Simulation-Aided Development of Prechamber Ignition System for a Lean-Burn Gasoline Direct Injection Motor-Sport Engine

2020 ◽  
Vol 142 (8) ◽  
Author(s):  
Muhammed Fayaz Palakunnummal ◽  
Priyadarshi Sahu ◽  
Mark Ellis ◽  
Marouan Nazha
Keyword(s):  
Thermal Efficiency ◽  
Direct Injection ◽  
Fuel Mixture ◽  
Gasoline Direct Injection ◽  
Lean Burn ◽  
Ignition System ◽  
Motor Sport ◽  
Auto Ignition ◽  
Computational Fluid Dynamics Cfd ◽  
Sport Events

Abstract Due to recent regulation changes to restricted fuel usage in various motor-sport events, motor-sport engine manufacturers have started to focus on improving the thermal efficiency and often claim thermal efficiency figures well above equivalent road car engines. With limited fuel allowance, motor-sport engines are operated with a lean air–fuel mixture to benefit from higher cycle efficiency, requiring an ignition system that is suitable for the lean mixture. Prechamber ignition is identified as a promising method to improve lean limit and has the potential to reduce end gas auto-ignition. This paper analyses the full-load performance of a motor-sport lean-burn gasoline direct injection (GDI) engine and a passive prechamber is developed with the aid of a computational fluid dynamics (CFD) tool. The finalized prechamber design benefited in a significant reduction in burn duration, reduced cyclic variation, knock limit extension, and higher performance.

Numerical study of the effect of split direct injection on the lean-burn combustion characteristics in a poppet-valve two-stroke gasoline engine at high loads

2020 ◽  
pp. 146808742093240
Author(s):  
Xiao Li ◽  
Bang-Quan He ◽  
Hua Zhao
Keyword(s):  
Heat Release ◽  
Heat Release Rate ◽  
Release Rate ◽  
Thermal Efficiency ◽  
Direct Injection ◽  
Lean Burn ◽  
Gasoline Engines ◽  
Poppet Valve ◽  
Auto Ignition ◽  
Second Peak

Poppet-valve two-stroke gasoline engines can increase specific power of four-stroke gasoline engines with the same displacement. But knocking combustion may also occur at high loads in two-stroke engines. The application of stratified lean-burn on poppet-valve two-stroke gasoline engines can avoid knocking and increase combustion stability. To investigate the effect of the mixture stratification on lean-burn events at high loads, simulation was conducted in different split direct injection conditions with constant fuel mass when equivalence ratio is 0.625. Results show that most fuel distributes near the center of the cylinder at any second direct injection ratio ( rSOI2). At different rSOI2s, auto-ignition occurs during flame propagation, causing shortened combustion duration. Auto-ignition causes the second peak of the heat release rate. The second peak of the heat release rate first decreases and then increases with increased rSOI2. Indicated mean effective pressure and indicated thermal efficiency increase with increased maximum pressure rise rate. The maximum indicated thermal efficiency of 42% can be reached without knocking combustion at 1500 rpm. The proportion of fuel mass through auto-ignition in the cylinder is an important factor to change the indicated thermal efficiency of a lean-burn engine at high loads.

Investigation of combustion and emissions of an SI engine with ethanol port injection and gasoline direct injection under lean burn conditions

Energy ◽  
2019 ◽  
Vol 189 ◽  
pp. 116231 ◽  
Author(s):  
Xiumin Yu ◽  
Zezhou Guo ◽  
Ping Sun ◽  
Sen Wang ◽  
Anshi Li ◽  
...  
Keyword(s):  
Direct Injection ◽  
Gasoline Direct Injection ◽  
Si Engine ◽  
Lean Burn

scholarly journals Numerical Simulation of Knock Combustion in a Downsizing Turbocharged Gasoline Direct Injection Engine

2019 ◽  
Vol 9 (19) ◽  
pp. 4133 ◽  
Author(s):  
Wang ◽  
Zhang ◽  
Wang ◽  
Han ◽  
Chen
Keyword(s):  
Direct Injection ◽  
Combustion Process ◽  
Three Dimensional ◽  
Operating Conditions ◽  
Gasoline Direct Injection ◽  
Valve Lift ◽  
Fuel Droplets ◽  
Gasoline Direct Injection Engine ◽  
Auto Ignition ◽  
Combustion Simulation

