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Empirical Modeling of Electrical Discharge in an Inert Medium at High-speed Flows

Michigan Technological University-Mary P. Zadeh, Henry Schmidt, Seong-Young Lee, Jeffrey Naber
  • Technical Paper
  • 2020-01-1120
To be published on 2020-04-14 by SAE International in United States
Energy discharge models have been used to gain insights into the spark discharge process and early flame kernel development in spark-ignition engines. However, the existing models are reported to be applicable for a limited range of gas pressures and flow fields. This study aims to evaluate these models and propose an improved one to predict the spark ignition at pressurized conditions up to 45 bar and high-speed flows up to 32 m/s. The model captures the spark discharge behavior that has been observed experimentally in an optically accessible constant-volume combustion vessel. This includes discharge characteristics and the occurrence of the spark blowouts and re-strikes. Results indicate that the voltage and current waveforms of the spark discharge are correlated to the flow velocity across the spark plug gap. Further investigations were performed to study the stretching rate of the spark channel under the high crossflow.
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Crevice Corrosion Accelerated Test for Cylinder Head/Gasket/Monoblock Assemblies from Lightweight Engines Exposed to Overheating Cycles

Instituto Politecnico Nacional Esime Zac-Gerardo Rodríguez-Bravo, Roberto Vega-Moron
Instituto Politécnico Nacional ESIQIE-Jesús Godínez-Salcedo
  • Technical Paper
  • 2020-01-1067
To be published on 2020-04-14 by SAE International in United States
Severe crevice corrosion occurring at the joint of cylinder head/gasket/mono-block from lightweight engines causes accelerated dissolution of lightweight material, in particular, in cylinder head producing the linking of the cooling vessels with the combustion chambers or oil vessels. It is conductive to combustion of coolant or oil, and contamination of oil with coolant or vice versa, which is considered as catastrophic engine failure. Since crevice corrosion is dependent of many of the actual assembly characteristics, coolant and engine operation conditions, full-scale tests are the most frequent alternative for this type of evaluations. Nonetheless, they are very long and expensive, and sometimes, unreliable tests. Alternatively, the standard procedure ASTM-G78 is widely used to evaluate crevice corrosion propensity of different metallic materials under certain specified conditions trough immersion tests in a corrosive media in shorter test times. However, the method does not cover the characteristics and conditions existing at the cylinder head/gasket/mono-block joint. Hence, this paper presents an accelerated test consisting on three-electrode cyclic potentiodynamic anodic polarization and polarization resistance standard trials using special assembly samples to…
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Control Measures for Laser Safety in the Navigable Airspace

G10T Laser Safety Hazards Committee
  • Aerospace Standard
  • ARP5572A
  • Current
Published 2020-03-10 by SAE International in United States
This SAE Aerospace Recommended Practice (ARP) provides information and guidance for the control of hazardous laser energy in the navigable airspace. This ARP does not address techniqies that pilots can apply to mitigate laser illuminations during a critical phase of flight. Such mitigation strategies are described in ARP6378.
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Insect-Inspired Motion Sensing

  • Magazine Article
  • TBMG-35993
Published 2020-02-01 by Tech Briefs Media Group in United States

Researchers have taken inspiration from flying insects to demonstrate a miniaturized gyroscope, a special sensor used in navigation technologies. Gyroscopes sense rotational motions to provide directional guidance without relying on satellites, so they are immune to signal jamming and other cyber threats, making them ideal for aircraft and submarines.

Underwater Signal Processing System

  • Magazine Article
  • TBMG-36054
Published 2020-02-01 by Tech Briefs Media Group in United States

DSIT Solutions Ltd. Givat Shmuel, Israel +972-3-531-3333

Robotic “Cockroach” Explores Underwater Environments

  • Magazine Article
  • TBMG-35799
Published 2020-01-01 by Tech Briefs Media Group in United States

In nature, cockroaches can survive underwater for up to 30 minutes. A robotic cockroach was developed that can walk on land, swim on the surface of water, and walk underwater for as long as necessary.

