Mixture Quality Evaluation for Transient Mode Gasoline Engine Calibration

2010 ◽  
Author(s):  
Heribert Fuchs ◽  
Alois Hirsch ◽  
Martin Ogris ◽  
Ernst Winklhofer
Keyword(s):  
Fuel Injection ◽  
Measurement Techniques ◽  
Operating Conditions ◽  
Combustion Stability ◽  
Boost Pressure ◽  
Cylinder Pressure ◽  
Mixture Formation ◽  
Flame Radiation ◽  
Part Load ◽  
Engine Start

Gasoline engines have perfect emissions quality in stationary part load operation — how to ensure such ideal operation also at engine start, at tip-in tip-out, and at full load conditions? Key to the solution of these issues is the optimum use of components for mixture formation, combustion and exhaust gas aftertreatment with the focus on actuator calibration yielding reliable and low emissions combustion under transient operating conditions. Conventional testing of actuator parameter settings for such transients is evaluated with engine out emissions measurements. Any emissions peaks are well understood to be the result of some specific cycles which suffer from inadequate mixture formation due to limitations of fuel injection, evaporation or air supply. Consequently, improvements are achieved with adaptation of actuator parameters such as fuel injection timing, multiple injections or throttle and boost pressure settings in part load operation. With in-cylinder events being the root cause for emissions related issues, there is demand for diagnostic techniques capable of identifying emissions relevant in-cylinder processes for individual cylinders and on a cycle by cycle basis. This demand is met with the measurement of in-cylinder pressure together with flame radiation intensity. As cylinder pressure signals are evaluated for combustion stability, the simultaneously recorded flame signals provide information on mixture preparation quality. Well premixed charge results in flame radiation signals which are typical for homogeneous turbulent flames. Insufficiently evaporated and partially mixed fuel, especially at engine start, yields flame signals typical for diffusion flames. This simple relation between flame signals and soot formation events provides the basis for measurement techniques enabling mixture formation evaluation for individual cylinders and individual cycles. The application of such in-cylinder pressure and flame measurement techniques to PFI and GDI engines is presented with examples for engine cold start testing. The technique is further applied in the calibration of engine tip-in transients.

scholarly journals Evaluation of a Semiempirical, Zero-Dimensional, Multizone Model to Predict Nitric Oxide Emissions in DI Diesel Engines’ Combustion Chamber

2016 ◽  
Vol 2016 ◽  
pp. 1-14 ◽  
Author(s):  
Nicholas S. Savva ◽  
Dimitrios T. Hountalas
Keyword(s):  
Nitric Oxide ◽  
Diesel Engines ◽  
Fuel Injection ◽  
Operating Conditions ◽  
Injection Timing ◽  
Boost Pressure ◽  
Cylinder Pressure ◽  
No Formation ◽  
Calculation Step ◽  
Multizone Model

In the present study, a semiempirical, zero-dimensional multizone model, developed by the authors, is implemented on two automotive diesel engines, a heavy-duty truck engine and a light-duty passenger car engine with pilot fuel injection, for various operating conditions including variation of power/speed, EGR rate, fuel injection timing, fuel injection pressure, and boost pressure, to verify its capability for Nitric Oxide (NO) emission prediction. The model utilizes cylinder’s basic geometry and engine operating data and measured cylinder pressure to estimate the apparent combustion rate which is then discretized into burning zones according to the calculation step used. The requisite unburnt charge for the combustion in the zones is calculated using the zone equivalence ratio provided from a new empirical formula involving parameters derived from the processing of the measured cylinder pressure and typical engine operating parameters. For the calculation of NO formation, the extended Zeldovich mechanism is used. From this approach, the model is able to provide the evolution of NO formation inside each burned zone and, cumulatively, the cylinder’s NO formation history. As proven from the investigation conducted herein, the proposed model adequately predicts NO emissions and NO trends when the engine settings vary, with low computational cost. These encourage its use for engine control optimization regarding NOxabatement and real-time/model-based NOxcontrol applications.

