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Technical Paper

Noise and Vibration Optimization Using TMR Analysis for CI Engine Fueled by Blends of Simarouba Methyl Ester

2019-09-16
2019-01-1894
Today’s frenetic engine manufacturing and transportation sector and its related traces viz; noise and vibration of our modern societies has adverse effect on environment as well as all of us. Generally, vehicle extensively tested to withstand against mechanical shocks, noise, vibration etc. While, accordingly make the provision such as suspension, dampers, air bags etc. still the problem of noise/vibration day-by-day incrementally arise and become severe with the age of vehicles. Noise/vibration is a controllable pollutant that deserves the attention were all the scientific community work hard for controlling their harmful effects. Modern research affords us the opportunity to understand the subject better and to develop advance technologies. Widely immediate slogan and goal of all industries might be to reduce Noise/vibration on predominantly basis while, make the quietest and smoothest running Engines.
Technical Paper

Optimization of CI Engine Performance and Emissions Fueled by Blends of Alternative Fuels Methyl Ester Using Taguchi and Multi Regression Analysis

2019-09-16
2019-01-1893
Today’s frenetic engine manufacturing and transportation sector and its related traces viz; noise and vibration of our modern societies has adverse effect on environment as well as all of us. Modern research affords us the opportunity to understand the subject better and to develop advance technologies. Widely immediate slogan and goal of all industries might be to improve the performance and reduce emission using alternative fuel while, make the quietest and smoothest running Engines. To, reduce the dependency on diesel fuel (Due to rapid worldwide depletion) Biodiesel is one of the immediate, alternative and complimentary solution. In the Present study, to optimize the operating parameters of the Direct Injection Single Cylinder (5.2 kw) CI engine with respect to Brake Thermal Efficiency (BTE), Carbon monoxide (CO), Oxides of Nitrogen, Hydrocarbons (HC) etc..
Technical Paper

CFD Investigation of the Effects of Gas’ Methane Number on the Performance of a Heavy-Duty Natural-Gas Spark-Ignition Engine

2019-08-15
2019-24-0008
Natural gas (NG) is an alternative fuel for spark-ignition engines. In addition to its cleaner combustion, recent breakthroughs in drilling technologies increased its availability and lowered its cost. NG consists of mostly methane, but it also contains heavier hydrocarbons and inert diluents, the levels of which vary substantially with geographical source, time of year, and treatments applied during production or transportation. To investigate the effects of NG composition on engine performance and emissions, a 3D CFD model of a heavy-duty diesel engine retrofitted to spark ignition operations simulated engine operation under lean-combustion, low-speed, and medium load conditions. To eliminate the effect of different gas energy density, three NG blends of similar lower heating value but different H/C ratio have been investigated at fixed spark timing.
Technical Paper

Effects of In-cylinder flow structures on soot formation and oxidation in a swirl-supported light-duty diesel engine

2019-08-15
2019-24-0009
In this paper, computation fluid dynamics (CFD) simulations are performed to describe the effect of in-cylinder flow structures on the formation and oxidation of soot in a swirl-supported light-duty diesel engine. The focus of the paper is on the effect of swirl motion and injection pressure on late cycle soot oxidation. The structure of the flow at different swirl numbers is studied to investigate the effect that varying swirl number imposes on the coherent flow structures. These coherent flow structures are studied to understand the mechanism that leads to efficient soot oxidation in late cycle. Effect of varying injection pressure at different swirl numbers and the interaction between spray and swirl motions are discussed. The complexity of diesel combustion, especially when soot and other emissions are of interest, requires using a detailed chemical mechanism to have a correct estimation of temperature and species distribution.
Technical Paper

A Computationally Efficient Progress Variable Approach for In-Cylinder Combustion and Emissions Simulations

2019-08-15
2019-24-0011
The use of complex reaction schemes is accompanied by high computational cost in 3D CFD simulations but is particularly important to predict pollutant emissions in in-cylinder simulations. One solution to tackle this problem is to use tabulated chemistry. The approach presented herein combines pre-tabulated progress variable-based source terms for auto-ignition as well as soot and NOx source terms for advanced emission predictions. The method is coupled to CONVERGE v2.4 via user-coding and tested over various speed and load passenger-car Diesel engine conditions. This work includes the comparison between the combustion progress variable (CPV) model and the on-line chemistry solver in CONVERGE 2.4. Both models are also compared against experimental data by means of combustion and emission parameters. A detailed mechanism comprising 190 species, having n-decane/α-methyl-naphthalene as main fuels, is used for both on-line and tabulated chemistry simulations.
Technical Paper