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Qualified Hoses for Marine Applications

Hydraulic Hose and Hose Fittings Committee
  • Ground Vehicle Standard
  • J1942/1_201912
  • Current
Published 2019-12-27 by SAE International in United States
The following list consists of hose data provided as of December, 2019, and is for convenience in determining acceptability of nonmetallic flexible hose assemblies intended for usage under 46 CFR 56.60-25. Where the maximum allowable working pressure (MAWP) or type of fitting is not specified, use the manufacturer's recommended MAWP or type of fitting. This list has been compiled by SAE staff from information provided by the manufacturers whose product listings appear in this document. Manufacturers wishing to list their products in this document shall: a Successfully test their hose to the requirements of SAE J1942, Table 1. b Submit a letter of certification to the SAE J1942 test requirements for each specific type of hose tested (see sample table, Table 1) along with the test results. All sizes should be included in the same letter which must also include all of the information necessary to make a SAE J1942-1 listing. c The SAE will review the letter and may, at their discretion, request to see further test results. A copy of the submittal letter…
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Study on Multicomponent Fuel Spray with High Injection Pressure

Doshisha University-Jiro Senda, Eriko Matsumura
Doshisha University Graduate School-Kohsuke Nishiura
  • Technical Paper
  • 2019-01-2282
Published 2019-12-19 by SAE International in United States
In previous study, the model for flash-boiling spray of multicomponent fuel was constructed and was implemented into KIVA code. This model considered the detailed physical properties and evaporation process of multicomponent fuel and the bubble nucleation, growth and disruption in a nozzle orifice and injected fuel droplets. These numerical results using this model were compared with experimental data which were obtained in the previous study using a constant volume vessel. The spray characteristics from numerical simulation qualitatively showed good agreement with the experimental results. Especially, it was confirmed from both the numerical and experimental data that flash-boiling effectively accelerated the atomization and vaporization of fuel droplets. However, in this previous study, injection pressure was very low (up to 15 MPa), and the spray characteristics of high pressure injection could not be analyzed. It is necessary to investigate the spray characteristics with high injection pressure for the application of multicomponent fuel to modern diesel engine.In this study, this model was validated by comparing with the results from experiment using constant volume vessel. The effects of initial…
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Vaporization and Turbulence Characteristics of High Pressure Gasoline Sprays Impinging on a Wall

Mazda Motor Corporation-Wu Zhang, Ryosuke Hara, Tatsuya Fujikawa, Masahisa Yamakawa
University of Hiroshima-Tomohiro Watanabe, Yukihiko Ichikawa, Keiya Nishida, Yoichi Ogata
  • Technical Paper
  • 2019-01-2247
Published 2019-12-19 by SAE International in United States
To get a better understanding of the characteristics of the high pressure gasoline sprays impinging on a wall, a fundamental study was conducted in a high-temperature high-pressure constant volume vessel under the simulated engine conditions of in-cylinder pressures, temperatures, and wall temperatures. The injection pressure was varied from 20 to 120 MPa. The spray tip penetration, vapor mass distribution, and vaporization rate were quantitatively measured with the laser absorption-scattering (LAS) technique. The velocity fields of the wall-impinging sprays under vaporizing conditions were measured with the particle image velocimetry (PIV) technique using silicone oil droplets as tracers. The effects of injection pressure and spray/wall interactions on spray characteristics were investigated. The results showed that the increased injection pressure improved penetration, vaporization, and turbulence of the sprays.
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Effect of pressure cycling on gas exchange in a transparent fuel injector

Sandia National Laboratories, 7011 East Ave, 94550 Livermore-Paul M. Abers, Emre Cenker, Koji Yasutomi, Joonsik Hwang, Lyle M. Pickett
  • Technical Paper
  • 2019-01-2280
Published 2019-12-19 by SAE International in United States
Gas ingested into the sac of a fuel injector after the injector needle valve closes is known to have crucial impacts on initial spray formation and plume growth in a following injection cycle. Yet little research has been attempted to understand the fate sac gases during pressure expansion and compression typical of an engine. This study investigated cavitation and bubble processes in the sac including the effect of chamber pressure decrease and increase consistent with an engine cycle. A single axial-hole transparent nozzle based on the Engine Combustion Network (ECN) Spray D nozzle geometry was mounted in a vessel filled with nitrogen, and the nitrogen gas pressure was cycled after the end of injection. Interior nozzle phenomena were visualized by high-speed longdistance microscopy with a nanosecond pulsed LED back-illumination. Experimental results showed that the volume of gas in the sac after the needle closes depends upon the vessel gas pressure. Higher back pressure results in less cavitation and a smaller volume of non-condensable gas in the sac. But a pressure decrease mimicking the expansion stroke…
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