scholarly journals A Numerical Study on the In-cylinder Flow and Fuel Distribution with the Change of Intake Valve Lift in a GDI Engine

2013 ◽  
Vol 18 (2) ◽  
pp. 100-105
Author(s):  
K.B. Kim ◽  
M.J. Song ◽  
K.S. Kim ◽  
S.H. Kang ◽  
Y.H. Lee ◽  
...  
Keyword(s):  
Numerical Study ◽  
Valve Lift ◽  
Intake Valve ◽  
Fuel Distribution ◽  
Gdi Engine ◽  
Cylinder Flow

Intake Turbulence Generated by a Steady Valve-Cylinder Flow

2002 ◽  
Author(s):  
Gearle Bailey ◽  
John Kuhlman
Keyword(s):  
Laser Doppler Anemometry ◽  
Axisymmetric Flow ◽  
Valve Lift ◽  
Intake Port ◽  
Intake Valve ◽  
Toroidal Vortex ◽  
Velocity Measurements ◽  
Mean Velocity ◽  
Cylinder Flow ◽  
Turbulence Generation

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.

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

2012 ◽  
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.

Numerical study of the effect of piston top contour on GDI engine performance under catalyst heating mode

Fuel ◽  
2015 ◽  
Vol 157 ◽  
pp. 64-72 ◽  
Author(s):  
Zhaolei Zheng ◽  
Chuntao Liu ◽  
Xuefeng Tian ◽  
Xiaoyu Zhang
Keyword(s):  
Numerical Study ◽  
Engine Performance ◽  
Gdi Engine ◽  
Heating Mode

Experimental research on pumping losses and combustion performance in an unthrottled spark ignition engine

2018 ◽  
Vol 232 (7) ◽  
pp. 888-897 ◽  
Author(s):  
Tingting Sun ◽  
Yingjie Chang ◽  
Zongfa Xie ◽  
Kaiyu Zhang ◽  
Fei Chen ◽  
...  
Keyword(s):  
Spark Ignition ◽  
Spark Ignition Engine ◽  
Valve Lift ◽  
Combustion Characteristic ◽  
Spark Ignition Engines ◽  
Intake Valve ◽  
Valve System ◽  
Combustion Performance ◽  
Intake Swirl ◽  
Variable Valve

A novel fully hydraulic variable valve system is described in this paper, which achieves continuous variations in maximum valve lift, valve opening duration, and the timing of valve closing. The load of the unthrottled spark ignition engine with fully hydraulic variable valve system is controlled by using an early intake valve closing rather than the conventional throttle valve. The experiments were carried out on BJ486EQ spark ignition engine with fully hydraulic variable valve system. Pumping losses of the throttled and unthrottled spark ignition engines at low-to-medium loads are compared and the reason of it decreasing significantly in the unthrottled spark igntion engine is analyzed. The combustion characteristic parameters, such as cyclic variation, CA50, and heat release rate, were analyzed. The primary reasons for the lower combustion rate in the unthrottled spark ignition engines are discussed. In order to improve the evaporation of fuel and mix with air in an unthrottled spark ignition engine, the in-cylinder swirl is organized with a helical intake valve, which can generate a strong intake swirl at low intake valve lifts. The effects of the intake swirl on combustion performance are investigated. Compared with the throttled spark ignition engine, the brake specific fuel consumption of the improved unthrottled spark ignition engine is reduced by 4.1% to 11.2%.

Simulation of Extended Expansion Lean Burn Spark Ignition Engine

2004 ◽  
Author(s):  
A. Manivannan ◽  
R. Ramprabhu ◽  
P. Tamilporai ◽  
S. Chandrasekaran
Keyword(s):  
Heat Transfer ◽  
Compression Ratio ◽  
Thermal Efficiency ◽  
Numerical Study ◽  
Spark Ignition ◽  
Spark Ignition Engine ◽  
Valve Closure ◽  
Intake Valve ◽  
Lean Burn ◽  
Atkinson Cycle

This paper deals with Numerical Study of 4-stoke, Single cylinder, Spark Ignition, Extended Expansion Lean Burn Engine. Engine processes are simulated using thermodynamic and global modeling techniques. In the simulation study following process are considered compression, combustion, and expansion. Sub-models are used to include effect due to gas exchange process, heat transfer and friction. Wiebe heat release formula was used to predict the cylinder pressure, which was used to find out the indicated work done. The heat transfer from the cylinder, friction and pumping losses also were taken into account to predict the brake mean effective pressure, brake thermal efficiency and brake specific fuel consumption. Extended Expansion Engine operates on Otto-Atkinson cycle. Late Intake Valve Closure (LIVC) technique is used to control the load. The Atkinson cycle has lager expansion ratio than compression ratio. This is achieved by increasing the geometric compression ratio and employing LIVC. Simulation result shows that there is an increase in thermal efficiency up to a certain limit of intake valve closure timing. Optimum performance is attained at 90 deg intake valve closure (IVC) timing further delaying the intake valve closure reduces the engine performance.

Design and Dynamic Analysis of an Innovative Axial Shift Valvetrain System (ASVS) for Variable Stroke Engine

2021 ◽  
pp. 146808742110653
Author(s):  
Jingchen Cui ◽  
Liping Chen ◽  
Wuqiang Long ◽  
Xiangyu Meng ◽  
Bo Li ◽  
...  
Keyword(s):  
Contact Force ◽  
Engine Speed ◽  
Exhaust Valve ◽  
Valve Lift ◽  
Intake Valve ◽  
Power Performance ◽  
Working Cycle ◽  
Valve Motion ◽  
Axial Shift ◽  
Stroke Engine

A variable valvetrain system is the key part of the variable stroke engine (VSE), which could achieve higher power performance and low-speed torque. An innovative axial shift valvetrain system (ASVS) was put forward to meet the air-charging requirements of a 2/4-stroke engine and complete a changeover within one working cycle. Two sets of intake and exhaust cam profiles for both intake and exhaust sides in the 2/4-stoke mode were designed for 2/4-stoke modes. Furthermore, a simulation model based on ADAMS was established to evaluate the dynamic valve motion and the contact force at different engine speeds. The dynamic simulation results show that the valve motion characteristics meet the challenges at the target engine speed of 3000 r/min. In two-stroke mode, the maximum intake valve lift could achieve 7.3 mm within 78°CaA, and the maximum exhaust valve lift could achieve 7.5 within 82°CaA on the exhaust side. In four-stroke mode, the maximum intake valve lift can achieve 8.8 mm within 140°CaA, and the maximum exhaust valve lift can achieve 8.4 mm within 140°CaA. The valve seating speeds are less than 0.3 m/s in both modes, and the fullness coefficients are more than 0.5 and 0.6 in the 2-stroke and 4-stroke mode, respectively. At the engine speed of 3000 r/min, the contact force on each component is acceptable, and the stress between cam and roller can meet the material requirement.

Engine In-Cylinder Flow Control via Variable Intake Valve Timing

2013 ◽  
Author(s):  
Isabella Bücker ◽  
Daniel-Christian Karhoff ◽  
Michael Klaas ◽  
Wolfgang Schröder
Keyword(s):  
Flow Control ◽  
Intake Valve ◽  
Valve Timing ◽  
Cylinder Flow
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