A Study on the Refinement of Turbulence Intensity Prediction for the Estimation of In-Cylinder Pressure in a Spark-Ignited Engine

Kim, Nam-Ho; Kim, Joohan; Ko, Insuk; Choi, Hae-Jin; Min, Kyoungdoug

doi:10.4271/2017-01-0525

Cited by 8 publications

(8 citation statements)

References 25 publications

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“…As the depletion of petroleum resources continues and environmental pollution becomes more serious, fuel economy and exhaust regulations of internal combustion engines are rapidly strengthening around the world. Various techniques are being developed to increase the efficiency of gasoline engines to satisfy the emission regulations, such as fuel and knock characteristics [1], engine turbulence [2], exhaust gas recirculation strategies [3] and valve timing strategies [4].…”

Section: Introductionmentioning

confidence: 99%

Effects of the Bore to Stroke Ratio on Combustion, Gaseous and Particulate Emissions in a Small Port Fuel Injection Engine Fueled with Ethanol Blended Gasoline

Jang

Choi

et al. 2020

Energies

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The purpose of this study is to analyze the combustion characteristics of the port fuel injection (PFI) engine considering the fuel mixing ratio, bore to stroke (B/S) ratio and gaseous and particle emissions. Experiments were conducted in a small single-cylinder PFI engine with a displacement of 125 cc. The fuel used in the experiment was a mixture of pure gasoline and ethanol. The engine was operated at 5000 rpm at full load and wide-open throttle. In addition, combustion and exhaust characteristics of the engines with a B/S ratio of 0.88 and 1.15 were analyzed. The combustion pressure inside the combustion chamber was measured to analyze the indicated mean effective pressure (IMEP) and the heat release rate, and the combustion rate was calculated. In the results of combustion characteristics by the difference of B/S ratio, the influence of flame propagation velocity and turbulence intensity is the largest. The 0.88 B/S ratio engine, which has a small bore, has a faster combustion rate than the 1.15 B/S ratio engine due to its larger flame surface area and larger turbulence intensity. This represents a higher efficiency combustion result. Finally, the high oxygen content of ethanol has the characteristic of decreasing soot formation and increasing particle oxidation.

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Section: Introductionmentioning

confidence: 99%

Effects of the Bore to Stroke Ratio on Combustion, Gaseous and Particulate Emissions in a Small Port Fuel Injection Engine Fueled with Ethanol Blended Gasoline

Jang

Choi

et al. 2020

Energies

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“…A more recent version of such approach is proposed in [12]. A different method consists in describing the energy cascade from mean flow kinetic energy, K, into turbulent kinetic energy, k, usually referred as K-k models [13,14]. Turbulence dissipation is, hence, derived from the integral length scale, LI.…”

Section: Introductionmentioning

confidence: 99%

“…Turbulence dissipation is, hence, derived from the integral length scale, LI. The evolution of LI during the engine cycle is commonly related to the instantaneous cylinder volume, piston-head distance, or reconstructed by mathematical functions [13,14]. Such a choice is supported by the observation that the integral length scale evolution does not significantly change with the operating conditions.…”

Section: Introductionmentioning

confidence: 99%

Refinement of a 0D Turbulence Model to Predict Tumble and Turbulent Intensity in SI Engines. Part II: Model Concept, Validation and Discussion

