Effect of Retarded Injection Timing on Knock Resistance and Cycle to Cycle Variation in Gasoline Direct Injection Engine

2018 ◽  
Vol 140 (7) ◽  
Author(s):  
Lei Zhou ◽  
Aifang Shao ◽  
Jianxiong Hua ◽  
Haiqiao Wei ◽  
Dengquan Feng
Keyword(s):  
Gasoline Engine ◽  
Direct Injection ◽  
High Energy ◽  
Gasoline Direct Injection ◽  
Injection Timing ◽  
Spark Ignition Engines ◽  
Compression Stroke ◽  
Gasoline Direct Injection Engine ◽  
Cycle Variation ◽  
Electrically Actuated

In spark ignition engines, gasoline direct injection (GDI) is surely the most attractive technology to achieve the demand of high energy efficiency by directly injecting fuel into combustion chamber. This work, as a preliminary study, investigates the effect of retarded injection timing on knock resistance and cycle-to-cycle variation in gasoline engine by experimental method. The retarded injection timing during compression stroke coupled with increased intake air temperature was employed to concentrate on suppressing knock occurrence with stable combustion. Based on the great advantage of injection timing retard on knock suppression, intake temperature was used in this work to reduce cycle-to-cycle variation. In addition, piezo-electrically actuated injector was employed. The results show that injection timing retard during compression stroke can significantly suppress the knock tendency, but combustion becomes unstable and cycle-to-cycle variation is larger than 10%. Thus, increasing intake temperature decreased the cycle-to-cycle variation but increased significantly the knock tendency, as expect. Meanwhile, rich fuel–air mixture in this work also had the same effect as intake temperature did. It can be concluded that retarded injection timing is of significant potential to suppress the knock in GDI engine, although the high intake temperature causes high probability of large knock occurrence. The percentages of knock at the spark timings of 24 °CA before top dead center (BTDC) and 26 °CA BTDC were significantly reduced from approximately 40% to 7% and from approximately 60% to 10%, respectively. Furthermore, the retarded injection timing not only reduced the probability of knock occurrence, but also decreased the knock intensity obviously.

scholarly journals Predicting Cycle-to-Cycle Variation With Concurrent Cycles in a Gasoline Direct Injected Engine With Large Eddy Simulations

2018 ◽  
Author(s):  
Daniel Probst ◽  
Sameera Wijeyakulasuriya ◽  
Eric Pomraning ◽  
Janardhan Kodavasal ◽  
Riccardo Scarcelli ◽  
...  
Keyword(s):  
Gasoline Engine ◽  
Direct Injection ◽  
Engine Performance ◽  
Turnaround Time ◽  
Operating Conditions ◽  
Gasoline Direct Injection ◽  
Cycle Variation ◽  
Spark Timing ◽  
Large Eddy ◽  
Operating Points

