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.

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.

Optimization of the Scavenging System Based on Specific Time-Area Value of a Compact Two-Stroke Gasoline Engine

2012 ◽  
Vol 538-541 ◽  
pp. 3094-3097
Author(s):  
Shou Chen Xing ◽  
Chen Hai Guo ◽  
Pu Kang Xie ◽  
Fei Dong
Keyword(s):  
Numerical Simulation ◽  
Optimal Design ◽  
Gas Exchange ◽  
Mathematical Models ◽  
Gasoline Engine ◽  
Exchange Process ◽  
Specific Time ◽  
Gas Exchange Process ◽  
Stroke Engine

The specific time-area values describe the circulating ability of two-stroke engine ports during the gas exchange process, so they are the main parameters to affect the engine performances [1]. This paper establishes mathematical models of port parameters for symmetrically timing ports of two-stroke gasoline engine with carburetor and crankcase loop scavenging, the emphasis of analysis is specific time-area values of the ports. The mathematical models of specific time-area values which introduced in this paper give the initiative for further research on the numerical simulation and the optimal design of two-stroke engine.

CFD Analysis of Gas Exchange Process in a Motored Small Two-stroke Engine

2010 ◽  
Vol 11 (1) ◽  
pp. 36-45 ◽  
Author(s):  
Ramamurthy Hariharan ◽  
N.V. Mahalakshm ◽  
Jeyachandran Krishnamoo
Keyword(s):  
Gas Exchange ◽  
Exchange Process ◽  
Cfd Analysis ◽  
Gas Exchange Process ◽  
Stroke Engine

An Experimental and Analytical Investigation of the Gas Exchange Process in a Multi-Cylinder Pressure-Charged Two-Stroke Engine

1968 ◽  
Vol 183 (1) ◽  
pp. 253-279 ◽  
Author(s):  
R. S. Benson ◽  
K. Galloway
Keyword(s):  
Gas Exchange ◽  
Steady Flow ◽  
Exchange Process ◽  
Exhaust Pipe ◽  
Computer Programme ◽  
Cylinder Pressure ◽  
Temperature Records ◽  
Gas Exchange Process ◽  
Stroke Engine ◽  
Good Agreement

The results are given of a comprehensive investigation of the pressure and temperature diagrams in a multi-cylinder two-stroke engine during the gas-exchange process. A six-cylinder turbocharged two-stroke diesel engine was fully instrumented to record transient pressures in three cylinders, in the scavenge belt, and in a number of positions in a specially designed exhaust pipe. Transient-temperature records were taken in the exhaust pipe. Steady-flow tests were carried out on the inlet ports, the exhaust valves, and the exhaust pipe. The steady-flow data were then used in a computer programme (see references (9) (12)‡) to predict the pressure in the cylinder and the pressures and temperatures in the exhaust pipe. Discounting some measured cylinder-pressure records, which were suspect, the investigation showed good agreement between the predicted and measured pressures in the cylinders and exhaust pipe. The analysis of the temperature records showed there was evidence of mixing and longitudinal heat transfer in the exhaust pipe; however, the mean computed temperature in the exhaust pipe at the nozzle end agreed with the measured temperature. Comparison of the measured and computed mass flows at the nozzle end of the pipe using the theoretical diagrams gave good agreement. It was concluded that the computer programme was a satisfactory method for calculating the pressures in the cylinder and exhaust pipe during the gas-exchange process.

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.

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