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Abidin, Zainal
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Development of a Natural Gas Engine with Diesel Engine-like Efficiency Using Computational Fluid Dynamics

Southwest Research Institute-Ahmed Abdul Moiz, Zainal Abidin, Robert Mitchell, Michael Kocsis
Published 2019-04-02 by SAE International in United States
Present day natural gas engines have a significant efficiency disadvantage but benefit with low carbon-dioxide emissions and cheap three-way catalysis aftertreatment. The aim of this work is to improve the efficiency of a natural gas engine on par with a diesel engine. A Cummins-Westport ISX12-G (diesel) engine is used for the study. A baseline model is validated in three-dimensional Computational Fluid Dynamics (CFD). The challenge of this project is adapting the diesel engine for the natural gas fuel, so that the increased squish area of the diesel engine piston can be used to accomplish faster natural gas burn rates. A further increase efficiency is achieved by switching to D-EGR technology. D-EGR is a concept where one or more cylinders are run with excess fueling and its exhaust stream, containing H2 and CO, is cooled and fed into the intake stream. With D-EGR although there is an in-cylinder presence of a reactive H2-CO reformate, there is also higher levels of dilution. A new piston was designed that can match the high squish burn rates with not…
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A Comprehensive CFD-FEA Conjugate Heat Transfer Analysis for Diesel and Gasoline Engines

Southwest Research Institute-Bansal Shah, Ahmed Moiz, Matthew Hoffmeyer, Zainal Abidin, Anthony Megel, Kevin Hoag
Published 2019-04-02 by SAE International in United States
As the efforts to push capabilities of current engine hardware to their durability limits increases, more accurate and reliable analysis is necessary to ensure that designs are robust. This paper evaluates a method of Conjugate Heat Transfer (CHT) analysis for a gasoline and a diesel engine that combines combustion Computational Fluid Dynamics (CFD), engine Finite Element Analysis (FEA), and cooling jacket CFD with the goal of obtaining more accurate temperature distribution and heat loss predictions in an engine compared to standard de-coupled CFD and FEA analysis methods. This novel CHT technique was successfully applied to a 2.5 liter GM LHU gasoline engine at 3000 rpm and a 15.0 liter Cummins ISX heavy duty diesel engine operating at 1250 rpm. Combustion CFD simulations results for the gasoline and diesel engines are validated with the experimental data for cylinder pressure and heat release rate. Radiation models were implemented to estimate heat transfer more accurately for diesel engine. FEA simulations are performed in a separate software platform. Data exchanges between CFD and FEA software codes are performed at…
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Evaluation of Diesel Spray with Non-Circular Nozzle - Part I: Inert Spray

Southwest Research Institute-Khanh Cung, Ahmed Abdul Moiz, Bansal Shah, Vickey Kalaskar, Jason Miwa, Zainal Abidin
Published 2019-01-15 by SAE International in United States
Numerous studies have characterized the impact of high injection pressure and small nozzle holes on spray quality and the subsequent impact on combustion. Higher injection pressure or smaller nozzle diameter usually reduce soot emissions owing to better atomization quality and fuel-air mixing enhancement. The influence of nozzle geometry on spray and combustion of diesel continues to be a topic of great research interest. An alternate approach impacting spray quality is investigated in this paper, specifically the impact of non-circular nozzles. The concept was explored experimentally in an optically accessible constant-volume combustion chamber (CVCC). Non-reacting spray evaluations were conducted at various ambient densities (14.8, 22.8, 30 kg/m3) under inert gas of Nitrogen (N2) while injection pressure was kept at 100 MPa. Shadowgraph imaging was used to obtain macroscopic spray characteristics such as spray structure, spray penetration, and the spray cone angle. Analysis from image processing showed expected result of lower penetration rate and higher spray cone angle as ambient density increased. Two slot nozzles with different aspect ratios but similar flow area as compared with one…
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FSI - MRF Coupling Approach For Faster Turbocharger 3D Simulation

