Gasoline Direct Injection Research Articles

Experimental and computational fluid dynamics analysis on the influence of fuel injection pressure on engine's behavior of a gasohol based gasoline direct injection engine

AbstractThis work examines the impact of fuel injection pressure (FIP) on engine's behavior of a multi cylinder gasoline direct injection (GDI) engine using gasohol (85% gasoline+15% ethanol by mass) as fuel. The FIP was varied from 90r to 120 bar at 10 bar intervals with the fuel injection timing 320° before top dead center (BTDC). experiments were performed at variable power at a constant speed of 2500 rpm. Computational fluid dynamics (CFD) simulations were carried out for the above said conditions to understand engine's behavior. Considering the conventional FIP (i.e.90 bar), increasing the FIP showed improvement in engine's brake thermal efficiency (BTE) up to110 bar. The maximum BTE was observed as 33.5% at the engine power output of 21 kW (where as it was 27.2% with the FIP of 90 bar). CFD results confirmed the improvement in the air‐fuel mixing rate and swirl motion due to the increased FIP. The hydrocarbon (HC) and carbon monoxide (CO) emission were reduced with increased FIPs. CFD results on the HC and CO emissions indicated well agreement with the experiments. With the higher injection pressures, oxides of nitrogen (NOx) emissions showed an increase at all loads. The in cylinder pressure was observed to be higher with higher FIPs. It is concluded that increasing the FIP might improve performance and lower HC and CO emissions of a Gasohol based fuel in GDI engine. The optimized FIP of 110 bar could be recommended for the aforementioned engine's greatest performance without any modifications in the engine design while injecting the fuel at 320° BTDC. Increase in NOx emissions at higher injection pressure needs attention. The present study restricted the amount of ethanol as 15% by mass. Higher proportions of ethanol admissions require major modifications in the engine design.

In-Cylinder Imaging and Emissions Measurements of Cold-Start Split Injection Strategies

Abstract Strategies to mitigate cold-start emissions are critical to meet stringent standards for particulate and regulated gaseous emissions from direct injection spark ignition (DISI) engines. The objective of the current work was to establish an experimental protocol for cold-start studies and to identify the in-cylinder phenomena important during engine warming in terms of engine power and stability and engine-out particulates, NOx, and unburned hydrocarbon emissions. Metal-engine experiments were conducted with ambient intake air temperature and coolant air temperature of 20 °C to quantify the sensitivity of the performance of a single-cylinder engine to timing of a strategy using two injection events per power cycle and late spark ignition. The results showed strong sensitivity to the timing of the second injection event and weak sensitivity to the timing of the first injection. Complementary high-speed imaging experiments were conducted with the same engine where the fuel spray and combustion characteristics were visualized during cold-start split-injection operation. The imaging data showed the sources of particulates were due to fuel impingement on combustion chamber surfaces and due to fuel rich regions, in particular regions where the fuel recondensed due to the conditions associated with late ignition timing. The combination of engine-out particulate and imaging measurements indicated smaller particles (10–20 nm) were associated with fuel impingement on surfaces, and larger particles (20–200 nm) were associated with fuel rich “pockets”.

In- and near-nozzle and external flow characterization in Gasoline Direct injection (GDi) engines – A review of latest technologies and trends. Part 2: Computational background

In- and near-nozzle and external flow characterization in Gasoline Direct injection (GDi) engines – A review of latest technologies and trends. Part 2: Computational background

Exhaust Emissions from a Direct Injection Spark-Ignition Engine Fueled with High-Ethanol Gasoline

Exhaust Emissions from a Direct Injection Spark-Ignition Engine Fueled with High-Ethanol Gasoline

Simulation of Liquid NH3 Spray Characteristics for Gasoline Direct Injection (GDI) under Engine-Relevant Conditions

Fuel/air mixing characteristics of liquid ammonia under direct injection engines have gained significant attention in the automotive industry due to their potential for improving fuel efficiency and reducing emissions. This study employed a simulation approach to investigate the spray characteristics of liquid ammonia for Gasoline Direct Injection (GDI) under Engine-Relevant Conditions. Conversely, lower injection pressures resulted in shorter spray penetration due to reduced fuel momentum and weaker atomisation. The main variable in this study is injection pressure, which is 50 bar, 80 bar and 110 bar. Meanwhile, the parameters for the orifice diameter used in the CFD simulation by Ansys Fluent are 0.3 mm and the ambient pressures, which are atmosphere pressure and the other hand, remain constant throughout the research. The simulation results showed a clear relationship between injection pressure and spray penetration. Higher injection pressures increased spray penetration, indicating improved fuel dispersion and atomisation. This is attributed to the higher kinetic energy of the fuel, leading to enhanced breakup and smaller droplet sizes.

