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Viewing 1 to 30 of 72
2011-08-30
Technical Paper
2011-01-1883
Atsushi Matsumoto, Yi Zheng, Xingbin Xie, Ming-Chia Lai, Wayne Moore
Advanced valvetrain coupled with Direct Injection (DI) provides an opportunity to simultaneous reduction of fuel consumption and emissions. Because of their robustness and cost performance, multi-hole injectors are being adopted as gasoline DI fuel injectors. Ethanol and ethanol-gasoline blends synergistically improve the performance of a turbo-charged DI gasoline engine, especially in down-sized, down-sped and variable-valvetrain engine architecture. This paper presents Mie-scattering spray imaging results taken with an Optical Accessible Engine (OAE). OAE offers dynamic and realistic in-cylinder charge motion with direct imaging capability, and the interaction with the ethanol spray with the intake air is studied. Two types of cams which are designed for Early Intake Valve Close (EIVC) and Later Intake Valve Close (LIVC) are tested, and the effect of variable valve profile and deactivation of one of the intake valves are discussed.
2011-08-30
Technical Paper
2011-01-1881
Ming-Chia Lai, Yi Zheng, Mark Shost, Xingbin Xie, Atsushi Matsumoto, Jin Wang, Xusheng Zhang, Seoksu Moon, Jian Gao, Kamel Fezzaa, Lars Zigan, Ingo Schmitz, Michael Wensing, Alfred Leipertz
Multi-hole DI injectors are being adopted in the advanced downsized DISI ICE powertrain in the automotive industry worldwide because of their robustness and cost-performance. Although their injector design and spray resembles those of DI diesel injectors, there are many basic but distinct differences due to different injection pressure and fuel properties, the sac design, lower L/D aspect ratios in the nozzle hole, closer spray-to-spray angle and hense interactions. This paper used Phase-Contrast X ray techniques to visualize the spray near a 3-hole DI gasoline research model injector exit and compared to the visible light visualization and the internal flow predictions using with multi-dimensional multi-phase CFD simulations. The results show that strong interactions of the vortex strings, cavitation, and turbulence in and near the nozzles make the multi-phase turbulent flow very complicated and dominate the near nozzle breakup mechanisms quite unlike those of diesel injections.
2011-04-12
Technical Paper
2011-01-1221
Wayne Moore, Matthew Foster, Ming-Chia Lai, Xing-Bin Xie, Yi Zheng, Atsushi Matsumoto
Requirements for reduced fuel consumption with simultaneous reductions in regulated emissions require more efficient operation of Spark Ignited (SI) engines. An advanced valvetrain coupled with Gasoline Direct injection (GDi) provide an opportunity to simultaneously reduce fuel consumption and emissions. Work on a flex fuel GDi engine has identified significant potential to reduce throttling by using Early Intake Valve Closing (EIVC) and Late Intake Valve Closing (LIVC) strategies to control knock and load. High loads were problematic when operating on gasoline for particulate emissions, and low loads were not able to fully minimize throttling due to poor charge motion for the EIVC strategy. The use of valve deactivation was successful at reducing high load particulate emissions without a significant airflow penalty below 3000 RPM. Valve deactivation did increase the knocking tendency for knock limited fuels, due to increased heat transfer that increased charge temperature.
2014-04-01
Technical Paper
2014-01-1168
Bo Yang, Xing Wei, Ke Zeng, Ming-Chia Lai
Abstract Natural gas has been considered to be one of the most promising alternative fuels due to its lower NOx and soot emissions, less carbon footprint as well as attractive price. Furthermore, higher octane number makes it suitable for high compression ratio application compared with other gaseous fuels. For better economical and lower emissions, a turbocharged, four strokes, direct injection, high pressure common rail diesel engine has been converted into a diesel/natural gas dual-fuel engine. For dual-fuel engine operation, natural gas as the main fuel is sequentially injected into intake manifold, and a very small amount of diesel is directly injected into cylinder as the ignition source. In this paper, a dual-fuel electronic control unit (ECU) based on the PowerPC 32-bit microprocessor was developed. It cooperates with the original diesel ECU to control the fuel injection of the diesel/natural gas dual-fuel engine.
