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Viewing 1 to 30 of 5641
Technical Paper
2014-09-15
Kai Chen
The synthetic paraffinic kerosine (SPK) produced via HEFAs is of great interest for civil aviation industry as it exhibits an excellent thermal oxidative stability with significantly lower particulate matter emission. However, due to its aromatic free characteristics, the widespread use of SPK is limited by its compatibility with non-metal materials such as fuel tank elastomers. In this research the compatibility of SPK and its blends with widely used aircraft fuel tank elastomers were systematically studied. Experimental results demonstrated the volume swellability of all selected materials showed a linear relationship with volume percentage of No.3 jet fuel in SPK blend. The increase of volume percentage of No.3 jet fuel in the SPK blend increased volume swellability for all materials except fluorosilicone gasket. The alkyl benzenes and naphthalenes in the blend acted as the hydrogen donors, which facilitated the formation of polymer matrix and led to the increase of the distance between polymer chains.
Technical Paper
2014-04-01
Yanfei Li, Hengjie Guo, Xiao Ma, Jian-Xin Wang, Hongming Xu
Abstract The near-field diesel spray process in diesel engines is the intermediate one that connects the in-nozzle flow with far field spray process and high-speed imaging techniques with high-quality temporal and spatial resolution are required in order to record this short process (< 300 μs). In this study, a high-speed charge-coupled-device (CCD) camera with the speed of up to 1,000,000 fps was used to study the near-field spray process for a diesel injector with different nozzle diameters. The tests were carried out in a constant volume vessel over a range of injection pressure and ambient pressure in non-evaporating conditions. The observed zone of the spray was where penetration length is less than 18 mm. The development of spray penetration length against time after start of injection (ASOI) was used to evaluate the spray process. The significant difference on spray penetration length development is found when the nozzle diameter varied. Injection delay decreases with the increase of injection and ambient pressure.
Technical Paper
2014-04-01
Yongming Bao, Qing Nian Chan, Sanghoon Kook, Evatt Hawkes
Abstract This study aims to clarify the spray development of ethanol, gasoline and iso-octane fuel, delivered by a multi-hole injector and spark-ignition direct-injection (SIDI) fuelling system. The focus is on how fuel properties impact temporal and spatial evolution of sprays at realistic ambient conditions. Two optical facilities were used: (1) a constant-flow spray chamber simulating cold-start conditions and (2) a single-cylinder SIDI engine running at normal, warmed-up operating conditions. In these optical facilities, high-speed Mie-scattering imaging is performed to measure penetrations of spray plumes at various injection pressures of 4, 7, 11 and 15 MPa. The results show that the effect of fuel type on the tip penetration length of the sprays depends on the injection conditions and the level of fuel jet atomisation and droplet breakup. It is observed that at 4 MPa injection pressure, the tip penetration length of ethanol sprays is shorter than that of gasoline sprays, likely due to lower injection velocity and increased nozzle loss associated with higher density and increased viscosity of ethanol, respectively.
Technical Paper
2014-04-01
José V. Pastor, José M. Garcia-Oliver, Vicente Bermudez, Carlos Micó
Abstract Major accuracy for prediction tools like CFD codes require precise experimental validation. The ultraviolet and visible light absorption and scattering (UV-VIS LAS) is proposed for characterizing air-fuel mixture formation. UV-VIS LAS technique is employed to quantitatively determine spatial concentration distribution of vapor fuel, in combination with simultaneous liquid length and spray penetration measurements by means of Mie-scattering and Schlieren. Decane, Hexadecane and a 50/50 of both fuels have been chosen for this study, to evaluate mixing formation under Diesel conditions. Work has been performed at an optical engine under non-reacting atmosphere, with ambient pressures and temperatures up to 7.3 MPa and 900 K. Fuel optical properties for the two paraffines under engine conditions have been analyzed, and fuel concentration distribution has been obtained for pure fuels. For each of them, mass fraction has been measured, combining attenuation signal with an adiabatic mixing model.