High cycle-to-cycle variation (CCV) is detrimental to engine performance, as it leads to poor combustion and high noise and vibration. In this work, CCV in a gasoline engine is studied using large eddy simulation (LES). The engine chosen as the basis of this work is a single-cylinder gasoline direct injection (GDI) research engine. Two stoichiometric part-load engine operating points (6 BMEP, 2000 RPM) were evaluated: a non-dilute (0% EGR) case and a dilute (18% EGR) case. The experimental data for both operating conditions had 500 cycles. The measured CCV in IMEP was 1.40% for the non-dilute case and 7.78% for the dilute case. To estimate CCV from simulation, perturbed concurrent cycles of engine simulations were compared to consecutively obtained engine cycles. The motivation behind this is that running consecutive cycles to estimate CCV is quite time-consuming. For example, running 100 consecutive cycles requires 2–3 months (on a typical cluster), however, by running concurrently one can potentially run all 100 cycles at the same time and reduce the overall turnaround time for 100 cycles to the time taken for a single cycle (2 days). The goal of this paper is to statistically determine if concurrent cycles, with a perturbation applied to each individual cycle at the start, can be representative of consecutively obtained cycles and accurately estimate CCV. 100 cycles were run for each case to obtain statistically valid results. The concurrent cycles began at different timings before the combustion event, with the motivation to identify the closest time before spark to minimize the run time. Only a single combustion cycle was run for each concurrent case. The calculated standard deviation of peak pressure and coefficient of variance (COV) of indicated mean effective pressure (IMEP) were compared between the consecutive and concurrent methods to quantify CCV. It was found that the concurrent method could be used to predict CCV with either a velocity or numerical perturbation. A large and small velocity perturbation were compared and both produced correct predictions, implying that the type of perturbation is not important to yield a valid realization. Starting the simulation too close to the combustion event, at intake valve close (IVC) or at spark timing, under-predicted the CCV. When concurrent simulations were initiated during or before the intake even, at start of injection (SOI) or earlier, distinct and valid realizations were obtained to accurately predict CCV for both operating points. By simulating CCV with concurrent cycles, the required wall clock time can be reduced from 2–3 months to 1–2 days. Additionally, the required core-hours can be reduced up to 41%, since only a portion of each cycle needs to be simulated.

Effect of Conical Spray and Multi-Hole Spray on Gasoline Engine Mixture Formation and Combustion Performance Based on Different Injection Strategies

2020 ◽  
Vol 143 (6) ◽  
Author(s):  
Shengli Wei ◽  
Zhiqing Yu ◽  
Zhilei Song ◽  
Fan Yang ◽  
Chengcheng Wu
Keyword(s):  
Gasoline Engine ◽  
Direct Injection ◽  
Mixture Distribution ◽  
Gasoline Direct Injection ◽  
Injection Timing ◽  
Mixture Formation ◽  
Injection Strategy ◽  
Gdi Engine ◽  
The Difference ◽  
Injection Strategies

Abstract This article presents a numerical investigation carried out to determine the effects of second and third injection timing on combustion characteristics and mixture formation of a gasoline direct injection (GDI) engine by comparing conical spray against multihole spray. The results showed that at the engine 80% full load of 2000 r/min, the difference in mixture distribution between the two sprays was obvious with double and triple injection strategies. With the second injection timing from 140 deg CA delay to 170 deg CA, the in-cylinder pressure, the in-cylinder temperature, and the heat release rate of the conical spray increased by 20.8%, 9.8%, and 30.7% and that of the multihole spray decreased by 30.7%, 13.6%, and 37.8%. The delay of the injection time reduced the performance of the engine with the multihole spray, and the performance of the multihole spray was obviously in the simulation of the triple injection strategy. However, for the conical spray, the application of the triple injection strategy increased the temperature and the pressure compared with the double injection strategy.

Analysis of cycle-by-cycle variation in a direct injection gasoline engine using a laser-induced fluorescence technique

2003 ◽  
Vol 4 (2) ◽  
pp. 143-153 ◽  
Author(s):  
T Fujikawa ◽  
Y Nomura ◽  
Y Hattori ◽  
T Kobayashi ◽  
M Kanda
Keyword(s):  
Gasoline Engine ◽  
Direct Injection ◽  
Mixture Distribution ◽  
Fuel Mixture ◽  
Laser Induced Fluorescence ◽  
Injection Timing ◽  
Indicated Mean Effective Pressure ◽  
Cycle Variation ◽  
Spark Timing ◽  
Direct Injection Gasoline Engine