2005-10-24
Technical Paper
2005-01-3691
Srinivasan Venugopalan, Ming-Chia Lai, Feng Wu, Frank M. Washko
Variable Valve Timing (VVT) strategy on both intake and exhaust valves has a pivotal influence on the specific fuel consumptions and engine performance. In addition to this, fuel economy can also be enhanced by the application of Variable Compression Ratio (VCR) strategy. This paper presents three possible strategies to enhance fuel economy improvement: A possible VVT strategy Early Intake Valve Opening (EIVO) and Late Exhaust Valve Closure (LEVC) that alters the valve overlap to reduce fuel consumption A two-position VCR system that improves fuel conversion factor to realize fuel economy A strategy that combines above two technologies to produce a complementary effect on fuel economy All three strategies have been tested on a 1.8L DOHC four cylinder PFI engine. AVL BOOST a 1D engine gas exchange and cycle simulation code was used to model this engine to get fuel economy gains at part-load points.
2005-09-11
Technical Paper
2005-24-093
Kamel Fezzaa, Wah-Keat Lee, Seong-Kyun Cheong, Christopher F. Powell, Jin Wang, Ming-Chia Lai
Propagation-based and phase-enhanced x-ray imaging was developed as a unique metrology technique to visualize the internal structure of high-pressure fuel injection nozzles. We have visualized the microstructures inside 200-μm fuel injection nozzles in a 3-mm-thick steel housing using this novel technique. Furthermore, this new x-ray-based metrology technique has been used to directly study the highly transient needle motion in the nozzles in situ and in real-time, which is virtually impossible by any other means. The needle motion has been shown to have the most direct effect on the fuel jet structure and spray formation immediately outside of the nozzle. In addition, the spray cone-angle has been perfectly correlated with the numerically simulated fuel flow inside the nozzle due to the transient nature of the needle during the injection.
2014-04-01
Technical Paper
2014-01-1331
Nick Polcyn, Ming-Chia Lai, Po-I Lee
Abstract The need for using alternative fuel sources continues to grow as industry looks towards enhancing energy security and lowering emissions levels. In order to capture the potential of these megatrends, this study focuses on the relationship between ignition energy, thermal efficiency, and combustion stability of a 0.5 L single cylinder engine powered by compressed natural gas (CNG) at steady state operation. The goal of the experiment was to increase ignition energy at fixed lambda values to look for gains in thermal efficiency. Secondly, a lambda sweep was performed with criteria of maintaining a 4% COVIMEP by increasing the ignition energy until an appropriate threshold for stable combustion was found. The engine performance was measured with a combustion analysis system (CAS), to understand the effects of thermal efficiency and combustion stability (COVIMEP). Emissions of the engine were measured with an FTIR.
2014-04-01
Journal Article
2014-01-1389
Ziliang Zheng, PO-I Lee, Amit Shrestha, Tamer Badawy, Ming-Chia Lai, Naeim Henein, Eric Sattler
Surrogates for JP-8 have been developed in the high temperature gas phase environment of gas turbines. In diesel engines, the fuel is introduced in the liquid phase where volatility plays a major role in the formation of the combustible mixture and autoignition reactions that occur at relatively lower temperatures. In this paper, the role of volatility on the combustion of JP-8 and five different surrogate fuels was investigated in the constant volume combustion chamber of the Ignition Quality Tester (IQT). IQT is used to determine the derived cetane number (DCN) of diesel engine fuels according to ASTM D6890. The surrogate fuels were formulated such that their DCNs matched that of JP-8, but with different volatilities. Tests were conducted to investigate the effect of volatility on the autoignition and combustion characteristics of the surrogates using a detailed analysis of the rate of heat release immediately after the start of injection.
2010-04-12
Technical Paper
2010-01-1173
PO-I Lee, Amy Peterson, Ming-Chia Lai, Mark Casarella, Ming-Cheng Wu
The current study focused on the effects B20 fuel (20% soybean-based biodiesel) and SCR entrance shapes on a light-duty, high-speed, 2.8L common-rail 4-cylinder diesel engine, at different exhaust temperatures. The results indicate that B20 has less deNOX efficiency at low temperature than ULSD, and that N₂O emission need to be characterized as well as NH₃ slip. If a mixer and enough mixing length are used, longer divergence section does not improve the deNOX efficiency significantly under the speed ranges tested.