Technical Paper
2014-04-01
Lyle M. Pickett, Julien Manin, Alan Kastengren, Christopher Powell
A full understanding and characterization of the near-field of diesel sprays is daunting because the dense spray region inhibits most diagnostics. While x-ray diagnostics permit quantification of fuel mass along a line of sight, most laboratories necessarily use simple lighting to characterize the spray spreading angle, using it as an input for CFD modeling, for example. Questions arise as to what is meant by the “boundary” of the spray since liquid fuel concentration is not easily quantified in optical imaging. In this study we seek to establish a relationship between spray boundary obtained via optical diffused backlighting and the fuel concentration derived from tomographic reconstruction of x-ray radiography. Measurements are repeated in different facilities at the same specified operating conditions on the “Spray A” fuel injector of the Engine Combustion Network, which has a nozzle diameter of 90 μm. Long-distance microscopy at >100 kHz speeds is used to characterize the opening, steady, and closing phases of injection.
Technical Paper
2014-04-01
José María Desantes, Raúl Payri, Jaime Gimeno, Pedro Marti-Aldaravi
Abstract The Fick's law is commonly used to model diffusion problems, but from some time ago it has been also used to model liquid jet atomization and mixing into gaseous atmosphere under certain hypothesis. An OpenFOAM computer model based on this principle has been developed and validated on axisymmetric geometries. This model has also been used to study the atomization process on the Engine Combustion Network (ECN) single-hole Spray A injector. Results have been compared to X-Ray and Mie-Scattering experimental data, showing that the Fick's law and its variants predict well the liquid core but tend to over-predict the spray angle/width in the first millimeters after the nozzle exit.
Technical Paper
2014-04-01
Donghoon Kim, Kihyun Kim
Abstract Researches about gasoline direct injection compression ignition engine (GDCI), a compression Ignition (CI) engine fueled with gasoline instead of diesel, are getting great attention for operation of the CI engine under higher load conditions with low smoke and nitrogen oxides (NOx) emission due to high volatility and low auto-ignitability of gasoline. In this engine, it is very important to investigate gasoline spray characteristics inside the cylinder compared to diesel. Recently, many researchers are using computational fluid dynamics (CFD) as a useful tool to investigate the spray characteristics of these two fuels inside the internal combustion engines. To simulate gasoline and diesel sprays inside the cylinder, higher volatility of gasoline than those of diesel should be considered properly. Of many spray sub-models, evaporation model is more important model to simulate liquid-vapor phase change in evaporating condition and the accuracy of calculated liquid length is decided by this model.
Technical Paper
2014-04-01
Shaoping Quan, Meizhong Dai, Eric Pomraning, P. K. Senecal, Keith Richards, Sibendu Som, Scott Skeen, Julien Manin, Lyle M. Pickett
Shock waves have been recently observed in high-pressure diesel sprays. In this paper, three-dimensional numerical simulations of supersonic diesel spray injection have been performed to investigate the underlying dynamics of the induced shock waves and their interactions with the spray. A Volume-of-Fluid based method in the CFD software (CONVERGE) is used to model this multiphase phenomena. An adaptive Mesh Refinement (AMR) scheme is employed to capture the front of the spray and the shock waves with high fidelity. Simulation results are compared to the available experimental observations to validate the numerical procedure. Parametric studies with different injection and ambient conditions are conducted to examine the effect of these factors on the generation of shock waves and their dynamics.
Technical Paper
2014-04-01
Michele Bolla, Aleš Srna, Yuri M. Wright, Beat Von Rotz, Kai Herrmann, Konstantinos Boulouchos
Abstract In this study, the influence of injector diameter on the combustion of diesel sprays in an optically accessible combustion chamber of marine engine dimensions and conditions has been investigated experimentally as well as numerically. Five different orifice diameters ranging between 0.2 and 1.2 mm have been considered at two different ambient temperatures: a “cold” case with 800 K and a “warm” case with 900 K, resulting in a total of ten different test conditions. In the experiment, the reactive spray flames were characterized by means of high-speed OH* chemiluminescence imaging. The measurements revealed a weak impact of the injector diameter on ignition delay (ID) time and flame lift-off length (LOL) whereas the influence of ambient temperature was found to be more pronounced, consistent with former studies in the literature for smaller orifice diameters. Computational fluid dynamics (CFD) simulations were performed using the Conditional Moment Closure (CMC) combustion model and the numerical results have been validated with the experimental data by means of ignition delay time, flame lift-off length and temporal evolution of flame region.
