An Experimental Study of the Cyclic Variability in Spark Ignition Engines

Ozdor, Nir; Dulger, Mark; Sher, Eran

doi:10.4271/960611

Cited by 35 publications

(13 citation statements)

References 15 publications

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“…The final electrode orientation with the spark plug tightened is determined by the thread in the cylinder head and the actual location of the welded ground electrode relative to the plug thread. This is apparently random for different production plugs but is known to have an effect on combustion [2,21,22]. Therefore, for the work presented here, the same spark plug orientation was used in all the experiments with the electrode pointing towards the exhaust valves ~165° along an axis passing between the intake and exhaust valves (as seen in images later in this paper).…”

Section: Optical Enginementioning

confidence: 99%

Mixture Preparation and Combustion Variability in a Spray-Guided DISI Engine

Serras-Pereira¹,

Aleiferis²,

Richardson

et al. 2007

SAE Technical Paper Series

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In an attempt to study the numerous contributors towards cyclic variations in combustion in a direct injection spark ignition engine, simultaneous high-speed imaging of fuel injection and flame growth are undertaken on a crankangle resolved basis in a single-cylinder optical research engine. Batches of images from 100 consecutive cycles are acquired for all conditions with synchronised incylinder pressure logging. The engine is motored and fired at stoichiometric conditions at 1500 RPM under part-load and wide-open-throttle conditions (0.5-1.0 bar intake pressure), with injection timing set early in the intake stroke to promote homogeneous mixture formation with a centrally mounted multi-hole injector. Liquid impingement is observed on the cylinder walls and on the piston crown with early intake injection and multiple injection strategies are employed in an attempt to reduce impingement and alter mixture preparation and subsequent combustion. The effects are investigated for iso-octane and pump-grade gasoline at engine coolant temperatures of 50 and 90 °C. Gasoline sprays showed severe deformation and partial collapse of the individual spray plumes at 90 °C, leading to a different mixture formation process relative to iso-octane, which showed no such effects at this engine temperature. Using multiple fuel injections per cycle, but maintaining the same overall air-to-fuel ratio with single-injection strategies, a significant reduction in direct impingement on the walls was observed, together with different flame growth relative to single injection. These results suggest that injection strategy and type of fuel is playing an important role in the mixture preparation process, even for homogeneous early direct injection, and that different types of multiple-injection strategies alone have the potential to modify significantly in-cylinder phenomena, affect combustion and potentially exhaust emissions.

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Section: Optical Enginementioning

confidence: 99%

Mixture Preparation and Combustion Variability in a Spray-Guided DISI Engine

Serras-Pereira¹,

Aleiferis²,

Richardson

et al. 2007

SAE Technical Paper Series

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“…One known cause of this level of cyclic variations is the initial flame development related to the mixture variations near the spark [2,3,8] and the variations in the spark stretch -both direction and size [10,11]. The flame quenching due to the intense turbulence in the vicinity of spark plug is another wellknown cause [2,3], which is addressed by applying extended spark discharge period in production engines at a cost of efficiency [2,8,10].…”

Section: Resultsmentioning

confidence: 99%

“…A previous study found the cyclic variation is responsible for about 10% change in the engine brake power in a DISI engine [7]. Therefore, the reduction and control of the cyclic variation is important in further improving the performance and efficiency of DISI engines [2,[8][9][10][11][12]. In this regard, a strong relationship between the engine performance represented by the measured in-cylinder pressure and the flame propagation imaged using a high-speed camera will be important, to which the present study makes a contribution.…”

Section: Introductionmentioning

confidence: 99%

Cyclic variations of in-cylinder pressure and turbulent flame propagation in an optical direct-injection spark-ignition engine

Lu¹,

Kim²,

Kook³

2020

Australasian Fluid Mechanics Conference (AFMC)

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The direct injection spark ignition (DISI) engines, while showing the extended controllability in operation conditions over port-injection engines, have a cyclic variation issue. For the past decade, many studies have been conducted to identify the causing factors of the cyclic variation and mitigate its negative effects. However, the fundamental knowledge of cyclic variation in DISI engines is still lacking. This experimental study measures cyclic variations in the in-cylinder pressure, early-stage burn duration and flame growth rate in a single-cylinder optical DISI engine and evaluates their correlations. While the in-cylinder pressure was recorded by the pressure sensor mounted in the spark plug, a high-speed camera was used to capture the flame propagation for over 100 individual cycles. The results show significant cyclic variations in both pressure derived data and flame image derived data; however, a clear positive correlation is observed between the burn duration and flame growth rate. Further analysis of the flames indicates higher level of flame front wrinkling measured in some individual cycles is a cause of the higher flame growth rate.

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“…Cyclic torque imbalance acts as a limiting factor to enhance engine performance as these variations affect fuel economy and exhaust emissions, 2 degrade vehicle drivability by causing fluctuations in engine output torque, and vibrations in the driveline. 3 Variations in the cyclic torque also effects wear and degradation of the engine parts due to excessive periodic loading of engine components.…”

Section: Introductionmentioning

confidence: 99%

Cyclic torque imbalance detection in gasoline engines using a uniform second-order sliding mode observer

Anjum

Bhatti

Yar

et al. 2019

Proceedings of the Institution of Mechanical Engineers, Part D:

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Engine torque imbalance is a wide-ranging problem which is caused due to variance of the combustion mixture in the engine cylinder. In this research work, cyclic torque imbalance detection is carried out by formulating a uniform second-order sliding mode observer using the First Principle–based Engine Model. Oscillations in the crankshaft angular speed were modeled in the novel First Principle–based Engine Model, which were suppressed in the Mean Value Engine Models. Cyclic torque imbalance is simulated at multiple instances by varying the injected fuel mass. Estimation of the net piston force is carried out for cyclic torque imbalance detection using rotational dynamics of the engine model. This force is treated as unknown input to the torque production subsystem of the model. Cyclic torque imbalance detection is validated using the GT-Power engine model. Variations in the cyclic torque were detected proximate to actual values which demonstrated validity of the proposed technique.

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An Experimental Study of the Cyclic Variability in Spark Ignition Engines

Cited by 35 publications

References 15 publications

Mixture Preparation and Combustion Variability in a Spray-Guided DISI Engine

Mixture Preparation and Combustion Variability in a Spray-Guided DISI Engine

Cyclic variations of in-cylinder pressure and turbulent flame propagation in an optical direct-injection spark-ignition engine

Cyclic torque imbalance detection in gasoline engines using a uniform second-order sliding mode observer

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