Effects of Two-Stage Injection on Combustion and Particulate Emissions of a Direct Injection Spark-Ignition Engine Fueled with Methanol–Gasoline Blends

Effects of Two-Stage Injection on Combustion and Particulate Emissions of a Direct Injection Spark-Ignition Engine Fueled with Methanol–Gasoline Blends

Optimization of ethanol injected ratio of a stoichiometric spark-ignited ethanol port-injected plus gasoline direct-injected engine at various throttle openings

Optimization of ethanol injected ratio of a stoichiometric spark-ignited ethanol port-injected plus gasoline direct-injected engine at various throttle openings

Spray dynamics characteristics in gasoline direct injection injectors at varied orifice inlet angles

Spray dynamics characteristics in gasoline direct injection injectors at varied orifice inlet angles

In- and near- nozzle and external flow characterization in Gasoline Direct injection (GDi) engines – A review of latest technologies and trends. Part 1: Experimental background

In an era of increasingly stringent emissions regulations, environmental standards are driving gasoline engine research and development toward more widespread use of direct injection systems. It is also of interest to know what kind of phenomena cause these types of emissions in order to address and reduce them as much as possible. Therefore, it has been considered of interest to summarize in this article the latest research topics related to the gasoline direct injection (GDI) process, providing researchers with a valuable resource to understand the current state of research, the different technologies of gasoline direct injection and the phenomena that take place in this process. Research applied to GDI engines can be approached in several ways. The one chosen for this article is mainly based on separating the relevant processes within the engine with the objective of going deeper into each of them. In this sense, it is proposed to study the injection without taking into account the combustion phenomenon. In the same way, it is suggested to study the injection process in several phases: in- and near-field of the injector and downstream of the injector. Therefore, this work performs an extensive analysis of the experimental techniques employed for the study of each of the phenomena that take place in the injection process. The objective of the research is a better understanding of the phenomena, an improved characterization of the internal flow and spray and consequently the final optimization of the engine design. In a subsequent publication (Part 2), the same literature review will be addressed but only taking into account the computational work carried out in recent years with the same objective of investigating the injection, the mixture formation process, and the associated emissions characterization.

Effects of injection timing on combustion and mixture formation of a methanol direct injection engine equipped with a small volume passive pre-chamber

The pursuit of high efficiency and cleanliness has always been the focus of engine research. As one of the most promising low-carbon renewable alternative fuel, methanol has gained increasing attention in engine applications. Inspired by the advantages of gasoline direct injection (GDI) in fuel economy, methanol direct injection (MDI) engine has also become a research hot spot. Similar to GDI, the mixture distribution is crucial for MDI engines, especially in the late injection stratified operation mode, an unreasonable mixture distribution of rich and lean regions will result in slow and incomplete combustion, or even flame quenching. Due to the characteristics of multi-point ignition and the high ignition energy, pre-chamber jet flame ignition has the potential to effectively enhance combustion. In this paper, the effect of injection timing on combustion characteristics in a methanol direct injection engine equipped with a small volume pre-chamber are studied experimentally. The mixture formation processes in both the main-chamber and the pre-chamber at different injection timings were also explored through simulations. The research findings indicated that the engine exhibits optimal power performance at the injection timing of − 270 °CA ATDC (after top dead center), primarily attributed to the enhanced volumetric efficiency and improved mixture homogeneity. However, the mixture concentration in the pre-chamber is leaner, resulting in the longest ignition delay period. When the injection timing is located on the middle state of the intake stroke, specifically − 210 °CA ATDC, the ignition delay period is the shortest, indicating that the mixture concentration and temperature in the pre-chamber are conducive to the flame kernel formation and flame propagation. In addition, the volumetric efficiency of this injection case is maximized due to the combined effects of spray-wall interaction, spray-air interaction, and the flow field. When injection occurs on compression stroke, the mixture concentration in the pre-chamber is higher; however, there exists a significant and discontinuous concentration gradient in the main-chamber, which limits the enhancement of the flame propagation speed and the combustion efficiency, especially for − 120 °CA ATDC injection case, the engine exhibits longest combustion duration and the lowest IMEP. The conclusions can provide theoretical basis and empirical data support for enhancing the combustion of methanol direct injection engines equipped with passive pre-chambers.

