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Development of a Modular, Dry-Running Bowditch Piston with Efficient Window Cleaning

University of British Columbia-Oliver Terry, Jeremy Rochussen, Patrick Kirchen
Published 2018-04-03 by SAE International in United States
Optically-accessible engines provide valuable insight into in-cylinder combustion mechanisms and are widely considered an essential tool in fundamental internal combustion engine research. Here, a 2-piece Bowditch-type optical piston is developed as a replacement for a single-piece piston used in a 2 L, heavy-duty compression-ignition engine, which is convertible for use in both an optical and all-metal configuration. This piston was designed to provide long measurement durations, to simplify cleaning of the piston window, and to facilitate changes in piston crown geometry.A 2-piece piston architecture allows application of different piston bowl, crown, and compression ring geometries with minimal manufacturing and design cost. It was experimentally found that the cyclic loading experienced by piston rings permits the use of a lower grade material than plain bearing theory predicts. A set of 3 glass-filled PTFE compression rings were designed to replace the 2 conventional steel split-rings, resulting in improved gas sealing, reduced window fouling from lubrication grease, and longer testing intervals. The selection of these rings was validated by experimental measurement of break-in performance and pressure sealing. A new…
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Development of a Research-Oriented Cylinder Head with Modular Injector Mounting and Access for Multiple In-Cylinder Diagnostics

University of British Columbia-Jeremy Rochussen, Jeff Son, Jeff Yeo, Mahdiar Khosravi, Patrick Kirchen
Westport Fuel Systems Inc-Gordon McTaggart-Cowan
Published 2017-09-04 by SAE International in United States
Alternative fuel injection systems and advanced in-cylinder diagnostics are two important tools for engine development; however, the rapid and simultaneous achievement of these goals is often limited by the space available in the cylinder head. Here, a research-oriented cylinder head is developed for use on a single cylinder 2-litre engine, and permits three simultaneous in-cylinder combustion diagnostic tools (cylinder pressure measurement, infrared absorption, and 2-color pyrometry). In addition, a modular injector mounting system enables the use of a variety of direct fuel injectors for both gaseous and liquid fuels. The purpose of this research-oriented cylinder head is to improve the connection between thermodynamic and optical engine studies for a wide variety of combustion strategies by facilitating the application of multiple in-cylinder diagnostics.The cylinder head design was derived from the original production cylinder head used on this engine, which was sectioned and laser scanned to create a parametric model. This model was used as the basis for the design and analysis of the new cylinder head with provisions for a modular injector mounting scheme, multiple simultaneous…
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Comparing the Whole Body Vibration Exposures across Three Truck Seats

University of British Columbia-Hugh Davies
University of Washington-Fangfang Wang, Peter Johnson
Published 2017-06-05 by SAE International in United States
Whole-body vibration (WBV) is associated with several adverse health and safety outcomes including low-back pain (LBP) and driver fatigue. The objective of this study was to evaluate the efficacy of three commercially-available air-suspension truck seats for reducing truck drivers’ exposures to WBV. Seventeen truck drivers operating over a standardized route were recruited for this study and three commercially-available air suspension seats were evaluated. The predominant, z-axis average weighted vibration (Aw) and Vibration Dose Values (VDV) were calculated and normalized to represent eight hours of truck operation. In addition, the Seat Effective Amplitude Transmissibility (SEAT), the ratio of the seat-measured vibration divided by the floor-measured vibration, was compared across the three seats. One seat had significantly higher on-road WBV exposures whereas there were no differences across seats in off-road WBV exposures. The SEAT values, calculated over the whole route (which was predominantly on-road) indicated that one seat reduced WBV exposure by 9% on average and the other two seats had nearly double the attenuation performance based on A(8) exposures. The performance differences across seats may have…
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Effect of Injection Strategies on Emissions from a Pilot-Ignited Direct-Injection Natural-Gas Engine- Part I: Late Post Injection

