Optical Investigation on the Combustion Process Differences between Double-Pilot and Closely-Coupled Triple-Pilot Injection Strategies in a LD Diesel Engine

2019 ◽  
Author(s):  
Michael Denny ◽  
Alexios Matamis ◽  
Zhenkan Wang ◽  
Håkan Persson ◽  
Per Tunestal ◽  
...  
Keyword(s):  
Diesel Engine ◽  
Combustion Process ◽  
Pilot Injection ◽  
Optical Investigation ◽  
Injection Strategies

scholarly journals Optical Investigation of a Partial Fuel Stratification Strategy to Stabilize Overall Lean Operation of a DISI Engine Fueled with Gasoline and E30

Energies ◽  
2021 ◽  
Vol 14 (2) ◽  
pp. 396
Author(s):  
Cinzia Tornatore ◽  
Magnus Sjöberg
Keyword(s):  
Volume Fraction ◽  
Direct Injection ◽  
Combustion Process ◽  
Pilot Injection ◽  
Optical Investigation ◽  
Flame Kernel ◽  
Lean Combustion ◽  
Fuel Stratification ◽  
Spark Plug ◽  
Initial Flame

This paper offers new insights into a partial fuel stratification (PFS) combustion strategy that has proven to be effective at stabilizing overall lean combustion in direct injection spark ignition engines. To this aim, high spatial and temporal resolution optical diagnostics were applied in an optically accessible engine working in PFS mode for two fuels and two different durations of pilot injection at the time of spark: 210 µs and 330 µs for E30 (gasoline blended with ethanol by 30% volume fraction) and gasoline, respectively. In both conditions, early injections during the intake stroke were used to generate a well-mixed lean background. The results were compared to rich, stoichiometric and lean well-mixed combustion with different spark timings. In the PFS combustion process, it was possible to detect a non-spherical and highly wrinkled blue flame, coupled with yellow diffusive flames due to the combustion of rich zones near the spark plug. The initial flame spread for both PFS cases was faster compared to any of the well-mixed cases (lean, stoichiometric and rich), suggesting that the flame propagation for PFS is enhanced by both enrichment and enhanced local turbulence caused by the pilot injection. Different spray evolutions for the two pilot injection durations were found to strongly influence the flame kernel inception and propagation. PFS with pilot durations of 210 µs and 330 µs showed some differences in terms of shapes of the flame front and in terms of extension of diffusive flames. Yet, both cases were highly repeatable.

scholarly journals Experimental study of multiple pilot injection strategy in an automotive direct injection diesel engine

2018 ◽  
Vol 234 ◽  
pp. 03007
Author(s):  
Plamen Punov ◽  
Tsvetomir Gechev ◽  
Svetoslav Mihalkov ◽  
Pierre Podevin ◽  
Dalibor Barta
Keyword(s):  
Experimental Study ◽  
Diesel Engine ◽  
Diesel Engines ◽  
Direct Injection ◽  
Combustion Process ◽  
Injection Timing ◽  
Pilot Injection ◽  
Injection Strategy ◽  
Direct Injection Diesel Engine ◽  
Rate Of Heat Release

The pilot injection strategy is a widely used approach for reducing the noise of the combustion process in direct injection diesel engines. In the last generation of automotive diesel engines up to several pilot injections could occur to better control the rate of heat release (ROHR) in the cylinder as well as the pollutant formation. However, determination of the timing and duration for each pilot injection needs to be precisely optimised. In this paper an experimental study of the pilot injection strategy was conducted on a direct injection diesel engine. Single and double pilot injection strategy was studied. The engine rated power is 100 kW at 4000 rpm while the rated torque is 320 Nm at 2000 rpm. An engine operating point determined by the rotation speed of 1400 rpm and torque of 100 Nm was chosen. The pilot and pre-injection timing was widely varied in order to study the influence on the combustion process as well as on the fuel consumption.

Numerical Investigation of Effect Pilot Injection on Combustion Noise and Exhaust Emission of Diesel Engine

2012 ◽  
Vol 472-475 ◽  
pp. 1528-1531
Author(s):  
Tie Min Xuan ◽  
Zhi Xia He ◽  
Zhao Chen Jiang ◽  
Yi Yan
Keyword(s):  
Diesel Engine ◽  
Numerical Investigation ◽  
Fuel Injection ◽  
Numerical Models ◽  
Combustion Noise ◽  
Exhaust Emission ◽  
Pilot Injection ◽  
Engine Combustion ◽  
Emission Models ◽  
Injection Strategies

Numerical Investigation of Effect Pilot Injection on Combustion Noise and Exhaust Emission of Diesel Engine The traditional mechanical fuel supply system has already been no way to satisfy the requirement of more stringent fuel consumption and emission legislation. For the past few years, it has been a hot topic to improve performance of diesel engine combustion and emission through optimizing the fuel injection strategy. All kinds of spray, combustion and emission models were studied and then the numerical models for the single-injection combustion of 1015 diesel engine were setup and validated through comparing with results from experimental data. With the above verified models, different injection strategies were further investigated to get the effect mechanism of pilot injection (PI) timing and quantity on combustion noise and exhaust emission.