Technical Paper
2014-04-01
Federico Brusiani, Gian Marco Bianchi, Stefania Falfari, Angelo Onorati, Tommaso Lucchini, Rita Di Gioia
Abstract Today, multi-hole Diesel injectors can be mainly characterized by three different nozzle hole shapes: cylindrical, k-hole, and ks-hole. The nozzle hole layout plays a direct influence on the injector internal flow field characteristics and, in particular, on the cavitation and turbulence evolution over the hole length. In turn, the changes on the injector internal flow correlated to the nozzle shape produce immediate effects on the emerging spray. In the present paper, the fluid dynamic performance of three different Diesel nozzle hole shapes are evaluated: cylindrical, k-hole, and ks-hole. The ks-hole geometry was experimentally characterized in order to find out its real internal shape. First, the three nozzle shapes were studied by a fully transient CFD multiphase simulation to understand their differences in the internal flow field evolutions. In detail, the attention was focused on the turbulence and cavitation levels at hole exit. The adopted simulation strategy was previously validated against experimental data.
Technical Paper
2014-04-01
Mathis Bode, Felix Diewald, David Oliver Broll, Jan Felix Heyse, Vincent Le Chenadec, Heinz Pitsch
Abstract Diesel injection systems have a significant impact on the performance as well as emission and pollutant formation of modern diesel engines. Even though the geometry of atomizers became more and more complex over the last years, injection systems still have a large potential for improving the overall diesel engine combustion process. Due to the complexity of the atomization process, reliable models are not available, yet these are highly desired for supporting the design process. They have to be developed using detailed numerical simulations. In this work, the “Spray A” reference case defined by the Engine Combustion Network is simulated under realistic operation conditions using a recently developed numerical framework for multiphase flows. A Large-Eddy Simulation of the nozzle internal flow is coupled with a Direct Numerical Simulation of the interfacial outside flow and the resulting primary breakup is analyzed. Additionally, the impact of the injector geometry on primary breakup is studied.
Technical Paper
2014-04-01
Kenth Svensson, Chad Koci
Abstract The characterization of fuel injector orifices is important for engine performance engineers, combustion engineers, and as input into 3-D spray and combustion simulations. Typical steady flow measurements done by fuel injector manufacturers are not indicative of their flow at engine injection pressures. Orifice characterization is commonly done on a rate bench or for further detail by using momentum rate measurements. The common Bernoulli equation assumptions made for momentum rate measurements are not always proper. This work compares the common approach with a more detailed approach for calculating the nozzle flow coefficients and sac pressure. The detailed approach includes friction and contraction pressure losses. A discussion on sac velocity is included. A non-iterative calculation of the Darcy friction factor is reviewed and an uncertainty analysis is also provided.
Technical Paper
2014-04-01
Joseph Oefelein, Guilhem Lacaze, Rainer Dahms, Anthony Ruiz, Antony Misdariis
Abstract This paper first summarizes a new theoretical description that quantifies the effects of real-fluid thermodynamics on liquid fuel injection processes as a function of pressure at typical engine operating conditions. It then focuses on the implications this has on modeling such flows with emphasis on application of the Large Eddy Simulation (LES) technique. The theory explains and quantifies the major differences that occur in the jet dynamics compared to that described by classical spray theory in a manner consistent with experimental observations. In particular, the classical view of spray atomization as an appropriate model at some engine operating conditions is questionable. Instead, non-ideal real-fluid behavior must be taken into account using a multicomponent formulation that applies to hydrocarbon mixtures at high-pressure supercritical conditions. To highlight the implications and needs related to modeling, we present a series of studies using LES that focus on experiments being conducted in the high-pressure combustion vessel at Sandia National Laboratories.