Numerical Investigation on Mixture Formation in a Turbocharged Port-Injection Natural Gas Engine Using Multiple Cycle Simulation

2018 ◽  
Vol 140 (5) ◽  
Author(s):  
Zhenkuo Wu ◽  
Zhiyu Han
Keyword(s):  
Fuel Injection ◽  
Load Condition ◽  
Operating Conditions ◽  
Injection Timing ◽  
Mixture Formation ◽  
Natural Gas Engine ◽  
Cycle Simulation ◽  
Mixture Preparation ◽  
Spark Timing ◽  
Multiple Cycle

In the present study, multidimensional computational fluid dynamics (CFD) simulations were carried out to study mixture formation in a turbocharged port-injection natural gas engine. In order to achieve robust simulation results, multiple cycle simulation was employed to remove the inaccuracies of initial conditions setting. First, the minimal number of simulation cycles required to obtain convergent cycle-to-cycle results was determined. Based on this, the in-cylinder mixture preparation for three typical operating conditions was studied. The effects of fuel injection timing and intake valve open scheme on the mixture formation were evaluated. The results demonstrated that three simulation cycles are needed to achieve convergence of the results for the present study. The analysis of the mixture preparation revealed that only in the initial phase of the intake stroke, there is an obvious difference between the three operating conditions. At the spark timing, for 5500 rpm, full load condition mixture composition throughout the cylinder is flammable, and for 2000 rpm, 2 bar operating condition part of the mixture is lean and nonflammable. The fuel injection timing has an insignificant impact on the mixture flammability at the spark timing. It was observed that the designed nonsynchronous intake valve open scheme has stronger swirl and x-direction tumble motion than the baseline case, leading to better mixture homogeneity and spatial distribution. With an increase in volumetric efficiency, particularly at 2000 rpm, full load condition, by 4.85% compared to the baseline, which is in line with experimental observation.

Parametric Study of Ignition and Combustion Characteristics From a Gasoline Compression Ignition Engine Using Two Different Reactivity Fuels

2016 ◽  
Author(s):  
Khanh Cung ◽  
Toby Rockstroh ◽  
Stephen Ciatti ◽  
William Cannella ◽  
S. Scott Goldsborough
Keyword(s):  
High Speed ◽  
Injection Pressure ◽  
Operating Conditions ◽  
Combustion Stability ◽  
Injection Timing ◽  
Strong Impact ◽  
Boost Pressure ◽  
Compression Ignition ◽  
Compression Ignition Engine ◽  
Ignition And Combustion

Unlike homogeneous charge compression ignition (HCCI) that has the complexity in controlling the start of combustion event, partially premixed combustion (PPC) provides the flexibility of defining the ignition timing and combustion phasing with respect to the time of injection. In PPC, the stratification of the charge can be influenced by a variety of methods such as number of injections (single or multiple injections), injection pressure, injection timing (early to near TDC injection), intake boost pressure, or combination of several factors. The current study investigates the effect of these factors when testing two gasoline-like fuels of different reactivity (defined by Research Octane Number or RON) in a 1.9-L inline 4-cylinder diesel engine. From the collection of engine data, a full factorial analysis was created in order to identify the factors that most influence the outcomes such as the location of ignition, combustion phasing, combustion stability, and emissions. Furthermore, the interaction effect of combinations of two factors or more was discussed with the implication of fuel reactivity under current operating conditions. The analysis was done at both low (1000 RPM) and high speed (2000 RPM). It was found that the boost pressure and air/fuel ratio have strong impact on ignition and combustion phasing. Finally, injection-timing sweeps were conducted whereby the ignition (CA10) of the two fuels with significantly different reactivity were matched by controlling the boost pressure while maintaining a constant lambda (air/fuel equivalence ratio).

