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0-D and 1-D Modeling and Numerics, 2017

2017-03-28
Papers in the session cover zero-dimensional, one-dimensional, and quasi-dimensional models for simulation of SI and CI engines with respect to: engine breathing, boosting, and acoustics; SI combustion and emissions; CI combustion and emissions; fundamentals of engine thermodynamics; numerical modeling of gas dynamics; thermal management; mechanical and lubrication systems; system level models for controls; and system level models for vehicle fuel economy and emissions predictions.
Collection

0-D and 1-D Modeling and Numerics, 2018

2018-04-03
Papers in the session cover zero-dimensional, one-dimensional, and quasi-dimensional models for simulation of SI and CI engines with respect to: engine breathing, boosting, and acoustics; SI combustion and emissions; CI combustion and emissions; fundamentals of engine thermodynamics; numerical modeling of gas dynamics; thermal management; mechanical and lubrication systems; system level models for controls; and system level models for vehicle fuel economy and emissions predictions.
Technical Paper

0D/1D Turbulent Combustion Model Assessment from an Ultra-Lean Spark Ignition Engine

2019-03-25
2019-01-1409
This paper focuses on an assessment of predictive combustion model using a 0D/1D simulation tool under high load, different excess air ratio λ , and different combustion stabilities (based on coefficient of variation of indicated mean effective pressure COVimep). To consider that, crank angle resolved data of experimental pressure of 500 cycles are recorded under engine speed 1000 RPM and 2000 RPM, wide-open throttle, and λ=1.0, 1.42, 1.7, and 2.0. Firstly, model calibration is conducted using 18 cases at 2000 RPM using 500 cycle-averaged in-cylinder pressure to find optimized model constants. Then, the model constants are unchanged for other cases. Next, different cycle-averaged pressure data are used as inputs in the simulation based on the COVimep for studying sensitivity of the turbulent model constants. The simulation is conducted using 1D simulation software GT-Power.
Technical Paper

0D/3D Simulations of Combustion in Gasoline Engines Operated with Multiple Spark Plug Technology

2015-04-14
2015-01-1243
A simulation method is presented for the analysis of combustion in spark ignition (SI) engines operated at elevated exhaust gas recirculation (EGR) level and employing multiple spark plug technology. The modeling is based on a zero-dimensional (0D) stochastic reactor model for SI engines (SI-SRM). The model is built on a probability density function (PDF) approach for turbulent reactive flows that enables for detailed chemistry consideration. Calculations were carried out for one, two, and three spark plugs. Capability of the SI-SRM to simulate engines with multiple spark plug (multiple ignitions) systems has been verified by comparison to the results from a three-dimensional (3D) computational fluid dynamics (CFD) model. Numerical simulations were carried for part load operating points with 12.5%, 20%, and 25% of EGR. At high load, the engine was operated at knock limit with 0%, and 20% of EGR and different inlet valve closure timing.
Technical Paper

1-D Modeling and Experimental Evaluation of Secondary Air Injection System for a Small SI Engine

2013-10-15
2013-32-9091
In order to comply with the existing emission norms of BSIII in India or EURO III and beyond that also, it is not sufficient to use the catalytic converter technology alone over the wide range of engine operating maps. Different studies across the world have proved that the cost, drivability, operating range against AFR, heat dissipation rate characteristics of catalytic converter limit their use in startup and idling conditions. One common way to tackle this condition is to use the Secondary Air Injection (SAI) system. In this system, small amount of air is injected after the exhaust port to initiate the thermal oxidation of gases. The right amount of air injected at the right time and at right location will reduce the emission by 37-90%. In the following study, SI engine vehicle with single cylinder, 160 cc and having carburetor is used as a test vehicle to evaluate the performance of SAI. The SAI system is modeled in AVL BOOST software and validated against the experimental data.
Journal Article

1-D Simulation Study of Divided Exhaust Period for a Highly Downsized Turbocharged SI Engine - Scavenge Valve Optimization