Experimental study of combustion and emissions characteristics of low blend ratio of 2-methylfuran/ 2-methyltetrahyrofuran with gasoline in a DISI engine

The nearing depletion of fossil fuels and the possible consequences of its emissions on the global climate has prompted a worldwide probe for their alternatives. 2-methylfuran and 2-methyltetrahydrofuran are considered promising alternative fuels for spark ignition engines. In this study, the combustion and emission characteristics of low blending ratio MF20 (2-methylfuran 20 %, gasoline 80 % by volume) and MTHF20 (2-methyltetrahydrofuran 20 %, gasoline 80 % by volume) were first implemented and compared to neat gasoline in a single-cylinder direct injection spark ignition engine. The combustion performance of the test fuels was analyzed across a range of loads from 3.5 to 8.5 bar indicated mean effective pressure and fuel injection timings between 180 and 280 crank angle degrees before top dead center. Meanwhile, the compositions of the hydrocarbon emissions were experimentally investigated using the Fourier Transform Infrared Spectroscopy technique. Results show that MF20 exhibits advanced spark timing flexibility of 8 and 7 crank angle degrees before top dead center compared to the unleaded gasoline and MTHF20 respectively at the peak load. MTHF20 exhibits the highest maximum cylinder pressure at medium load compared to other fuels but drops sharply at peak load accompany with the audible knock. Additionally, MTHF20 exhibits specific fuel consumption advantage over MF20 across the entire load range. The unburned furan of the total hydrocarbon emissions was recorded to be 3 % of total hydrocarbon emissions. The concept of low blending ratio furan-based fuel proposed could provide a solution for the transition period of carbon neutrality.

Numerical one-dimensional investigation on GDI engine using LPG,water-ethanol-gasoline micro-emulsion fuel and Hydrogen, for net zero carbon emissions

The current issue of pollution has prompted researchers to reconsider emission control measures, leading many countries to focus on the development of Euro VII Emission Regulations. The present study aims to contribute to this goal by exploring ways to reduce emissions while improving performance. To achieve this, one-dimensional numerical simulations were conducted using AVL Boost software to predict the emission characteristics and performance of a gasoline direct injection (GDI) engine fuelled with LPG, water-gasoline emulsion, and hydrogen in dual fuel mode. Specifically, the study compares the performance of 100 % LPG and 100 % hydrogen with that of a water-based gasoline emulsion fuel consisting of 90 % gasoline, 8 % ethanol, and 2 % water (H2O 2 %). The geometrical properties of the GDI engine were kept consistent with those of the test rig. The results obtained from the numerical simulations demonstrate that the use of 100 % hydrogen and 100 % LPG significantly enhances the overall performance of the engine. Notably, hydrogen fuel exhibits a 50 % increase in brake power compared to the water–ethanol-gasoline emulsion fuel. Furthermore, 100 % LPG fuel generates 33 % more power than the emulsion fuel. Additionally, Hydrogen demonstrates a 30 % reduction in fuel consumption compared to micro emulsion fuel, while LPG exhibits a 15 % decrease in fuel usage compared to micro emulsion fuel. The study also examines the emission characteristics of the alternative fuels. Once again, 100 % hydrogen fuel proves to be the most efficient, producing zero carbon-based emissions. In comparison, 100 % LPG fuel emits 20 % less carbon monoxide and 15 % less hydrocarbon than the emulsion-based fuel.

Comparative study on combustion and emission characteristics of methanol/gasoline blend fueled DISI engine under different stratified lean burn modes

Combining stratified lean-burn techniques with methanol offers a promising path to achieving high efficiency and low emissions in direct-injection spark-ignition (DISI) engines. This work compares the stratified and homogeneous-stratified lean-burn characteristics of methanol/gasoline fuels on a DISI engine. Combustion and emissions characteristics under two stratified lean-burn strategies were investigated. The results indicate that compared to double-injection stratified lean-burn (DISL), single-injection stratified lean-burn (SISL) leads to more timely combustion, which deteriorates more slowly as the excess air ratio increases. Using M20 fuel with SISL achieves a higher tolerance for air dilution. At the same excess air ratio, SISL results in higher maximum in-cylinder pressure and combustion temperature, but lower exhaust temperature. The economic zone for SISL occurs with M40 fuel at λ = 1.3–1.6, whereas DISL's economic zone is within λ = 1.1–1.3. When λ is below 1.5, SISL produces higher hydrocarbon (HC) emissions but lower nitrogen oxides (NOx) emissions. However, as λ exceeds 1.5, HC emissions from DISL increase sharply while NOx emissions decrease significantly. The particle concentration from SISL is at least an order of magnitude higher than that from DISL, with particle size distribution forming a unimodal curve centered around accumulation mode particles. Conversely, DISL exhibits a quasi-bimodal distribution.