Technical Paper
2014-04-01
Mark A. Shost, Ming-Chia Lai, Bizhan Befrui, Peter Spiekermann, Daniel L. Varble
Abstract Development of in-cylinder spray targeting, plume penetration and atomization of the gasoline direct-injection (GDi) multi-hole injector is a critical component of combustion developments, especially in the context of the engine downsizing and turbo-charging trend that has been adopted in order to achieve the European target CO2, US CAFE, and concomitant stringent emissions standards. Significant R&D efforts are directed towards the optimization of injector nozzle designs in order to improve spray characteristics. Development of accurate predictive models is desired to understand the impact of nozzle design parameters as well as the underlying physical fluid dynamic mechanisms resulting in the injector spray characteristics. This publication reports Large Eddy Simulation (LES) analyses of GDi single-hole skew-angled nozzles, with β=30° skew (bend) angle and different nozzle geometries. The objective is to extend previous works to include the effect of nozzle-hole length over diameter ratio (l/d) and fuel injection pressure on spray skew angle, spray plume cone angle and primary breakup length.
Technical Paper
2014-04-01
Alessandro Montanaro, Marianna Migliaccio, Luigi Allocca, Valentina Fraioli, Seong-Young Lee, Anqi Zhang, Jeffrey Naber
Abstract This paper reports an experimental and numerical investigation on the spatial and temporal liquid- and vapor-phase distributions of diesel fuel spray under engine-like conditions. The high pressure diesel spray was investigated in an optically-accessible constant volume combustion vessel for studying the influence of the k-factor (0 and 1.5) of a single-hole axial-disposed injector (0.100 mm diameter and 10 L/d ratio). Measurements were carried out by a high-speed imaging system capable of acquiring Mie-scattering and schlieren in a nearly simultaneous fashion mode using a high-speed camera and a pulsed-wave LED system. The time resolved pair of schlieren and Mie-scattering images identifies the instantaneous position of both the vapor and liquid phases of the fuel spray, respectively. The studies were performed at three injection pressures (70, 120, and 180 MPa), 23.9 kg/m3 ambient gas density, and 900 K gas temperature in the vessel. The predictive capabilities of the Lib-ICE code, which is a set of applications and libraries for IC engine simulations developed using the OpenFOAM® technology, were evaluated in describing fuel sprays.
Technical Paper
2014-04-01
PoWen Tu, Changzhao Jiang, Haichun Ding, Cao Li, Hongming Xu, Akbar Ghafourian, Shi-jin Shuai
Abstract Little research has been done on spray characteristics of 2,5-dimethylfuran (DMF), since the breakthrough in its production method as an alternative fuel candidate. In this paper, the spray characteristics of pure fuels (DMF, Isooctane) and DMF-Isooctane blends under different ambient pressures (1 bar, 3 bar and 7 bar) and injection pressures (50 bar, 100 bar and 150 bar) were studied using Phase Doppler Particle Analyzer (PDPA) and high speed imaging. Droplet velocity, size distribution, spray angle and penetration of sprays were examined. Based on the results, DMF had larger SMD and penetration length than isooctane. The surface tension of fuel strongly influenced spray characteristics. Increasing the surface tension by 26 % resulted in 12 % increase in SMD. Higher ambient pressure increased the drag force, but SMD was not influenced by the increased drag force. However, the increased ambient pressure reduced the injection velocity and We number resulting in higher SMD. High turbulence level from increased injection pressure decreased the SMD of D15 by 20 and 35% when injection pressure was increased to 50 and 150 bar respectively.
Technical Paper
2014-04-01
Ireneusz Pielecha, Przemyslaw Borowski
Abstract The paper discusses the results of investigations into fuel atomization with the use of two high-pressure angularly arranged injectors fitted in a combustion of constant volume chamber. Using two Direct Injection injectors is a new conception, which was not applied yet. Nowadays, the conceptions where two injectors are used, one in direct injection and one in port injection are used. It is expected, that new gasoline Direct Injection system will allow better fuel spray and following combustion process. It is especially important in spray-guided mixture creating. The analysis mainly relates to the parameters of the fuel spray: spray penetration, observed fuel spray area in reference to both a single fuel spray and two angularly fuel sprays. The assessment of the uniformity of the fuel spray penetration for both sprays has been carried out. The authors have shown a growth in the fuel spray volume and a reduction of the time of the fuel spray penetration during the angularly arranged injection at identical fuel doses (identical accumulative injection duration for a single fuel dose and two angularly fuel doses).