SAE International Journal of Advances and Current Practices in Mobility

Convergent Science Inc.-Jasim Sadique, Yunliang Wang
Southwest Research Institute-Zainal Abidin, Andrew Morris, Jason Miwa
  • Journal Article
  • 2019-01-0007
Published 2019-01-15 by SAE International in United States
Fluid-Structure Interaction (FSI) simulation approach can be used to simulate a turbocharger. However, this predictive 3D simulation encounters the challenge of a long computational time. The impeller speed can be above 100,000 rpm, and generally a CFD solver limits the maximum movement of the impeller surface per time step. The maximum movement must be a fraction (~0.3) of the cell length, thus the time step will be very small. A Multiple Reference Frame (MRF) approach can reduce computational time by eliminating the need to regenerate the mesh at each time-step to accommodate the moving geometry. A static local reference zone encompassing the impeller is created and the impact of the impeller movement is modeled via a momentum source. However, the MRF approach is not a predictive simulation because the impeller speed must be given by the User. A new simulation approach was introduced that coupled the FSI and MRF approach. Like in the FSI approach, the total moment of the impeller was calculated based on the resultant force acting over the impeller surface. This calculation…
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Investigation of an Advanced Combustion System for Stoichiometric Diesel to Reduce Soot Emissions

Southwest Research Institute-Avery Chase, Jason Miwa, Zainal Abidin, Khanh Cung
Published 2019-01-15 by SAE International in United States
Diesel engines are facing increased competition from gasoline engines in the light-duty and small non-road segments, primarily due to the high relative cost of emissions control systems for lean-burn diesel engines. Advancements in gasoline engine technology have decreased the operating cost advantage of diesels and the relatively high initial-cost disadvantage is now too large to sustain a strong business position. SwRI has focused several years of research efforts toward enabling diesel engine combustion systems to operate at stoichiometric conditions, which allows the application of a low-cost three-way catalyst emission control system which has been well developed for gasoline spark-ignited engines. One of the main barriers of this combustion concept is the result of high smoke emissions from poor fuel/air mixing. The current study focuses on improving the combustion system by investigating different fuel/air mixing strategies that enhance fuel spray - piston bowl interaction while simultaneously optimizing the fuel injection system. Computational Fluid Dynamics (CFD) simulations were carried out in conjunction with engine testing to evaluate different piston bowl designs as well as injector nozzle designs…
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Advances Toward the Goal of a Genuinely Conjugate Engine Heat Transfer Analysis

Southwest Research Institute-Matthew Hoffmeyer, Ahmed Abdul Moiz, Kevin Hoag, Anthony Megel, Bansal Shah, Zainal Abidin
Published 2019-01-15 by SAE International in United States
As the design of engines advances and continues to push the capabilities of current hardware closer to their durability limits, more accurate and reliable analysis is necessary to ensure that designs are robust. This research evaluates a method of conjugate heat transfer analysis for a diesel engine that combines the combustion CFD, Engine FEA, and cooling jacket CFD with the aim of getting more accurate heat loss predictions and a more accurate temperature distribution in the engine than with current analysis methods. A 15.0 L Cummins ISX heavy duty engine operating at 1250 RPM and 15 bar BMEP load is selected for this work. Spray combustion computational fluid dynamics (CFD) simulations are performed for the diesel engine and the results are validated with experimental data. Finite Element Analysis (FEA) simulations were performed in a separate software platform. Data interchanges between CFD and FEA software codes were performed at specified sub-cycle engine intervals and the simulations ran for multiple engine cycles. A comprehensive CFD-FEA conjugate heat transfer (CHT) methodology is proposed and the accuracy of this…
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Effect of Micro-Hole Nozzle on Diesel Spray and Combustion

Southwest Research Institute-Khanh Cung, Daniel Christopher Bitsis, Thomas Briggs, Vickey Kalaskar, Zainal Abidin, Bansal Shah, Jason Miwa
Published 2018-04-03 by SAE International in United States
The influence of nozzle geometry on spray and combustion of diesel continues to be a topic of great research interest. One area of promise, injector nozzles with micro-holes (i.e. down to 30 μm), still need further investigation. Reduction of nozzle orifice diameter and increased fuel injection pressure typically promotes air entrainment near-nozzle during start of injection. This leads to better premixing and consequently leaner combustion, hence lowering the formation of soot. Advances in numerical simulation have made it possible to study the effect of different nozzle diameters on the spray and combustion in great detail. In this study, a baseline model was developed for investigating the spray and combustion of diesel fuel at the Spray A condition (nozzle diameter of 90 μm) from the Engine Combustion Network (ECN) community. Upon validation of parameters such as spray penetration, lift-off length, and ignition delay the baseline simulation was extended to study different nozzle orifice diameters. All simulations were performed using a constant-volume combustion chamber (CVCC) geometry with similar ambient conditions of pressure (60 bar) and temperature (900 K). It was shown…
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Dilute Combustion Assessment in Large Bore, Low Speed Engines

