Effects of Intake Port Design and Valve Lift on In-Cylinder Flow and Burnrate

Axial and swirl velocities have been measured for steady axisymmetric flow in a cylinder past a fixed intake valve located on the cylinder centerline, for two different intake port geometries and two valve lifts, in order to study the effects of swirl and valve lift on turbulence generation. Both Laser Doppler Anemometry (LDA) and Constant Temperature Anemometry (CTA) velocity measurements were obtained. The cylinder diameter was 82.6 mm, cylinder height was 114.3 mm, and the centrally located valve had a diameter of 41.9 mm. The LDA mean axial velocity data indicated a conical jet issuing from the valve, and a recirculating toroidal vortex above the valve for each case. Also, for the swirl intake cases, the swirl mean velocity in the toroidal vortex increased linearly with radius. Axial fluctuation velocities were about 1 m/sec away from the conical jet, for both valve lifts and both inlet flow geometries. In the conical jet, axial fluctuation velocities of 2–2.5 m/sec were observed. The swirl fluctuation was consistently lower than the axial fluctuation. The swirl inlet increased the magnitude of the swirl fluctuation in the conical jet.

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The Effect of Injector and Intake Port Design on In-Cylinder Fuel Droplet Distribution, Airflow and Lean Burn Performance for a Honda VTEC-E Engine

10.4271/961923 ◽

1996 ◽

Cited By ~ 13

Author(s):

N. E. Carabateas ◽

A. M. K. P. Taylor ◽

J. H. Whitelaw ◽

Kiyoshi Ishii ◽

Kazuo Yoshida ◽

...

Keyword(s):

Intake Port ◽

Fuel Droplet ◽

Lean Burn ◽

Droplet Distribution ◽

Port Design

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Numerical Analysis of Swirl Control Strategies in a Four Valve HSDI Diesel Engine

ASME 2004 Internal Combustion Engine Division Fall Technical Conference ◽

10.1115/icef2004-0909 ◽

2004 ◽

Author(s):

S. Fontanesi ◽

E. Mattarelli ◽

L. Montorsi

Keyword(s):

Flow Field ◽

Control Strategies ◽

Cfd Simulations ◽

Full Load ◽

Partial Load ◽

Swirl Intensity ◽

Port Design ◽

Current Production ◽

Hsdi Diesel Engine ◽

Cylinder Flow

Recent four value HSDI Diesel engines are able to control the swirl intensity, in order to enhance the in-cylinder flow field at partial load without decreasing breathing capabilities at full load. Making reference to a current production engine, the purpose of this paper is to envestiage the influence of port design and flow-control strategies on both engine permeability and in-cylinder flow field. Using previously validated models, 3-D CFD simulations of the intake and compression strokes are performed in order to predict the in-cylinder flow patterns originated by the different configurations. The comparison between the two configurations in terms of airflow at full load indicates that Geometry 2 can trap 3.03% more air than Geometry 1, while the swirl intensity at IVC is reduced (−30%). The closure of one intake valve (the left one) is very effective to enhance the swirl intensity at partial load: the Swirl Ratio at IVC passes from 0.7 to 2.6 for Geometry 1, while for Geometry 2 it varies from 0.4 to 2.9.

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Numerical Comparative Analysis of In-Cylinder Tumble Flow Structures in Small PFI Engines Equipped by Heads Having Different Shapes and Squish Areas

ASME 2012 Internal Combustion Engine Division Spring Technical Conference ◽

10.1115/ices2012-81095 ◽

2012 ◽

Cited By ~ 12

Author(s):

Stefania Falfari ◽

Gian Marco Bianchi ◽

Luca Nuti

Keyword(s):

Flow Structure ◽

Mutual Influence ◽

Ignition Time ◽

Three Dimensional ◽

Valve Lift ◽

Spark Plug ◽

Piston Valve ◽

Cylinder Flow ◽

Roof Angle ◽

Motorcycle Engine

For increasing the thermal engine efficiency, faster combustion and low cycle-to-cycle variation are required. In PFI engines the organization of in-cylinder flow structure is thus mandatory for achieving increased efficiency. In particular the formation of a coherent tumble vortex with dimensions comparable to engine stroke largely promotes proper turbulence production extending the engine tolerance to dilute/lean mixture. For motorbike and scooter applications, tumble has been considered as an effective way to further improve combustion system efficiency and to achieve emission reduction since layout and weight constraints limit the adoption of more advanced concepts. In literature chamber geometry was found to have a significant influence on bulk motion and turbulence levels at ignition time, while intake system influences mainly the formation of tumble vortices during suction phase. The most common engine parameters believed to affect in-cylinder flow structure are: 1. Intake duct angle; 2. Inlet valve shape and lift; 3. Piston shape; 4. Pent-roof angle. The present paper deals with the computational analysis of three different head shapes equipping a scooter/motorcycle engine and their influence on the tumble flow formation and breakdown, up to the final turbulent kinetic energy distribution at spark plug. The engine in analysis is a 3-valves pent-roof motorcycle engine. The three dimensional CFD simulations were run at 6500 rpm with AVL FIRE code on the three engines characterised by the same piston, valve lift, pent-roof angle and compression ratio. They differ only in head shape and squish areas. The aim of the present paper is to demonstrate the influence of different head shapes on in-cylinder flow motion, with particular care to tumble motion and turbulence level at ignition time. Moreover, an analysis of the mutual influence between tumble motion and squish motion was carried out in order to assess the role of both these motions in promoting a proper level of turbulence at ignition time close to spark plug in small 3-valves engines.

