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RANS simulation of a multicomponent underexpanded gaseous jet mixing – effects of composition and injection conditions

Technion - Israel Institute of Technology-Andy Thawko, Leonid Tartakovsky
  • Technical Paper
  • 2019-32-0515
To be published on 2020-01-24 by Society of Automotive Engineers of Japan in Japan
Fuel injection and mixing processes determine quality of the subsequent combustion in a DI engine, and description of these processes is vital to optimize the engine performance. Reynolds-averaged Navier–Stokes approach was applied as a cost-effective tool to simulate the mixing process of a multicomponent gaseous fuel jet of various compositions typical for alcohol reformates. To learn about the physics of reformate mixing, a hydrogen-rich multicomponent jet behavior in a constant-volume chamber was investigated at conditions typical for ICE. The CFD model was validated using a reference case from the published literature. Various Impact of the gaseous jet composition, injection pressure and nozzle diameter on its behavior were studied. The important new finding shows that rising the injection pressure or increasing the nozzle diameter won't affect the jet wall impingement timing for bore sizes typical for light-duty vehicle ICEs. Furthermore, it is shown that the integral parameters of a multicomponent gaseous jet in ICE are mainly determined by the molar weight of the injected gas mixture even with high molecular diffusivity species in the mixture like…
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Performance Investigation of a PFI Gasoline Engine by Applying Various Kinds of Fuel Injectors

Bosch Corporation-Toshiya Iio, Yudai Miyatani, Akira Tsunoi
Chiba University-Fuchao Shen, Yasuo Moriyoshi, Tatsuya Kuboyama
  • Technical Paper
  • 2019-32-0546
To be published on 2020-01-24 by Society of Automotive Engineers of Japan in Japan
In this report, the effect of injection specification, such as droplet size, lengths of nozzle tip and spray angle, on the engine performance was investigated using a 1.2 L port fuel injection (PFI) four-cylinder gasoline engine. The experimental conditions were selected to cover the daily operating mode, including the cold start and catalyst heating process. The experiments were conducted by varying not only the injectors but also the injection timing which was shifted from the exhaust to intake stroke. The results were evaluated by the fuel consumption and exhaust gas emissions. When these tests were conducted on a production engine, a carefully designed tumble generator was installed at the intake port to enhance the intake air flow. As a result, the injection specifications showed a potential to obtain less fuel consumption and lower engine-out emissions was evaluated.
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Prediction of Cavitation Erosion Intensity Using Large-Scale Diesel Nozzles

DENSO CORPORATION-Toshiaki Hijima, Kazufumi Serizawa
SOKEN, INC.-Motoya Kambara, Takanobu Aochi, Fumiaki Arikawa
  • Technical Paper
  • 2019-01-2278
Published 2019-12-19 by SAE International in United States
In the field of heavy-duty diesel engines, which require lifetime durability and high fuel efficiency, there is a growing demand for increased injection pressure and increased flow rate inside injection holes. This trend makes it important to prevent cavitation erosion of injector nozzles. This paper aims to clarify the relation between cavitation behavior and erosion damage experimentally by visualizing the flow inside diesel nozzles and to establish a new method for predicting cavitation erosion. To visualize internal flow, authors used the large-scale transparent nozzle whose Reynolds number and Cavitation number were matched with those of the actual real-size nozzle. Direct observation showed that the form of the cavitation changed from string-type cavitation to film-type cavitation with increasing needle lift. In addition, comparison between the locations where cavitation bubbles collapse and the locations where erosion occurs suggested that collapse of the film-type cavitation at high needle lift contributed significantly to the erosion damage. Furthermore, it is found that the location and intensity of erosion can be predicted by calculating the local quantity of film-type cavitation collapse.
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Study of Nozzle Fouling: Deposit Build-Up and Removal