2014-04-01
2014-01-1656
Fuel efficiency and torque performance are two major challenges for highly downsized turbocharged engines. However, the inherent characteristics of the turbocharged SI engine such as negative PMEP, knock sensitivity and poor transient performance significantly limit its maximum potential. Conventional ways of improving the problems above normally concentrate solely on the engine side or turbocharger side leaving the exhaust manifold in between ignored. This paper investigates this neglected area by highlighting a novel means of gas exchange process. Divided Exhaust Period (DEP) is an alternative way of accomplishing the gas exchange process in turbocharged engines. The DEP concept engine features two exhaust valves but with separated function. The blow-down valve acts like a traditional turbocharged exhaust valve to evacuate the first portion of the exhaust gas to the turbine.
Technical Paper

100% LPG Long Haul Truck Conversion - Economy and Environmental Benefits

2012-09-24
2012-01-1983
Advanced Vehicle Technologies (AVT), a Ballarat Australia based company, has developed the World's first diesel to 100% LPG conversion for heavy haul trucks. There is no diesel required or utilized on the trucks. The engine is converted with minimal changes into a spark ignition engine with equivalent power and torque of the diesel. The patented technology is now deployed in 2 Mercedes Actros trucks. The power output in engine dynamometer testing exceeds that of the diesel (in excess of 370 kW power and 2700 Nm torque). In on-road application the power curve is matched to the diesel specifications to avoid potential downstream power-train stress. Testing at the Department of Transport Energy & Infrastructure, Regency Park, SA have shown the Euro 3 truck converted to LPG is between Euro 4 and Euro 5 NOx levels, CO2 levels 10% better than diesel on DT80 test and about even with diesel on CUEDC tests.
Technical Paper

15 Combustion Characteristics of an Improved Design of a Stratified Charge Spark Ignition Engine

2002-10-29
2002-32-1784
The characteristics of the combustion process in an improved design of a novel spark ignition engine studied by means of Computational Fluid Dynamics are presented. The engine is designed to work at low average combustion temperatures to achieve very low NOx emissions. The engine is a two-stroke, two piston in-line engine. The main combustion occurs in four combustion pre-chambers that have an annular shape with a nozzle on the side facing the cylinder. Fuel is directly injected into the pre-chambers by using high-pressure fuel injectors. A progressive burning process is expected to keep the flame inside the pre-chambers while the fast ejection of combustion products should produce effective mixing with the cold air in the cylinder. This fast dilution should guarantee a temperature drop of the combustion products thus reducing the formation of NOx via a thermal path.
Technical Paper

1997 Propane Vehicle Challenge Design Strategy -University of Waterloo

1998-02-23
980491
The conversion design strategy, and emissions and performance results for a dedicated propane, vapour injected, 1995 Dodge Dakota truck are reported. Data is obtained from the University of Waterloo entry in the 1997 Propane Vehicle Challenge. A key feature of the design strategy is its focus on testing and emissions while preserving low engine speed power for drivability. Major changes to the Dakota truck included the following: installation of a custom shaped fuel tank, inclusion of a fuel temperature control module, addition of a vaporizer and a fuel delivery metering unit, installation of a custom vapour distribution manifold, addition of an equivalence ratio electronic controller, inclusion of a wide range oxygen sensor, addition of an exhaust gas recirculation cooler and installation of thermal insulation on the exhaust system. A competition provided natural gas catalyst was used.
Technical Paper

1997 UTEP LPP-FI Propane Challenge Vehicle

1998-02-23
980490
As part of the 1997 Propane Vehicle Challenge, a team of twelve UTEP students converted a 1996 Dodge Grand Caravan with a 3.3 L V6 engine to dedicated Liquefied Petroleum Gas (LPG) operation according to the 1997 Propane Vehicle Challenge (PVC) competition rules (16). The 1997 UTEP team developed an LPG liquid phase port fuel injection (LPP-FI) system for the minivan. The UTEP design strategy combines simplicity and sound engineering practices with the effective use of heat resistant materials to maintain the LPG in the liquid phase at temperatures encountered in the fuel delivery system. The team identified two options for fuel storage with in-tank fuel pumps. The competition vehicle incorporates a five-manifold eight inch diameter Sleegers Engineering LPG tank fitted with a Walbro LPTS in-tank pump system, providing a calculated range of 310 city miles and 438 highway miles.
Technical Paper

1D and 3D CFD Investigation of Burning Process and Knock Occurrence in a Gasoline or CNG fuelled Two-Stroke SI Engine

