Fuel-Line Stationary Waves and Variability in CI Combustion During Complex Injection Strategies

2010 ◽  
Author(s):  
A. D. Michailidis ◽  
R. K. Stobart ◽  
G. P. McTaggart-Cowan
Keyword(s):  
Fuel Injection ◽  
Stationary Wave ◽  
Potential Method ◽  
Combustion Stability ◽  
Injection System ◽  
Stationary Waves ◽  
Main Injection ◽  
Total Fuel Consumption ◽  
Start Of Combustion ◽  
Injection Strategies

This study investigated the effects of increased injection regime complexity on injector and combustion stability in a naturally aspirated single cylinder diesel engine equipped with a common rail fuel injection system and an instrumented injector. The injection regimes investigated included a single injection, a main injection with a pilot, and a split-main with a pilot. Injector performance was found to be very stable over all injection regimes and did not contribute to variations in combustion stability. Cylinder pressure variation during the initiation of combustion was identified as a potential method of identifying the start of combustion phasing and compared to current methods. Three series of tests were conducted at various speeds and injection pressures to demonstrate the influence of multi-pulse injection phasing on combustion stability and total fuel consumption. These results demonstrate that the presence of a stationary wave in the high-pressure fuel line, induced by an early injection, can dramatically affect the amount of fuel injected in subsequent injections within the same cycle.

Experimental investigation of dwell time characteristics in high-pressure double-solenoid-valve fuel injection system

2019 ◽  
Vol 233 (13) ◽  
pp. 3281-3292
Author(s):  
Dan Xu ◽  
Qing Yang ◽  
Xiaodong An ◽  
Baigang Sun ◽  
Dongwei Wu ◽  
...  
Keyword(s):  
Fuel Injection ◽  
Injection Pressure ◽  
Solenoid Valve ◽  
Injection System ◽  
Fuel Injection System ◽  
Pilot Injection ◽  
Main Injection ◽  
Injection Interval ◽  
The Difference ◽  
Variation Rule

The double-solenoid-valve fuel injection system consists of an electronic unit pump and an electronic injector. It can realize the separate control of fuel supply and injection and has the advantages of adjusting pressure by cycle and flexible controlling of the injection rate. The interval angle between the pilot and main injection directly affects the action degree and the characteristics of two adjacent injections, affecting engine performance. This work realizes multiple injection processes on the test platform of a high-pressure double-solenoid-valve fuel injection system, with maximum injection pressure reaching 200 MPa. In this study, the interval between driven current signal of pilot injection termination and that of main injection initiation is defined as the signal interval (DT1), whereas the interval between pilot injection termination and main injection initiation is defined as the injection interval (DT2). The differences between the signal and the injection intervals are calculated, and the variation rule of the difference with respect to the signal interval is analyzed. Results show that the variation rule of the difference with the signal interval first decreases, then increases, and finally decreases. The variation rule of the delay angle from the start of needle movement to the start of fuel injection is found to be the root cause of this rule. The influence of the injection pressure on needle deformation and fuel flow rate of the nozzle results in the variation rule. In addition, the influence of the cam speed, temperature, and pipe length on the difference between the signal and injection interval is determined. This research provides guidance for an optimal control strategy of the fuel injection process.

Effect of Injection System Parameters on Performance and Emission Characteristics of a Small Single Cylinder Diesel Engine

2021 ◽  
Vol 18 (2) ◽  
Author(s):  
D.K. Dond ◽  
N.P. Gulhane
Keyword(s):  
Diesel Engine ◽  
Fuel Injection ◽  
Direct Injection ◽  
Common Rail ◽  
Injection System ◽  
Injection Timing ◽  
Emission Characteristics ◽  
Performance And Emission ◽  
System Parameters ◽  
Main Injection

