Development of High Tumble Intake-Port for High Thermal Efficiency Engines

Yoshihara, Yasushi; Nakata, Kohei; Takahashi, Daishi; Omura, Tetsuo; Ota, Atsuharu

doi:10.4271/2016-01-0692

Cited by 35 publications

(18 citation statements)

References 10 publications

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“…The characterization results are Since the fractional distribution can serve its role only when the correct total mass flow rate is provided, the discharge coefficient is also a major factor of concern. As mentioned previously, a stronger tumble is attained when the lower-side flow is restricted [11], implying the trade-off relationship between the tumble strength and flow coefficient [7]. Thus, when port geometry is altered to manipulate tumble, its impact on charging efficiency must be considered concurrently.…”

Section: Head Characterizationmentioning

confidence: 92%

“…Turbulence originates from the large-scale flow motion generated by the intake flow, and among different types of large-scale motion, tumble possesses several advantageous structural characteristics for turbulence enhancement: (1) Tumble is spontaneously generated with pentroof cylinder head, which is most common for recent four-valve engines, (2) as a relatively stable mean motion, tumble can store a certain amount of the intake kinetic energy, and (3) having rotation axis perpendicular to the cylinder axis, even well-ordered tumble cannot avoid its breakdown into small-scale motions (or turbulence) near the end of compression, at which high turbulence is desired [4][5][6][7][8]. In summary, the intake-generated tumble can preserve the turbulence potential and release it in a timely manner.…”

Section: Introductionmentioning

confidence: 99%

“…Modulation of tumble strength can be implemented by altering the head design (e.g., straight intake port [7,9], intake port angle [10], valve masking [9,11], etc.) or by using some auxiliary device (shrouded valve [12], tumble flap [4], etc.).…”

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

A New Physics-Based Modeling Approach for a 0D Turbulence Model to Reflect the Intake Port and Chamber Geometries and the Corresponding Flow Structures in High-Tumble Spark-Ignition Engines

Kim

et al. 2019

Energies

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Turbulence is one of the most important aspects in spark-ignition engines as it can significantly affect burn rates, heat transfer rates, and combustion stability, and thus the performance. Turbulence originates from a large-scale mean motion that occurs during the induction process, which mainly consists of tumble motion in modern spark-ignition engines with a pentroof cylinder head. Despite its significance, most 0D turbulence models rely on calibration factors when calculating the evolution of tumble motion and its conversion into turbulence. In this study, the 0D tumble model has been improved based on the physical phenomena, as an attempt to develop a comprehensive model that predicts flow dynamics inside the cylinder. The generation and decay rates of tumble motion are expressed with regards of the flow structure in a realistic combustion chamber geometry, while the effects of port geometry on both charging efficiency and tumble generation rate are reflected by supplementary steady CFD. The developed tumble model was integrated with the standard k-ε model, and the new turbulence model has been validated with engine experimental data for various changes in operating conditions including engine speed, load, valve timing, and engine geometry. The calculated results showed a reasonable correlation with the measured combustion duration, verifying this physics-based model can properly predict turbulence characteristics without any additional calibration process. This model can suggest greater insights on engine operation and is expected to assist the optimization process of engine design and operating strategies.

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Section: Head Characterizationmentioning

confidence: 92%

Section: Introductionmentioning

confidence: 99%

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A New Physics-Based Modeling Approach for a 0D Turbulence Model to Reflect the Intake Port and Chamber Geometries and the Corresponding Flow Structures in High-Tumble Spark-Ignition Engines

Kim

et al. 2019

Energies

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“…The metrics discussed above provide methods of quantifying the differences between flow fields, both simulated and experimental. However, typical flows setup during the induction stroke in a modern GDI engine are characterised by strong tumble motion [24][25][26]. Using the Relevance Index to compare flow fields with a vortex can lead to misleading results due to the regions of low velocities around the vortex centre.…”

