Numerical Analysis of Gas Exchange and Combustion Process in a Small Two-Stroke Gasoline Engine

et al. 2013

AMR

The advantages and basic structure of hydraulic free-piston engine (HFPE) were presented. And the operation principle of a single piston compression-ignition HFPE was analyzed. Based on the basic theory of thermodynamics, hydraulic fluid mechanics and dynamics, the system simulation model for a single-piston compression-ignition HFPE was established in the environment of MATLAB/SIMULINK. The simulation results, which accord with the related literature data, indicate that the asymmetric characteristics of piston motion in the entire cycle are very obvious, the compression stroke duration is longer than the expansion stroke, the time at around the top dead center (TDC) is short. The piston assembly motion is a process when the energy balance is fulfilled, and some factors must be taken into account for design optimization, such as the piston assembly mass, compression accumulator pressure, fuel injection timing and fuel injection quantity.

Section: Resultsmentioning

confidence: 99%

Motion Characteristics and Influence Factors of Piston Assembly in a Compression-Ignition Hydraulic Free-Piston Engine

et al. 2013

AMR

“…These small particles travel down the turbulent jet towards the head vortex, while growing in size through surface growth and coagulation. Oxidation of the soot particles occurs when they move close to or through the diffusion flame formed around the periphery of the fuel spray [7]. Here the particles are subjected to high temperatures and exposed to oxygen attack.…”

Section: Cfd Modelingmentioning

confidence: 99%

Multi-Dimensional Analysis of NO<sub>x</sub> and Soot Formation in a Diesel-Fueled Hydraulic Free Piston Engine

Yu¹,

et al. 2013

AMR

This paper is aimed at simulating and analyzing emission NOxand Soot formation in the hydraulic free piston engine (HFPE) designed and constructed by Jilin University. The combustion process of HFPE is simulated by using the commercial CFD software AVL FIRE, and the flow field and factors that influence NOxand Soot formation were analyzed. The simulated results indicate that NO is mainly distributed in the burned zone, whereas the distribution of Soot acts in accord with high unburnt equivalence ratio and high temperature burned zone. Injection timing increases, the amount of the formation of NO is reduced, whereas the mass fraction of Soot rises to a peak and descends. And small swirl ratio exerts a minor influence on emission mass fraction of HFPE.

“…The scavenging ports and scavenging case were initialized with homogenous fresh charge, whereas the exhaust port and cylinder with high pressure burned gas. A fixed pressure was applied to inlet and outlet boundary, and constant wall temperatures were also used [7].…”

Section: Configuration Of Scavenging Systemmentioning

confidence: 99%

Modeling and Analysis of the Scavenging System for a Two-Stroke Cycle Hydraulic Free Piston Engine

et al. 2013

AMR

A prototype of hydraulic free piston engine (HFPE) is being designed and constructed by Jilin University to achieve direct hydraulic wheel-drive and replace the current hydraulic drivers. This paper is aimed at modeling and analyzing the scavenging system for the HFPE. Based on the prototype engine E150, two stroke scavenging system for HFPE has been designed by analogy, the gas flow of HFPE during the scavenging process is simulated by using the commercial CFD software AVL FIRE. So some key scavenging parameters and flow field were obtained, the simulated results indicate that scavenging efficiency of loop scavenging system can meet the design requirement, it lies between perfect displacement and perfect mixing scavenging, and keeps decreasing while the operation frequency keeps increasing.