Near-Wall Characteristics of an Impinging Gasoline Spray at Increased Ambient Pressure and Wall Temperature

Stratmann, Jochen; Martin, Diana; Unterlechner, Peter; Kneer, Reinhold

doi:10.1615/atomizspr.v19.i11.10

Cited by 4 publications

(2 citation statements)

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“…This vapor film on the top of the piston may change the spray breakup and alter the direction of the fuel rebound. This is similar to the observation by Stratmann et al, who observed the influence of wall temperature on the velocity and direction of the spray tip and the fuel rebound. The larger roll-up angle may generate more mixing with the piston motion, thus suppressing soot formation for E100.…”

Section: Resultssupporting

confidence: 92%

Effects of Ethanol on In-Cylinder and Exhaust Gas Particulate Emissions of a Gasoline Direct Injection Spark Ignition Engine

et al. 2015

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The effects of ethanol on reducing the particulate emissions of a direct injection spark ignition (DISI) engine were investigated using a single-cylinder, optically accessible engine. Neat anhydrous ethanol was compared with a baseline fuel of reference grade gasoline. A high speed camera was used to record crank-angle resolved in-cylinder images of the fuel spray, combustion, and thermal radiation from the soot formed for the engine operating conditions studied. Particulate emissions in the engine exhaust gas were also measured using opacity measurements (i.e., using a smoke meter). All experiments were conducted at the same load conditions with a net indicated mean effective pressure of IMEPnet ≈ 5.5 bar and an intake manifold absolute pressure of 76 kPa. The engine speed was fixed at 1500 rpm, and the fuel injection duration was controlled to achieve stoichiometric combustion. Spark timing was adjusted to target combustion phasing (CA50) of 8°aTDC. The effects of engine coolant temperature and fuel injection timing on fuel spray characteristics and soot formation were studied for each fuel. The imaging data indicate that soot formation is a strong function of liquid fuel impingement on the piston surface, consistent with previous in-cylinder imaging studies of soot formation in DISI engines using different engine hardware and imaging orientation. A quantitative metric was applied to the imaging data of this work, and the in-cylinder soot formation based on the imaging data were in good agreement with the engine-out smoke measurements, indicating the optical imaging results are representative of engine-out particulate emissions. Higher coolant temperatures and later fuel injection timing significantly mitigated the incylinder soot emissions for both fuels by altering the fuel spray interactions with the piston surface and cylinder liner. As expected based on previous studies, ethanol systematically produced less soot than gasoline for each operating condition. Features of the fuel spray roll-up were identified as important indicators of pool fires on the piston surface for the earliest fuel injection timings.

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Section: Resultssupporting

confidence: 92%

Effects of Ethanol on In-Cylinder and Exhaust Gas Particulate Emissions of a Gasoline Direct Injection Spark Ignition Engine

et al. 2015

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“…Arcoumanis et al [3] studied the detailed structure of diesel spray when it impacts the normal temperature wall (20 • C) and heated wall (150 • C), and they found that higher wall temperature reduced the accumulation of droplets in front of the wall jet, and enhanced the vortex in front of the wall jet. In addition, Stratmann et al [4] found that the increase of environmental density will also enhance the vortex in the front of the spray. Mathew et al [5] used isooctane instead of gasoline to study the spray wall impact characteristics of a single-hole low-pressure injector.…”

Section: Introductionmentioning

confidence: 99%

Investigation of the Behaviors of Methanol Spray Impingement and Wall Wetting

et al. 2022

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Port fuel injection is an important technical route in methanol engines. To obtain a theoretical basis for injector arrangement and injection strategy development in methanol engines, an optimal experimental platform based on diffuse back-illumination and the refractive index matching method (RIM) was designed and built in this study. The experiments on the behavior of low-pressure methanol spray-wall impingement and wall film were carried out and the influence of the three boundary conditions of spray distance (Dimp), wall temperature (Twall), and injection pressure (Pinj) were analyzed comprehensively. Results showed that with the increase of Dimp, the overall shape of spray before impinging the wall changed from conical to cylindrical. The impinging spray height Hi and impinging spray width Wi increased with the decrease of Dimp and the increase of Pinj. Adhesive fuel film mass Mf increased with the increase of Dimp due to the decrease of kinetic energy during wall impact. In addition, the increase of the wall temperature Twall reduced Mf due to evaporation, but when Twall reached 423 K, Mf rebounded due to the Leidenfrost effect. The results of this study are helpful to improve the accuracy of the numerical methanol engine model.

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Study on Fuel Distribution of Wall-Impinging Diesel Spray under Different Wall Temperatures by Laser-Induced Exciplex Fluorescence (LIEF)

et al. 2018

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Spray wall-impingement has large effects on the pollutant emissions and thermal efficiency of engines. Different wall temperatures can affect the gas-liquid phase transition of the spray, and the temperature gradient from the ambient to the wall will cause a different mixture process in the region nearby the wall. However, there are few studies on spray wall-impingement with different wall temperatures, particularly on the liquid-gas phase transition of the spray. Therefore, in this paper, the effects of different wall temperatures on spray-impingement have been investigated in a high-temperature, high-pressure constant volume combustion vessel. Cooling equipment was used to adjust the temperature difference between the wall and the ambient gas. n-Dodecane was chosen as the diesel surrogate to study the spray process. The spray wall-impingement was tested by changing the injection pressures (P i ) and wall temperatures (T w ). The ambient temperature (T a ) and ambient pressure (P a ) were kept constant at 773 K and 4 MPa, and the distance (L) between wall and injector was set to 35 mm to mimic the radius of the combustion chamber in heavy-duty diesel engines. A laser-induced exciplex fluorescence (LIEF) technique was used to probe the vapor and liquid phases of the injected fuel. Results show that the liquid phases of the spray do not reach the wall except in the condition of low wall temperature and high injection pressure. The liquid penetration develops and then becomes constant after 1 ms from the start of injection. With the increase of injection pressures (600-1600 bar), the liquid concentration of the spray decreases; however the liquid penetration decreases insignificantly. The wall temperature and the injection pressure have little influence on the liquid interpenetration process. For the vapor phase of the spray, the high concentration regions (equivalence ratio (φ) > 1) mainly distribute in the area of 10 mm away from the impact point on the wall. With the decrease of wall temperatures, the high-concentration regions are enlarged at the near wall regions. However, at the injection pressure of 1600 bar, the influence of wall temperatures on the equivalence ratio is small. The decreasing wall temperature deteriorates the mixing process of the fuel and ambient gas, but the effect is weakened with the increase of injection pressure.

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Near-Wall Characteristics of an Impinging Gasoline Spray at Increased Ambient Pressure and Wall Temperature

Cited by 4 publications

References 0 publications

Effects of Ethanol on In-Cylinder and Exhaust Gas Particulate Emissions of a Gasoline Direct Injection Spark Ignition Engine

Effects of Ethanol on In-Cylinder and Exhaust Gas Particulate Emissions of a Gasoline Direct Injection Spark Ignition Engine

Investigation of the Behaviors of Methanol Spray Impingement and Wall Wetting

Study on Fuel Distribution of Wall-Impinging Diesel Spray under Different Wall Temperatures by Laser-Induced Exciplex Fluorescence (LIEF)

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