University of British Columbia-Ethan Faghani, Pooyan Kheirkhah, Christopher W.J. Mabson, Patrick Kirchen, Steve Rogak
Westport Fuel Systems-Gordon McTaggart-Cowan
Published 2017-03-28 by SAE International in United States
High-pressure direct-injection (HPDI) in heavy duty engines allows a natural gas (NG) engine to maintain diesel-like performance while deriving most of its power from NG. A small diesel pilot injection (5-10% of the fuel energy) is used to ignite the direct injected gas jet. The NG burns in a predominantly non-premixed combustion mode which can produce particulate matter (PM). Here we study the effect of injection strategies on emissions from a HPDI engine in two parts. Part-I will investigates the effect of late post injection (LPI) and Part II will study the effect of slightly premixed combustion (SPC) on emission and engine performance. PM reductions and tradeoffs involved with gas late post-injections (LPI) was investigated in a single-cylinder version of a 6-cylinder,15 liter HPDI engine. The post injection contains 10-25% of total fuel mass, and occurs after the main combustion event. When timed appropriately, LPI results in significant PM reductions with only small effects on other emissions and engine performance. The morphology of particles produced by LPI is similar to that from conventional HPDI (and…
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Effect of Injection Strategies on Emissions from a Pilot-Ignited Direct-Injection Natural-Gas Engine- Part II: Slightly Premixed Combustion

University of British Columbia-Ethan Faghani, Pooyan Kheirkhah, Christopher W.J. Mabson, Patrick Kirchen, Steve Rogak
Westport Fuel Systems-Gordon McTaggart-Cowan
Published 2017-03-28 by SAE International in United States
High-pressure direct-injection (HPDI) in heavy duty engines allows a natural gas (NG) engine to maintain diesel-like performance while deriving most of its power from NG. A small diesel pilot injection (5-10% of the fuel energy) is used to ignite the direct injected gas jet. The NG burns in a predominantly mixing-controlled combustion mode which can produce particulate matter (PM). Here we study the effect of injection strategies on emissions from a HPDI engine in two parts. Part-I investigated the effect of late post injection (LPI); the current paper (Part-II) reports on the effects of slightly premixed combustion (SPC) on emission and engine performance. In SPC operation, the diesel injection is delayed, allowing more premixing of the natural gas prior to ignition. PM reductions and tradeoffs involved with gas slightly premixed combustion was investigated in a single-cylinder version of a 6-cylinder, 15 liter HPDI engine. SPC operation at a high-load point reduces over 90% of the PM with a 2% improvement in fuel efficiency while having almost the same level of NOx and methane. The drawback…
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Application of an In-Cylinder Local Infrared Absorption Fuel Concentration Sensor in a Diesel-Ignited Dual-Fuel Engine

University of British Columbia-Jeff Yeo, Jeremy Rochussen, Patrick Kirchen
Published 2016-10-17 by SAE International in United States
As global energy demands continue to be met with ever evolving and stricter emissions requirements, natural gas (NG) has become a highly researched alternative to conventional fossil fuels in many industrial sectors. Transportation is one such field that can utilize the benefits of NG as a primary fuel for use in internal combustion engines (ICEs). In the context of heavy-duty on-highway transportation applications, diesel-ignited dual-fuel (DIDF) combustion of NG has been identified as a commercially viable alternative technology. Previous investigations of DIDF have examined the various trends present across the spectrum of DIDF operating space. However, in-cylinder processes are still not well understood and this investigation aims to further understanding in this area.An in-cylinder, local infrared absorption fuel concentration sensor is used to examine in-cylinder processes by comparison with previous optical and thermodynamic studies. A 2-litre single-cylinder research engine was operated at selected DIDF operating modes with significantly different fuel conversion mechanisms. Fuelling was achieved through port injection of CH4 and direct injection of diesel. The operating modes were specified by varying the relative pilot…
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Fast Exhaust Nephelometer (FEN): A New Instrument for Measuring Cycle-Resolved Engine Particulate Emission