Section: /19/2mentioning

confidence: 99%

Novel Metrics for Validation of PIV and CFD in IC Engines

Scott

Willman

Stone

et al. 2019

SAE Technical Paper Series

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In-cylinder flow motion has a significant effect on mixture preparation and combustion. Therefore, it is vital that CFD engine simulations are capable of accurately predicting the in-cylinder velocity fields. Highspeed planar Particle Image Velocimetry (PIV) experiments have been performed on a single-cylinder GDI optical engine in order to validate CFD simulations for a range of engine conditions. Novel metrics have been developed to quantify the differences between experimental and simulated velocity fields in both alignment and magnitude. The Weighted Relevance Index (WRI) is a variation of the standard Relevance Index that accounts for the local velocity magnitudes to provide a robust comparison of the alignment between two vector fields. Similarly, the Weighted Magnitude Index (WMI) quantifies the differences in the local magnitudes of the two velocity fields. The WRI and WMI are normalised and combined to produce a combined metric, the Combined Magnitude and Relevance Index (CMRI), that quantifies the differences between two flow fields in both magnitude and alignment simultaneously.PIV measurements were made every 5°ca in the central tumble plane during the induction and compression strokes. The WRI, WMI and CMRI metrics are used to validate numerical simulations of the motored in-cylinder flow measured with PIV for a range of valve lift profiles and engine speeds.

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“…29 A high tumble intakeport design can be used to intensify the in-cylinder tumble flow, which can strengthen the turbulence intensity. 30 For generating increased in-flow tumble motion, an alternative method to optimize the throat shape design of the intake-port is used in this study to avoid completely re-designing the intake-port or cylinder head. This method adds some machining steps in manufacture of the engine head without any changes to the casting.…”

Section: Introductionmentioning

confidence: 99%

Combustion optimization for fuel economy improvement of a dedicated range-extender engine

Han

Shi³

et al. 2021

Proceedings of the Institution of Mechanical Engineers, Part D:

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In this study, the combustion system of a dedicated range-extender engine was optimized based on a production engine for fuel economy improvement with the use of enhanced tumble flow, higher compression ratio, Atkinson cycle and exhaust gas recirculation (EGR). First, the shape of the intake port was optimized to improve in-cylinder tumble and turbulence for combustion enhancement. The computational fluid dynamics (CFD) results showed that compared to the original intake port, the peak tumble ratio during the compression stroke of the new port is improved by 74.0%, and the turbulent kinetic energy at the spark timing is increased by 33.0%, and the results were verified through the flow test bench experiment. The dyno experiment showed that, with the new intake port, the engine brake specific fuel consumption (BSFC) was improved for all test conditions. Then, the late intake valve closing (IVC) and a higher compression ratio were used in combination to adopt the Atkinson cycle. The IVC timing was set to 642° ATDC based on the preset power target. And the compression ratio was set to 12 to balance knock tendency and BSFC improvement. Finally, the cooled EGR was optimized to further suppress the knocking tendency to improve fuel consumption. The results showed that, with the cooling Strategy 2, the attainable maximum EGR ratio at 2400 rpm full load and 70 Nm conditions was increased, the spark timing could be significantly advanced, and the BSFC was improved. The improvement of BSFC is between 6 g/kW·h and 13 g/kW·h for the load range from 40 Nm to the full load. After the optimization, the minimum BSFC of the range-extender engine reaches 233 g/kW·h, while it is around 242 g/kW·h for the base engine. The operation area where fuel consumption is lower than 240 g/kW·h becomes much wider.

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Development of High Tumble Intake-Port for High Thermal Efficiency Engines

Cited by 35 publications

References 10 publications

A New Physics-Based Modeling Approach for a 0D Turbulence Model to Reflect the Intake Port and Chamber Geometries and the Corresponding Flow Structures in High-Tumble Spark-Ignition Engines

A New Physics-Based Modeling Approach for a 0D Turbulence Model to Reflect the Intake Port and Chamber Geometries and the Corresponding Flow Structures in High-Tumble Spark-Ignition Engines

Novel Metrics for Validation of PIV and CFD in IC Engines

Combustion optimization for fuel economy improvement of a dedicated range-extender engine

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