Experimental research on scavenging process of opposed-piston two-stroke gasoline engine based on tracer gas method

2021 ◽  
pp. 146808742110366
Author(s):  
Fukang Ma ◽  
Wei Yang ◽  
Yifang Wang ◽  
Junfeng Xu ◽  
Yufeng Li
Keyword(s):  
Gas Exchange ◽  
Exchange Process ◽  
Delivery Ratio ◽  
Tracer Gas ◽  
Piston Motion ◽  
Trapped Air ◽  
Exchange Performance ◽  
Gdi Engine ◽  
Gas Exchange Process ◽  
Scavenging Efficiency

The scavenging process of two stroke engine includes free exhaust, scavenging, and post intake process, which clears the burned gas in cylinder and suctions the fresh air for next cycle. The gas exchange process of Opposed-Piston Two-Stroke (OP2S) engine with gasoline direct injection (GDI) engine is a uniflow scavenging method between intake port and exhaust port. In order to investigate the characteristics of the gas exchange process in OP2S-GDI engine, a specific tracer gas method (TGM) was developed and the experiments were carried out to analyze the gas exchange performance under different intake and exhaust conditions and opposed-piston movement rule. The results show that gas exchange performance and trapped gas mass are significantly influenced by intake pressure and exhaust pressure. And it has a positive effect on the scavenging efficiency and the trapped air mass. Scavenging efficiency and trapped air mass are almost independent of pressure drop when the delivery ratio exceeds 1.4. Consequently, the delivery ratio ranges from 0.5 to 1.4 is chosen to achieve an optimization of steady running and minimum pump loss. The opposed piston motion phase difference only affects the scavenging timing. Scavenging performance is mainly influenced by scavenging timing and scavenging duration. With the increased phase difference of piston motion, the scavenging efficiency and delivery ratio increased gradually, the trapping efficiency would increase first and decrease then and reaches its maximum at 14°CA.

Improving the Performance of a Crankcase-Scavenged Two-Stroke Engine with a Fluid Diode

1982 ◽  
Vol 196 (1) ◽  
pp. 23-34 ◽  
Author(s):  
E Sher
Keyword(s):  
Theoretical Model ◽  
Gas Exchange ◽  
Theoretical Analysis ◽  
Exchange Process ◽  
Engine Performance ◽  
Delivery Ratio ◽  
Engine Torque ◽  
Model Equations ◽  
Gas Exchange Process ◽  
Stroke Engine

A fluid diode was installed at the inlet port of a crankcase-scavenged two-stroke engine. Experiments on the fired engine showed that the engine torque was significantly improved at low engine speeds. A theoretical model to simulate the gas exchange process, including the flow inside the diode, was developed. The model equations were solved numerically. Theoretical analysis showed that with the diode, backflow was prevented, the delivery ratio was increased and the scavenging mechanism and efficiency were improved. It was concluded that a further improvement in engine performance may be achieved by installing an additional fluid diode at the scavenge port.

Design of a Stepped Tube Exhaust Primary for High Performance Applications Using Unsteady Computational Fluid Dynamics

2012 ◽  
Author(s):  
Justin D. Callies ◽  
David E. Anderson ◽  
Robert G. Prucka
Keyword(s):  
Gas Exchange ◽  
High Performance ◽  
Internal Combustion Engines ◽  
Exchange Process ◽  
Pressure Waves ◽  
Step Size ◽  
Exchange Performance ◽  
Effective Use ◽  
Performance Gains ◽  
Scavenging Efficiency

High performance naturally-aspirated internal combustion engines require effective use of exhaust pressure waves during the gas exchange process to maximize volumetric efficiency and torque. Under certain conditions sudden increases, or steps, in exhaust runner diameter are used to control pressure wave reflections to provide appropriately timed low pressure waves to the cylinder that reduce pumping work and improve air scavenging. This research evaluates gas exchange performance for an exhaust port and an attached stepped-tube primary using unsteady conditions with 1-D and 3-D CFD. The objectives of this research are to (1) discuss the importance of using unsteady flow simulations in the design of high performance exhaust systems, (2) describe the use of stepped-runners to provide performance gains, and (3) discuss the influence of runner step geometry and the number of steps on gas exchange. Simulations are correlated with experimental data to ensure accuracy of the results. A correlation is found between the step size and the magnitude as well as phase of tuning effects. The number of steps is also found to have a direct impact on tuning. The pumping work of the cycle was significantly affected by the stepped primary design, while the scavenging efficiency was not.

scholarly journals Development and experimental validation of a real-time capable field programmable gate array–based gas exchange model for negative valve overlap