Limited fossil fuel reservoir capacity and pollution caused by them is the big problem in front of researchers. In the present paper, an attempt was made to find a solution to the same. The conventional fuel injection system was retrofitted with a simple version of the common rail direct injection system for the small diesel engine. Further, the effect of injection system parameters was observed on the performance and emission characteristics of the retrofitted common rail direct injection diesel engine. The parameters such as injection pressure, the start of pilot injection timing, the start of main injection timing and quantity of percentage fuel injection during the pilot and main injection period were considered for experimental investigation. It was observed that all the evaluated parameters were found vital for improving the engine’s performance and emission characteristics. The retrofitted common rail direct injection system shows an average 7% rise in brake thermal efficiency with economic, specific fuel consumption. At the same time, much more reduction in hydrocarbon, carbon monoxide and smoke opacity with a penalty of a slight increase in nitrogen oxides.

scholarly journals Effect of Premixed Fuel Preparation for Partially Premixed Combustion With a Low Octane Gasoline on a Light-Duty Multicylinder Compression Ignition Engine

2015 ◽  
Vol 137 (11) ◽  
Author(s):  
Adam B. Dempsey ◽  
Scott Curran ◽  
Robert Wagner ◽  
William Cannella
Keyword(s):  
High Pressure ◽  
Thermal Efficiency ◽  
Fuel Injection ◽  
Premixed Combustion ◽  
Injection System ◽  
Injection Timing ◽  
Pilot Injection ◽  
Compression Ignition ◽  
Partially Premixed Combustion ◽  
Injection Strategies

Gasoline compression ignition (GCI) concepts with the majority of the fuel being introduced early in the cycle are known as partially premixed combustion (PPC). Previous research on single- and multicylinder engines has shown that PPC has the potential for high thermal efficiency with low NOx and soot emissions. A variety of fuel injection strategies have been proposed in the literature. These injection strategies aim to create a partially stratified charge to simultaneously reduce NOx and soot emissions while maintaining some level of control over the combustion process through the fuel delivery system. The impact of the direct injection (DI) strategy to create a premixed charge of fuel and air has not previously been explored, and its impact on engine efficiency and emissions is not well understood. This paper explores the effect of sweeping the direct injected pilot timing from −91 deg to −324 deg ATDC, which is just after the exhaust valve closes (EVCs) for the engine used in this study. During the sweep, the pilot injection consistently contained 65% of the total fuel (based on command duration ratio), and the main injection timing was adjusted slightly to maintain combustion phasing near top dead center. A modern four cylinder, 1.9 l diesel engine with a variable geometry turbocharger (VGT), high pressure common rail injection system, wide included angle injectors, and variable swirl actuations was used in this study. The pistons were modified to an open bowl configuration suitable for highly premixed combustion modes. The stock diesel injection system was unmodified, and the gasoline fuel was doped with a lubricity additive to protect the high pressure fuel pump and the injectors. The study was conducted at a fixed speed/load condition of 2000 rpm and 4.0 bar brake mean effective pressure (BMEP). The pilot injection timing sweep was conducted at different intake manifold pressures, swirl levels, and fuel injection pressures. The gasoline used in this study has relatively high fuel reactivity with a research octane number of 68. The results of this experimental campaign indicate that the highest brake thermal efficiency (BTE) and lowest emissions are achieved simultaneously with the earliest pilot injection timings (i.e., during the intake stroke).

Improvement of Gas Turbine Injection Systems by Combined Experimental/Numerical Approach

2002 ◽  
Author(s):  
G. Riccio ◽  
P. Adami ◽  
F. Martelli ◽  
D. Cecchini ◽  
L. Carrai
Keyword(s):  
Combustion Chamber ◽  
Gas Turbine ◽  
Fuel Injection ◽  
Numerical Approach ◽  
Combustion Stability ◽  
Pollutant Emissions ◽  
Injection System ◽  
Flame Stability ◽  
Fuel Injection System ◽  
Joint Application

An aerodynamic study for the premixing device of an industrial turbine gas combustor is discussed. The present work is based on a joint application of numerical CFD and experimental investigation tools in order to verify and optimize the combustor gaseous fuel injection system. The objective is the retrofit of an old generation gas turbine combustion chamber that is carried out considering new targets of NOx emission keeping the same CO and combustion stability performances. CFD has been used to compare different premixing duct configurations for improved mixing features. Experimental test has been carried out in order to assess the pollutant emissions, flame stability and pattern factor characteristics of the full combustion chamber retrofitted with the modified injection system.