Engine knock has become the prime barrier to significantly improve power density and efficiency of the engines. To further look into the essence of the abnormal combustion, this work studies the working processes of normal combustion and knock combustion under practical engine operating conditions using a three-dimensional computation fluid dynamics (CFD) fluid software CONVERGE (Version 2.3.0, Convergent Science, Inc., Madison, USA). The results show that the tumble in the cylinder is gradually formed with the increase of the valve lift, enhances in the compression stroke and finally is broken due to the extrusion of the piston. The fuel droplets gradually evaporate and move to the intake side under the turbulent and high temperature in the cylinder. During the normal combustion process, the flame propagates faster on the intake side and it facilitates mixture in cylinder combustion. During the knock combustion simulation, the hotspots near the exhaust valve are observed, and the propagating detonation wave caused by multiple hotspots auto-ignition indicates significant effects on knock intensity of in-cylinder pressure.

Extending Lean and Exhaust Gas Recirculation-Dilute Operating Limits of a Modern Gasoline Direct-Injection Engine Using a Low-Energy Transient Plasma Ignition System

2016 ◽  
Vol 138 (11) ◽  
Author(s):  
James Sevik ◽  
Thomas Wallner ◽  
Michael Pamminger ◽  
Riccardo Scarcelli ◽  
Dan Singleton ◽  
...  
Keyword(s):  
Direct Injection ◽  
Exhaust Gas Recirculation ◽  
Low Energy ◽  
Gasoline Direct Injection ◽  
Combustion Stability ◽  
Exhaust Gas ◽  
Ignition System ◽  
Plasma Ignition ◽  
Gas Recirculation ◽  
Transient Plasma

The efficiency improvement and emissions reduction potential of lean and exhaust gas recirculation (EGR)-dilute operation of spark-ignition gasoline engines is well understood and documented. However, dilute operation is generally limited by deteriorating combustion stability with increasing inert gas levels. The combustion stability decreases due to reduced mixture flame speeds resulting in significantly increased combustion initiation periods and burn durations. A study was designed and executed to evaluate the potential to extend lean and EGR-dilute limits using a low-energy transient plasma ignition system. The low-energy transient plasma was generated by nanosecond pulses and its performance compared to a conventional transistorized coil ignition (TCI) system operated on an automotive, gasoline direct-injection (GDI) single-cylinder research engine. The experimental assessment was focused on steady-state experiments at the part load condition of 1500 rpm 5.6 bar indicated mean effective pressure (IMEP), where dilution tolerance is particularly critical to improving efficiency and emission performance. Experimental results suggest that the energy delivery process of the low-energy transient plasma ignition system significantly improves part load dilution tolerance by reducing the early flame development period. Statistical analysis of relevant combustion metrics was performed in order to further investigate the effects of the advanced ignition system on combustion stability. Results confirm that at select operating conditions EGR tolerance and lean limit could be improved by as much as 20% (from 22.7 to 27.1% EGR) and nearly 10% (from λ = 1.55 to 1.7) with the low-energy transient plasma ignition system.

Effect of ultra-high injection pressure up to 50 MPa on macroscopic spray characteristics of a multi-hole gasoline direct injection injector fueled with ethanol

2017 ◽  
Vol 232 (8) ◽  
pp. 1092-1104 ◽  
Author(s):  
Xiang Li ◽  
Yi-qiang Pei ◽  
Jing Qin ◽  
Dan Zhang ◽  
Kun Wang ◽  
...  
Keyword(s):  
High Speed ◽  
Direct Injection ◽  
Cone Angle ◽  
Injection Pressure ◽  
Fuel Mixture ◽  
Gasoline Direct Injection ◽  
Spray Characteristics ◽  
High Injection ◽  
High Injection Pressure ◽  
Wall Impingement

This research systematically studied the effect of injection pressure on macroscopic spray characteristics of a five-hole gasoline direct injection (GDI) injector fueled with ethanol, especially under ultra-high injection pressure up to 50 MPa. The front and side views of sprays were photographed by the schlieren method using a high-speed camera. Various parameters, including spray development stages, cone angle, penetration, area and irregular ratio, were fully analyzed to evaluate macroscopic characteristics of the whole spray and spray core with varying injection pressure. The results demonstrated that the effect of ultra-high injection pressure on macroscopic spray characteristics was significant. As injection pressure increased from 10 MPa to 50 MPa, the occurrence time of branch-like structure decreased; the cone angle increased little; the area increased significantly; the area ratio dropped by 6.4 and 5.8 percentage points on average for the front view and side view spray, respectively. There was a significant increase in the trend for penetration as the injection pressure rose from 10 MPa to 30 MPa. However, this trend became weak when the injection pressure further increased. The penetration ratio under ultra-high injection pressure was slightly higher than it was under 10 or 20 MPa. Ultra-high injection pressure would not obviously raise the possibility of spray/wall impingement, but led to the impingement quantity increasing to some extent. Increasing injection pressure could enhance the vortex scale, finally resulting in better air/fuel mixing quality. Ultra-high injection pressure was a potential way to improve air/fuel mixture homogeneity for a GDI injector fueled with ethanol.