2010-04-12
Technical Paper
2010-01-1224
Liangjun Hu, Ce Yang, Harold Sun, Eric Krivizky, Louis Larosiliere, Jizhong Zhang, Ming-Chia Lai
Self recirculation casing treatment has been showed to be an effective technique to extend the flow range of the compressor. However, the mechanism of its surge extension on turbocharger compressor is less understood. Investigation and comparison of internal flow filed will help to understand its impact on the compressor performance. In present study, experimentally validated CFD analysis was employed to study the mechanism of surge extension on the turbocharger compressor. Firstly a turbocharger compressor with replaceable inserts near the shroud of the impeller inlet was designed so that the overall performance of the compressor with and without self recirculation casing treatment could be tested and compared. Two different self recirculation casing treatments had been tested: one is conventional self recirculation casing treatment and the other one has deswirl vanes inside the casing treatment passage.
2010-04-12
Technical Paper
2010-01-0877
Zunping Liu, Kyoung-Su Im, Yuejie Wang, Kamel Fezzaa, Xing-Bin Xie, Ming-Chia Lai, Jin Wang
By taking advantage of high-intensity and high-brilliance x-ray beams available at the Advanced Photon Source (APS), ultrafast (150 ps) propagation-based phase-enhanced imaging was developed to visualize high-pressure high-speed diesel sprays in the optically dense near-nozzle region. The sub-ns temporal and μm spatial resolution allows us to capture the morphology of the high-speed fuel sprays traveling at 500 m/s with a negligible motion blur. Both quality and quantitative information about the spray feature can be readily obtained. In the experiment, two types of single-hole nozzles have been used, one with a hydroground orifice inlet and the other with a sharp one. Within 3 mm from the nozzle, the sprays from these nozzles behave differently, ranging from laminar flow with surface instability waves to turbulent flow. The sprays are correlated with the nozzle internal geometry, which provides practical information for both nozzle design and supporting numerical simulation models.
2010-04-12
Journal Article
2010-01-0596
Diana Martin, Jochen Stratmann, Philipp Pischke, Reinhold Kneer, Ming-Chia Lai
In present GDI engines, multiple injection strategies are often employed for engine cold start mixture formation. In the future, these strategies may also be used to control the combustion process, and to prevent misfiring or high emission levels. While the processes occurring during individual injections of GDI injectors have been investigated by a number of researchers, this paper concentrates on the interactions of multiple injection events. Even though multiple injection strategies are already applied in most GDI engines, the impact of the first injection event on the second injection event has not been analyzed in detail yet. Different optical measurement techniques are used in order to investigate the interaction of the two closely timed injection events, as well as the effect of dwell time and the in-cylinder conditions. The injector investigated is a GDI piezo injector with an outwardly opening needle.
2010-04-12
Journal Article
2010-01-0601
Atsushi Matsumoto, Wayne R. Moore, Ming-Chia Lai, Yi Zheng, Matthew Foster, Xing-Bin Xie, David Yen, Keith Confer, Eunjoo Hopkins
Operation of flex fuel vehicles requires operation with a range of fuel properties. The significant differences in the heat of vaporization and energy density of E0-E100 fuels and the effect on spray development need to be fully comprehended when developing engine control strategies. Limited enthalpy for fuel vaporization needs to be accounted for when developing injection strategies for cold start, homogeneous and stratified operation. Spray imaging of multi-hole gasoline injectors with fuels ranging from E0 to E100 and environmental conditions that represent engine operating points from ambient cold start to hot conditions was performed in a spray chamber. Schlieren visualization technique was used to characterize the sprays and the results were compared with Laser Mie scattering and Back-lighting technique. Open chamber experiments were utilized to provide input and validation of a CFD model.
2014-04-01
Technical Paper
2014-01-1434
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.
2013-04-08
Technical Paper
2013-01-0898
Kan Zha, Xin Yu, Ming-Chia Lai, Marcis Jansons
Low cetane JP-8 fuels have been identified as being difficult to use under conventional diesel operation. However, recent focus on low-temperature combustion (LTC) modes has led to an interest in distillate hydrocarbon fuels having high volatility and low autoignition tendency. An experimental study is performed to evaluate low-temperature combustion processes in a small-bore optically-accessible diesel engine operated in a partially-premixed combustion mode using low-cetane Sasol JP-8 fuel. This particular fuel has a cetane number of 25. Both single and dual injection strategies are tested. Since long ignition delay is a consequence of strong autoignition resistance, under the conditions examined, low cetane Sasol JP-8 combustion can only take place with a double injection strategy: one pilot injection event in the vicinity of exhaust TDC and one main injection event near firing TDC.