Gas jet structure effects on fuel concentrations and flames in a hydrogen low-pressure direct-injection spark-ignition engine

This study aims to find the impact of the nozzle shape of a side-mounted, 3.5-MPa pintle injector on hydrogen concentration and flame development in a low-pressure direct-injection spark ignition (H2LPDI) engine. To this end, endoscopic high-speed imaging of gas jet laser shadowgraph and flames as well as spark-induced breakdown-spectroscopy (SIBS) method are applied to one of the inline four cylinders of H2LPDI engine. Two engines with endoscopic access are used: one motored engine for high-speed laser shadowgraph imaging of gas jet development and the other combustion engine for SIBS-based spark gap [Formula: see text] measurements and high-speed hydrogen flame imaging. The gas jet visualisation showed that a nozzle with a narrower jet spreading angle leads to more turbulent jet boundaries and the jet axis being directed more towards the piston. Due to higher axial momentum, the narrower spreading angle nozzle also caused enhanced jet penetration across the in-cylinder tumble flow. This jet development pattern resulted in locally leaner hydrogen mixtures near the centrally mounted spark plug at the time of ignition, evidenced by a higher difference between spark gap λ and global λ. As a result, the flame size was measured smaller at any fixed combustion stage. For both nozzle types, the injection timing was also varied between 150 and 120 °CA bTDC but there was no significant difference measured in spark gap [Formula: see text] and flame size compared to that associated with the nozzle type.

Acceleration of Modeling Capability for GDI Spray by Machine-Learning Algorithms

Cold start causes a high amount of unburned hydrocarbon and particulate matter emissions in gasoline direct injection (GDI) engines. Therefore, it is necessary to understand the dynamics of spray during a cold start and develop a predictive model to form a better air-fuel mixture in the combustion chamber. In this study, an Artificial Neural Network (ANN) was designed to predict quantitative 3D liquid volume fraction, liquid penetration, and liquid width under different operating conditions. The model was trained with data derived from high-speed and Schlieren imaging experiments with a gasoline surrogate fuel, conducted in a constant volume spray vessel. A coolant circulator was used to simulate the low-temperature conditions (−7 °C) typical of cold starts. The results showed good agreement between machine learning predictions and experimental data, with an overall accuracy R2 of 0.99 for predicting liquid penetration and liquid width. In addition, the developed ANN model was able to predict detailed dynamics of spray plumes. This confirms the robustness of the ANN in predicting spray characteristics and offers a promising tool to enhance GDI engine technologies.

Microscopic and macroscopic analysis of the flashing and non-flashing ethanol blended fuel for the direct injection sprays

Gasoline direct injection (GDI) engines offer improved fuel atomization, performance, and reduced emissions. Flash boiling in GDI engines enhances atomization. This study investigates ethanol-gasoline blended fuel spray using a single-hole direct atomizer. Micro- and macroscopic experimental analysis was conducted using a Galilean beam expander and Nd: YAG laser. The current study focused on initial, quasi-steady, and post-injection stages of flashing and non-flashing sprays. The transitional flashing jet exhibited various shapes similar to non-flashing sprays. An orbicular-shaped jet was observed during flare flashing at 0.03 MPa chamber pressure and 363 K fuel temperature. It exhibits rapid axial momentum, resulting in a Reynolds number of 8.0 x 104, 1.3 and 2.15 times higher than the transitional and non-flashing sprays. Additionally, it has an estimated nucleation rate of 3.22 x 10-2 m-3s−1 using classical nucleation theory, which is 10 times higher than the transitional flashing, leading to improved atomization. However, spray collapse was observed under flare flashing with reduced chamber pressure, attributed to local condensation and subsequent pressure drop in spray core. Under flare flashing at a fuel temperature of 403 K, the Ohnesorge number is 2.95 x 10-3, which is 0.8 times and 0.7 times lower than the fuel at 383 K and 363 K, respectively. The nucleation rate for flare flashing increases with higher fuel temperature, leading to improved atomization and a reduced likelihood of spray collapse. Post-injection spray structures in the near-nozzle show a transition from coarse to fine and dilute to densely populated, with changes in degree of superheating.

