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Effect of Turbulence-Chemistry Interaction on Spray Combustion: a Large Eddy Simulation Study

Dalian University of Technology-Ming Jia
Tianjin University-Junqian Cai, Tianyou Wang, Kai Sun, Zhen Lu, Gang Xiao, Shiquan Shen
  • Technical Paper
  • 2019-01-0203
To be published on 2019-04-02 by SAE International in United States
Although turbulence plays a critical role in engines operated within low temperature combustion (LTC) regime, its interaction with chemistry on auto-ignition at low-ambient-temperature and lean-oxygen conditions remains inadequately understood. Therefore, it is worthwhile taking turbulence-chemistry interaction (TCI) into consideration in LTC engine simulation by employing advanced combustion models. In the present study, large eddy simulation (LES) coupled with linear eddy model (LEM) is performed to simulate the ignition process in n-heptane spray under engine-relevant conditions, known as Spray H. With LES, more details about unsteady spray flame could be captured compared to Reynolds-averaged Navier-Stokes equations (RANS). With LEM approach, both scalar fluctuation and turbulent mixing on sub-grid level are captured, accounting for the TCI. A skeletal mechanism is adopted in this numerical simulation, including 41 species and 124 reactions. Validations is carried out and numerical results show good agreement with experimental data. It is found that, Damköhler number (Da) at the onset of high temperature reaction evidently decreases as ambient temperature and oxygen reduces. Consequently, combustion mode varies from flamelet regime to slow chemistry regime,…

Ducted Fuel Injection: Effects of Stand-off Distance and Duct Length on Soot Reduction

Caterpillar Inc.-Kenth I. Svensson, Glen C. Martin
  • Technical Paper
  • 2019-01-0545
To be published on 2019-04-02 by SAE International in United States
Ducted fuel injection (DFI) has been shown to be an effective method to significantly reduce soot formation in mixing controlled compression ignition (MCCI) diesel flames. This reduction has been demonstrated in both combustion vessels and in an optical engine. The mechanisms driving the soot reduction are, at this time, not fully understood. There are many geometrical variable options, and optimal configurations are also not immediately evident. The objective of this study is to show the effects of some of these geometric variables, namely stand-off distance (0.1-6mm) for a 2x14mm duct, and duct length (8-14mm) at a given stand-off distance of 0.1mm. A 137m on-axis single-hole injector operated at 100-250MPa was used in a continuous flow, constant pressure vessel. Results show that the shortest stand-off distance of 0.1mm yields the greatest soot reduction for a 2x14mm duct. Also, at the stand-off distance of 0.1mm, the longer the duct, the greater the soot reduction. Additionally, the performance of a 2x8mm duct placed at a longer stand-off distance is comparable to a longer duct with a short stand-off…

Features of forming the information V2I model of the transport vessel power plant remote monitoring under operating conditions

Kherson State Maritime Academy-Igor Gritsuk
Odessa National Maritime University-Andrii Golovan
  • Technical Paper
  • 2019-01-1062
To be published on 2019-04-02 by SAE International in United States
Remote monitoring is one of the most important steps in operating the technical condition of a modern transport vessel under operating conditions. Remote monitoring of technical condition includes the use of information V2I systems for the formation and application of separate systems of the ship power plant maintenance and repair. The information V2I model developed by the authors is characterized by the vibrational field of the transport vessel, means of monitoring of the technical condition parameters and infrastructure components for monitoring of any transport vessel. The article describes the features of the information V2I system, the process of preparation, monitoring and assessment of the technical condition of the transport vessel power plant under operating conditions with the possibility of predicting its technical condition. The information monitoring system is designed to ensure the efficient operation of the vehicle in non-stationary operating conditions, characterized by the lack of quality data transmission networks. The developed monitoring system is adapted for constructive modernization of the transport vessel taking into account the conditions of its operation. The system also uses…

Numerical Investigation of Wiper Drawback

Dassault Systemes-Jonathan Jilesen
Exa Corporation-Tom Linden
  • Technical Paper
  • 2019-01-0640
To be published on 2019-04-02 by SAE International in United States
Windscreen wipers are an integral component of the windscreen cleaning systems of most vehicles, trains, cars, trucks, boats and some planes. Wipers are used to clear rain, snow, and dirt from the windscreen pushing the water from the wiped surface. Under certain conditions however, water which has been pushed from the windscreen by the wiper can be pulled back on the windscreen by aerodynamic forces introduced by the wiper motion, wiper pull back. This is an undesirable phenomenon as the water which is pulled back on to the windscreen can reduce driver visibility and makes the wiper less effective. The phenomena of wiper pull back can be tested for in climatic tunnels using sprayer systems to wet the windscreen. However, these tests require a prototype vehicle, which means that the tests are done fairly late in the development of the vehicle. Furthermore, these results do not provide significant insight into the mechanisms driving the wiper pull back. In order to better understand wiper pull back a numerical simulation of a configuration known to exhibit wiper…