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Research on Homogeneous Charge Compression Ignition Combustion of Intake Port Exhaust Gas Recirculation Based on Cam Drive Hydraulic Variable Valve Actuation Mechanism

Energies ◽

10.3390/en15020438 ◽

2022 ◽

Vol 15 (2) ◽

pp. 438

Author(s):

Linghai Han ◽

Jiaquan Duan ◽

Dingchao Qian ◽

Yanfeng Gong ◽

Yaodong Wang ◽

...

Keyword(s):

Engine Speed ◽

Valve Lift ◽

Intake Port ◽

Cyclic Variation ◽

Response Characteristics ◽

Variable Valve Actuation ◽

Hcci Combustion ◽

Variation Range ◽

Variable Valve ◽

Valve Actuation

The thermal efficiency of an efficient gasoline engine is only about 40% and it will produce a large number of harmful products. Curbing harmful emissions and enhancing thermal efficiency have always been the goals pursued and emission regulations are also being tightened gradually. As one of the main consumers of fossil fuels, automobile engines must further reduce fuel consumption and emissions to comply with the concept of low-carbon development, which will also help them compete with electric vehicles. Homogeneous charge compression ignition (HCCI) combustion combined with variable valve actuation (VVA) technology is one of the important ways to improve engine emissions and economy. HCCI combustion based on VVA can only be realized at small and medium loads. The actual application on the entire vehicle needs to be combined with spark ignition (SI) combustion to achieve full working condition coverage. Therefore, HCCI combustion needs fast valve response characteristics; however, the valve lift and timing of the existing VVA mechanisms are mostly controlled separately, resulting in poor valve response. In order to solve this problem, the cam driven hydraulic variable valve actuation (CDH-VVA) mechanism was designed. The valve lift and timing can be adjusted at the same time and the switching of valve lift and timing can be completed in 1~2 cycles. A set of combustion mode switching data is selected to show the response characteristics of the CDH-VVA mechanism. When switching from spark ignition (SI) to HCCI, it switches to HCCI combustion after only one combustion cycle and it switches to stable HCCI combustion after two combustion cycles, which proves the fast response characteristics of the CDH-VVA mechanism. At the same time, the CDH-VVA mechanism can form the intake port exhaust gas recirculation (EGR), as one type of internal EGR. This paper studies the HCCI combustion characteristics of the CDH-VVA mechanism in order to optimize it in the future and enable it to realize more forms of HCCI combustion. At 1000 rpm, if the maximum lift of the exhaust valve (MLEV) is higher than 5.0 mm or lower than 1.5 mm, HCCI combustion cannot operate stably, the range of excess air coefficient (λ) is largest when the MLEV is 4.5 mm, ranging from 1.0~1.5. Then, as the MLEV decreases, the range of λ becomes smaller. When the MLEV drops to 1.5 mm, the range of λ shortens to 1.0~1.3. The maximum value of the MLEV remains the same at the three engine speeds (1000 rpm, 1200 rpm and 1400 rpm), which is 5.0 mm. The minimum value of the MLEV gradually climbs as the engine speed increase, 1000 rpm: 1.5 mm, 1200 rpm: 2.0 mm, 1400 rpm: 3.0 mm. With the increase of engine speed, the range of indicated mean effective pressure (IMEP) gradually declines, 3.53~6.31 bar (1000 rpm), 4.11~6.75 bar (1200 rpm), 5.02~6.09 bar (1400 rpm), which proves that the HCCI combustion loads of the intake port EGR are high and cannot be extended to low loads. The cyclic variation of HCCI combustion basically climbs with the decrease of the MLEV and slightly jumps with the increase of the engine speed. At 1000 rpm, when the MLEV is 5.0 mm, the cyclic variation range is 0.94%~1.5%. As the MLEV drops to 1.5 mm, the cyclic variation range rises to 3.5%~4.5%. Taking the maximum value of the MLEV as an example, the cyclic variation range of 1000 rpm is 0.94%~1.5%, 1200 rpm becomes 1.5%~2.3% and 1400 rpm rises to 2.0%~2.5%.