Heavy-Duty Compression-Ignition Engines Retrofitted to Spark-Ignition Operation Fueled with Natural Gas

2019-08-15
2019-24-0030
Natural gas is a promising alternative gaseous fuel due to its availability, economic, and environmental benefits. A solution to increase its use in the heavy-duty transportation sector is to convert existing heavy-duty compression ignition engines to spark-ignition operation by replacing the fuel injector with a spark plug and injecting the natural gas inside the intake manifold. The use of numerical simulations to design and optimize the natural gas combustion in such retrofitted engines can benefit both engine efficiency and emission. However, experimental data of natural gas combustion inside a bowl-in-piston chamber is limited. Consequently, the goal of this study was to provide high-quality experimental data from such a converted engine fueled with methane and operated at steady-state conditions, exploring variations in spark timing, engine speed and equivalence ratio.
Technical Paper

Optimization of Multi Stage Direct Injection-PSCCI Engines

2019-08-15
2019-24-0029
The more stringent regulations on emissions induce the automotive companies to develop new solutions for engine design, including the use of advanced combustion strategies and the employment of mixture of fuels with different thermochemical properties. The HCCI combustion coupled with the partial direct injection of the charge, in order to control the performance and emissions and to extend the operating range, is a promising technique. In this work an in-house developed multi-dimensional CFD software package was used to analyse the behaviour of a multi stage direct injection (DI)-partially stratified charge compression ignition engine fueled with PRF. A skeletal kinetic mechanism for PRF oxidation was employed, with a dynamic adaptive chemistry technique to reduce the computational cost and a model based on the partially stirred reactor model to couple turbulence and chemistry.
Technical Paper

Optical diagnostics investigation on the effect of fuel injection timing on Partially Premixed Combustion stratification and soot formation in a single-cylinder optical compression ignition engine

2019-08-15
2019-24-0028
The present work investigates the effect of fuel injection timing on combustion stratification and soot formation in an optically accessible, single cylinder light duty diesel engine. The engine operated under low load and low engine speed conditions, employing a single injection scheme. The conducted experiments considered three different injection timings, which promoted Partially Premixed Combustion (PPC) operation. The fuel quantity of the main injection was adjusted to maintain the same Indicated Mean Effective Pressure (IMEP) value among all cases considered. Findings were analysed via means of pressure trace and apparent heat release rate (AHRR) analyses, as well as a series of optical diagnostics techniques, namely flame natural luminosity, CH* and C2* chemiluminescence high-speed imaging, as well as planar Laser Induced Incandescence (pLII).
Technical Paper

Cylinder Pressure based Method for In-Cycle Pilot Misfire Detection

2019-08-15
2019-24-0017
For the reduction of emissions and combustion noise in a internal combustion Diesel engine, multiple injections are normally used. A pilot injection reduces the ignition delay of the main injection and hence the combustion noise. However, normal variations of the operating conditions, component tolerances and aging may result in the lack of combustion (misfire) or even the lack of injection (miss-injection) for short on-times. The result is a lower indicated thermal efficiency, higher emissions and louder combustion noise. Closed-loop combustion control techniques aim to monitor in real-time these variations and act accordingly to counteract their effect. To ensure the in-cycle controllability of the main injection, the misfire diagnosis must be performed before the start of the main injection. This paper focuses on the development and evaluation of in-cycle algorithms for the pilot misfire detection.
Technical Paper

Experimental tests on the feasibility of passive regeneration in a catalytic DPF at the exhaust of a light-duty Diesel engine

2019-08-15
2019-24-0045
Diesel engines are attractive thanks to good performance in terms of fuel consumption, drivability, power output and efficiency. Nevertheless in the last years, increasing restrictions have been imposed to particulate emissions, concerning both mass (PM) and number (PN). Different technologies have been proposed to meet emissions standards and the wall-flow Diesel Particulate Filter (DPF) is currently the most common after-treatment system used to trap PM from the exhaust gases. This technology exhibits good features such that it can be regenerated to remove any accumulation of PM. However, this process involves oxidation of the filtered PM at a high temperature through after and post fuel injection strategies, which results in an increase of fuel consumption and may lead to physical damages of the filter in the long term. This work deals with the experimental testing of a catalytic silicon carbide (SiC) wall flow DPF, aiming at decreasing the soot oxidation temperature.
Technical Paper

Design and development of a new piston for an off-road Diesel engine with special focus on improvements of the piston cooling jet. Part I: root cause analysis of initial design failure.