2018 ◽  
Vol 21 (3) ◽  
pp. 421-436 ◽  
Author(s):  
David Gordon ◽  
Christian Wouters ◽  
Maximilian Wick ◽  
Feihong Xia ◽  
Bastian Lehrheuer ◽  
...  
Keyword(s):  
Gas Exchange ◽  
Real Time ◽  
Field Programmable Gate Array ◽  
Homogeneous Charge Compression Ignition ◽  
Exchange Process ◽  
Compression Ignition ◽  
Field Programmable ◽  
Gate Array ◽  
Gas Exchange Process ◽  
Homogeneous Charge

Homogeneous charge compression ignition has the potential to significantly reduce NO x emissions, while maintaining a high fuel efficiency. Homogeneous charge compression ignition is characterized by compression-induced autoignition of a lean homogeneous air–fuel mixture. Combustion timing is highly dependent on the in-cylinder state including pressure, temperature and trapped mass. To control homogeneous charge compression ignition combustion, it is necessary to have an accurate representation of the gas exchange process. Currently, microprocessor-based engine control units require that the gas exchange process is linearized around a desired operating point to simplify the model for real-time implementation. This reduces the models’ ability to handle disturbances and limits the flexibility of the model. However, using a field programmable gate array, a detailed simulation of the physical gas exchange process can be implemented in real time. This paper outlines the process of converting physical governing equations to an offline zero-dimensional gas exchange model. The process used to convert this model to a field programmable gate array capable model is described. This model is experimentally validated using a single cylinder research engine with electromagnetic valves to record real-time field programmable gate array gas exchange results and comparing to the offline zero-dimensional physical model. The field programmable gate array model is able to accurately calculate the cylinder temperature and cylinder mass at 0.1 °CA intervals during the gas exchange process for a range of negative valve overlaps, boost conditions and engine speeds making the model useful for future real-time control applications.

Control-Oriented Gas Exchange Model for Diesel Engines Utilizing Variable Intake Valve Actuation

2014 ◽  
Vol 136 (6) ◽  
Author(s):  
Lyle Kocher ◽  
Ed Koeberlein ◽  
Karla Stricker ◽  
D. G. Van Alstine ◽  
Greg Shaver
Keyword(s):  
Gas Exchange ◽  
Diesel Engines ◽  
Exchange Process ◽  
Exhaust Gas ◽  
Intake Valve ◽  
Physically Based ◽  
Valve Position ◽  
Gas Exchange Process ◽  
And Control ◽  
Valve Actuation

Modeling and control of the gas exchange process in modern diesel engines is critical for the promotion and control of advanced combustion strategies. However, most modeling efforts to date use complex stand-alone simulation packages that are not easily integrated into, or amenable for the synthesis of, engine control systems. Simpler control-oriented models have been developed; however, in many cases, they do not directly capture the complete dynamic interaction of air handling system components and flows in multicylinder diesel engines with variable geometry turbocharging (VGT), high pressure exhaust gas recirculation (EGR), and flexible intake valve actuation. Flexibility in the valvetrain directly impacts the gas exchange process not only through the effect on volumetric efficiency but also through the combustion process and resulting exhaust gas enthalpy utilized to drive the turbomachinery. This paper describes a low-order, five state model of the air handling system for a multicylinder variable geometry turbocharged diesel engine with cooled EGR and flexible intake valve actuation, validated against 286 steady state and 62 transient engine operating points. The model utilizes engine speed, engine fueling, EGR valve position, VGT nozzle position, and intake valve closing (IVC) time as inputs to the model. The model outputs include calculation of the engine flows as well as the exhaust temperature exiting the cylinders. The gas exchange model captures the dynamic effects of the not only the standard air handling actuators (EGR valve position and VGT position) but also IVC timing, exercised over their useful operating ranges. The model's capabilities are enabled through the use of analytical functions to describe the performance of the turbocharger, eliminating the need to use look-up maps; a physically based control-oriented exhaust gas enthalpy submodel and a physically based volumetric efficiency submodel.

LES of the Gas-Exchange Process Inside an Internal Combustion Engine Using a High-Order Method

2019 ◽  
Vol 104 (2-3) ◽  
pp. 673-692 ◽  
Author(s):  
G. K. Giannakopoulos ◽  
C. E. Frouzakis ◽  
P. F. Fischer ◽  
A. G. Tomboulides ◽  
K. Boulouchos
Keyword(s):  
Gas Exchange ◽  
Internal Combustion Engine ◽  
Combustion Engine ◽  
Exchange Process ◽  
Internal Combustion ◽  
High Order ◽  
Order Method ◽  
High Order Method ◽  
Gas Exchange Process
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