (SPHEVs), mode transition from pure electrical drive to hybrid drive has attracted considerable attention. The presence of time delay due to response capacity of actuators and signal transmission of communication may lead to decrease of speed tracking accuracy, even instable dynamics. Consequently, drivability of the SPHEV is unacceptable, and durability of the components is reduced. So far, plenty of control strategies have been proposed for the mode transition, however, no previous research has been reported to deal with the time delay during the mode transition. In this paper, a dynamic model with time delay of hybrid electric system is established. Next, a mode transition time-delay controller is proposed by combining a two degree of freedom internal model controller (2DOF-IMC) and a Smith compensator. Considering the control plant has three inputs (the engine output torque, clutch transmitted torque and motor output torque) and two outputs (the engine speed and motor speed), the generalized inverse matrix is used to solve the non-square control problem for the inverse matrix…
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Improved Potential Field-based Collision Avoidance Control for Autonomous Vehicles

Shanghai Jiao Tong University-Weishun Deng, Kaijiong Zhang, Xi Zhang, Fan Yu
PATAC-Shiliang Shang, Mengge Guo
  • Technical Paper
  • 2020-01-0123
To be published on 2020-04-14 by SAE International in United States
Limiting factors for autonomous vehicle (AV) to be widely used are not only technical, but also psychological. Considering the psychological feelings of drivers during switching manned to unmanned driving status, this paper proposes an algorithm for avoiding collisions combining driver psychological feelings for AVs. The confidence-limit-distance of the driver is experimentally obtained by many real track tests which require the test driver to approach the obstacle as close as possible. The confidence-limit-distance from driver is defined as the distance between the obstacle and the last steering point allowed for the psychological limit of the driver to avoid collisions. Based on Artificial Potential Field (APF), a road potential field is accordingly established to characterize the characteristics and boundary constraints of the real road. To express the different influences of relative speed and direction on the driver's psychological feeling, the confidence potential field is established based on a two-dimensional normal distribution combining von Mises distribution. A second-order Taylor expansion of road potential field and confidence potential field are firstly introduced into the cost functions for model predictive…
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Adaptive Energy Management Strategy for Hybrid Vehicles Based on Pontryagin’s Minimum Principle

Shanghai Jiao Tong University-Mingliang Zhu, Xiaodong Wu, Min Xu
  • Technical Paper
  • 2020-01-1191
To be published on 2020-04-14 by SAE International in United States
The energy management strategies (EMS) for hybrid electric vehicles (HEV) have a great impact on the fuel economy (FE). The Pontryagin's minimum principle (PMP) has been proved to be a viable control strategy for HEV. The optimal costate of the PMP control can be determined by the given information of the driving conditions. Thus various methods are proposed to estimate the optimal costate of PMP by the prediction of the driving cycle. But in practice, full knowledge of future driving conditions is not available. In most studies, the design of EMS without the prediction of driving conditions is determined by the upper and lower bounds of the PMP costate, which is changed by the state of batteries. However, the predefined bounds of the PMP costate limits the scope of application, and cannot achieve best FE performance in all driving conditions. To solve this issue, this paper proposed a dynamic optimization method for PMP costate from the view of energy. It is known that the lower fuel consumption the method yields, the more efficiently the engine…
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Investigation of the Impacts of Spark Plug Orientation on Combustion Stability under lean SI Operation

Chang Ye
Shanghai Jiao Tong University-Qifan Gu, Min Xu, David Hung, Xuesong Li
  • Technical Paper
  • 2020-01-1121
To be published on 2020-04-14 by SAE International in United States
The increasingly stringent restrictions on vehicle emissions and fuel consumption are driving the development of gasoline engines towards lean combustion. Increasing the ignition energy has been considered an effective way to achieve lean operation. To further improve the lean limit of the engine combustion, the influence of the spark plug on the combustion stability under lean operation should be explored. In this investigation, the original machine spark plug orientation, 90 degrees clockwise rotation, and 180 degrees clockwise rotation are studied to analyze the impact of spark plug orientation. The combustion experiment was carried out under the condition of low ignition air-fuel ratio of the original machine and high air-fuel ratio of 400 mA high energy ignition. It is found that changing the orientation of the spark plug had little effect on combustion at low air-fuel ratio; however, under high air-fuel ratio (ultra-lean operation), spark plug orientation had a great influence on combustion stability. The combustion stability was significantly improved when the spark plug orientation was consistent with the intake direction. Correspondingly, the lean operation limit…