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

Brear, Michael
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.

An Optical and Numerical Characterization of Directly Injected Compressed Natural Gas Jet Development at Engine-Relevant Conditions

Continental-Mike Hornby, Doug Cosby, Perry Czimmek
Ford Motor Co Ltd-Adam Smith
Published 2019-04-02 by SAE International in United States
Compressed natural gas (CNG) is an attractive, alternative fuel for spark-ignited (SI), internal combustion (IC) engines due to its high octane rating, and low energy-specific CO2 emissions compared with gasoline. Directly-injected (DI) CNG in SI engines has the potential to dramatically decrease vehicles’ carbon emissions; however, optimization of DI CNG fueling systems requires a thorough understanding of the behavior of CNG jets in an engine environment.This paper therefore presents an experimental and modeling study of DI gaseous jets, using methane as a surrogate for CNG. Experiments are conducted in a non-reacting, constant volume chamber (CVC) using prototype injector hardware at conditions relevant to modern DI engines. The schlieren imaging technique is employed to investigate how the extent of methane jets is impacted by changing thermodynamic conditions in the fuel rail and chamber.Post-processing of these optical results presents challenges because of the similarity between the density of methane and the background nitrogen. A methodology to interpret the jet extent in the high-speed movies is therefore proposed and used to quantify methane jet propagation and structure. The…
This content contains downloadable datasets
Annotation ability available
   This content is not included in your SAE MOBILUS subscription, or you are not logged in.

Effects of Engine Speed on Spray Behaviors of the Engine Combustion Network “Spray G” Gasoline Injector

Robert Bosch LLC-Mohammad Fatouraie
University of Melbourne-Joshua Lacey, Michael Brear
Published 2018-04-03 by SAE International in United States
Non-reacting spray behaviors of the Engine Combustion Network “Spray G” gasoline fuel injector were investigated at flash and non-flash boiling conditions in an optically accessible single cylinder engine and a constant volume spray chamber. High-speed Mie-scattering imaging was used to determine transient liquid-phase spray penetration distances and observe general spray behaviors. The standardized “G2” and “G3” test conditions recommended by the Engine Combustion Network were matched in this work and the fuel was pure iso-octane. Results from the constant volume chamber represented the zero (stationary piston) engine speed condition and single cylinder engine speeds ranged from 300 to 2,000 RPM. As expected, the present results indicated the general spray behaviors differed significantly between the spray chamber and engine. The differences must be thoughtfully considered when applying spray chamber results to guide spray model development for engine applications. Overall, increases in engine speed correlated well with enhanced vaporization, loss of distinct plume structure, and enhanced spray collapse which led to reductions in wetted-footprint area. Furthermore, while loss of distinct plume structures appeared to be strongly dependent…
Annotation ability available
   This content is not included in your SAE MOBILUS subscription, or you are not logged in.

The Direct Transition of Fuel Sprays to theDense-Fluid Mixing Regime in the Contextof Modern Compression Ignition Engines

Georgia Institute of Technology-Farzad Poursadegh
University of Melbourne-Joshua Lacey, Michael Brear, Robert Gordon
Published 2018-04-03 by SAE International in United States
Fuel supercriticality has recently received significant attention due to the elevated pressures and temperatures that directly-injected (DI) fuel sprays encounter in modern internal combustion (IC) engines. This paper presents a theoretical examination of conventional and alternative DI fuels at conditions relevant to the operation of compression ignition (CI) engines. The focus is to identify the conditions under which the injected liquid fuel can bypass the atomization process and directly transition to a diffusional mixing regime with the chamber gas. Evaluating the microscopic length-scales of the phase boundary associated with the injection of liquid nitrogen into its own vapor, it is found that the conventional threshold based on the interfacial Knudsen number (i.e. Kn = 0.1) does not adequately quantify the direct transition between sub- and supercriticality. Instead, a threshold that is an order of magnitude smaller is more appropriate for this purpose. Extending the analysis to a range of diesel fuel surrogates (e.g. n-heptane and n-dodecane), and alternative engine fuels that can be blended for use in CI engines (e.g. dimethyl ether and propane), it is then…
This content contains downloadable datasets
Annotation ability available
   This content is not included in your SAE MOBILUS subscription, or you are not logged in.

