Flow in the Piston-Cylinder-Ring Crevices of a Spark-Ignition Engine: Effect on Hydrocarbon Emissions, Efficiency and Power

Namazian, M.; Heywood, John B.

doi:10.4271/820088

Cited by 192 publications

(98 citation statements)

References 27 publications

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“…In a Schlieren visualization study conducted at the Sloan Automotive Laboratory Namazian [27] showed that during the expansion stroke the crevice gas slowly expands upward and is left in a thin layer above the crevice as the piston moves downward. Expanding on a crevice outflow model developed by Namazian, Min looked at crevice outflow velocities and characteristics [28,29].…”

Section: Crevice Outflowmentioning

confidence: 99%

Crevice Volume Effect on Spark Ignition Engine Efficiency

Smith¹,

Cheng²,

Heywood³

2014

SAE Technical Paper Series

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A set of experiments and a simulation study are completed to quantify the effect of the piston crevice on engine efficiency. The simulation study breaks down the loss mechanisms on brake efficiency at different displacement volumes (300 -500 cc) and compression ratios (8-20). Experiments focus on indicated efficiencies for a narrow range of compression ratios (9.24-12.57) with different piston crevice volumes. Piston crevice volume is increased in two steps by machining a groove into the piston top land, and is decreased by raising the top ring. Indicated efficiency is measured at various loads (0.4 -1.0 bar MAP), speeds (1500, 2000, 2500 rpm), and coolant temperatures (50'C and 80'C). All data points compared in this study are recorded at MBT timing with a relative air-fuel ratio (k) of 1.For the baseline case (CR = 9.24, speed = 2000 rpm, coolant = 80'C), increased crevice volume results in an indicated efficiency degradation of 0.3-0.5%-points per 1000 mm 3 . This absolute decrease corresponds to a 1.2-1.5% relative decrease for a 100% increase in crevice volume; referenced to the control piston crevice modification. Decreasing crevice volume leads to a gain in indicated efficiency of 2.3-3.5%-points per 1000 mm 3 , which corresponds to a 6.9-11.8% relative increase for a 100% decrease in crevice volume; referenced to the control piston crevice modification.Results of the experimental investigation, when compared across compression ratio, engine speed, and coolant temperature, show that the crevice effect on efficiency is largely independent of these three parameters. Large gains from decreased piston crevice volume prompt renewed discussions on piston top land, top ring, and crown design.

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Section: Crevice Outflowmentioning

confidence: 99%

Crevice Volume Effect on Spark Ignition Engine Efficiency

Smith¹,

Cheng²,

Heywood³

2014

SAE Technical Paper Series

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“…In the publications where isothermal flow, i.e. an extensive heat exchange, was assumed their authors simultaneously stress [18,20,22] that gas flow within stages is laminar at low values of Reynolds numbers. It seems to be an inconsequence as at laminar flow heat exchange intensity is relatively low.…”

Section: Introductionmentioning

confidence: 99%

“…Furuhama and Tada, taking into account results of measurements conducted on a motionless piston model stand, assumed that flow through labyrinth stages can be considered isothermal [3]. In prevailing majority of the models , usually referring to Furuhama , it was assumed that gas flow is isothermal and gas temperature within stage is equal to that of piston [18,17,20], or quasi-isothermal , i.e. that gas temperature changes but is determined on the basis of temperature of walls surrounding a given inter-ring space [9,26,22].…”

Section: Introductionmentioning

confidence: 99%

“…In the majority of models [2, 4,27,17,18,13,31,20,1,22] it was assumed that cross-sections of gas flow through ring lock and spaces of labyrinth stages are constant. In actual engine, volumes of inter-ring and behind-ring spaces , and especially cross-sections of gaps in locks , may change within a broad range during one cycle of engine work due to displacing motion of the piston together with rings along cylinder liner of a variable diameter.…”

Section: Introductionmentioning

confidence: 99%

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Mathematical Model of Piston Ring Sealing in Combustion Engine

Koszałka

Guzik

2015

Polish Maritime Research

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“…However, in reality combustion gases do pass through several crevices, leading to blowby [27]. This affects engine performance and exhaust emissions [28,29]. For a gasoline engine running at 2000 rev/min, the pressure behind the top ring was measured as ≈ 25% of the combustion pressure [27], which (as a representative value) was also used in the current study.…”

Section: Introductionmentioning

confidence: 99%

Cavitation induced starvation for piston-ring/liner tribological conjunction

Chong

Teodorescu

Vaughan

2011

Tribology International

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The study investigates the mechanism of ring-liner lubrication in the vicinity of the top and bottom dead centres of an internal combustion engine. Predicting lubricant transient behaviour is critical when the inlet reversal leads to thin films and inherent metal-to-metal interaction. It was found that the cavitation, which is located at the trailing edge of the contact before reversal, briefly survives after reversal as a confined bubble at the leading edge. This depletes the film promoting starvation. Several algorithms were compared. It is concluded that the lubricant film is thinner than initially thought.Keywords: Piston ring, lubrication, tribology, Elrod cavitation algorithm, cavitation, starvationViscostiy-temperature index (-) T Temperature

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Flow in the Piston-Cylinder-Ring Crevices of a Spark-Ignition Engine: Effect on Hydrocarbon Emissions, Efficiency and Power

Cited by 192 publications

References 27 publications

Crevice Volume Effect on Spark Ignition Engine Efficiency

Crevice Volume Effect on Spark Ignition Engine Efficiency

Mathematical Model of Piston Ring Sealing in Combustion Engine

Cavitation induced starvation for piston-ring/liner tribological conjunction

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