The SAE MOBILUS platform will continue to be accessible and populated with high quality technical content during the coronavirus (COVID-19) pandemic. x

Your Selections

Gentz, Gerald
Show Only

Collections

File Formats

Content Types

Dates

Sectors

Topics

Authors

Publishers

Affiliations

Events

   This content is not included in your SAE MOBILUS subscription, or you are not logged in.

Experimental evaluation of a custom gasoline-like blend designed to simultaneously improve φ-sensitivity, RON and octane sensitivity.

Sandia National Laboratories-Dario Lopez Pintor, John Dec, Gerald Gentz
  • Technical Paper
  • 2020-01-1136
To be published on 2020-04-14 by SAE International in United States
φ-sensitivity is a fuel characteristic that has important benefits for the operation and control of low-temperature gasoline combustion (LTGC) engines. However, regular gasoline is only weakly φ–sensitive at naturally aspirated conditions, so intake boosting is required to take advantage of this property. Thus, there is strong motivation for designing gasoline-like blends that improve φ–sensitivity and simultaneously increase RON and octane sensitivity, to improve performance for LTGC and modern SI engines. In a previous study [SAE 2019-01-0961], a 5-component regulation-compliant fuel blend (CB#1) was computationally designed; and simulations showed promising results compared to regular E10 gasoline (RD5-87). The current study experimentally evaluates CB#1 in a LTGC research engine, and the results are compared to RD5-87. For premixed naturally aspirated conditions, the intake heating required to autoignite CB#1 was similar to RD5-87, ensuring that CB#1 can operate under these conditions as easily as regular gasoline. Furthermore, similar maximum engine loads were reached with both CB#1 and RD5-87 under premixed, high-boost conditions. An independent analysis showed that the RON and octane sensitivity were increased 1.3 and 3.6 units,…
   This content is not included in your SAE MOBILUS subscription, or you are not logged in.

Combustion-Timing Control of Low-Temperature Gasoline Combustion (LTGC) Engines by Using Double Direct-Injections to Control Kinetic Rates

General Motors LLC-Jeremie Dernotte
Sandia National Laboratories-Gerald Gentz, Chunsheng Ji, Dario Lopez Pintor, John Dec
Published 2019-04-02 by SAE International in United States
Low-temperature gasoline combustion (LTGC) engines can provide high efficiencies and extremely low NOx and particulate emissions, but controlling the combustion timing remains a challenge. This paper explores the potential of Partial Fuel Stratification (PFS) to provide fast control of CA50 in an LTGC engine. Two different compression ratios are used (CR=16:1 and 14:1) that provide high efficiencies and are compatible with mixed-mode SI-LTGC engines. The fuel used is a research grade E10 gasoline (RON 92, MON 85) representative of a regular-grade market gasoline found in the United States. The fuel was supplied with a gasoline-type direct injector (GDI) mounted centrally in the cylinder. To create the PFS, the GDI injector was pulsed twice each engine cycle. First, an injection early in the intake stroke delivered the majority of the fuel (70 - 80%), establishing the minimum equivalence ratio in the charge. Then, a second injection supplied the remainder of the fuel (20 - 30%) at a variable timing during the compression stroke, from 200° to 330°CA (0°CA = TDC-intake, 360°CA = TDC-compression) to provide controlled…
This content contains downloadable datasets
Annotation ability available
   This content is not included in your SAE MOBILUS subscription, or you are not logged in.

Φ-Sensitivity for LTGC Engines: Understanding the Fundamentals and Tailoring Fuel Blends to Maximize This Property

Sandia National Laboratories-Dario Lopez Pintor, John Dec, Gerald Gentz
Published 2019-04-02 by SAE International in United States
Φ-sensitivity is a fuel characteristic that has important benefits for the operation and control of low-temperature gasoline combustion (LTGC) engines. A fuel is φ-sensitive if its autoignition reactivity varies with the fuel/air equivalence ratio (φ). Thus, multiple-injection strategies can be used to create a φ-distribution that leads to several benefits. First, the φ-distribution causes a sequential autoignition that reduces the maximum heat release rate. This allows higher loads without knock and/or advanced combustion timing for higher efficiencies. Second, combustion phasing can be controlled by adjusting the fuel-injection strategy. Finally, experiments show that intermediate-temperature heat release (ITHR) increases with φ-sensitivity, increasing the allowable combustion retard and improving stability.A detailed mechanism was applied using CHEMKIN to understand the chemistry responsible for φ-sensitivity. For fuels with NTC behavior, φ-sensitivity is greatest in the NTC region due to enhanced ITHR reactions, which explains the experimental correlation between φ-sensitivity and ITHR. Under engine conditions, higher intake pressure means lower intake temperature to balance the reactivity, and both effects increase the φ-sensitivity. However, φ-sensitivity remains almost constant if decreased oxygen concentration…
This content contains downloadable datasets
Annotation ability available
   This content is not included in your SAE MOBILUS subscription, or you are not logged in.

Spark Assist for CA50 Control and Improved Robustness in a Premixed LTGC Engine – Effects of Equivalence Ratio and Intake Boost

General Motors LLC-Jeremie Dernotte
Sandia National Laboratories-Gerald Gentz, John Dec
Published 2018-04-03 by SAE International in United States
Low-temperature gasoline combustion (LTGC) engines can deliver high efficiencies, with ultra-low emissions of nitrogen oxides (NOx) and particulate matter (PM). However, controlling the combustion timing and maintaining robust operation remains a challenge for LTGC engines. One promising technique to overcoming these challenges is spark assist (SA). In this work, well-controlled, fully premixed experiments are performed in a single-cylinder LTGC research engine at 1200 rpm using a cylinder head modified to accommodate a spark plug. Compression ratios (CR) of 16:1 and 14:1 were used during the experiments. Two different fuels were also tested, with properties representative of premium- and regular-grade market gasolines. SA was found to work well for both CRs and fuels. The equivalence ratio (ϕ) limits and the effect of intake-pressure boost on the ability of SA to compensate for a reduced Tin were studied. For the conditions studied, ϕ=0.42 was found to be most effective for SA. At lower equivalence ratios the flame propagation was too weak, whereas ϕ=0.45 was closer to the CI knock/stability limit, which resulted in a smaller range of CA50…
This content contains downloadable datasets
Annotation ability available
   This content is not included in your SAE MOBILUS subscription, or you are not logged in.