Technical Paper
2014-04-01
Karthik Nithyanandan, Deyang Hou, Gregory Major, Chia-Fon Lee
This paper focuses on the spray and atomization characteristics of a Dual-Fuel Injector (DFI) which includes a primary and a secondary fuel inlet. Three injectors were analyzed in this study. Apart from the DFI, two conventional diesel injectors were tested as baselines for comparison - a piezo-electric and a solenoid injector. The rail pressures ranged from 200 - 500 bar for the conventional injectors. The DFI was tested first as a single-fuel injector (by sealing the secondary inlet) at pressures ranging from 100 - 300 bar, and then in its dual-fuel mode with the primary inlet pressure ranging from 100 - 300 bar, and the secondary inlet at 25 bar higher than the primary pressure. Injection duration of 0.5 ms was chosen for the experiment. High-speed Mie scattering images were recorded to capture the spray evolution. Phase Doppler Anemometry (PDA) measurements were conducted at different locations in the spray for the acquisition of droplet sizes and velocity distributions. The high-speed images showed that the conventional injectors produced a spray with a wider spray cone angle, relative to the DFI injector which had a narrower spray cone angle leading to equal radial and axial spray penetration, and displaying a fine mist of gasoline droplets surrounding the diesel fuel jets.
Technical Paper
2014-04-01
Xiao Ma, Liang Zheng, Yanfei Li, Zhi Wang, Hongming Xu, Jian-Xin Wang
Dieseline combustion as a concept combines the advantages of gasoline and diesel by offline or online blending the two fuels. Dieseline has become an attractive new compression ignition combustion concept in recent years and furthermore an approach to a full-boiling-range fuel. High speed imaging with near-parallel backlit light was used to investigate the spray characteristics of dieseline and pure fuels with a common rail diesel injection system in a constant volume vessel. The results were acquired at different blend ratios, and at different temperatures and back pressures at an injection pressure of 100MPa. The penetrations and the evaporation states were compared with those of gasoline and diesel. The spray profile was analyzed in both area and shape with statistical methods. The effect of gasoline percentage on the evaporation in the fuel spray was evaluated. The blend ratio shows large impacts particularly in liquid phase area, on the liquid core length and the gas-to-liquid ratio (by area) at higher temperatures.
Technical Paper
2014-04-01
David Greif, Wilfried Edelbauer, Jure Strucl
Abstract The paper addresses aspects of modeling cavitating flows within high pressure injection equipment while considering the effects of liquid compressibility. The presented numerical study, performed using the commercial CFD code AVL FIRE®, mimics common rail conditions, where the variation in liquid density as a function of pressure may be relevant owing to very high pressure injection scenarios. The flow through the injector has been calculated and the conditions at the outlet of the nozzle orifice have been applied as inlet condition for subsequent Euler-Lagrangian spray calculations to investigate the effects of liquid compressibility treatment on spray propagation. Flows of such nature are of interest within automotive and other internal combustion (IC) related industries to obtain good spray and emissions characteristics. In the development process of the injection equipment, predictive methods using Computational Fluid Dynamics (CFD) contribute to lower development costs, improved engine efficiency, decreased emissions and nevertheless shorter development cycles.
Technical Paper
2014-04-01
Weidi Huang, Zhijun Wu, Liguang Li, Zongjie Hu, Ya Gao, Jun Deng
Abstract In this study, in order to form a wide range of ambient gas density, Nitrogen and sulfur hexafluoride (SF6) are employed as ambient gas. Based on the common rail and high speed imaging system, the spray characteristics in extremely high ambient density and different ambient temperature are investigated in a constant volume vessel, and the influences of gas physical property on the spray characteristics have also been analyzed. The investigation results show that: the spray tip penetration and spray cone angle vary phenomenally with the increase of the ambient gas density. Due to the generation of shock wave, the results of the spray characteristics from two ambient gas densities are different nevertheless the same densities. Furthermore, the spray tip penetrations from the different ambient gases do not vary obviously from each other until the detachment of the shock wave from the spray tip. Hence, it is believed that the properties of the ambient gas between the shock wave front and the spray tip are influenced due to the detachment of the shock wave from the spray tip with energy and turbulence, thereby inducing the variation of the spray characteristics.