Advanced Numerical Approach to Simulate GDI Sprays Under Engine-Like Conditions

2014 ◽  
Author(s):  
Eiji Ishii ◽  
Motoyuki Abe ◽  
Hideharu Ehara ◽  
Yoshihito Yasukawa
Keyword(s):  
Flow Direction ◽  
Direct Injection ◽  
Fuel Mixture ◽  
Numerical Approach ◽  
Gasoline Direct Injection ◽  
Fuel Spray ◽  
Density Region ◽  
Penetration Length ◽  
Spray Penetration ◽  
Fuel Injectors

Gasoline direct-injection (GDI) engines provide both higher engine power and better fuel efficiency than port-injection gasoline engines. However, they emit more particulate matter (PM) than the latter engines. Fuel stuck on walls of pistons and combustion chambers forms a high-density region of fuel in the air/fuel mixture, which becomes a source of PM. To decrease the amount of PM, fuel injectors with short length of spray-penetration are required. A fuel-spray simulation was previously developed; that is, the air/fuel-mixture simulation was integrated with the liquid-column-breakup simulation. The developed fuel-spray simulation was used to optimize the nozzle shapes of fuel injectors for gasoline direct-injection engines. In the present study, the factors that influence spray-penetration length were identified by the numerical simulation. The simulation results were validated by comparing the simulated spray-penetration length with the measured ones and revealing good agreement between them. Angle α was defined as that formed between the direction of flow entering the nozzle inlet and the direction of flow leaving the nozzle outlet; in other words, a indicates a change of flow direction. It was found that α and spray-penetration length was closely related. Velocity that are accelerated with a were studied, and it was found that the velocity within a plane perpendicular to the center axis of the nozzle increases with increasing α.

Development of Gasoline Direct Injection Engine for Improving Brake Thermal Efficiency Over 44%

2020 ◽  
Vol 142 (10) ◽  
Author(s):  
Dongwon Jung ◽  
Byeongseok Lee ◽  
Jinwook Son ◽  
Soohyung Woo ◽  
Youngnam Kim
Keyword(s):  
Thermal Efficiency ◽  
Direct Injection ◽  
Stability Limit ◽  
Spark Ignition ◽  
Gasoline Direct Injection ◽  
Brake Thermal Efficiency ◽  
Gasoline Direct Injection Engine ◽  
Combustion Duration ◽  
Test Engine ◽  
Gas Recirculation

Abstract This study demonstrates the effects of technologies applied for the development of gasoline direct injection (GDI) engine for improving the brake thermal efficiency (BTE). The test engine has a relatively high stroke to bore ratio of 1.4 with a displacement of 2156 cm3. All experiments have been conducted for stoichiometric operation at 2000 RPM. First, since compression ratio (CR) is directly related to the thermal efficiency, four CR were explored for operation without exhaust gas recirculation (EGR). Then, for the same four CR, EGR was used to suppress the knock occurrence at high loads, and its effect on initial and main combustion duration was compared. Second, the shape of intake port was revised to increase tumble flow for reducing combustion duration, and extending EGR-stability limit further. Then, as an effective method to ensure stable combustion for EGR-diluted stoichiometric operation, the use of twin spark ignition (SI) system is examined by modifying both valve diameters of intake and exhaust, and its effect is compared against that of single spark ignition. In addition, the layout of twin spark ignition was also examined for the location of front-rear and intake-exhaust. To get the maximum BTE at high load, 12 V electronic super charger (eSC) was applied. Under the condition of using 12 V eSC, the effect of intake cam duration was identified by increasing from 260 deg to 280 deg. Finally, 48 V eSC was applied with the longer intake camshaft duration of 280 deg. As a result, the maximum BTE of 44% can be achieved for stoichiometric operation with EGR.

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