Experimental Investigation of a RQL Burner With Jet in Cross Flow Fuel Injection: Characterization of the Reacting Flow Field at Realistic Operating Conditions

2019 ◽  
Author(s):  
T. Soworka ◽  
T. Behrendt ◽  
C. Hassa ◽  
J. Heinze ◽  
E. Magens ◽  
...  
Keyword(s):  
Flow Field ◽  
Fuel Injection ◽  
Measurement Techniques ◽  
Cross Flow ◽  
Mie Scattering ◽  
Operating Conditions ◽  
Reacting Flow ◽  
Axial Location ◽  
Primary Zone ◽  
Jet In Cross Flow

Abstract Future rich-burn/quick-quench/lean-burn (RQL) burners for aero engines face the challenge to further reduce the emission of soot. Alternative ways of fuel injection are therefore in the focus of modern RQL combustion systems. This contribution aims to investigate experimentally the influence of fuel injection on the reacting flow field, with the emphasis on soot production in the primary zone. For the test, a Rolls-Royce prototype burner was used in two different configurations which differ only in the axial location of jet in cross flow fuel injection and thereby provoke different ways of fuel atomization. In the upstream configuration the burner features characteristics of a pre-filming airblast atomizer. Whereas with the fuel tip in downstream position solely Jet-in-Cross-Flow fuel atomisation is expected. The burner was tested at realistic aero engine combustor conditions (p30 = 9.28 bar, T30 = 603 K, AFR = 7.6). Several optical measurement techniques were used to characterise the reacting flow field. Their difficult application in a rich burn environment is described briefly. The structure of the reacting flow field is illustrated by Particle-Image-Velocimetry (PIV). Planar Mie scattering and Planar Laser-Induced Fluorescence (PLIF) are used to characterise the placement of liquid and gaseous fuel respectively. The location and structure of heat release zones are captured in terms of OH* and CO2* chemiluminescence. Finally Laser-Induced-Incandescence (LII) is used to obtain three dimensional soot distributions in the primary zone. On this basis 20% less soot was measured for the upstream configuration at the axial location of maximal soot concentration. This remarkable difference could be attributed to the different placement of liquid fuel and the resulting better mixing.

Liquid Fuel Placement and Mixing of Generic Aeroengine Premix Module at Different Operating Conditions

2003 ◽  
Vol 125 (4) ◽  
pp. 901-908 ◽  
Author(s):  
J. Becker ◽  
C. Hassa
Keyword(s):  
Momentum Flux ◽  
Liquid Fuel ◽  
Fuel Injection ◽  
Measurement Techniques ◽  
Flux Ratio ◽  
Mie Scattering ◽  
Operating Conditions ◽  
Operating Pressure ◽  
Flow Measurements ◽  
Momentum Flux Ratio

Fuel placement and air-fuel mixing in a generic aeroengine premix module employing plain jet liquid fuel injection into a counter-swirling double-annular crossflow were investigated at different values of air inlet pressure (6 bar, 700 K and 12 bar, 700 K) and liquid-to-air momentum flux ratio, both parameters being a function of engine power. Kerosene Jet A-1 was used as liquid fuel. Measurement techniques included LDA for investigation of the airflow and Mie-scattering laser light sheets and PDA for investigation of the two-phase flow. Measurements were taken at various axial distances from the fuel nozzle equivalent to mean residence times of up to 0.47 ms. It was found that the initial fuel placement reacts very sensitively to a variation of liquid-to-air momentum flux ratio. Susceptibility of the spray to dispersion due to centrifugal forces and to turbulent mixing is primarily a function of the fuel droplet diameters, which in turn depend on operating pressure. The data are interpreted by evaluation of the corresponding Stokes numbers.

