Influence of Valve Lift and Throttle Angle on Intake Flow in a High-Performance Four-Stroke Motorcycle Engine

2006 ◽  
Vol 128 (4) ◽  
pp. 934-941 ◽  
Author(s):  
Angelo Algieri ◽  
Sergio Bova ◽  
Carmine De Bartolo
Keyword(s):  
Flow Structure ◽  
High Performance ◽  
Laser Doppler Anemometry ◽  
Fluid Dynamic ◽  
Great Influence ◽  
Flow Coefficient ◽  
Valve Lift ◽  
Cylinder Axis ◽  
Intake Flow ◽  
Motorcycle Engine

A high-performance four-stroke motorcycle engine was analyzed at a steady flow rig. The aim of the work was to characterize the fluid dynamic behavior of the engine head during the intake phase. To this purpose a twofold approach was adopted: the dimensionless flow coefficient was used to evaluate the global breathability of the intake system, while the laser doppler anemometry (LDA) technique was employed to define the flow structure within the combustion chamber. The analysis gave evidence of two contrarotating vortices with axes parallel to the cylinder axis and showed variations in the flow structure when moving away from the engine head. Furthermore, the study highlighted the great influence of the throttle angle on the head fluid dynamic efficiency and how this influence changes with the valve lift. Experimental data were correlated by a single curve adopting a new dimensionless plot. Moreover, LDA measurements were used to evaluate the angular momentum of the flux and an equivalent swirl coefficient, and to correlate them to a previous global swirl characterization carried out on the same engine head using an impulse swirl meter.

Numerical and Experimental Analysis of the Intake Flow in a High Performance Four-Stroke Motorcycle Engine: Influence of the Two-Equation Turbulence Models

2007 ◽  
Vol 129 (4) ◽  
pp. 1095-1105 ◽  
Author(s):  
Angelo Algieri ◽  
Sergio Bova ◽  
Carmine De Bartolo ◽  
Alessandra Nigro
Keyword(s):  
Flow Field ◽  
Combustion Chamber ◽  
High Performance ◽  
Laser Doppler Anemometry ◽  
Fluid Dynamic ◽  
Turbulence Models ◽  
Mean Flow ◽  
Intake System ◽  
Cylinder Flow ◽  
Motorcycle Engine

An experimental and numerical analysis of the intake system of a production high performance four-stroke motorcycle engine was carried out. The aim of the work was to characterize the fluid dynamic behavior of the engine during the intake phase and to evaluate the capability of the most commonly used two-equation turbulence models to reproduce the in-cylinder flow field for a very complex engine head. Pressure and mass flow rates were measured on a steady-flow rig. Furthermore, velocity measurements were obtained within the combustion chamber using laser Doppler anemometry (LDA). The experimental data were compared to the numerical results using four two-equation turbulence models (standard k-ε, realizable k-ε, Wilcox k-ω, and SST k-ω models). All the investigated turbulence models well predicted the global performances of the intake system and the mean flow structure inside the cylinder. Some differences between measurements and computations were found close to the cylinder head while an improving agreement was evident moving away from the engine head. Furthermore, the Wilcox k-ω model permitted the flow field inside the combustion chamber of the engine to be reproduced and the overall angular momentum of the flux with respect to the cylinder axis to be quantified more properly.

Simulation of Unsteady Flow Characteristics of the Reciprocating Pump Check Valve for High Pressure and High Flow Water Medium

2021 ◽  
Vol 144 (3) ◽  
Author(s):  
Jie Dong ◽  
Yinshui Liu ◽  
Hong Ji ◽  
Liejiang Wei ◽  
Defa Wu
Keyword(s):  
High Pressure ◽  
Fluid Dynamic ◽  
Check Valve ◽  
Initial Pressure ◽  
Lower Surface ◽  
Flow Coefficient ◽  
Valve Lift ◽  
Water Medium ◽  
Flow State ◽  
Reciprocating Pump