Bozza¹,

Teodosio²,

Bellis³

et al. 2018

SAE Technical Paper Series

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As known, reliable information about underlying turbulence intensity is a mandatory prerequisite to predict the burning rate in quasidimensional combustion models. Based on 3D results reported in the companion part I paper, a quasi-dimensional turbulence model, embedded under the form of "user routine" in the GT-Power™ software, is here presented in detail. A deep discussion on the model concept is reported, compared to the alternative approaches available in the current literature. The model has the potential to estimate the impact of some geometrical parameters, such as the intake runner orientation, the compression ratio, or the bore-to-stroke ratio, thus opening the possibility to relate the burning rate to the engine architecture. Preliminarily, a well-assessed approach, embedded in GT-Power commercial software v.2016, is utilized to reproduce turbulence characteristics of a VVA engine. This test showed that the model fails to predict tumble intensity for particular valve strategies, such LIVC, thus justifying the need for additional refinements. The model proposed in this work is conceived to solve 3 balance equations, for mean flow kinetic energy, tumble vortex momentum, and turbulent kinetic energy (3-eq. concept). An extended formulation is also proposed, which includes a fourth equation for the dissipation rate, allowing to forecast the integral length scale (4-eq. concept). The impact of the model constants is parametrically analyzed in a first step, and a tuning procedure is advised. Then, a comparison between the 3-and the 4-eq. concepts is performed, highlighting the advantages of the 3-eq. version, in terms of prediction accuracy of turbulence speed-up at the end of the compression stroke. An extensive 3-eq. model validation is then realized according to different valve strategies and engine speeds. The user-model is then utilized to foresee the effects of main geometrical parameters analyzed in part I, namely the intake runner orientation, the compression ratio, and the bore-to-stroke ratio. A two-valve per cylinder engine is also considered. Temporal evolutions of 0D-and 3D-derived mean flow velocity, turbulent intensity, and tumble velocity present very good agreements for each investigated engine geometry and operating condition. The model, particularly, exhibits the capability to accurately predict the tumble trends by varying some geometrical parameter of the engine, which is helpful to estimate the related impact on the burning rate. Summarizing, the developed 0D model well estimates the in-cylinder turbulence characteristics, without requiring any tuning constants adjustment with engine speed and valve strategy. In addition, it demonstrates the capability to properly take into account the intake duct orientation and the compression ratio without tuning adjustments. Some minor tuning variation allows predicting the effects of bore-to-stroke ratio, as well. Finally, the model is verified to furnish good agreements also for a two-valve per cylinder engine, and with reference to two different h...

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“…A more recent version of such approach is presented in [12]. A different method consists in describing the energy cascade from the mean flow kinetic energy, K, into the turbulent kinetic energy, k, usually referred as K-k models [13,14]. In this case, the turbulence dissipation is derived from the integral length scale, LI.…”

Section: Introductionmentioning

confidence: 99%

“…In this case, the turbulence dissipation is derived from the integral length scale, LI. The evolution of LI during the engine cycle is commonly related to the instantaneous cylinder volume, pistonhead distance, or reconstructed by mathematical functions [13,14]. This last methodology is supported by the observation that the integral length scale evolution does not significantly change with the operating conditions.…”

Section: Introductionmentioning

confidence: 99%

A Refined 0D Turbulence Model to Predict Tumble and Turbulence in SI Engines

Bozza¹,

Teodosio

Bellis

et al. 2018

SAE Int. J. Engines

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In this work, the refinement of a phenomenological turbulence model developed in recent years by the authors is presented in detail. As known, reliable information about the underlying turbulence intensity are a mandatory prerequisite to predict the burning rate in phenomenological combustion models. The model is embedded under the form of "user routine" in the GT-Power™ software. The main advance of the proposed approach is the potential to describe the effects on the in-cylinder turbulence of some geometrical parameters, such as the intake runner orientation, the compression ratio, the bore-to-stroke ratio and the valve number. The model is based on 3 balance equations, referring to the mean flow kinetic energy, the tumble vortex momentum, and the turbulent kinetic energy (3-eq. concept). An extended formulation is also proposed, which includes a fourth equation for the dissipation rate, allowing to forecast also the integral length scale (4-eq. concept). The model consistency is verified against 3D results under motored operations for various operating conditions and engine geometrical architectures. The temporal evolutions of the 0D-derived mean flow velocity, turbulent intensity, and tumble velocity present very good agreement with the 3D outcomes. The model exhibits the capability to accurately predict the tumble trends by varying some engine geometrical parameters. The proposed 0D model proves to correctly estimate the in-cylinder turbulence characteristics, without requiring any tuning adjustment with the engine speed and the valve strategy. In addition, it demonstrates the capability to properly take into account the intake duct orientation and the compression ratio without any case-dependent tuning. Some minor tunings are required to predict the effects of the bore-to-stroke ratio. The model also shows an adequate accuracy for a two-valve per cylinder engine, and for two different high-performance engines.

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A Study on the Refinement of Turbulence Intensity Prediction for the Estimation of In-Cylinder Pressure in a Spark-Ignited Engine

Cited by 8 publications

References 25 publications

Effects of the Bore to Stroke Ratio on Combustion, Gaseous and Particulate Emissions in a Small Port Fuel Injection Engine Fueled with Ethanol Blended Gasoline

Effects of the Bore to Stroke Ratio on Combustion, Gaseous and Particulate Emissions in a Small Port Fuel Injection Engine Fueled with Ethanol Blended Gasoline

Refinement of a 0D Turbulence Model to Predict Tumble and Turbulent Intensity in SI Engines. Part II: Model Concept, Validation and Discussion

A Refined 0D Turbulence Model to Predict Tumble and Turbulence in SI Engines

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