Liquid Fuel Placement and Mixing of a Generic Aeroengine Premix Module at Different Operating Conditions

2002 ◽  
Author(s):  
Julian Becker ◽  
Christoph Hassa
Keyword(s):  
Momentum Flux ◽  
Liquid Fuel ◽  
Fuel Injection ◽  
Measurement Techniques ◽  
Flux Ratio ◽  
Mie Scattering ◽  
Operating Conditions ◽  
Operating Pressure ◽  
Flow Measurements ◽  
Momentum Flux Ratio

Fuel placement and air-fuel mixing in a generic aeroengine premix module employing plain jet liquid fuel injection into a counter-swirling double-annular crossflow were investigated at different values of air inlet pressure (6 bar, 700 K and 12 bar, 700 K) and liquid-to-air momentum flux ratio, both parameters being a function of engine power. Kerosene Jet A-1 was used as liquid fuel. Measurement techniques included LDA for investigation of the airflow and Mie-scattering laser light sheets and PDA for investigation of the two-phase flow. Measurements were taken at various axial distances from the fuel nozzle equivalent to mean residence times of up to 0.47 ms. It was found that the initial fuel placement reacts very sensitively to a variation of liquid-to-air momentum flux ratio. Susceptibility of the spray to dispersion due to centrifugal forces and to turbulent mixing is primarily a function of the fuel droplet diameters, which in turn depend on operating pressure. The data are interpreted by evaluation of the corresponding Stokes numbers.

scholarly journals Idling Performance under Valve Deactivation Strategy in Port Fuel Injection Engine

2019 ◽  
Vol 16 (4) ◽  
pp. 7155-7169
Author(s):  
A. S. Paimon ◽  
S. Rajoo ◽  
W. Jazair ◽  
M. A. Abas ◽  
Z. H. Che Daud
Keyword(s):  
Coefficient Of Variation ◽  
Engine Speed ◽  
Fuel Injection ◽  
Swirl Flow ◽  
Combustion Stability ◽  
Cylinder Pressure ◽  
Fuel Injector ◽  
Port Fuel Injection ◽  
Indicated Mean Effective Pressure ◽  
Significant Difference

This paper investigates the effect of valve deactivation (VDA) on idling performance in port fuel injection (PFI) engine. The test was conducted on 1.6L, 4-cylinder engine with PFI configuration. One of the two intake valves in each cylinder was deactivated (zero lift on deactivated port) and fuel injector was modified to only provide fuel spray on the active intake port. In-cylinder pressure was recorded by the combustion analyzer in order to measure and analyze the combustion characteristics. From the test, there are up to 6% of fuel consumption improvements across all the test conditions. Better combustion stability is achieved at very low idling speed (throttle position, TP = 2%) as a lower coefficient of variation of engine speed (COVrpm) and coefficient of variation indicated mean effective pressure (COVimep) were recorded. Increased intake velocity and swirl flow in the VDA strategy creates more turbulence intensity causing higher heat release rate and faster combustion. However, there is no significant difference in the pumping work during the intake cycle but there is extra pumping work recorded towards the end of expansion stroke due to the very early end of combustion. Therefore, valve deactivation strategy provides limited positive improvement to the idling performance in PFI engine.

Experimental Investigation of Spray and Combustion Performances of a Fuel-Staged Low Emission Combustor: Part II — Effects of Venturi Angle

2018 ◽  
Author(s):  
Cunxi Liu ◽  
Fuqiang Liu ◽  
Jinhu Yang ◽  
Yong Mu ◽  
Gang Xu
Keyword(s):  
Flow Field ◽  
High Altitude ◽  
Gas Turbines ◽  
Fuel Injection ◽  
Operating Conditions ◽  
Combustion Stability ◽  
Main Stage ◽  
Fuel Injector ◽  
Lean Burn ◽  
Low Emission

In order to reduce NOx emissions, modern gas turbines are often equipped with lean burn combustion systems, where the high-velocity fuel-lean conditions that limit NOx formation in combustors also inhibit the ability of ignition, high altitude relight, and lean combustion stability. To face these issues, an internally staged scheme of fuel injection is proposed. The pilot and main fuel staging enable fuel distribution control and high turn-down ratio, multi-injections of main fuel leads to a fast and efficient fuel/air mixing. A fuel-staged low emission combustor in the framework of lean burn combustion is developed in the present study, the central pilot stage of fuel injector working singly at low power operating conditions is swirl-cup prefilming atomization and main stage is jet-in-crossflow multi-injection atomization, a combination of pilot and main stage injection is provided for higher power operating conditions. A significant amount of the air mass flow utilised for fuel preparation and initiation is adverse to the operability specifications, such as ignition, lean blow-out, and high-altitude relight etc. The spray characteristics of pilot spray and flow field are one of the key factors affecting combustion operability. This work investigates the effects of the venturi angle on combustion operability, the ignition and lean blow-out performances were evaluated in a single dome rectangular combustor. Furthermore, the spray patterns and flow field are characterized by kerosene-planar laser induced fluorescence and particle image velocimetry to provide insight into the correlation between spray, flow field and combustion operability performances.

