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Effects of Injection Timing on Fluid Flow Characteristics of Partially Premixed Combustion Based on High-Speed Particle Image Velocimetry

SAE International Journal of Engines

Dantec Dynamics A/S-Hua Wang
Eindhoven University Of Technology-Mohammad Izadi Najafabadi, Bart Somers, Nico Dam
  • Journal Article
  • 2017-01-0744
Published 2017-03-28 by SAE International in United States
Partially Premixed Combustion (PPC) is a promising combustion concept ,based on judicious tuning of the charge stratification, to meet the increasing demands of emission legislation and to improve fuel efficiency. Longer ignition delays of PPC in comparison with conventional diesel combustion provide better fuel/air mixture which decreases soot and NOx emissions. Moreover, a proper injection timing and strategy for PPC can improve the combustion stability as a result of a higher level of fuel stratification in comparison with the Homogeneous Charge Compression Ignition (HCCI) concept. Injection timing is the major parameter with which to affect the level of fuel and combustion stratification and to control the combustion phasing and the heat release behavior. The scope of the present study is to investigate the fluid flow characteristics of PPC at different injection timings. To this end, high-speed Particle Image Velocimetry (PIV) is implemented in a light-duty optical engine to measure fluid flow characteristics, including the flow fields, mean velocity and cycle-resolved turbulence, inside the piston bowl as well as the squish region with a temporal resolution…
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High-Speed Particle Image Velocimetry Measurement of Partially Premixed Combustion (PPC) in a Light Duty Engine for Different Injection Strategies

Dantec Dynamics A/S-Hua Wang
Lund University-Zhenkan Wang, Slavey Tanov, Mattias Richter, Bengt Johansson, Marcus Alden
Published 2015-09-06 by SAE International in United States
It has been proven that partially premixed combustion (PPC) has the capability of high combustion efficiency with low soot and NOx emissions, which meet the requirements of increasingly restricted emission regulations. In order to obtain more homogenous combustion and longer ignition delay in PPC, different fuel injection strategies were employed which could affect the fuel air mixing and control the combustion. In the present work, a light duty optical diesel engine was used to conduct high speed particle image velocimetry (PIV) for single, double and triple injections with different timings. A quartz piston and a cylinder liner were installed in the Bowditch configuration to enable optical access. The geometry of the quartz piston crown is based on the standard diesel combustion chamber design for this commercial passenger car engine, including a re-entrant bowl shape. The severe image distortions caused by the optical piston shape are minimized through recordings of reference targets and an image dewarping algorithm. To the authors knowledge this is the first time the flow field inside such realistic re-entrant piston bowl has…
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Effects of Injection Strategies on Fluid Flow and Turbulence in Partially Premixed Combustion (PPC) in a Light Duty Engine

Slavey Tanov
Dantec Dynamics A/S-Hua Wang
Published 2015-09-06 by SAE International in United States
Partially premixed combustion (PPC) is used to meet the increasing demands of emission legislation and to improve fuel efficiency. With gasoline fuels, PPC has the advantage of a longer premixed duration of the fuel/air mixture, which prevents soot formation. In addition, the overall combustion stability can be increased with a longer ignition delay, providing proper fuel injection strategies.In this work, the effects of multiple injections on the generation of in-cylinder turbulence at a single swirl ratio are investigated. High-speed particle image velocimetry (PIV) is conducted in an optical direct-injection (DI) engine to obtain the turbulence structure during fired conditions. Primary reference fuel (PRF) 70 (30% n-heptane and 70% iso-octane) is used as the PPC fuel. In order to maintain the in-cylinder flow as similarly as possible to the flow that would exist in a production engine, the quartz piston retains a realistic bowl geometry. The distortion caused by the complex shape of the optical piston is corrected by an advanced image-dewarping algorithm. The in-cylinder charge motion is evaluated and investigated over a range of crank…
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An Experimental Study of Gaseous Transverse Injection and Mixing Process in a Simulated Engine Intake Port

SAE International Journal of Fuels and Lubricants

Politecnico di Milano-Hua Wang, Lucio Araneo, Aldo Coghe
  • Journal Article
  • 2013-01-0561
Published 2013-04-08 by SAE International in United States
The flow field resulting from injecting a gas jet into a crossflow confined in a narrow square duct has been studied under steady regime using schlieren imaging and laser Doppler velocimetry (LDV). This transparent duct is intended to simulate the intake port of an internal combustion engine fueled by gaseous mixture, and the jet is issued from a round nozzle. The schlieren images show that the relative small size of the duct would confine the development of the transverse jet, and the interaction among jet and sidewalls strongly influences the mixing process between jet and crossflow. The mean velocity and turbulence fields have been studied in detail through LDV measurements, at both center plane and several cross sections. The well-known flow feature formed by a counter rotating vortex pair (CVP) has been observed, which starts to appear at the jet exit section and persists far downstream contributing to enhancing mixing process.In addition, jets of different gases have been investigated with various injection orientations, aiming to fully understand the behaviors of transverse jet and the mixing…
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Development of a Two-Dimensional Driver Side Airbag Deployment Algorithm

Bioengineering Center Wayne State Univ.-Hua Wang, Hui-Chang Wang, Albert I. King
Dept. of Mechanical Engineering and Bioengineering Center Wayne State Univ.-King H. Yang
Published 1990-10-01 by SAE International in United States
A PC based interactive program was developed to simulate the unfolding and deploying process of a driver side airbag in the sagittal plane. The airbag was represented by a series of nodes. The maximum allowable stretch was less or equal to one between any two nodes. We assumed that the airbag unfolding was pivoted about folded points. After the completion of the unfolding process the airbag would begin to deploy. During the deploying process, two parameters were used to determine the nodal priority of the inflation. The first parameter was the distance between the instantaneous and final positions of a node. Nodes with longer distances to travel will have to move faster. We also considered the distance between the current nodal position and the gas inlet location. For a node closer to the gas inlet, we assumed that the deploying speed was faster. A graphical procedure was used to calculate the area of the airbag. At each time step, this area was checked against four convergence criteria set up by the user, using an iterative…
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