Technical Paper
2014-04-01
Qingluan Xue, Michele Battistoni, Sibendu Som, Shaoping Quan, P. K. Senecal, Eric Pomraning, David Schmidt
Abstract This paper implements a coupled approach to integrate the internal nozzle flow and the ensuing fuel spray using a Volume-of-Fluid (VOF) method in the CONVERGE CFD software. A VOF method was used to model the internal nozzle two-phase flow with a cavitation description closed by the homogeneous relaxation model of Bilicki and Kestin [1]. An Eulerian single velocity field approach by Vallet et al. [2] was implemented for near-nozzle spray modeling. This Eulerian approach considers the liquid and gas phases as a complex mixture with a highly variable density to describe near nozzle dense sprays. The mean density is obtained from the Favreaveraged liquid mass fraction. The liquid mass fraction is transported with a model for the turbulent liquid diffusion flux into the gas. Simulations were performed in three dimensions and the data for validation were obtained from the x-ray radiography measurements Kastengren et al. [3] at Argonne National Laboratory for a diesel fuel surrogate n-dodecane.
Technical Paper
2014-04-01
Ezio Mancaruso, Renato Marialto, Luigi Sequino, Bianca Maria Vaglieco
Abstract In recent years, several studies on the efficiency of modern diesel engines have focused on the modeling of combustion process in its different phases. Here, analytical equations are used to describe the physical phenomena that occur in the cylinder. The good agreement between the experimental and simulated data could improve the predictive capabilities of the computational code and reduce the cost of experimental activities. For the modeling of a diesel spray, the first step has been to investigate its behavior in a non-combusting environment; in particular, Musculus and Kattke proposed a model for the simulation of the injection of fuel in non-reacting still environment. Starting from that knowledge, the authors apply the injection model to a compression ignition research engine. By means of an optical engine, injection phase has been investigated via 2D digital imaging. The main jet characteristics like penetration and dispersion angle have been measured. The penetration data were compared with those provided by the 1D model with the same in-cylinder conditions.
Technical Paper
2014-04-01
Hua Zhou, Chia-Fon Lee, Shi-jin Shuai
Abstract The primary breakup of a planar liquid sheet produced by an air-blast atomizer was studied through numerical simulations, in order to reveal physical mechanisms involved during this process. The reliability of simulations was verified by comparing the macroscopic parameters, e.g. breakup time and spatial growth rate, with experimental data. Shear instability and RT (Rayleigh-Taylor) instability were found to play important roles during the primary breakup. By analyzing the acceleration of a fluid parcel within liquid sheet using Discrete Particle Method, and measuring the wave length of transverse unstable wave, RT instability was found to be partially responsible for transverse instability. The predictions of LISA (Linearized Instability Sheet Atomization) model on breakup time were compared to experiments, and obvious differences were found to exist. By analyzing the velocity distribution around liquid sheet and the variation of the amplitude of unstable wave versus spatial position, the reasons why LISA's predictions differ from experiments were partially revealed, and the perspectives to improve LISA model to get better accuracy were suggested.
Technical Paper
2014-04-01
Ogheneruona E. Diemuodeke, Ilai Sher
Abstract The theory of liquid fuel jet instabilities has been developed under several assumptions, which include the assumption that the jets breakup processes are isothermal. However, liquid fuels are normally injected into an elevated combustion-chamber temperature to maintain a desirable homogeneous combustible mixture - liquid vapour and air. Therefore, a new linear theory model is developed for the instability and breakup of non-isothermal liquid jets, with consideration of a spatially variation of surface tension along the liquid-gas interface. The spatial variation of surface tension is obtained through temperature-dependent surface tension and transient heat-transfer from the combusting gases to the liquid jet. The classical interface hydrodynamic breakup theory and solution of heat-transfer through semi-infinite medium are coupled through the surface tension gradient. The analytical model accounts for the non-isothermal effects on jet breakup. The model is shown to maintain plausibility of investigating liquid fuel breakup mechanisms under the combustion-chamber operating conditions.
Technical Paper
2014-04-01
Xiaohua Zhang, Alan Palazzolo, Chol-Bum Kweon, Erwin Thomas, Randall Tucker, Albert Kascak
The objective of this study is to optimize the injector power drive system for improved fuel injection quantity and timing control. The power drive system was optimized for improved injection repeatability under different operating conditions such as fuel supply pressures. A coupled simulation of injector electromagnetic, pintle (needle) rigid body motion and computational fluid dynamics (CFD) model was employed to generate the optimal values of the 1st stage current, the 1st stage on-time and the 2nd stage current. The simulation results were validated against the experimental data measured with a photo detector measurement system.