Computational fluid dynamics study of the effects of the re-entrant lip shape and toroidal radii of piston bowl on a high-speed direct-injection diesel engine's performance and emissions

2005 ◽  
Vol 219 (8) ◽  
pp. 1011-1023 ◽  
Author(s):  
Y Zhu ◽  
H Zhao ◽  
N Ladommatos
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
High Speed ◽  
Fuel Injection ◽  
Direct Injection ◽  
Combustion Process ◽  
Operating Conditions ◽  
Injection System ◽  
Part Load ◽  
Piston Bowl

The piston bowl design is one of the most important factors that affect the air-fuel mixing and the subsequent combustion and pollutant formation processes in a direct-injection diesel engine. The bowl geometry and dimensions, such as the pip region, bowl lip area, and toroidal radius, are all known to have an effect on the in-cylinder mixing and combustion process. In order to understand better the effect of re-entrant geometry, three piston bowls with different toroidal radii and lip shapes were investigated using computational fluid dynamics engine modelling. KIVA3V with improved submodels was used to model the in-cylinder flows and combustion process, and it was validated on a high-speed direct-injection engine with a second-generation common-rail fuel injection system. The engine's performance, in-cylinder flow, and combustion, and emission characteristics were analysed at maximum power and maximum torque conditions and at part-load operating conditions. Three injector protrusions and injection timings were investigated at full-load and part-load conditions.

scholarly journals Extending Lean and EGR-Dilute Operating Limits of a Modern GDI Engine Using a Low-Energy Transient Plasma Ignition System

2015 ◽  
Author(s):  
James Sevik ◽  
Thomas Wallner ◽  
Michael Pamminger ◽  
Riccardo Scarcelli ◽  
Dan Singleton ◽  
...  
Keyword(s):  
Direct Injection ◽  
Load Condition ◽  
Operating Conditions ◽  
Low Energy ◽  
Gasoline Direct Injection ◽  
Combustion Stability ◽  
Ignition System ◽  
Part Load ◽  
Plasma Ignition ◽  
Transient Plasma

The efficiency improvement and emissions reduction potential of lean and EGR dilute operation of spark-ignition gasoline engines is well understood and documented. However, dilute operation is generally limited by deteriorating combustion stability with increasing inert gas levels. The combustion stability decreases due to reduced mixture flame speeds resulting in significantly increased combustion initiation periods and burn durations. A study was designed and executed to evaluate the potential to extend lean and EGR-dilute limits using a low-energy transient plasma ignition system. The low-energy transient plasma was generated by nano-second pulses and its performance compared to a conventional transistorized coil ignition system operated on an automotive, gasoline direct injection (GDI) single-cylinder research engine. The experimental assessment was focused on steady-state experiments at the part load condition of 1500 rpm 5.6 bar IMEP, where dilution tolerance is particularly critical to improving efficiency and emissions performance. Experimental results suggest that the energy delivery process of the low-energy transient plasma ignition system significantly improves part load dilution tolerance by reducing the early flame development period. Statistical analysis of relevant combustion metrics was performed in order to further investigate the effects of the advanced ignition system on combustion stability. Results confirm that at select operating conditions EGR tolerance and lean limit could be improved by as much as 20% (from 22.7 to 27.1% EGR) and nearly 10% (from λ=1.55 to 1.7) with the low-energy transient plasma ignition system.

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