2019-08-15
2019-24-0043
Similarly to passenger car engine manufacturers, it is increasingly common for off-road engine manufactures to extend the array of their products increasing the engine BMEP or, in other words, downsizing the engine. This strategy leads to increase the thermos-mechanical stress of the engine components, which therefore need often to be re-designed. Pistons, in particular, are among the most critical components, because high local temperatures strongly reduce their mechanical properties. Therefore, relevant design efforts to ensure increased piston cooling are demanded. This paper, based on a real case occurred during the early development stage of a new Diesel unit, focuses on the criticalities of piston cooling design.
Technical Paper

Biogenous Ethanol: CO2 Savings and Operation in a Dual-Fuel Designed Diesel Engine

2019-08-15
2019-24-0040
The usage of ethanol and two different mixtures of ethanol and gasoline (E85 and E65) was investigated on a modified diesel engine designed to work in a dual-fuel combustion mode with intake manifold alcohol injection. The maximum ratio of alcohol to diesel fuel was limited by irregular combustion phenomena like degrading combustion quality and poor process controllability at low load and knock as well as auto-ignition at high load. With rising alcohol amount, a significant reduction of soot mass and particle number was observed. At some testing points, substituting diesel with ethanol, E65 or E85 led to a reduction of NOx emissions; however, the real benefit concerning the nitrogen oxides was introduced by the mitigation of the soot-NOx trade-off. With regard to the engine efficiency aspect, the results show bidirectional behaviour: at low load points engine efficiency degrades, whereas the process becomes by up to 6 % (rel.) more effective at higher engine loads.
Technical Paper

Design and Development of a new piston for an off-road Diesel engine with special focus on improvements of the piston cooling jet. Part II: design improvements and final validation.

2019-08-15
2019-24-0041
This paper is the conclusion of a joint experimental/simulation effort to improve the effectiveness of piston cooling for a new generation engine for off-road applications. Motivations for the activity were described in the preceding part I of the paper. This part II describes a design improvement process aimed at increasing the effectiveness of piston cooling In particular, steady-state CFD simulations of several piston cooling jet solutions are initially carried out to select the most promising variants, which are then prototyped using 3D printing. Prototypes are tested using a specific hydraulic bench to compare and to validate the CFD analyses. Three design variants are then selected and analysed using a more complex CFD approach involving fully transient Volume of Fluid simulations of the piston gallery.
Technical Paper

Combustion and Emission Characteristics of a Compression Ignition Engine Fuelled with Diesel-LPG Blends

2019-08-15
2019-24-0038
Alternative fuels have recently attracted considerable attention due to their potential role in improving ambient air quality and mitigating global warming. Recent research has applied a variety of alternative fuels in an attempt to satisfy these requirements. Clearly, the alternative fuels industry needs to build confidence from fuels that perform well without adding considerable cost to the consumer. Although not a renewable fuel, liquefied petroleum gas (LPG) is a low-cost alternative fuel that might meet these needs; albeit temporarily. LPG is well known as an alternative fuel for spark ignition (SI) engines and, more recently, LPG systems have also been introduced to compression ignition (CI) engines. In this framework, to investigate the practical application and potential of this concept, diesel was blended with LPG, in different ratios (20-35% w/w). For this purpose, a single-cylinder test rig was properly adapted and, a standard common rail fuel injection system was employed.
Technical Paper

Experimental High Temperature Analysis of a Low-Pressure Diesel Spray for DPF Regeneration

2019-08-15
2019-24-0035
In the current automotive scenario, particulate filter technology is mandatory in order to attain emission limits in terms of particulate matter for Diesel engines. Despite DPF is often considered a mature technology, significant issues can derive from the use of the engine fuel injectors to introduce in the exhaust pipe the fuel needed to light on the particulate matter in the filter during its regeneration, primarily the lubricant oil dilution with fuel a consequence of significant spray impact on the cylinder liner. As an alternative, the fuel required to start regeneration can be introduced in the exhaust pipe by an auxiliary low pressure injector spraying in the hot exhaust gas stream. In this conditions, the spray evolution and its possible interaction with the surrounding gas stream are relevant in order to better identify the overall layout of the system, so to have the fuel vaporized at the DPF inlet section.
Technical Paper