Abstract The distribution efficiency of the check valve directly affects the performance of the reciprocating pump. The flow coefficient is an important evaluation criterion for the flow capacity of the valve port, and it is of great significance to the design of the valve structure and even the control of cavitation. The traditional design uses flow coefficient as a fixed value, however, the flow state and flow coefficient will change during valve movement. In this study, a three-dimensional transient computational fluid dynamic model for high-pressure and large-flow reciprocating pump valve is established. The dynamic grid simulation method of coupling for the valves and plunger is innovatively proposed, and experimental verification was carried out. The flow state and pressure characteristics for the suction valve under high outlet pressure are analyzed, and the change rule of the suction coefficient is found. The research results show that the initial pressure of the plunger cavity prolongs the negative pressure duration of the plunger cavity when the valve is opened and increases the risk of cavitation of the valve. During the process from valve opening to maximum lift, the suction coefficient first increases and then decreases, and finally remains between 0.5 and 0.6. When the valve lift is large, two-stage throttling occurs, and the flow state will change from cylindrical jet on the lower surface of the valve disk to annular jet, which is beneficial to improve the suction coefficient.

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.

scholarly journals An Experimental Analysis of the Fluid Dynamic Efficiency of a Production Spark-Ignition Engine during the Intake and Exhaust Phase

2011 ◽  
Vol 2011 ◽  
pp. 1-8 ◽  
Author(s):  
Angelo Algieri
Keyword(s):  
Combustion Engine ◽  
Fluid Dynamic ◽  
Great Influence ◽  
Exhaust System ◽  
Spark Ignition ◽  
Spark Ignition Engine ◽  
Valve Lift ◽  
Induction Phase ◽  
Dynamic Efficiency ◽  
Experimental Characterization

The present work aims at analyzing the fluid dynamic efficiency of a four-stroke spark-ignition engine. Specifically, a production four-cylinder internal combustion engine has been investigated during the intake and exhaust phase. The experimental characterization has been carried out at the steady flow rig adopting the dimensionless flow and discharge coefficients. The analysis has highlighted the great influence of the valve lift on the volumetric efficiency of the intake and exhaust system. Furthermore, the global investigation has demonstrated that the throttle angle has a significant influence on the head permeability during the induction phase. Particularly, the throttling process effect increases with the valve lift. Finally, the work has shown that all experimental data can be correlated by a single curve if an opportune dimensionless plot is adopted.

Steady-State Intake Flow in a High-Performance V-Twin Engine

2006 ◽  
Author(s):  
Ryan K. Guy ◽  
Rudolf H. Stanglmaier
Keyword(s):  
Steady State ◽  
High Performance ◽  
Internal Combustion Engines ◽  
Flow Behavior ◽  
Flow Characteristics ◽  
Optimization Techniques ◽  
Valve Lift ◽  
Intake Port ◽  
Head Development ◽  
Intake Flow

The design of intake ports for high-performance internal combustion engines has traditionally relied on steady-state flow benches and prototype core boxes. In this study, Computational Fluid Dynamics (CFD) methods were employed to gain further insight into the characteristics of a high-performance motorcycle engine. In this particular engine configuration, the throttle is located in very close proximity to the intake port, and the effects of throttle position on the intake flow characteristics were examined. This study shows that steady-state CFD analysis can be used in combination with traditional flow optimization techniques to provide further insight for cylinder head development. The intake flow behavior in this engine was found to vary considerably as a function of valve lift and throttle position. It was found that at low valve lifts the intake flow is relatively uniform around the periphery of the intake port, but at high valve lifts the flow into the cylinder is biased towards the top of the intake port. This results in a tendency to promote tumble at high valve lifts, but not at low valve lifts. Small throttle opening angles were found to magnify the flow biasing effect at high valve lifts.