Lean Burn Combustion of Iso-Octane in a Rapid Compression Machine Using Dual Mode Turbulent Jet Ignition System

SAE International Journal of Engines

Michigan State University-Ravi Teja Vedula, Thomas Stuecken, Elisa Toulson, Harold Schock
Sandia National Laboratories-Gerald Gentz
  • Journal Article
  • 03-11-01-0007
Published 2018-03-23 by SAE International in United States
Turbulent jet ignition (TJI) is a pre-chamber initiated combustion technology that has been demonstrated to provide low temperature, faster burn rate combustion of lean and intake charge diluted air-fuel mixtures. Dual mode turbulent jet ignition (DM-TJI) is a novel concept wherein a separate air supply is provided for the pre-chamber apart from the conventional auxiliary fuel as supplied for TJI systems. The current study aims to extend the lean flammability limit of a gasoline-fueled engine using DM-TJI. Ignition delay time and combustion behavior of ultra-lean iso-octane/air mixture (Lambda ≅ 3.0) was studied using a TJI-based optically accessible rapid compression machine. High-speed fuel spray recordings in the pre-chamber were obtained using borescope imaging setup. Images of the reacting turbulent jet and subsequent combustion in the main chamber were captured using a visible color camera. The focus of the current study was to investigate (i) the effect of auxiliary fuel injection timing in TJI mode and (ii) the influence of having pre-chamber air injection in DM-TJI mode, on jet propagation and combustion behavior in the main chamber.…
This content contains downloadable datasets
Annotation ability available
   This content is not included in your SAE MOBILUS subscription, or you are not logged in.

CFD Modeling of an Auxiliary Fueled Turbulent Jet Ignition System in a Rapid Compression Machine

Michigan State University-Masumeh Gholamisheeri, Bryce Thelen, Gerald Gentz, Elisa Toulson
Published 2016-04-05 by SAE International in United States
Three-dimensional numerical simulation of the turbulent jet ignition combustion process of a premixed methane-air mixture in a Rapid Compression Machine (RCM) was performed using the Converge computational software. Turbulent jet ignition is a prechamber initiated combustion system that can replace the spark plug in a spark ignition engine. The prechamber is a small volume chamber where an injector and spark plug are located and is connected to the main combustion chamber via one or multiple small orifices. Turbulent jet ignition is capable of enabling low temperature combustion, through either lean or dilute combustion. A RANS model, which included a k-ε turbulence model to solve the mean flow and the SAGE chemistry solver with a reduced methane mechanism to solve the chemistry, was used to model the turbulent jet ignition system.The novelty of this research is the investigation of the impacts of an auxiliary fueled prechamber on the burn rate and on the lean or dilute limit extension of the RCM. The numerical results are compared to data and optical images obtained from high speed imaging…
Annotation ability available
   This content is not included in your SAE MOBILUS subscription, or you are not logged in.

Computational Study of a Turbulent Jet Ignition System for Lean Burn Operation in a Rapid Compression Machine

Michigan State University-Bryce Charles Thelen, Gerald Gentz, Elisa Toulson
Published 2015-04-14 by SAE International in United States
Fully three-dimensional computational fluid dynamic simulations with detailed chemistry of a single-orifice turbulent jet ignition device installed in a rapid compression machine are presented. The simulations were performed using the computational fluid dynamics software CONVERGE and its RANS turbulence models. Simulations of propane fueled combustion are compared to data collected in the optically accessible rapid compression machine that the model's geometry is based on to establish the validity and limitations of the simulations and to compare the behavior of the different air-fuel ratios that are used in the simulations.
Annotation ability available
   This content is not included in your SAE MOBILUS subscription, or you are not logged in.

Combustion Visualization, Performance, and CFD Modeling of a Pre-Chamber Turbulent Jet Ignition System in a Rapid Compression Machine

SAE International Journal of Engines

Innovative Scientific Solutions Inc-John Hoke
Michigan State University-Gerald Gentz, Bryce Thelen, Elisa Toulson
  • Journal Article
  • 2015-01-0779
Published 2015-04-14 by SAE International in United States
Turbulent jet ignition is a pre-chamber ignition enhancement method that produces a distributed ignition source through the use of a chemically active turbulent jet which can replace the spark plug in a conventional spark ignition engine. In this paper combustion visualization and characterization was performed for the combustion of a premixed propane/air mixture initiated by a pre-chamber turbulent jet ignition system with no auxiliary fuel injection, in a rapid compression machine. Three different single orifice nozzles with orifice diameters of 1.5 mm, 2 mm, and 3 mm were tested for the turbulent jet igniter pre-chamber over a range of air to fuel ratios. The performance of the turbulent jet ignition system based on nozzle orifice diameter was characterized by considering both the 0-10 % and the 10-90 % burn durations of the pressure rise due to combustion. It was found that the 1.5 mm orifice exhibited the shortest 0-10 % burn duration, which corresponded to the fastest flame initiation. The orifice diameter did not significantly affect the 10-90 % burn duration near stoichiometric air to…
Annotation ability available