Alternate Solution for EV Charge Point Infrastructure in Crowded Urban Areas along the Shore

General Motors-Tushar Khanzode
General Motors Technical Center India-Varun Chakrapani, Shivayogi Tippannanavar
Published 2019-01-09 by SAE International in United States
Many countries including India have aggressively aimed to implement electric vehicles (EVs) usage from 2030 onwards. Companies such as General Motors, Uber, Waymo and Nissan etc. are exploring the realm of autonomous vehicles (AV) for use as taxis as early as 2019. Above facts logically arrive at the solution of Autonomous EVs as taxis. With the commitment towards enabling an all-electric future, there exists a need to provide suitable infrastructure for recharging. Major urban cities located by the shoreline such as New York, Hong Kong, Mumbai, Los Angeles etc. have been facing the space crunch, with real estate prices sky-rocketing exponentially. With this premise, the operating company would need a large amount of space to store their EVs for charging which attributes to a longer downtime. This brings a need for an economical charging location that has a reduced usage of urban infrastructure and energy consumption. This study explores the possibility of an alternate charging location for electric AV ride sharing fleet charging with “e-Barge”, a barge dedicated to charge EV vehicles onboard with self-generated…
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Submarine Swims Without an Engine

  • Magazine Article
  • TBMG-33412
Published 2018-12-01 by Tech Briefs Media Group in United States

Researchers have developed a new propulsion concept for swimming robots that exploits temperature fluctuations in the water for propulsion without the need for an engine, propellant, or power supply.

System Makes Opaque Materials Totally Transparent

  • Magazine Article
  • TBMG-33411
Published 2018-12-01 by Tech Briefs Media Group in United States

Most naturally occurring materials have a disordered atomic structure that interferes with the propagation of both sound and electromagnetic waves. When the waves come into contact with these materials, they bounce around and disperse — and their energy dissipates according to a highly complex interference pattern, diminishing in intensity. That means it's virtually impossible to transmit data or energy intact across wave-scattering media and fully leverage the potential of wave technology.

Shrimp-Inspired Camera May Enable Underwater Navigation

  • Magazine Article
  • TBMG-33282
Published 2018-11-01 by Tech Briefs Media Group in United States

The underwater environment may appear to the human eye as a dull-blue, featureless space. However, a vast landscape of polarization patterns appear when viewed through a camera that is designed to see the world through the eyes of many of the animals that inhabit the water.

Design, Development and Integration of a Wing-Morphing, Bimodal Unmanned Vehicle

RMIT University-Mark Simpson, Dian Guo
Published 2018-10-30 by SAE International in United States
This paper relates to the design and development of a multi-modal UAV capable of aerial flight and underwater propulsion. A novel hybrid propulsion system has been manufactured and tested. Consisting of folding blades, the propeller has been optimized for propulsion both in air and water. The critical water to air transition phase is achieved by an additional impulsive thruster powered by a C02 cartridge. To decrease the drag in underwater cruise and reduce the potential damage when the vehicle impacts the water, a morphing wing has been developed. This consists of foam-carbon fiber lay-up constructed wings in a variable sweep configuration. The actuation of the sweep is achieved by linear servos mounted on the sleeve shaped spar. An integrated prototype is constructed, using an unconventional, anhedral horizontal stabilizers to allow clearance for the morphing wing. Using a combination of data taken from wind tunnel testing, CFD simulation and analytic methods, models of the vehicles stability are developed with the aim of better understanding the dynamics of the vehicle during transition between the mediums. This will…
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Effects of Ambient Density and Ambient O2 Concentration on Soot Formation and Oxidation Characteristics of Diesel Jet Flame in an Optically Accessible Small Sized Constant Volume Combustion Chamber

Osaka Gas Co Ltd-Takahiro Sako
Tokai University-Akihiko Azetsu, Yuta Saito
  • Technical Paper
  • 2018-32-0067
Published 2018-10-30 by SAE International in United States
The soot formation and oxidation characteristics under engine like condition were experimentally investigated using a small sized constant volume combustion chamber. The volume of this chamber is about 60 cc which is equivalent to the size of combustion chamber of automotive diesel engine and, therefore, the combustion characteristics under the engine-like overall air excess ratio can be examined in this vessel. The ambient high-pressure and high-temperature conditions in the chamber were achieved by the combustion of hydrogen in an enriched-oxygen air mixture. The common rail type injector with 8 injection holes for modern diesel engine is attached to this vessel. The optical window is attached on one side of this vessel and the full image of spray flame can be visualized and recorded through this window by a high-speed color video camera. From the visualized color image of diesel flame, the KL factor, the index of soot, and the soot temperature can be quantified by the two color method. The pressure sensor is also attached to this vessel and the temporal variation of heat release…