Journal of Thermal Science

, Volume 19, Issue 2, pp 141–147 | Cite as

Fluid dynamic modeling of a free piston engine with labyrinth seals

  • Jaakko Larjola
  • Juha Honkatukia
  • Petri Sallinen
  • Jari Backman


Preliminary design and simulation of a free piston engine suitable for small-scale energy production in distributed energy systems is presented in this paper. The properties, particularly the properties of gas seals of the engine are simulated using a simulation program developed for this case, and the results are utilized in preliminary main design parameter selection. The engine simulation program was developed by combining and modifying the source codes of the simulation and calculation programs obtained from Helsinki University of Technology, Tampere University of Technology, and Lappeenranta University of Technology. Because of the contact-free labyrinth seal used in the piston, the efficiency of the motor is lower than the efficiency of a conventional motor with oil lubricated piston rings. On the other hand, the lack of bearing losses, and the lack of losses associated with a crankshaft system and a gearbox, as well as the lack of lubrication oil expenses, compensates this effect. As a net result, this new motor would perform slightly better than the conventional one. Being completely oil-free, it is very environmentally friendly, and its exhaust gases are completely free of oil residuals which are causing problems in normal gas motors.


free piston engine distributed energy systems simulation labyrinth seal 


Unable to display preview. Download preview PDF.

Unable to display preview. Download preview PDF.


  1. [1]
    Innas B.V. commercial brochure, Accessed 1/2005.
  2. [2]
    Tikkanen S. 2000, Evolution of Engine — Hydraulic Free Piston Engine. Dissertation. Acta Polytechnica Scandinavica. Mechanical Engineering Series No. 145. Tampere University of Technology, 2000.Google Scholar
  3. [3]
    Pempek Systems commercial brochure, www., Accessed 3/2005.
  4. [4]
    Wechner E. 2003, Improvements to free-piston engines. Australian patent No 762530, 26.6.2003 (applied 4.5.2001).Google Scholar
  5. [5]
    Larjola, J., Honkatukia, J., Sallinen, P.: Environmentally friendly, oil-free free piston engine (in Finnish). Lappeenranta University of Technology, Dep. of Energy and Environmental Tech., Research Report EN B-163, 2005Google Scholar
  6. [6]
    Larjola J. 2002, Two-stroke engine (in Finnish). Patent No FI 108567 B, 15.2.2002 (applied 20.11.2000).Google Scholar
  7. [7]
    Larmi M., Isaksson S., Tikkanen S., Lammila M. 2001, Performance Simulation of a Compression Ignition Free Piston Engine. SAE Paper 2001-01-0280. 8 p.Google Scholar
  8. [8]
    Reunanen A., Backman J., Sahlberg P. 1994, Fluid mechanical design of an axial labyrinth seal (in Finnish). Research report EN B-85. LUT. Lappeenranta. 1994. 42 p. ISBN 951-763-871-X. ISSN 0787-0043.Google Scholar
  9. [9]
    Hirvonen M., Pyrhönen O., Handroos H. 2004, Force Ripple Compensator for a Vector Controlled PM Linear Synchronous Motor. ICINCO 2004, Setubal, Portugal 2004, Vol. 2, pp.177–184.Google Scholar
  10. [10]
    Tikkanen S., Vilenius M. 2004, The control system of a linear engine. Symopro-Control system. Tuotekehitys Oy Tamlink. Tampere 2004 (limited distribution).Google Scholar

Copyright information

© Science Press, Institute of Engineering Thermophysics, CAS and Springer-Verlag Berlin Heidelberg 2010

Authors and Affiliations

  • Jaakko Larjola
    • 1
  • Juha Honkatukia
    • 1
  • Petri Sallinen
    • 1
  • Jari Backman
    • 1
  1. 1.Lappeenranta University of TechnologyLappeenrantaFinland

Personalised recommendations