University of British Columbia-Pooyan Kheirkhah, Patrick Kirchen, Steven Rogak
Published 2016-10-17 by SAE International in United States
Soot emissions from direct-injection engines are sensitive to the fuel-air mixing process, and may vary between combustion cycles due to turbulence and injector variability. Conventional exhaust emissions measurements cannot resolve inter- or intra-cycle variations in particle emissions, which can be important during transient engine operations where a few cycles can disproportionately affect the total exhaust soot. The Fast Exhaust Nephelometer (FEN) is introduced here to use light scattering to measure particulate matter concentration and size near the exhaust port of an engine with a time resolution of better than one millisecond. The FEN operates at atmospheric pressure, sampling near the engine exhaust port and uses a laser diode to illuminate a small measurement volume. The scattered light is focused on two amplified photodiodes.Proof-of-concept tests were conducted on a heavy-duty single-cylinder research engine using a Westport high-pressure direct-injection (HPDI) natural gas fuel system. For this engine, the particulate emissions are dominated by soot at high loads, as they would be for a conventional diesel engine. When tested on the diluted exhaust, the FEN shows a close…
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Effect of Fueling Control Parameters on Combustion and Emissions Characteristics of Diesel-Ignited Methane Dual-Fuel Combustion

University of British Columbia-Jeremy Rochussen, Jeff Yeo, Patrick Kirchen
Published 2016-04-05 by SAE International in United States
Diesel-ignited dual-fuel (DIDF) combustion of natural gas (NG) is a promising strategy to progress the application of NG as a commercially viable compression ignition engine fuel. Port injection of gaseous NG applied in tandem with direct injection of liquid diesel fuel as an ignition source permits a high level of control over cylinder charge preparation, and therefore combustion. Across the broad spectrum of possible combustion conditions in DIDF operation, different fundamental mechanisms are expected to dominate the fuel conversion process. Previous investigations have advanced the understanding of which combustion mechanisms are likely present under certain sets of conditions, permitting the successful modeling of DIDF combustion for particular operating modes. A broader understanding of the transitions between different combustion modes across the spectrum of DIDF warrants further effort.In this investigation, a 2-litre single-cylinder research engine was operated in a variety of DIDF modes achieved through broad sweeps of fueling parameters. Through variations in the relative NG and diesel quantities, characterized using the global equivalence ratio (φglobal) and pilot fuel ratio (Rpilot), a DIDF operating space was…
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Natural Gas Partially Stratified Charge Combustion: Extended Analysis of Experimental Validation and Study of Turbulence Impact on Flame Propagation

University of British Columbia-Edward Chan
University of Rome Tor Vergata-Lorenzo Bartolucci, Stefano Cordiner, Vincenzo Mulone, Vittorio Rocco
Published 2016-04-05 by SAE International in United States
A Large Eddy Simulation (LES) numerical study of the Partially Stratified Charge (PSC) combustion process is here proposed, carried out with the open Source code OpenFOAM, in a Constant Volume Combustion Chamber (CVCC). The solver has already been validated in previous papers versus experimental data under a limited range of operating conditions. The operating conditions domain for the model validation is extended in this paper, mostly by varying equivalence ratio, to better highlight the influence of turbulence on flame front propagation. Effects of grid sizing are also shown, to better emphasize the trade-off between the level of accuracy of turbulent vortex description, and their impact on the kinematics of flame propagation. Results show the validity of the approach that is evident by comparing numerical and experimental data.
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Combustion and Emissions of Paired-Nozzle Jets in a Pilot-Ignited Direct-Injection Natural Gas Engine

University of British Columbia-Christopher W. J. Mabson, Ethan Faghani, Pooyan Kheirkhah, Patrick Kirchen, Steven N. Rogak
Westport Innovations Inc.-Gordon McTaggart-Cowan
Published 2016-04-05 by SAE International in United States
This paper examines the combustion and emissions produced using a prototype fuel injector nozzle for pilot-ignited direct-injection natural gas engines. In the new geometry, 7 individual equally-spaced gas injection holes were replaced by 7 pairs of closely-aligned holes (“paired-hole nozzle”). The paired-hole nozzle was intended to reduce particulate formation by increasing air entrainment due to jet interaction. Tests were performed on a single-cylinder research engine at different speeds and loads, and over a range of fuel injection and air handling conditions. Emissions were compared to those resulting from a reference injector with equally spaced holes (“single-hole nozzle”). Contrary to expectations, the CO and PM emissions were 3 to 10 times higher when using the paired-hole nozzles. Despite the large differences in emissions, the relative change in emissions in response to parametric changes was remarkably similar for single-hole and paired-hole nozzles. Compared to the reference injector, the paired-hole nozzle produced larger soot aggregates and larger numbers of particles; interestingly, soot primary particle size did not change significantly. In addition to the experimental results, select experiments were…
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