2013-04-08
Technical Paper
2013-01-1129
PO-I Lee, Nick Polcyn, Ming-Chia Lai
Gasoline-direct-injection (GDI) engines have been adopted increasingly by the automotive industry in the recent years due to their performance, effects on the environment, and customers' demand on advanced technology. However, the knowledge of detailed combustion process in such engines is still not thoroughly analyzed and understood. With optically accessible engines (OAE) and advanced measuring techniques, such as high-speed digital imaging, the in-cylinder combustion process is made available directly to researchers. The present study primarily focuses on the effects of different parameters of engine control on the combustion process, such as fuel types, valve deactivation, ignition timing, spark energy, injection timing, air-fuel ratio, and exhaust gas recirculation. Three engine heads of a 2.0L GDI engine are used with modification to acquire different optical access.
2010-10-25
Technical Paper
2010-01-2151
Atsushi Matsumoto, Yi Zheng, Xing-Bin Xie, Ming-Chia Lai, Wayne Moore
Because of their robustness and cost performance, multi-hole gasoline injectors are being adopted as the direct injection (DI) fuel injector of choice as vehicle manufacturers look for ways to reduce fuel consumption without sacrificing power and emission performance. To realize the full benefits of direct injection, the resulting spray needs to be well targeted, atomized, and appropriately mixed with charge air for the desirable fuel vapor concentration distributions in the combustion chamber. Ethanol and ethanol-gasoline blends synergistically improve the turbo-charged DI gasoline performance, especially in down-sized, down-sped and variable-valve-train engine architecture. This paper presents the spray imaging results from two multi-hole DI gasoline injectors with different design, fueled with pure ethanol (E100) or gasoline (E0), under homogeneous and stratified-charge conditions that represent typical engine operating points.
2013-04-08
Technical Paper
2013-01-0255
Bizhan Befrui, Andreas Aye, Peter Spiekermann, Daniel L. Varble, Mark A. Shost, Ming-Chia Lai, Jin Wang
Improvement of spray atomization and penetration characteristics of the gasoline direct-injection (GDi ) multi-hole injector is a critical component of the GDi combustion developments, especially in the context of engine down-sizing and turbo-charging trend that is adopted in order to achieve the European target CO₂, US CAFE, and concomitant stringent emissions standards. Significant R&D efforts are directed towards optimization of the nozzle designs, in order to improve the GDi multi-hole spray characteristics. This publication reports VOF-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 skew angle on the nozzle flow and spray primary breakup. VOF-LES simulations of a single nozzle-hole of a purpose-designed GDi multi-hole seat geometry, with three identical nozzle-holes per 120° seat segment, are performed.
2012-04-16
Journal Article
2012-01-0392
Bizhan Befrui, Giovanni Corbinelli, Peter Spiekermann, Mark Shost, Ming-Chia Lai
The improvement of spray atomization and penetration characteristics of GDI multi-hole injector sprays is a major component of the engine combustion developments, in order to achieve the fuel economy and emissions standards. Significant R&D efforts are directed towards optimization of the nozzle designs, in order to achieve optimum multi-objective spray characteristics. The Volume-of-Fluid Large-Eddy-Simulation (VOF-LES) of the injector internal flow and spray break-up processes offers a computational capability to aid development of a fundamental knowledge of the liquid jet breakup process. It is a unique simulation method capable of simultaneous analysis of the injector nozzle internal flow and the near-field jet breakup process. Hence it provides a powerful toll to investigate the influence of nozzle design parameters on the spray geometric and atomization features and, consequently, reduces reliance on hardware trial-and-tests for multi-objective spray optimizations.
1998-02-23
Technical Paper
980166
Eric N. Balles, Edward A. VanDyne, Alexandre M. Wahl, Kenneth Ratton, Ming-Chia Lai
Experiments were conducted on a single cylinder engine to measure the ionization current across the spark plug electrodes as a function of key operating parameters including air/fuel ratio. A unique ignition circuit was adapted to measure the ion current as early as 300 microseconds after the initiation of spark discharge. A strong relationship between air/fuel ratio and features of the measured ion current was observed. This relationship can be exploited via relatively simple algorithms in a wide range of electronic engine control strategies. Measurements of spark plug ion current for approximating air/fuel ratio may be especially useful for use with low cost mixture control in small engine applications. Cylinder-to-cylinder mixture balancing in conjunction with a global exhaust gas oxygen sensor is another promising application of spark plug ion current measurement.