KTH Royal Institute of Technology-Hanna Bernemyr, Botond Csontos
Scania CV AB-Henrik Hittig, Oscar Forsberg
  • Technical Paper
  • 2019-01-2231
Published 2019-12-19 by SAE International in United States
The global demand for decreased emission from engines and increased efficiency drives manufactures to develop more advanced fuel injection systems. Today's compression-ignited engines use common rail systems with high injection pressures and fuel injector nozzles with small orifice diameters. These systems are highly sensitive to small changes in orifice diameters since these could lead to deteriorations in spray characteristics, thus reducing engine performance and increasing emissions. Phenomena that could create problems include nozzle fouling caused by metal carboxylates or biofuels. The problems increase with extended use of biofuels. This paper reports on an experimental study of nozzle hole fouling performed on a single-cylinder engine. The aim was to identify if the solubility of the fuel has an effect on deposit build-up and, thus, the reduction in fuelling with associated torque loss, and if there is a probability of regenerating the contaminated injectors. Additionally, the influence of the nozzle geometry was tested by using injectors of various designs. In the experiments, high-load engine operation was used to create the effect of fouling in the presence of…
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Effects of Nozzle Hole Diameter and Injection Pressure on Fuel Adhesion of Flat-Wall Impinging Spray

Department of Mechanical Systems Engineering, Hiroshima Univ-Hongliang Luo, Shintaro Uchitomi, Tomohiro Watanabe, Keiya Nishida, Youichi Ogata
Mazda Motor Corporation, Aki-gun, Hiroshima, 730-8670, Japan-Wu Zhang, Ryosuke Hara, Tatsuya Fujikawa
  • Technical Paper
  • 2019-01-2246
Published 2019-12-19 by SAE International in United States
In direct injection spark ignition (DISI) engine, it is difficult to avoid the spray impingement of fuel on the cylinder wall and piston head, which is a possible source of hydrocarbons and soot emission. The injector nozzle geometry and injection pressure are essential components for the spray atomization and mixture formation. For better understanding the effects of injector hole diameters and injection pressure, the fuel spray and adhesion on a flat wall by different mini-sac injectors with a single hole was examined in this study. A flat-wall made of quartz glass was used as the impingement plate. Refractive Index Matching (RIM) method was applied to measure the thickness of fuel adhesion on the wall. All the cases performed in constant high-pressure chamber were under high temperature condition considering the real gasoline engine condition. Time-resolved behaviors of the fuel adhesion as well as adhesion mass, area and thickness were discussed. Results show that the decreased nozzle hole diameter and increased injection pressure reduce the fuel adhesion mass, area and thickness. Moreover, the enlarged nozzle hole diameter…
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Eccentric Needle Motion Effect on Spray Dynamics of Multi-hole Diesel Nozzle

National Institute of Advanced Industrial Science and Techno-Huifeng Gong, Weidi Huang, Raditya Hendra Pratama
  • Technical Paper
  • 2019-01-2281
Published 2019-12-19 by SAE International in United States
The needle eccentricity has been found to be able to influence the in-nozzle flow characteristics and fuel sprays in the near-nozzle region. However, very few investigations have been conducted to unveil its inherent mechanism. In this study, the effect of needle eccentricity on the hole-to-hole variation is numerically studied using a simplified sac nozzle geometry with three fixed needle positions. The results showed that the effect of needle eccentricity on the hole-to-hole variation is dependent on the sac volume, and only when the sac volume is relatively small, the needle eccentricity can lead to an effective hole-to-hole variation.
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Study on Diesel Atomization Characteristics for Hot Exhaust Gas Burner

School of Automotive Studies, Tongji University-Mengdi Li, Shipeng Li, Liguang Li, Jun Deng
  • Technical Paper
  • 2019-01-2238
Published 2019-12-19 by SAE International in United States
A hot exhaust gas burner system is applied to break through the limitations of the traditional diesel engine bench. Sufficient atomization is needed to realize spark ignition in a low-pressure burner system. Hence, the design of the atomization system is studied both experimentally and numerically. Through the reasonable optimization of the nozzle diameter, the air assist pressure, the angle among the four nozzles of four V-structures as well as the diameter and the angle of co-flow holes, an even distribution of small diesel droplets in the ignition area of the burner is realized. Consequently, diesel spray can be spark ignited in a low-pressure burner system, which can simulate the diesel exhaust. And the DPF can be installed downstream of the burner to quickly analyze the effect of ash accumulation on the DPF.
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Effects of ratio and dwell of split injection on fuel spray and mixture formation process under evaporating, non-reacting condition