An investigation of in-cylinder tumbling motion in a four-valve spark ignition engine

2001 ◽  
Vol 215 (2) ◽  
pp. 273-284 ◽  
Author(s):  
Y Li ◽  
S Liu ◽  
S-X Shi ◽  
M Feng ◽  
X Sui
Keyword(s):  
Combustion Chamber ◽  
Flow Structure ◽  
Laser Doppler Anemometry ◽  
Spark Ignition ◽  
Spark Ignition Engine ◽  
Cylinder Wall ◽  
Data Processing Method ◽  
Break Up ◽  
Tumbling Motion ◽  
Intake Flow

The formation and break-up of the tumble in the cylinder were studied in a single-cylinder four-valve spark ignition engine using laser Doppler anemometry (LDA) measurements and multidimensional numerical simulations. The flow structure generated by the tumble break-up was also analysed using the cycle-resolved LDA data processing method. These results show that, during the intake stroke, two counter-rotating vortices are generated in the cylinder by the intake flow along the two sides of the cylinder. They then gradually evolve into the tumble vortex at the initial stage of the compression stroke. Tumble motion can be strengthened by increasing the intake flow going along the surface of the exhaust valves and/or decreasing the intake flow descending directly along the cylinder wall on the side of intake valves. Although a partially decayed tumble vortex still exists in the central part of the combustion chamber near the end of compression, in other parts of the combustion chamber the tumble distorts and breaks up into small vortices and eddies so that the root mean square velocity fluctuation increases. The flow structure generated by the tumble break-up has a characteristic of lower frequency and larger eddy scale.

scholarly journals Numerical investigation of the effect of swirl flow in-homogeneity and stability on diesel engine combustion and emissions

2012 ◽  
Vol 13 (5) ◽  
pp. 482-496 ◽  
Author(s):  
Reza Rezaei ◽  
Stefan Pischinger ◽  
Jens Ewald ◽  
Philipp Adomeit
Keyword(s):  
Diesel Engine ◽  
Flow Structure ◽  
High Speed ◽  
Fluid Dynamic ◽  
Test Procedure ◽  
Swirl Flow ◽  
Valve Lift ◽  
Experimental Investigations ◽  
Charge Motion ◽  
Noticeable Effect

The present study is aimed at numerically investigating the effect of in-cylinder charge motion on mixture preparation, combustion and emission formation in a high-speed direct-injection diesel engine. Previous investigations have shown that different valve-lift strategies nominally lead to similar in-cylinder filling and global swirl levels. However, significant differences in engine-out emissions, especially soot emission, give rise to the assumption that the flow structure and local differences of the swirl motion distribution have a noticeable effect on emission behaviour. In this work, different swirl generation strategies applying different intake valve actuation schemes are numerically investigated by applying transient in-cylinder computational fluid dynamic simulations using both the Reynolds-averaged Navier–Stokes model and the multi-cycle large-eddy simulation approach. Two operating points within the operating range of current diesel passenger cars during federal test procedure 75 and new European driving cycles are simulated. The injection and combustion simulations of different valve strategies show that an in-homogeneity in the in-cylinder flow structure leads to a significant increase in soot emissions, and agree with the observed trends of corresponding experimental investigations.

scholarly journals Simultaneously controlling heat conduction and infrared absorption with a textured dielectric film to enhance the performance of thermopiles

2021 ◽  
Vol 7 (1) ◽  
Author(s):  
Yunqian He ◽  
Yuelin Wang ◽  
Tie Li
Keyword(s):  
Heat Conduction ◽  
Infrared Absorption ◽  
High Performance ◽  
Performance Enhancement ◽  
Dielectric Film ◽  
Great Influence ◽  
Thermal Conductance ◽  
Molding Process ◽  
Absorption Properties