A Comparison of Four Methods for Determining the Octane Index and K on a Modern Engine with Upstream, Port or Direct Injection

Ford Motor Company-Thomas G. Leone, James E. Anderson, Michael H. Shelby
University of Melbourne-Zhenbiao Zhou, Yi Yang, Michael Brear, Joshua Lacey
Published 2017-03-28 by SAE International in United States
Combustion in modern spark-ignition (SI) engines is increasingly knock-limited with the wide adoption of downsizing and turbocharging technologies. Fuel autoignition conditions are different in these engines compared to the standard Research Octane Number (RON) and Motor Octane Numbers (MON) tests. The Octane Index, OI = RON - K(RON-MON), has been proposed as a means to characterize the actual fuel anti-knock performance in modern engines. The K-factor, by definition equal to 0 and 1 for the RON and MON tests respectively, is intended to characterize the deviation of modern engine operation from these standard octane tests. Accurate knowledge of K is of central importance to the OI model; however, a single method for determining K has not been well accepted in the literature.This paper first examines four different methods for determining K, using literature results from a modern SI engine operating with direct injection (DI), port fuel injection (PFI) and homogeneous, upstream fuel injection (UFI). The test fuels were ethanol-gasoline blends spanning a wide range of RON and MON, together with isooctane as a reference. The…
This content contains downloadable datasets
Annotation ability available
   This content is not included in your SAE MOBILUS subscription, or you are not logged in.

Optical Characterization of Propane at Representative Spark Ignition, Gasoline Direct Injection Conditions

Ford Motor Company of Australia-Charles Lakey, Steve Ryan, Brendan Butcher
RMIT University-Phred Petersen
Published 2016-04-05 by SAE International in United States
The focus of internal combustion (IC) engine research is the improvement of fuel economy and the reduction of the tailpipe emissions of CO2 and other regulated pollutants. Promising solutions to this challenge include the use of both direct-injection (DI) and alternative fuels such as liquefied petroleum gas (LPG).This study uses Mie-scattering and schlieren imaging to resolve the liquid and vapor phases of propane and iso-octane, which serve as surrogates for LPG and gasoline respectively. These fuels are imaged in a constant volume chamber at conditions that are relevant to both naturally aspirated and boosted, gasoline direct injection (GDI) engines. It is observed that propane and iso-octane have different spray behaviors across these conditions. Iso-octane is subject to conventional spray breakup and evaporation in nearly all cases, while propane is heavily flash-boiling throughout the GDI operating map. This severe flashing behavior has major implications for the design and calibration of LPG DI injection systems and engines.
Annotation ability available
   This content is not included in your SAE MOBILUS subscription, or you are not logged in.

Modeling of Trace Knock in a Modern SI Engine Fuelled by Ethanol/Gasoline Blends

Ford Motor Co.-Thomas Leone, James E. Anderson
University of Melbourne-Hao Yuan, Tien Mun Foong, Zhongyuan Chen, Yi Yang, Michael Brear
Published 2015-04-14 by SAE International in United States
This paper presents a numerical study of trace knocking combustion of ethanol/gasoline blends in a modern, single cylinder SI engine. Results are compared to experimental data from a prior, published work [1]. The engine is modeled using GT-Power and a two-zone combustion model containing detailed kinetic models. The two zone model uses a gasoline surrogate model [2] combined with a sub-model for nitric oxide (NO) [3] to simulate end-gas autoignition.Upstream, pre-vaporized fuel injection (UFI) and direct injection (DI) are modeled and compared to characterize ethanol's low autoignition reactivity and high charge cooling effects. Three ethanol/gasoline blends are studied: E0, E20, and E50. The modeled and experimental results demonstrate some systematic differences in the spark timing for trace knock across all three fuels, but the relative trends with engine load and ethanol content are consistent. Possible reasons causing the differences are discussed. Finally, the influence of NO on autoignition is investigated, yielding results that are consistent with prior works. Overall, the same, two-zone kinetic model appears to capture both the UFI and DI autoignition similarly well.…
Annotation ability available
   This content is not included in your SAE MOBILUS subscription, or you are not logged in.

Model Reduction of Diesel Mean Value Engine Models

DSTO-Peter Hield
The University of Melbourne-Timothy Broomhead, Chris Manzie, Michael Brear
Published 2015-04-14 by SAE International in United States
In the literature, a wide range of Mean Value Engine Models are used in the simulation and control of reciprocating engines. These models are often underpinned by a number of implicit assumptions, which determine the model structure and system states. Systematic model reduction approaches have been developed to avoid these assumptions, where high order models are reduced using singular perturbation techniques, eliminating states operating on irrelevant time-scales. While this framework allows the elimination of states based on sufficiently small perturbation parameters, a systematic method of identifying non-dimensional perturbation parameters has not yet been proposed. The development of a rigorous method to identify non-dimensional time scales present in the model is a natural and powerful extension to the existing approach.In this work, starting from a calibrated, high-order physics based non-linear mean value model of a diesel engine, non-dimensional analysis is used to identify system states on relevant time-scales. Singular perturbation techniques are then used to isolate the identified states. The resulting boundary layer is then approximated before the impact of linearising the state and output equations…
Annotation ability available
   This content is not included in your SAE MOBILUS subscription, or you are not logged in.