Technical Paper
2014-04-01
Xiangang Wang, Zhangsong Zhan, Xun Yu, Tiegang Hu, Yanjun Qiao, Yuming Zhu, Shuhui Jiang
Abstract Changan Automobile Company recently develops a new 1.0L turbocharged GDI engine for its future vehicle as an affordable fuel-saving option. Fuel direct injection and turbo-charging are integrated to significantly improve fuel economy and power. Injection spray pattern plays an important role on GDI engine combustion system because of its critical influences on combustion and oil dilution. In this paper, four injector patterns were tested in an optical engine with Planar, double sided Laser Induced Fluorescence (LIF) with fuel & tracer and flame imaging methods to evaluate spray, mixture formation and combustion process in cylinder. Spray pattern and mixture formation are studied using LIF, while flame and combustion characteristics are studied by flame natural luminosity. The pictures of piston crown and glass liner are also evaluated for fuel spray impingement. Four types of multi-hole injectors are prepared. The Initial spray pattern layouts are studied before the test by CAD for matching sprays with piston bowl for catalyst heating operation in split injection mode and avoiding spray impingement on inlet valves.
Technical Paper
2014-04-01
Harry Husted, Timothy D. Spegar, Joseph Spakowski
Abstract To meet future particulate number regulations, one path being investigated is higher fuel pressures for direct injection systems. At operating pressures of 30 MPa to 40 MPa, the fuel system components must be designed to withstand these pressures and additional power is required by the pump to pressurize the fuel to higher pressures than the nominal 15MPa to 20MPa in use today. This additional power to the pump can affect vehicle fuel economy, but may be partially offset by increases in combustion efficiency due to improved spray mixture preparation. This paper examines the impact on fuel economy from increased system fuel pressures from a combination of test results and simulations. A GDi pump and valvetrain model has been developed and correlated to existing pump torque measurements and subsequently used to predict the increase in torque and associated impact on fuel economy due to higher GDi system pressures.
Technical Paper
2014-04-01
Johan Hult, Simon Matlok, Stefan Mayer
A combination of optical and laser based methods have been employed for simultaneously studying fuel jet penetration and ignition behaviour of fuel jets inside the cylinder of a large marine two-stroke diesel engine during operation. Tests were performed on a four-cylinder Diesel engine with a bore diameter of 0.5 meter. Optical access was obtained through a custom designed engine cover. A double pulsed laser was employed for global illumination of the liquid fuel jet. For detection a dual camera set-up was employed, which allowed both simultaneous fuel jet and flame emission imaging, or dual frame fuel jet imaging for velocity measurements. From the data recorded the liquid penetration, jet cone angle, jet penetration velocity, ignition location, ignition time and flame lift-off could be extracted. Data was recorded for two different charge densities and temperatures, for two different atomizer designs, and for two different fuels. The fuel jet was observed to ignite at a position around 1/4 of the length downstream.
Technical Paper
2014-04-01
Anqi Zhang, Alessandro Montanaro, Luigi Allocca, Jeffrey Naber, Seong-Young Lee
High pressure diesel sprays were visualized under vaporizing and combusting conditions in a constant-volume combustion vessel. Near-simultaneous visualization of vapor and liquid phase fuel distribution were acquired using a hybrid shadowgraph/Mie-scattering imaging setup. This imaging technique used two pulsed LED's operating in an alternative manner to provide proper light sources for both shadowgraph and Mie scattering. In addition, combustion cases under the same ambient conditions were visualized through high-speed combustion luminosity measurement. Two single-hole diesel injectors with same nozzle diameters (100μm) but different k-factors (k0 and k1.5) were tested in this study. Detailed analysis based on spray penetration rate curves, rate of injection measurements, combustion indicators and 1D model comparison have been performed. It is concluded that the nozzle geometry is causing the velocity and liquid flow area to vary at the nozzle outlet, which has an impact on air entrainment into the spray and results different combustion behavior.
Viewing 1 to 30 of 5641