Split Injection Strategies for Biodiesel-Fueled Premixed Charge Compression Ignition Combustion Engine—Part II: Particulate Studies

2020 ◽  
Vol 142 (12) ◽  
Author(s):  
Akhilendra Pratap Singh ◽  
Avinash Kumar Agarwal
Keyword(s):  
Fuel Injection ◽  
Combustion Engine ◽  
Chemical Characterization ◽  
Injection Pressure ◽  
Morphological Characterization ◽  
Pilot Injection ◽  
Compression Ignition ◽  
Main Injection ◽  
Fuel Injection Pressure ◽  
Injection Strategies

Abstract In this study, experiments were performed in a single-cylinder research engine to investigate the particulate matter (PM) characteristics of the engine operated in premixed charge compression ignition (PCCI) mode combustion vis-a-vis baseline compression ignition (CI) mode combustion using three test fuels, namely, B20 (20% v/v biodiesel blended with mineral diesel), B40 (40% v/v/ biodiesel blended with mineral diesel), and baseline mineral diesel. The experiments were carried out at constant fuel injection pressure (FIP) (700 bar), constant engine speed (1500 rpm), and constant fuel energy input (0.7 kg/h diesel equivalent). PM characteristics of PCCI mode combustion were evaluated using two different fuel injection strategies, namely, single pilot injection (SPI) (35 deg before top dead center (bTDC)) and double pilot injection (DPI) (35 deg and 45 deg bTDC) at four different start of main injection (SoMI) timings. Results showed that both PCCI mode combustion strategies emitted significantly lower PM compared to baseline CI mode combustion strategy. However, the blending of biodiesel resulted in relatively higher PM emissions from both CI and PCCI combustion modes. Chemical characterization of PM showed that PCCI mode combustion emitted relatively lower trace metals compared to baseline CI mode combustion, which reduced further for B20. For detailed investigations of particulate structure, morphological characterization was done using transmission electron microscopy (TEM), which showed that PM emitted by B20-fueled PCCI mode combustion posed potentially lower health risk compared to baseline mineral diesel-fueled CI mode combustion.

scholarly journals Effect of biodiesel on the development of split injection characteristics

2019 ◽  
Vol 177 (2) ◽  
pp. 103-107
Author(s):  
Stasys SLAVINSKAS ◽  
Gvidonas LABECKAS ◽  
Tomas MICKEVIČIUS
Keyword(s):  
Diesel Fuel ◽  
Fuel Injection ◽  
Pressure Fluctuations ◽  
Injection Rate ◽  
Inlet Pressure ◽  
Injection System ◽  
Split Injection ◽  
Common Rail Injection System ◽  
Main Injection ◽  
Injection Phase

The paper presents the experimental test results of a common rail injection system operating with biodiesel and the diesel fuel. The three fuel split injection strategies were implemented to investigate the effects made by biodiesel and a fossil diesel fuel on the history of injector inlet pressure and the injection rate. In addition, the three intervals between split injections and the different injection pressures were used to obtain more information about the studied subjects. The obtained results showed that the peak mass injection rates of the main injection phase were slightly higher when using biodiesel than the respective values measured with the normal diesel fuel. Because the first injection phase activated the fuel pressure fluctuations along the high-pressure line and in front of the injector, the time-span between injections has an impact on the injector inlet pressure and thus the fuel injection rate during the second injection phase. Since the nozzle closes little later for biodiesel, the injector inlet pressure also occurred latter in the cycle.

scholarly journals Effect of Premixed Fuel Preparation for Partially Premixed Combustion With a Low Octane Gasoline on a Light-Duty Multi-Cylinder Compression Ignition Engine