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A Design of the Compression Chamber and Optimization of the Sealing of a Novel Rotary Internal Combustion Engine Using CFD

Energies ◽

10.3390/en13092362 ◽

2020 ◽

Vol 13 (9) ◽

pp. 2362

Author(s):

Savvas Savvakis ◽

Dimitrios Mertzis ◽

Elias Nassiopoulos ◽

Zissis Samaras

Keyword(s):

Internal Combustion Engine ◽

Cfd Simulation ◽

Combustion Engine ◽

Numerical Study ◽

Simulation Models ◽

Internal Combustion ◽

Intake Port ◽

Significant Difference ◽

Port Design ◽

Compression Chamber

The current paper investigates two particular features of a novel rotary split engine. This internal combustion engine incorporates a number of positive advantages in comparison to conventional reciprocating piston engines. As a split engine, it is characterized by a significant difference between the expansion and compression ratios, the former being higher. The processes are decoupled and take place simultaneously, in different chambers and on the different sides of the rotating pistons. Initially, a brief description of the engine’s structure and operating principle is provided. Next, the configuration of the compression chamber and the sealing system are examined. The numerical study is conducted using CFD simulation models, with the relevant assumptions and boundary conditions. Two parameters of the compression chamber were studied, the intake port design (initial and optimized) and the sealing system size (short and long). The best option was found to be the combination of the optimized intake port design with the short seal, in order to keep the compression chamber as close as possible to the engine shaft. A more detailed study of the sealing system included different labyrinth geometries. It was found that the stepped labyrinth achieves the highest sealing efficiency.

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Valve and In-Cylinder Flow Generated by a Helical Port in a Production Diesel Engine

Journal of Fluids Engineering ◽

10.1115/1.3242675 ◽

1987 ◽

Vol 109 (4) ◽

pp. 368-375 ◽

Cited By ~ 12

Author(s):

C. Arcoumanis ◽

C. Vafidis ◽

J. H. Whitelaw

Keyword(s):

Diesel Engine ◽

Laser Doppler Anemometry ◽

Operating Conditions ◽

Valve Lift ◽

Valve Closure ◽

Rapid Decay ◽

Inlet Valve ◽

Compression Stroke ◽

Axial Velocity Distribution ◽

Cylinder Flow

The flow generated by the helical port of a production Diesel engine has been investigated by laser Doppler anemometry under steady flow and operating conditions at ∼ 900 rpm and compression ratio of 8. The flow around the valve periphery was found to be non-uniform with the axial velocity distribution being more sensitive to valve lift. The in-cylinder swirl distribution at inlet valve closure exhibited an axial stratification in the disc-chamber while turbulence intensity remained constant in the clearance volume during the rest of the compression stroke with levels of 0.5 vp and a minimum of about 0.4 vp at top-dead-center following a rapid decay at θ=340°.

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Effect of Valve Opening/Closing Setup on CFD Prediction of Engine Flows

Volume 2: Emissions Control Systems; Instrumentation, Controls, and Hybrids; Numerical Simulation; Engine Design and Mechanical Development ◽

10.1115/icef2015-1022 ◽

2015 ◽

Cited By ~ 1

Author(s):

Xiaofeng Yang ◽

Seunghwan Keum ◽

Tang-wei Kuo

Keyword(s):

Internal Combustion Engines ◽

Best Practice ◽

Flow Simulation ◽

Grid Resolution ◽

Valve Lift ◽

Navier Stokes ◽

Solid Boundary ◽

Piv Measurement ◽

Parametric Studies ◽

Cylinder Flow

In Computational Fluid Dynamics (CFD) simulations of internal combustion engines, one of the critical modeling parameters is the valve setup. A standard workaround is to keep the valve opens at a certain clearance (minimum valve lift), while imposing a solid boundary to mimic valve closure. This method would yield a step change in valve lift during opening and closing event, and different valve event timing than hardware. Two parametric studies were performed to examine a) the effect of the minimum valve lift and b) the effect of grid resolution at the minimum valve lift on predicted in-cylinder flow fields in Reynolds Averaged Navier-Stokes (RANS) simulations. The simulation results were compared with the state-of-art PIV measurement from a two-valve transparent combustion chamber (TCC-3) engine. The comparisons revealed that the accuracy of flow simulation are sensitive to the choice of minimum valve lift and grid resolution in the valve seat region. In particular, the predicted in-cylinder flow field during the intake process was found to be very sensitive to the valve setup. A best practice CFD valve setup strategy is proposed as a result of this parametric studies. The proposed CFD valve setup was applied to Large Eddy Simulation (LES) of TCC-3 engine and preliminary results showed noticeable improvement already. Further evaluation of the valve setup strategy for LES simulations is on-going and will be reported in a separate report.

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