2011-11-08
2011-32-0526
The paper presents a combined experimental and numerical investigation of a small unit displacement two-stroke SI engine operated with gasoline and Natural Gas (CNG). A detailed multi-cycle 3D-CFD analysis of the scavenging process is at first performed in order to accurately characterize the engine behavior in terms of scavenging patterns and efficiency. Detailed CFD analyses are used to accurately model the complex set of physical and chemical processes and to properly estimate the fluid-dynamic behavior of the engine, where boundary conditions are provided by a in-house developed 1D model of the whole engine. It is in fact widely recognized that for two-stroke crankcase scavenged, carbureted engines the scavenging patterns (fuel short-circuiting, residual gas distribution, pointwise lambda field, etc.) plays a fundamental role on both of engine performance and tailpipe emissions.
Technical Paper

1D-3D Analysis of the Scavenging and Combustion Process in a Gasoline and Natural-Gas Fuelled Two-Stroke Engine

2008-04-14
2008-01-1087
The paper presents a 1D-3D numerical model to simulate the scavenging and combustion processes in a small-size spark-ignition two-stroke engine. The engine is crankcase scavenged and can be operated with both gasoline and Natural Gas (NG). The analysis is performed with a modified version of the KIVA3V code, coupled to an in-house developed 1D model. A time-step based, two-way coupled procedure is fully described and validated against a reference test. Then, a 1D-3D simulation of the whole two-stroke engine is carried out in different operating conditions, for both gasoline and NG fuelling. Results are compared with experimental data including instantaneous pressure signals in the crankcase, in the cylinder and in the exhaust pipe. The procedure allows to characterize the scavenging process and quantify the fresh mixture short-circuiting, as well as to analyze the development of the NG combustion process for a diluted mixture, typically occurring in a two-stroke engine.
Technical Paper

2-D Temperature Measurements of Unburned Gas Mixture in an Engine by Two-line Excitation LIF Technique

2006-10-16
2006-01-3336
Two-line excitation LIF (Laser-Induced Fluorescence) technique for 2-dimensional temperature measurements in an engine cylinder before ignition is presented. From the fundamental examinations, the combination of toluene tracer with a pair of excitation lines of 248nm and 266nm has been selected because of the high LIF intensity ratio and closer excitation wavelengths. In-cylinder thermometry is conducted using a visualized single cylinder spark ignition engine both in PFI (port-fuel-injection) and DI (direct-injection) operation. The accuracy of this technique is determined through the homogeneous PFI experiment. Temperature and fuel distribution in unburned mixture are measured simultaneously in DI operation. It exists a strong correlation between equivalence ratio and temperature inside the mixture. Temperature in the fuel rich region is lower than in the fuel lean region.
Technical Paper

2-step Variable Valve Actuation: System Optimization and Integration on an SI Engine

2006-04-03
2006-01-0040
2-step variable valve actuation using early-intake valve closing is a strategy for high fuel economy on spark-ignited gasoline engines. Two discrete valve-lift profiles are used with continuously variable cam phasing. 2-step VVA systems are attractive because of their low cost/benefit, relative simplicity, and ease-of-packaging on new and existing engines. A 2-step VVA system was designed and integrated on a 4-valve-per-cylinder 4.2L line-6 engine. Simulation tools were used to develop valve lift profiles for high fuel economy and low NOx emissions. The intake lift profiles had equal lift for both valves and were designed for high airflow & residual capacity in order to minimize valvetrain switching during the EPA drive cycle. It was determined that an enhanced combustion system was needed to maximize fuel economy benefit with the selected valve lift profiles. A flow-efficient chamber mask was developed to increase in-cylinder tumble motion and combustion rates.
Technical Paper

2D Residual Gas Visualization in an Optical Direct Injection Spark Ignition Engine with IR Laser Absorption

2015-04-14
2015-01-1648
The spatial distribution of internal exhaust gas recirculation (EGR) is evaluated in an optically accessible direct injection spark ignition engine using near infrared laser absorption to visualize the distribution of the H2O molecule. The obtained overall internal exhaust gas recirculation compares well to gas-exchange cycle calculations and the spatial distributions are consistent with those measured with inverse LIF. The experimental procedures described in this report are designed to be simple and rapidly implemented without the need to resort to unusual optical components. The necessary spectral data of the selected absorption line is obtained from the HITEMP database and is validated with prior experiments carried out in a reference cell. Laser speckle in the images is effectively reduced using a ballistic diffuser.
Technical Paper