Predictive CFD auto-tuning approach for in-cylinder EU6 LDD DI engine

2019-08-15
2019-24-0033
Tightening emission regulations and accelerating production cycles force engine developers to shift their attention towards virtual engineering tools. When simulating in-cylinder processes in commercial LDD DI engine development, the trade-off between runtime and accuracy is typically tipped towards the former. High-fidelity simulation approaches which require little tuning would be desirable but require excessive computing resources. For this reason, industry still favours low-fidelity simulation approaches and bridges remaining uncertainties with prototyping and testing. The problem with low-fidelity simulations is that simplifications in form of sub-grid-scale (SGS) models introduce multivariable tuning parameter dependencies which, if not understood, impair the predictive nature of CFD simulations. In previous work the authors have successfully developed a boundary condition dependant input parameter table.
Technical Paper

Gasoline Spray_Models_Calibration_Under_Diesel_Engine_Like_Conditions

2019-08-15
2019-24-0032
Atomization of liquid fuel jets is critical to the performance of Internal Combustion (IC) engine, as it plays a key role in affecting mixture formation, combustion efficiency and soot emissions. In the Gasoline Compression Ignition (GCI) engine investigation, the experimental measurements on the gasoline injection into diesel engine like condition, shows the difficulty in matching the liquid penetration length when the diesel spray model is used. Additional tests performed at lower ambient densities, seen in early injection, revealed a lot of information on liquid jet dynamics behavior. It requires a lot of model calibration effort in matching the measured liquid and vapor penetration length under different ambient pressure conditions. It is found that using droplet Sauter Mean Diameter distribution model shows better match with experiment at low density condition, whereas the KH-ACT breakup model correlates well with measurement at high density condition.
Technical Paper

Ignition Delay Model of Multiple Injections in CI engines

2019-08-15
2019-24-0071
In compression ignition engines, the combustion starts after the ignition delay period from the start of injection. The degree of mixing between air and fuel during the period have an impact on the combustion characteristic such as pressure rise rate which can worsen the combustion noise. The formation of particulate matter and nitrogen oxides also can be affected. In addition, ignition delay is required when estimating the in-cylinder pressure since it can provide information about the start of combustion. Therefore, a semi-empirical and 0-dimensional ignition delay model has been developed in this study for real-time control applications. As the ignition delay consists of physical and chemical delays in CI engines, the integrated ignition delay model established in this paper considered both of them.
Technical Paper

Set-up and Validation of an Integrated Engine Thermal Model in GT-SUITE for Heat Rejection Prediction

2019-08-15
2019-24-0078
Current approaches for heat rejection prediction during the development stage of a new engine are mostly based on maps built upon experimental data. However, these maps can be obtained fairly late in the development process, when at least a prototype of the engine can be run on the test bench. Furthermore, such experimental maps are limited to a discrete number of measured points, and they are not sensitive to variations in the engine calibration, vehicle installation and actual operating conditions. An innovative approach based on 1D simulation was tested in GT-SUITE, in order to shift in advance in the development cycle the moment at which reliable heat rejection calculations can be effectively used to support the engine and cooling system design. A fully physical Diesel engine performance model – featuring a predictive combustion model – was integrated with a detailed thermal model based on the 3D meshing feature available in GT-SUITE.
Technical Paper

Virtual Chassis Dyno for Diesel Engine Tuning and Calibration

2019-08-15
2019-24-0076
Since WLTP introduction, Exhaust Emission standards are now based on real driving conditions. The tuning and calibration work for Engine-out Emissions and Exhaust After-treatment Systems must therefore include all driving conditions in real life use of the vehicle. This includes temperature conditions, altitude, vehicle load and driving style. As a consequence the workload, cost and duration of the engine and after treatment system calibration activities, based on physical tests as today , are no more compatible with realistic development targets. The purpose of the methodology described in this paper is to replace chassis dyno vehicle tests by Hardware in the Loop, using only the Engine Electronic Control Unit as physical part. The vehicle, driver, engine, gearbox are all modeled by 0D/1D simulation running in real time. The methodology used to build the simulation models is described.
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