This content is not included in your SAE MOBILUS subscription, or you are not logged in.
Numerical Simulation of a Two-Stroke Linear Engine-Alternator Combination
ISSN: 0148-7191, e-ISSN: 2688-3627
Published March 01, 1999 by SAE International in United States
Annotation ability available
Series hybrid electric vehicles (HEVs) require power-plants that can generate electrical energy without specifically requiring rotary input shaft motion. A small-bore working prototype of a two-stroke spark ignited linear engine-alternator combination has been designed, constructed and tested and has been found to produce as much as 316W of electrical energy. This engine consists of two opposed pistons (of 36 mm diameter) linked by a connecting rod with a permanent magnet alternator arranged on the reciprocating shaft. This paper presents the numerical modeling of the operation of the linear engine. The piston motion of the linear engine is not mechanically defined: it rather results from the balance of the in-cylinder pressures, inertia, friction, and the load applied to the shaft by the alternator, along with history effects from the previous cycle. The engine computational model combines dynamic and thermodynamic analyses. The dynamic analysis performed consists of an evaluation of the frictional forces and the load (in this case the alternator load) across the full operating cycle of the engine. The thermodynamic analysis consists of an evaluation of each process that characterizes the engine cycle, including scavenging, compression, combustion and expansion, based on the first law of thermodynamics. Since the modeled engine was crankshaftless, a time-based Wiebe function (as opposed to a conventional crank angle-based approach) was used to express the mass fraction burned for the combustion process, while the combustion model used was a single-zone model. To render the model useful, the parameters used were based on experimental data obtained from the working example, including instantaneous shaft position, velocity and in-cylinder pressure. Also, a parametric study was performed to predict the behavior of the engine over a wide operating range, given variations in fuel combustion properties, the reciprocating mass of the piston shaft assembly, frictional load and the externally applied electrical load.
- Christopher M. Atkinson - West Virginia University
- Sorin Petreanu - West Virginia University
- Nigel N. Clark - West Virginia University
- Richard J. Atkinson - West Virginia University
- Thomas I. McDaniel - West Virginia University
- Subhash Nandkumar - West Virginia University
- Parviz Famouri - West Virginia University
CitationAtkinson, C., Petreanu, S., Clark, N., Atkinson, R. et al., "Numerical Simulation of a Two-Stroke Linear Engine-Alternator Combination," SAE Technical Paper 1999-01-0921, 1999, https://doi.org/10.4271/1999-01-0921.
- Diesel Cleveland, “History and description of the free piston engine-gas turbine power”, year unkown.
- Underwood A.F.,“GMR 4-4 Hyprex Free Piston Turbine Engine”, SAE Journal, June 1956, pp. 60-66.
- Frey D.N., Klotsch P. and Egli A.,“The Automotive Free-Piston-Turbine Engine”, SAE Transactions, Vol. 65, 1957, pp. 629-634.
- Bock R., U.S. Patent 4,128,083, December 5,1978,“Gas Cushion Free-Piston Type Engine”
- Heintz R. P., U.S. Patent 4,369,021, May 5,1980,“Free-Piston Engine Pump”
- Rittmaster P. A. et al., U.S. Patent 4,326,380, April 27,1982,“Hydraulic Engine”
- Iliev M. D. et al., U.S. Patent 4,532,431, July 30,1985,“Method and Apparatus for Producing Electrical Energy from a Cyclic Combustion Process utilizing Coupled Pistons which Reciprocate in Unison”
- Galitello K. A., Jr., U.S. Patent 4,876,991, October 31,1989,“Two Stroke Cycle Engine”
- Kos J. F., U.S. Patent 5,002,020, March 26,1991,“Computer Optimized Hybrid Engine”
- Widener S. K. and Ingram, K., “Free-Piston Engine Linear Generator Technology Development,” Final Report, Under Contract to U.S. Army TARDEC, Mobility Technology Center-Belvoir, Fort Belvoir, Virginia, January 1995.
- Clark N. N., McDaniel T. I., Atkinson R. J., Nandkumar S., Atkinson C. M., Petreanu S. and Famouri P., “Modeling and Development of a Linear Engine”, 1998 Spring Technical Conference, ASME ICE Division, Fort Lauderdale, FL.
- Clark N. N., McDaniel T. I., Atkinson R. J., Nandkumar S., Atkinson C. M., Petreanu S. and Famouri P., “Operation of a Small Bore Two-Stroke Linear Engine”, 1998
- Blair P.G., “Design and Simulation of Two-Stroke Engines”, SAE Inc., Warrendale, Pa., 1996
- Heywood J. B., “Internal Combustion Engine Fundamentals”, John Wiley and Sons, New York, 1986.
- Nandkumar S., “Modeling of a Linear Engine”, MSME Thesis, West Virginia University, 1998
- Achten P. A. J., “A Review of Free-Piston Engine Concepts”, SAE 941776, 1994.