3-D Computations of Premixed-Charge Natural Gas Combustion in Rotary Engines

1991-02-01
910625
A three-dimensional model for premixed- charge naturally-aspirated rotary engine combustion is used to identify combustion chamber geometries that could lead to increased indicated efficiency for a lean (equivalence ratio =0.75) natural gas/air mixture. Computations were made at two rpms (1800 and 3600) and two loads (approximately 345 Kpa and 620 Kpa indicated mean effective pressure). Six configurations were studied. The configuration that gave the highest indicated efficiency has a leading pocket with a leading deep recess, two spark plugs located circumferentially on the symmetry plane (one after the minor axis and the other before), a compression ratio of 9.5, and an anti-quench feature on the trailing flank.
Technical Paper

3-D LDV Measurement of In-Cylinder Air Flow in a 3.5L Four-Valve SI Engine

1995-02-01
950648
In-cylinder flows in a motored four-valve SI engine were examined by simultaneous three-component LDV measurement. The purpose of this study was to develop better physical understanding of in-cylinder flows and quantitative methods which correlate in-cylinder flows to engine performance. This study is believed to be the first simultaneous three-component LDV measurement of the air flow over a planar section of a four-valve piston-cylinder assembly. Special attention is paid to the tumble formation process, three-dimensional turbulent kinetic energy, and measurement of the tumble ratio. The influence of the induction system and the piston geometry are believed to have a significant effect on the in-cylinder flow characteristics. Using LDV measurement, the flows in two different piston top geometries were examined. One axial plane was selected to observe the effect of piston top geometries on the flow field in the combustion chamber.
Technical Paper

3-dimensional Simulation of Knock in a Heavy-Duty LPG Engine

2002-10-21
2002-01-2700
Three-dimensional transient simulation was performed and an autoignition model was implemented to predict knock occurrence and autoignition site in a heavy-duty liquefied petroleum gas (LPG) engine. A flame area evolution (FAE) premixed combustion model was applied to simulate flame propagation. Engine experiments using a single-cylinder research engine were performed to calibrate the reduced kinetic model and to verify the result of this modeling. A pressure transducer and a head-gasket type ion-probe circuit board were installed to detect knock occurrence, flame arrival angle, and autoignition site. The simulation result shows good agreement with engine experiments. It also provides much information about in-cylinder phenomena and some ways to reduce knocking tendency. This knock simulation can be used as a development tool of engine design.
Technical Paper

3D Modelling of Combustion and Pollutants in a 4-Valve SI Engine; Effect of Fuel and Residuals Distribution and Spark Location

1996-10-01
961964
The SI engine combustion model LI-CFM introduced by Boudier et, al. (1992) [8] is extended to deal with actual engines. New models are proposed to simulate ignition with convection at the spark and flame-wall interaction. The scalar properties of the unburnt gases within the combustion zone are computed. This allows for the computation of flame propagation in temperature, fuel and residual gas stratified charges. A model for NO and CO formation is introduced. It is based on a conditional burnt/unburnt averaging of the reaction rates. Pollutants are created at the flamelet level and evolve in the burnt, gases using a mixed equilibrium/kinetic scheme. All these physical models are implemented in a multi-block version of the Kiva 2 code, KMB. This code is used to simulate a 4-valve engine including intake ports. Initial and boundary conditions are obtained from a ID acoustic code.
Technical Paper

3D Simulationson Premixed Laminar Flame Propagation of iso-Octane/Air Mixture at Elevated Pressure and Temperature

2015-03-10
2015-01-0015
This paper aims to validate chemical kinetic mechanisms of surrogate gasoline three components fuel by calculating one-dimensional laminar burning velocity of iso-octane/air mixture. Next, the application of level-set method on premixed combustion without consideration the effect of turbulence eddies on flame front is also studied in three-dimensional computational fluid dynamic (3D-CFD) simulation. In the 3D CFD simulation, there is an option to calculate laminar burning velocity by using empirical correlations, however it is applicable only for particular initial pressure and temperature in spark ignition engine cases. One-dimensional burning velocities from lean to rich of iso-octane/air mixture are calculated by using CHEMKIN-PRO with detailed chemistry and transport phenomena as a function of different equivalence ratios, different unburnt temperature and pressure ranges.
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