University of Hiroshima-Jaeheun Kim, Shinichi Kakami, Keiya Nishida, Yoichi Ogata
  • Technical Paper
  • 2019-01-2323
Published 2019-12-19 by SAE International in United States
The effects of split injections of a diesel spray was evaluated in a constant volume chamber under evaporating, non-reacting condition. Laser absorption scattering (LAS) technique was utilized for the mixture concentration measurement, using a diesel surrogate fuel consists of n-tridecane and 2.5% of 1-methylnaphthalene in volume basis. While fixing the total injected fuel mass of 5.0 mg/hole, the effects of split ratio in mass basis and the dwell time (or injection interval) were investigated. Among the split ratios conducted in the current study (3,7, 5:5 and 7:3), the split ratio of 7:3 was the optimum for lean mixture formation regarding the overall distribution of the equivalence ratio at end-of-injection (EOI) timing. The air entrainment wave at the EOI timing of the first injection allowed the fuel at the vicinity of the nozzle to become leaner at a faster rate. It was thought that, the split ratio of 7:3 provided an adequate amount of fuel quantity and vapor penetration to fit into the fuel-lean region formed from the first injection. The increase of the dwell time…
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Effect of pressure cycling on gas exchange in a transparent fuel injector

Sandia National Laboratories, 7011 East Ave, 94550 Livermore-Paul M. Abers, Emre Cenker, Koji Yasutomi, Joonsik Hwang, Lyle M. Pickett
  • Technical Paper
  • 2019-01-2280
Published 2019-12-19 by SAE International in United States
Gas ingested into the sac of a fuel injector after the injector needle valve closes is known to have crucial impacts on initial spray formation and plume growth in a following injection cycle. Yet little research has been attempted to understand the fate sac gases during pressure expansion and compression typical of an engine. This study investigated cavitation and bubble processes in the sac including the effect of chamber pressure decrease and increase consistent with an engine cycle. A single axial-hole transparent nozzle based on the Engine Combustion Network (ECN) Spray D nozzle geometry was mounted in a vessel filled with nitrogen, and the nitrogen gas pressure was cycled after the end of injection. Interior nozzle phenomena were visualized by high-speed longdistance microscopy with a nanosecond pulsed LED back-illumination. Experimental results showed that the volume of gas in the sac after the needle closes depends upon the vessel gas pressure. Higher back pressure results in less cavitation and a smaller volume of non-condensable gas in the sac. But a pressure decrease mimicking the expansion stroke…
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Effect of Injection Amount on Diesel Spray Characteristics of Multi-Hole Nozzle

Fukuoka Institute of Technology-Keisuke Komada
IRS Corporation-Manabu Saito
  • Technical Paper
  • 2019-01-2284
Published 2019-12-19 by SAE International in United States
A laser 2-focus velocimeter(L2F) has been utilized for the measurements of the velocity and size of droplets in diesel fuel sprays injected from a 6-hole nozzle. The fuel was stored once in a common rail and was injected intermittently to the atmosphere by using a solenoid injector. The diameter of the nozzle orifice was 0.165 mm. The injection pressure was 60 MPa. The injector solenoid was driven by the current having a waveform consisted of 3 stages; boot, pull, and hold. The injection amounts were set at 0.8, 2.9, 3.9 and 4.7mg by changing the durations of the pull stage and the hold stage. The L2F measurement was conducted at 10 mm downstream from the nozzle exit. The fluctuation intensity of the droplet velocity was found to be larger under the smaller injection amount. It was clearly shown that the arithmetic mean droplet size under the smaller injection amount was smaller than that under the larger injection amount during the hold current duration. There was a negative correlation between the droplet size and the droplet…
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