1997-02-24
Technical Paper
971014
Fu-Quan Zhao, Ling Bai, Yi Liu, Tsan-Hai Chue, Ming-Chia Lai
An experimental study was performed, using cycle-resolved laser Doppler velocimetry (LDV) technique, to characterize the exhaust flow structure inside a catalytic converter retro-fitted to a firing four-cylinder gasoline engine over different operating conditions. A small fraction of titanium (IV) isopropoxide was dissolved in gasoline to generate titanium dioxide during combustion as seeding particles for LDV measurements. It was found that in the front plane of the catalytic monolith, the velocity is highly fluctuating due to the pulsating nature of the engine exhaust flow, which strongly depends on the engine operating conditions. Under unloaded condition, four pairs of major peaks are clearly observed in the time history of the velocity, which correspond to the main exhaust events of each individual cylinder.
1995-02-01
Technical Paper
950784
Fu-Quan Zhao, Li Li, Xingbin Xie, Ming-Chia Lai
The flow structure inside the catalytic converter of gasoline engines is very important for consideration of the catalyst light-off condition, converter durability and conversion efficiency. However, the available experimental data under actual engine exhaust conditions are quite limited due to its complicated configuration, critical operating conditions and difficult optical access. Therefore, an experimental study was performed, using laser Doppler velocimetry technique, to measure the velocity distributions inside two production dual-monolith catalytic converters fitted on a firing gasoline engine over several engine operating conditions. This paper reports the normal velocity characteristics measured in a plane 1 mm away from the front surface of first monolith. A small fraction of titanium (IV) isopropoxide was dissolved in gasoline for generating titanium dioxide seeding particles during the engine combustion.
1995-02-01
Technical Paper
950506
Fu-Quan Zhao, Ming-Chia Lai, David L. Harrington
The requirement of meeting the emission standards for low emission vehicles (LEV) and ultra low emission vehicles (ULEV) has resulted in a more stringent examination of all elements of the automotive internal combustion engine that contribute to emission formation. The fuel system, as one of the key elements, is the subject of renewed and expanded research in an effort to understand and optimize the important parameters. Only through such enhanced understanding of the basic processes of fuel injection, metering, atomization, targeting, pulse-to-pulse variability and induction of fuel under cold, normal and elevated temperature conditions can the very low emissions of today's vehicles be further reduced to ULEV values.
1995-10-01
Technical Paper
952486
Fu-Quan Zhao, Amer Ahmad Amer, Ming-Chia Lai, John L. Dressler
An experimental study was carried out to characterize the spray atomization process of automotive port fuel injectors retrofitted to a novel pressure modulation piezoelectric driver, which generates a pressure perturbation inside the fuel line. Unlike many other piezoelectric atomizers, this unit does not drive the nozzle directly. It has a small size and can be installed easily between regular port injector and fuel lines. There is no extra control difficulty with this system since the fuel injection rate and injection timing are controlled by the original fuel-metering valve. The global spray structures were characterized using the planar laser Mie scattering (PLMS) technique and the spray atomization processes were quantified using phase Doppler anemometry (PDA) technique.
1995-10-01
Technical Paper
952487
Fu-Quan Zhao, Joon-Ho Yoo, Ming-Chia Lai
An experimental study of sprayod structures from a regular dual-stream (RDS) injector and an air-shrouding dual-stream (ASDS) injector was carried out extensively to understand the spray characteristics of dual-stream (DS) port fuel injector for applications to 4-valve gasoline engines. The injectors were tested under steady and transient conditions at different injection pressures. The global spray structures were visualized using planar laser Mie scattering (PLMS) technique and spray atomization processes were quantified using phase Doppler anemometry (PDA) technique. The experimental results showed that at the beginning of fuel injection, the spray tip penetration for the RDS injector decreases with an increase in injection pressure; however, at the later stage of fuel injection, it increases when the injection pressure is increased. It is also found that the ligaments are dominant near the injector tip for the RDS injector with threads connecting the two streams.