Innovative Lift Direct Command to Inner Hydraulic Circuit Injector Comparison for Diesel Engines

2006 ◽  
Author(s):  
Luigi Allocca ◽  
S. Alfuso ◽  
A. Montanaro ◽  
G. Valentino ◽  
M. Lolli
Keyword(s):  
Diesel Engine ◽  
Electronic Control Unit ◽  
Combustion Process ◽  
Ccd Camera ◽  
Spray Angle ◽  
Spray Parameters ◽  
Hydraulic Circuit ◽  
Component Structure ◽  
Injection Strategies ◽  
Injection Pressures

In this paper a comparative investigation between two different injectors for Common Rail diesel apparatus has been carried out in terms of transient response and spray pattern for different injection strategies. Performances of an innovative Magneti Marelli (MM) gasoline derived injector have been evaluated against the Bosch generation injectors for multiple strategies. Both injectors have operated on an automotive apparatus controlled by a Programmable Electronic Control Unit to set injection strategies in terms of pulses number, duration and dwell time. The working mode of the two injectors is completely different: the Bosch injector is activated by the inner fuel hydraulic circuit while the Magneti Marelli one operates a direct control of the needle lift through the solenoid currents. The Bosch nozzle characteristics are 5 holes, 150° spray angle, and 0,13 mm diameter. The MM injector main characteristics are low hydraulic losses, simple component structure and ready use of the fuel at the nozzle opening being able to control small fuel flow rates (0.1 mg/str) in the injection pressures range 20–70 MPa. The geometry of the nozzle is quite similar to the Bosch one being a 5 hole, 150° spray angle, 0.12 mm diameter. Single, pilot+main and pilot+split main strategies have been explored for the two injectors at 50 and 60 MPa injection pressures investigating the spray behavior for two amounts of injected fuel (5.0 and 6.5 mg/str). The systems have been characterized in terms of injected fuel rate as well spatial and temporal behavior of the emerging jets from the nozzle. Images of the spray have been collected by a synchronized CCD camera at different time from the start of injection. The jets have evolved in an optically accessible high pressure vessel at ambient temperature as well in an optically accessible single-cylinder 2-stroke Diesel engine extracting the fuel spray parameters from the collected images applying a digital processing techniques. Due to the diverse mechanism of the injector actuation, a different temporal and spatial fuel distribution has been registered for the two apparatuses. These could strongly influence the air/fuel mixture formation and combustion process with effect on the emissions. Preliminary engine tests performed on a light duty direct injection diesel engine, equipped with the MM injector, have highlighted the potential of the MM injector to handle acceptable engine performances.

scholarly journals Assessment on the consequences of injection strategies on combustion process and particle size distributions in Euro VI medium-duty diesel engine

2019 ◽  
Vol 21 (4) ◽  
pp. 683-697 ◽  
Author(s):  
Vicente Bermúdez ◽  
Antonio García ◽  
David Villalta ◽  
Lian Soto
Keyword(s):  
Particle Size ◽  
Diesel Engine ◽  
Size Distribution ◽  
Particle Concentration ◽  
Combustion Process ◽  
Injection Pressure ◽  
Injection Timing ◽  
Injection Parameters ◽  
Main Injection ◽  
Injection Strategies

Although there are already several works where the influence of injection parameters on exhaust emissions, and specifically on particulate matter emissions, in diesel engines has been evaluated, the diversity in the results that can be found in the literature indicates the need to carry out new experiments that can provide more information about the influence of these parameters on modern diesel engines. This study intends to be placed within this scientific framework, hence a parametric study was carried out based on the independent modification of the main injection timing and the injection pressure with respect to the nominal conditions of a new Euro VI direct injection diesel engine. Four steady-state operation points of the engine map were chosen: 25% load and 950 r/min, 50% load and 1500 r/min, 75% load and 2000 r/min and 100% load and 2200 r/min, where in each of these operation points, the variations of the injection parameters in the study on the combustion process and its consequent impact on the particle size distribution, including an analysis of the geometric mean diameter values, were evaluated. The results showed that the different injection strategies adopted, despite not significantly affecting the engine efficiency, did cause a significant impact on particle number emissions. At the low load operation, the size distribution showed a bimodal structure, and as the main injection timing was delayed and the injection pressure was decreased, the nucleation-mode particle concentration decreased, while the accumulation-mode particle concentration increased. In addition, at medium load, the nucleation-mode particle emission decreased considerably while the accumulation-mode particle emission increased, and this increase was much greater with the main injection timing delay and the injection pressure reduction. Similar behavior was observed at high load, but with a much more prominent pattern.

scholarly journals Effects of Two Pilot Injection on Combustion and Emissions in a PCCI Diesel Engine

Energies ◽  
2021 ◽  
Vol 14 (6) ◽  
pp. 1651
Author(s):  
Deqing Mei ◽  
Qisong Yu ◽  
Zhengjun Zhang ◽  
Shan Yue ◽  
Lizhi Tu
Keyword(s):  
Diesel Engine ◽  
Combustion Process ◽  
Exhaust Gas ◽  
Pilot Injection ◽  
Compression Ignition ◽  
Ignition Timing ◽  
Turbocharged Diesel Engine ◽  
Injection Quantity ◽  
Low Load ◽  
Gas Recirculation

The effects of two pilot injections on combustion and emissions were evaluated in a single−cylinder turbocharged diesel engine, which operated in premixed charge compression ignition (PCCI) modes with multiple injections and heavy exhaust gas recirculation under the low load by experiments and simulation. It was revealed that with the delay of the start of the first pilot injection (SOI−P1) or the advance of the start of second pilot injection (SOI−P2), respectively, the pressure, heat release rate (HRR), and temperature peak were all increased. Analysis of the combustion process indicates that, during the two pilot injection periods, the ignition timing was mainly determined by the SOI−P2 while the first released heat peak was influenced by SOI−P1. With the delay of SOI−P1 or the advance of SOI−P2, nitrogen oxide (NOx) generation increased significantly while soot generation varied a little. In addition, increasing Q1 and decreasing the second pilot injection quantity (Q2) can manipulate the NOx and soot at a low level. The advance in SOI−P2 of 5 °CA couple with increasing Q1 and reducing Q2 was proposed, which can mitigate the compromise between emissions and thermal efficiency under the low load in the present PCCI mode.

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