Design and Analysis of a Modified CFR Engine for the Octane Rating of Liquefied Petroleum Gases (LPG)

SAE International Journal of Fuels and Lubricants

Princeton Univ.-Frederick Dryer
Univ. of Melbourne-Kai Morganti, Tien Mun Foong, Michael Brear, Gabriel Da Silva, Yi Yang
  • Journal Article
  • 2014-01-1474
Published 2014-04-01 by SAE International in United States
This paper presents a combined experimental and numerical study of a modified Cooperative Fuel Research (CFR) engine that allows both the Research and Motor octane numbers (RON and MON) of any arbitrary Liquefied Petroleum Gas (LPG) mixture to be determined. The design of the modified engine incorporates modern hardware that enables accurate metering of different LPG mixtures, together with measurement of the in-cylinder pressure, the air-fuel ratio and the engine-out emissions.The modified CFR engine is first used to measure the octane numbers of different LPG mixtures. The measured octane numbers are shown to be similar to the limited data acquired using the now withdrawn Motor (LP) test method (ASTM D2623). The volumetric efficiency, engine-out emissions and combustion efficiency for twelve alternative LPG mixtures are then compared with equivalent data acquired with the standard CFR engine operating on a liquid fuel.Finally, the modified CFR engine is modelled using GT-Power. The full engine model contains empirical sub-models of the intake and exhaust systems, the gas exchange processes, the flame propagation and the in-cylinder heat transfer. The calibrated…
Annotation ability available
   This content is not included in your SAE MOBILUS subscription, or you are not logged in.

Energy Balance of a Spark Ignition Engine Running on Hydrogen, Synthesis Gas and Natural Gas

Univ. of Melbourne-Pedro Orbaiz, Michael Brear
Published 2014-04-01 by SAE International in United States
This paper presents a study from the same, spark ignition, reciprocating engine running on natural gas, hydrogen and two different synthesis gases. The effects of varying fuel composition on the engine's energy balance is examined in detail, with a particular emphasis on the lean burn performance. Closure of the First Law over the engine is achieved through the integrated use of measurement and engine simulation. This integrated approach enables validation of the heat losses from the entire engine, and in particular the in-cylinder heat losses.These analyses demonstrate high in-cylinder heat losses for the hydrogen-rich fuels relative to those for the natural gas, which is consistent with the literature. Further, they also suggest a plausible explanation for the consistently observed lean air-fuel ratio for peak thermal efficiency. This appears to be primarily a trade-off between higher in-cylinder heat losses at richer conditions and higher unburned fuel losses due to flame quenching at leaner conditions, the latter considered in a previous work by the group. Thus, the physics of premixed turbulent flame propagation and the in-cylinder heat…
Annotation ability available
   This content is not included in your SAE MOBILUS subscription, or you are not logged in.

A Technical and Financial Analysis of Potentially Near-Zero Greenhouse Gas Emission Passenger Vehicles

SAE International Journal of Passenger Cars - Mechanical Systems

University of Melbourne-Michael Brear, Peter Dennis, Chris Manzie
University of Queensland-Rahul Sharma
  • Journal Article
  • 2013-01-0496
Published 2013-04-08 by SAE International in United States
This paper presents a technical and financial analysis of several, potentially near-zero greenhouse gas emission passenger vehicles for Australian driving conditions. Conventional, series hybrid, plug-in hybrid (PHEV) and fully electric (BEV) vehicles of class B and class E sizes are considered, with their propulsive energy assumed to originate from a source that is free of net greenhouse gas emissions.Extensions to the vehicle models developed by the authors in our previous works [1, 2, 3] are first developed. These enable estimation of the size of each major component in each powertrain, and therefore the total, in-service energy consumption and in-service greenhouse gas emissions. The component sizing also allows estimation of the each vehicle's purchase price, its embodied energy and its embodied greenhouse gas emissions, the latter assuming scenarios for both the current and a future, low emission intensity of Australian manufacturing.The ability of increasingly electric powertrains to reduce in-service energy consumption and emissions, with correspondingly higher up-front price and higher embodied emissions, are then evaluated. Overall, the results suggest that full vehicle electrification is not the…
Annotation ability available