To analyse the cycle-by-cycle variation of combustion in a direct injection gasoline engine equipped with a fan-shape spray nozzle and operated with exhaust gas recirculation (EGR), the fuel mixture distribution was measured at a time of spark and during the combustion period by the laser-induced fluorescence (LIF) technique. It was found that in the case of advanced or retarded injection timing, the initial combustion period tends to extend and the indicated mean effective pressure (i.m.e.p.) becomes low when lean mixtures appear at the spark position and at the spark timing. This suggests that the cycle-by-cycle variation of combustion under these conditions is dominated by the fuel concentration at the spark position and spark timing. In contrast to this, for the best injection timing, which allows the lowest cycle-by-cycle variation, the i.m.e.p. fluctuation is affected not by the initial combustion period but by the main combustion period. The observation of LIF images revealed that the i.m.e.p. fluctuation at this condition is strongly correlated to the unburned mixture quantity at the side area of the piston cavity during the latter half of the combustion period. It was shown by a computational fluid dynamics (CFD) calculation that the combination of a uniform spray pattern and a compact cavity shape is effective to reduce the over-lean mixture region in the edge of the piston cavity, which is responsible for the cycle-by-cycle variation of combustion at the condition of best-tuned injection timing.

scholarly journals Predicting Cycle-to-Cycle Variation With Concurrent Cycles in a Gasoline Direct Injected Engine With Large Eddy Simulations

2019 ◽  
Vol 142 (4) ◽  
Author(s):  
Daniel M. Probst ◽  
Sameera Wijeyakulasuriya ◽  
Eric Pomraning ◽  
Janardhan Kodavasal ◽  
Riccardo Scarcelli ◽  
...  
Keyword(s):  
Gasoline Engine ◽  
Direct Injection ◽  
Engine Performance ◽  
Operating Conditions ◽  
Gasoline Direct Injection ◽  
Effective Pressure ◽  
Cycle Variation ◽  
Brake Mean Effective Pressure ◽  
Large Eddy ◽  
Operating Points

Abstract High cycle-to-cycle variation (CCV) is detrimental to engine performance, as it leads to poor combustion and high noise and vibration. In this work, CCV in a gasoline engine is studied using large eddy simulation (LES). The engine chosen as the basis of this work is a single-cylinder gasoline direct injection (GDI) research engine. Two stoichiometric part-load engine operating points (6 brake mean effective pressure (BMEP) and 2000 revolutions per minute) were evaluated: a nondilute (0% exhaust gas recirculation (EGR)) case and a dilute (18% EGR) case. The experimental data for both operating conditions had 500 cycles. The measured CCV in indicated mean effective pressure (IMEP) was 1.40% for the nondilute case and 7.78% for the dilute case. To estimate CCV from simulation, perturbed concurrent cycles of engine simulations were compared with consecutively obtained engine cycles. The motivation behind this is that running consecutive cycles to estimate CCV is quite time consuming. For example, running 100 consecutive cycles requires 2–3 months (on a typical cluster); however, by running concurrently, one can potentially run all 100 cycles at the same time and reduce the overall turnaround time for 100 cycles to the time taken for a single cycle (2 days). The goal of this paper is to statistically determine if concurrent cycles, with a perturbation applied to each individual cycle at the start, can be representative of consecutively obtained cycles and accurately estimate CCV. 100 cycles were run for each case to obtain statistically valid results. The concurrent cycles began at different timings before the combustion event, with the motivation to identify the closest time before spark to minimize the run time. Only a single combustion cycle was run for each concurrent case. The calculated standard deviation of peak pressure and coefficient of variance (COV) of IMEP were compared between the consecutive and concurrent methods to quantify CCV. It was found that the concurrent method could be used to predict CCV with either a velocity or numerical perturbation. Both a large and small velocity perturbations were compared, and both produced correct predictions, implying that the type of perturbation is not important to yield a valid realization. Starting the simulation too close to the combustion event, at intake valve close (IVC) or at spark timing, underpredicted the CCV. When concurrent simulations were initiated during or before the intake even, at start of injection (SOI) or earlier, distinct and valid realizations were obtained to accurately predict CCV for both operating points. By simulating CCV with concurrent cycles, the required wall clock time can be reduced from 2–3 months to 1–2 days. In addition, the required core-hours can be reduced up to 41%, since only a portion of each cycle needs to be simulated.