AbstractThe heat conduction and infrared absorption properties of the dielectric film have a great influence on the thermopile performance. Thinning the dielectric film, reducing its contact area with the silicon substrate, or adding high-absorptivity nanomaterials has been proven to be effective in improving thermopiles. However, these methods may result in a decrease in the structural mechanical strength and increases in the fabrication complexity and cost. In this work, a new performance-enhancement strategy for thermopiles by simultaneously controlling the heat conduction and infrared absorption with a TExtured DIelectric (TEDI) film is developed and presented. The TEDI film is formed in situ by a simple hard-molding process that is compatible with the fabrication of traditional thermopiles. Compared to the control FLat DIelectric (FLDI) film, the intrinsic thermal conductance of the TEDI film can be reduced by ~18–30%, while the infrared absorption can be increased by ~7–13%. Correspondingly, the responsivity and detectivity of the fabricated TEDI film-based thermopile can be significantly enhanced by ~38–64%. An optimized TEDI film-based thermopile has achieved a responsivity of 156.89 V·W−1 and a detectivity of 2.16 × 108 cm·Hz1/2·W−1, while the response time constant can remain <12 ms. These results exhibit the great potential of using this strategy to develop high-performance thermopiles and enhance other sensors with heat transfer and/or infrared absorption mechanisms.

The inlet flow structure of a conceptual open-nose supersonic drone

2021 ◽  
pp. 095441002098304
Author(s):  
Eiman B Saheby ◽  
Xing Shen ◽  
Anthony P Hays ◽  
Zhang Jun
Keyword(s):  
Flow Structure ◽  
Stokes Equations ◽  
Fluid Dynamic ◽  
Three Dimensional ◽  
Computational Fluid Dynamic Simulation ◽  
Navier Stokes ◽  
Ansys Fluent ◽  
Navier Stokes Equations ◽  
Aerodynamic Efficiency ◽  
Performance Effects

This study describes the aerodynamic efficiency of a forebody–inlet configuration and computational investigation of a drone system, capable of sustainable supersonic cruising at Mach 1.60. Because the whole drone configuration is formed around the induction system and the design is highly interrelated to the flow structure of forebody and inlet efficiency, analysis of this section and understanding its flow pattern is necessary before any progress in design phases. The compression surface is designed analytically using oblique shock patterns, which results in a low drag forebody. To study the concept, two inlet–forebody geometries are considered for Computational Fluid Dynamic simulation using ANSYS Fluent code. The supersonic and subsonic performance, effects of angle of attack, sideslip, and duct geometries on the propulsive efficiency of the concept are studied by solving the three-dimensional Navier–Stokes equations in structured cell domains. Comparing the results with the available data from other sources indicates that the aerodynamic efficiency of the concept is acceptable at supersonic and transonic regimes.

Numerical Simulation of Flow in Imported Steam Turbine Inlet Components with Equilibrated Holes in High Performance

2013 ◽  
Vol 712-715 ◽  
pp. 1263-1267
Author(s):  
Shan Tu ◽  
Shu Ming Wu ◽  
Qi Zhou ◽  
Hong Mei Zhang ◽  
Xiao Qing Zhu
Keyword(s):  
Flow Field ◽  
Steam Turbine ◽  
High Performance ◽  
Optimization Design ◽  
Great Influence ◽  
Control Valve ◽  
Stable Operation ◽  
Valve Seat ◽  
Valve Disc ◽  
Interior Flow

The main inlet component of steam turbine is control valve. The stable operation of the steam turbine control valve is vital for safe and stable operation of the steam turbine and safety production of the power plant. However, due to the complexity of the structure and unsteady characteristics of steam flow in the valve, there is not enough experimental method about the detailed flow characteristics of the area near control valve disc and the inside of the valve chamber up to now. This article is to focus on the simulation of the steam turbine control valve interior flow field which includes the valve pre-inlet channel in different conditions, then find the reasons which caused instability and pressure loss of the control valve by analyzing the flow field details, finally further optimization design. The profile matching of the valve disc and valve seat has a great influence on the interior flow field of control valve, so analysis of the high performance valve disc shape and divergence angle of valve seat is carried out, and the research conclusion is used for guide design and development of the control valve.

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