Southwest Research Institute-Zainal Abidin, Kevin Hoag, Nicholas Badain
Published 2017-03-28 by SAE International in United States
The promising D-EGR gasoline engine results achieved in the test cell, and then in a vehicle demonstration have led to exploration of further possible applications. A study has been conducted to explore the use of D-EGR gasoline engines as a lower cost replacement for medium duty diesel engines in trucks and construction equipment. However, medium duty diesel engines have larger displacement, and tend to require high torque at lower engine speeds than their automobile counterparts. Transmission and final drive gearing can be utilized to operate the engine at higher speeds, but this penalizes life-to-overhaul. It is therefore important to ensure that D-EGR combustion system performance can be maintained with a larger cylinder bore, and with high specific output at relatively low engine speeds. Based on application projections studied in this work, an engine having a 107mm bore and 124mm stroke, operating at 2000 rpm at 17 bar Brake Mean Effective Pressure (BMEP) was selected as representative.The objective of the study was to use combustion modeling to make an initial assessment of combustion performance under the…
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Efficiency and Emissions Characteristics of Partially Premixed Dual-Fuel Combustion by Co-Direct Injection of NG and Diesel Fuel (DI2) - Part 2

Southwest Research Institute-Gary D. Neely, Radu Florea, Jason Miwa, Zainal Abidin
Published 2017-03-28 by SAE International in United States
The CO2 advantage coupled with the low NOX and PM potential of natural gas (NG) makes it well-suited for meeting future greenhouse gas (GHG) and NOX regulations for on-road medium and heavy-duty engines. However, because NG is mostly methane, reduced combustion efficiency associated with traditional NG fueling strategies can result in significant levels of methane emissions which offset the CO2 advantage due to reduced efficiency and the high global warming potential of methane. To address this issue, the unique co-direct injection capability of the Westport HPDI fuel system was leveraged to obtain a partially-premixed fuel charge by injecting NG during the compression stroke followed by diesel injection for ignition timing control. This combustion strategy, referred to as DI2, was found to improve thermal and combustion efficiencies over fumigated dual-fuel combustion modes. In addition, DI2 provided significant thermal efficiency improvement over the baseline diffusion-controlled combustion strategy (HPDI) where NG injection occurs after diesel injection. The DI2 combustion process was analyzed using 3D-CFD and indicated that additional CH4 reductions from the crevice region may be possible by…
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A Study Isolating the Effect of Bore-to-Stroke Ratio on Gasoline Engine Combustion Chamber Development

SAE International Journal of Engines

Southwest Research Institute-Kevin L. Hoag, Barrett Mangold, Terrence Alger, Zainal Abidin, Christopher Wray, Mark Walls, Christopher Chadwell
  • Journal Article
  • 2016-01-2177
Published 2016-10-17 by SAE International in United States
A unique single cylinder engine was used to assess engine performance and combustion characteristics at three different strokes, with all other variables held constant. The engine utilized a production four-valve, pentroof cylinder head with an 86mm bore. The stock piston was used, and a variable deck height design allowed three crankshafts with strokes of 86, 98, and 115mm to be tested. The compression ratio was also held constant. The engine was run with a controlled boost-to-backpressure ratio to simulate turbocharged operation, and the valve events were optimized for each operating condition using intake and exhaust cam phasers. EGR rates were swept from zero to twenty percent under low and high speed conditions, at MBT and maximum retard ignition timings. The increased stroke engines demonstrated efficiency gains under all operating conditions, as well as measurably reduced 10-to-90 percent burn durations. The results were quite non-linear, with the majority of the gains achieved in going from the 1:1 to 0.87:1 bore-to-stroke ratio cases. The further change to 0.75:1 showed significantly diminished returns. Flame speed and chamber geometry…
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