Studies of Spray Breakup and Mixture Stratification in a Gasoline Direct Injection Engine Using KIVA-3V

2000 ◽  
Vol 122 (3) ◽  
pp. 485-492 ◽  
Author(s):  
Dennis N. Assanis ◽  
Sang Jin Hong ◽  
Akihiro Nishimura ◽  
George Papageorgakis ◽  
Bruno Vanzieleghem
Keyword(s):  
Model Comparison ◽  
Direct Injection ◽  
Gasoline Direct Injection ◽  
Injection Timing ◽  
Hollow Cone ◽  
Qualitative And Quantitative ◽  
Gasoline Direct Injection Engine ◽  
Spark Plug ◽  
Optimization And Control ◽  
And Control

The Low Pressure spray Breakup (LPB) model of Papageorgakis and Assanis has been implemented in the multi-dimensional code KIVA-3V as an alternative to the standard Taylor Analogy Breakup (TAB) model. Comparison of spray predictions with measurements shows that the LPB model, in conjunction with the standard k-ε turbulence model, has the potential for simulating the evolution of hollow cone sprays with acceptable fidelity, both from qualitative and quantitative standpoints. After validating the LPB model, illustrative studies of mixture stratification are conducted for a Direct Injection Gasoline (DIG) combustion chamber resembling the Mitsubishi design. The effects of reverse tumble strength and injection timing on mixture quality in the vicinity of the spark plug are explored. Overall, the study demonstrates how the KIVA-3V code with the LPB model can contribute to the optimization and control of mixing in DIG engines. [S0742-4795(00)00303-3]

Analysis of the relationship between particle number and fuel cutoff in a single-cylinder gasoline direct injection engine

2020 ◽  
Vol 234 (13) ◽  
pp. 3001-3010
Author(s):  
Jingeun Song ◽  
Mingi Choi
Keyword(s):  
Particle Number ◽  
Direct Injection ◽  
Gasoline Direct Injection ◽  
Injection Timing ◽  
Cylinder Pressure ◽  
Engine Load ◽  
Direct Injection Engine ◽  
Single Cylinder ◽  
Gasoline Direct Injection Engine ◽  
Load Change

This study investigates the effects of fuel cutoff on particle number in a single-cylinder wall-guided gasoline direct injection engine. Various durations of fuel cutoff and change in load and engine stop were tested, and the in-cylinder pressure, particle number, and NO x emissions were measured. The change in in-cylinder temperature during combustion stop was calculated using the in-cylinder pressure and the ideal gas law. Experimental results showed that as the fuel cutoff duration increased, the particle number increased significantly when combustion resumed. For the injection timing before top dead center 330°, the particle number, which was 600 × 103 #/cm3 under the continuous combustion condition, increased to 6700 × 103 #/cm3 after 30 s of fuel cutoff. Both the fuel cutoff and engine stop showed enormous amount of particle number when combustion restarted. A major factor that increased particle number was the temperature reduction of piston during the combustion stop. The peak in-cylinder temperature decreased by 38 K during 30 s of motoring, which was induced by the temperature drop of the piston. Therefore, in terms of particulate emissions, it is more advantageous to lower the engine load than to stop combustion: the piston surface remains hot during load reduction. In addition, it is recommended to change the engine load slowly to reduce the particle number emissions. In this study, the rapid load change from indicated mean effective pressure of 0.25 to 0.55 MPa showed 7% higher particle number emissions than the gentle load change. On the contrary, NO x was reduced because none was generated during combustion stop. However, the fuel cutoff would increase NO x in gasoline vehicles because the oxygen in the unburned air would significantly reduce the conversion efficiency of a three-way catalytic converter. It is especially worth investigating the reason for the increase in emissions because it is easy to think that all kinds of emissions will be reduced if fuel is not burned.

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