CFD unified approach under Eulerian–Lagrangian framework for methanol and gasoline direct injection sprays in evaporative and flash boiling conditions

Innovative synthetic fuels for advanced propulsion systems, such as methanol and ammonia, and synthetic blended fuels (E00, E10, and E30), known for their high volatility, are often injected directly into combustion chambers. It follows that Eulerian–Lagrangian spray models need to accurately capture the spray collapse as a consequence of flash boiling onset and be capable of proficiently handling the preferential evaporation of multi-component fuels in evaporative scenarios.So, we performed the assessment of an Eulerian–Lagrangian CFD code for simulating methanol and E00 gasoline blend sprays in both early and late injection conditions involving flash boiling conditions and preferential evaporation. The adoption of an effervescent breakup model and of a non-equilibrium phase transition model for the discrete phase allows the adoption of a setup that is almost completely free from specific constant tuning, especially for what concerns the breakup model. We validated the simulations using experimental PLV maps of methanol and E00 sprays issued from the ECN Spray M injector. The results highlight a significantly different morphology of the methanol spray compared to the E00 one under late injection conditions. Under stratified combustion, low-volatile fuels are likely to be ignited first, and the flame propagates toward the high-volatile fuels. The spray collapse was also correctly reproduced, inducing the presence of a low-pressure zone and modifying the spray morphology.

Hydrogen-enriched lean-burn strategy for gasoline direct injection engine utilizing non-thermal plasma fuel reformer

The objective of the task is to sustain and enhance combustion stability at the extension of lean limit of customized Gasoline Direct Injection (GDI) Engine with the supplementation of Hydrogen Rich Gas (HRG) and hydrogen. HRG was supplemented from the on board non thermal Plasma Fuel Reformer (PFR) and hydrogen from the bottled storage through integrated gas control device to the GDI engine. The gas constituents of PFR was theoretically arrived from thermodynamic combustion equations to determine energy based fuel proportion in the ternary fuel injection system. Binary fuel mixture of HRG and hydrogen 10%, 18%, 30% of energy based proportion with gasoline were experimented on test engine. The impact of discrete and binary fuel mixture with gasoline at Stoichiometric Fuel Air ratio was observed and extended baseline equivalence ratio until misfire of the ternary fuel air mixture was occurred. Apart from significant improvement of performance the addition gaseous mixture increases oxides of nitrogen marginally. From the perspective it was noticed that combustion products exhibit better heat transfer out of cylinder at the Maximum Brake Torque Timing (MBT). This was attributed to higher combustion temperatures and improved quenching distances which in turn increased thermal efficiency against the specified equivalence ratio. However retarding MBT suppresses oxides of nitrogen and continued to increase thermal efficiency. It was concluded that lightning fast burn speed, fine fuel atomization of 10% mass based hydrogen and HRG 18%combination fraction increase engine thermal efficiency while decreasing NOx emission and alleviate HC trade-off characteristics.

Impact of fuel injection pressure on GDI engine performance: a numerical study with pre-combustion chamber

Impact of fuel injection pressure on GDI engine performance: a numerical study with pre-combustion chamber

Influence of steam induction on the performance and hydrogen knock limit of a hydrogen-gasoline spark ignition engine

This study examines the effect of steam induction on the performance and hydrogen knock limit of a hydrogen-gasoline dual-fuel Spark Ignition (SI) engine. The experimental setup includes gasoline direct injection, along with steam and hydrogen port induction. Steam-to-fuel ratios of 7.5 %, 15 %, and 22.5 % were used, and hydrogen was introduced in step sizes of 2 LPM until knock onset. The extension of the hydrogen knock limit was achieved through steam induction and retarding spark timing. Under the default configuration, the maximum achievable hydrogen flow rate was 8 LPM, which increased to 20 LPM with retarded spark timing and 22.5 % steam proportion. Steam induction initially increased and then decreased brake thermal efficiency, brake mean effective pressure, in-cylinder pressure, and heat release rate. In contrast, advancing spark timing and hydrogen enrichment consistently improved performance and combustion characteristics. Cyclic variation showed a decreasing trend with the introduction of steam and hydrogen. Unlike hydrogen enrichment, steam addition reduced CO and NOX emissions.