2014 ◽  
Author(s):  
Adam Dempsey ◽  
Scott Curran ◽  
Robert Wagner ◽  
William Cannella
Keyword(s):  
High Pressure ◽  
Thermal Efficiency ◽  
Fuel Injection ◽  
Premixed Combustion ◽  
Injection System ◽  
Injection Timing ◽  
Pilot Injection ◽  
Compression Ignition ◽  
Partially Premixed Combustion ◽  
Injection Strategies

Gasoline compression ignition concepts with the majority of the fuel being introduced early in the cycle are known as partially premixed combustion (PPC). Previous research on single- and multi-cylinder engines has shown that PPC has the potential for high thermal efficiency with low NOx and soot emissions. A variety of fuel injection strategies has been proposed in the literature. These injection strategies aim to create a partially stratified charge to simultaneously reduce NOx and soot emissions while maintaining some level of control over the combustion process through the fuel delivery system. The impact of the direct injection strategy to create a premixed charge of fuel and air has not previously been explored, and its impact on engine efficiency and emissions is not well understood. This paper explores the effect of sweeping the direct injected pilot timing from −91° to −324° ATDC, which is just after the exhaust valve closes for the engine used in this study. During the sweep, the pilot injection consistently contained 65% of the total fuel (based on command duration ratio), and the main injection timing was adjusted slightly to maintain combustion phasing near top dead center. A modern four cylinder, 1.9 L diesel engine with a variable geometry turbocharger, high pressure common rail injection system, wide included angle injectors, and variable swirl actuation was used in this study. The pistons were modified to an open bowl configuration suitable for highly premixed combustion modes. The stock diesel injection system was unmodified, and the gasoline fuel was doped with a lubricity additive to protect the high pressure fuel pump and the injectors. The study was conducted at a fixed speed/load condition of 2000 rpm and 4.0 bar brake mean effective pressure (BMEP). The pilot injection timing sweep was conducted at different intake manifold pressures, swirl levels, and fuel injection pressures. The gasoline used in this study has relatively high fuel reactivity with a research octane number of 68. The results of this experimental campaign indicate that the highest brake thermal efficiency and lowest emissions are achieved simultaneously with the earliest pilot injection timings (i.e., during the intake stroke).

scholarly journals Analysis of the Influence of Diesel Spray Injection on the Ignition and Soot Formation in Multiple Injection Strategy

Energies ◽  
2020 ◽  
Vol 13 (13) ◽  
pp. 3505
Author(s):  
Raul Payri ◽  
José M. García-Oliver ◽  
Victor Mendoza ◽  
Alberto Viera
Keyword(s):  
Ignition Delay ◽  
Soot Formation ◽  
Single Injection ◽  
Engine Performance ◽  
Injection System ◽  
Multiple Injection ◽  
Multiple Injection Strategy ◽  
Test Points ◽  
Start Of Combustion ◽  
Injection Strategies

Multiple injection strategies have increased their capabilities along with the evolution of injection system technologies up to the point that nowadays it is possible to inject eight different pulses, permitting to improve the engine performance, and consequently, emissions. The present work was realized for two simplified strategies: a pilot-main and a main-post, in order to analyze the influence of an auxiliary pulse on the main and otherwise, in reactive conditions for two pilot/post quantities and four hydraulic dwell times. The study was carried out by employing two optical techniques: diffused back-illumination with flame bandpass chemiluminescence for measuring soot, represented by soot-maps distribution, and single-pass schlieren for ignition delay (ID). Furthermore, a novel methodology for decoupling the start of combustion (SOC) of the second pulse was developed and successfully validated. From the ignition delay results, it was found for all test points that the pilot injection enhanced conditions, which promote a faster ignition of the main pulse, also at higher chamber temperatures, all conditions presented a separate combustion event for each injection. In emission terms, soot increased in the pilot-main strategies compared to its single injection case, as well as, in conditions that promote faster-premixed combustion.

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