1995-10-01
Technical Paper
952366
Ming-Chia Lai, Naeim A. Henein, Xingbin Xie, Tsan-Hal Chue, Yasuhiko Itoh, Walter Bryzik
An experimental and numerical study was carried out to simulate the diesel spray behavior during cold starting conditions inside two single-cylinder optically accessible engines. One is an AVL single-cylinder research diesel engine converted for optical access; the other is a TACOM/LABECO engine retrofitted with mirror-coupled endoscope access. The first engine is suitable for sophisticated optical diagnostics but is constrained to limited consecutive fuel injections or firings. The second one is located inside a micro-processor controlled cold room; therefore it can be operated under a wide range of practical engine conditions and is ideal for cycle-to-cycle variation study. The intake and blow-by flow rates are carefully measured in order to clearly define the operation condition. In addition to cylinder pressure measurement, the experiment used 16-mm high-speed movie photography to directly visualize the global structures of the sprays and ignition process.
1996-02-01
Technical Paper
960115
Fu-Quan Zhao, Joon-Ho Yoo, Ming-Chia Lai
An experimental study was carried out to investigate the spray behavior inside engine intake ports. Production-type intake ports of four-valve gasoline engines were modified for the optical access at directions. The global spray formation process was visualized through laser Mie scattering technique. The spray breakup and atomization processes, spray targeting and fuel dispersing characteristics were investigated as a function of elapse time after fuel injection. The spray interaction with the port wall and port air flow were examined with different types of port fuel injectors including single-stream, multi-stream, and air-shrouded ones. The spray targeting and dispersing characteristics inside two different intake ports were examined. It was found that spray targeting and fuel dispersion inside the intake port are strongly dependent on the spray characteristics, as a result of different injector designs and injector installation positions.
1996-10-01
Technical Paper
961925
Fu-Quan Zhao, Joon-Ho Yoo, Yi Liu, Ming-Chia Lai
An experimental study was made to investigate the spray characteristics of high pressure fuel injectors for direct-injection gasoline engines. The global spray development process was visualized using two-dimensional laser Mie scattering technique. The spray atomization process was characterized by Phase Doppler particle analyzer. The transient spray development process was investigated under different fuel injection conditions as a function of the time after the fuel injection start. The effects of injector design, fuel injection pressure, injection duration, ambient pressure, and fuel property on the spray breakup and atomization characteristics were studied in details. Two clear counter-rotating recirculation zones are observed at the later stage or after the end of fuel injection inside the fuel sprays with a small momentum. The circumferential distribution of the spray from the large-angle injector is quite irregular and looks like a star with several wings projected out.
1994-10-01
Technical Paper
941873
Ming-Chia Lai, Fu-Quan Zhao, Amer Ahmad Amer, Tsan-Hai Chue
Port fuel injection system in gasoline engines is receiving an increasing attention for its potential advantages in meeting the constrains of simultaneous reduction in fuel consumption and exhaust emission, and maintaining a good engine performance. The structure of port injector spray dominates the mixture preparation process and strongly affect the subsequent engine combustion characteristics over a wide range of operating conditions in port-injection gasoline engines. In this paper, an experimental and analytical study is made to characterize the breakup mechanism and atomization process of the non-air-assisted port injector sprays in gasoline engines. The liquid sprays resulted from various types of current and development-type automotive fuel injectors were visualized using planar laser-induced fluorescence imaging technique. A comparison was made on the spray structure of the single hole and multi-hole injectors.
1998-10-19
Technical Paper
982702
Joon-Ho Yoo, Sung-Kun Kim, Fu-Quan Zhao, Ming-Chia Lai, Ki-Sang Lee
Two-dimensional pulse-laser Mie scattering visualization of the direct-injection gasoline fuel sprays and wall impingement processes was carried out inside a single-cylinder optically accessible engine under motoring condition. The injectors have been first characterized inside a pressurized chamber using identical technique, as well as high-speed microscopic visualization and phase Doppler measurement techniques. The effects of injector cone angle, location, and injection timings on the wall impingement processes were investigated. It was found that the fuel vaporization is not complete at the constant engine speed tested. Fuel spray droplets were observed to disperse wider in the motored engine when compared with an isothermal quiescent ambient conditions. The extent of wall-impingement varies significantly with the injector mounting position and spray cone angle; however, its effect can be reduced to some extent by optimizing the injection timing.
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