Thesis-2008-Mishra.pdf (23.09 MB)
Transient thermo elastohydrodynamics of piston compression ring-cylinder liner contact
thesis
posted on 2013-12-02, 16:33 authored by P.C. MishraInternal combustion engine due to Thermodynamics deliver output of 25% of the
input fuel energy. Hence £75 out of every £ 100 invested in fuel in an engine is lost in
the form of emissions, vibration, or heat di ssipation. Mechanical losses in an IC
engine are referred to as " parasitic losses", which account for 15% of the total losses.
There is a possibility for reducing these losses through appropriate remedies.
The piston assembly is a common contributor to the mechanical losses. This could be
as high as 45% of it. A typical piston assembly consists of a compression ring, a
scraper ring and an oil ring mounted on the piston body. The most significant loss in
the piston assembly is from the ring pack and cylinder bore interaction and can
account for 80% of this. Two thirds of the total loss due to ring pack is contributed by
the compression ring. In the process of simultaneous sealing and reciprocation, a
compression ring is subjected to modal stresses, which imparts radially a outward
force, in-plane, out-of-plane bending moment and twisting moment; as well as axial
flutter and twist. The radial deformation of the ring and the issue of ring-bore
conformability are important, and are addressed in the current analysis, which
deve lops a tribo-dynamics model of the compression ring and cylinder liner
conjuction.
As part of the lubrication modelling, an isothermal model is developed to estimate
frictional losses, initially with a consideration of asperity interaction and viscosity pressure
dependency, when solving Reynolds equation. Further improvements include
the effect of roughness on flow behaviour of the lubricant. Both of these approaches
are combined for a transient analysis. The results are compared with measurements
from the literature and good agreement is found.
The novelty of the current research is the combined solution of Reynolds' equation,
and the energy equation using appropriate rheological behaviour for evaluating the
key lubrication performance parameters such as pressure, temperature, viscosity,
minimum film, friction loss, also considering asperity interaction for a globally
deformed compression ring.
History
School
- Mechanical, Electrical and Manufacturing Engineering
Publisher
© Prakash Chandra MishraPublication date
2008Notes
A Doctoral Thesis. Submitted in partial fulfilment of the requirements for the award of Doctor of Philosophy of Loughborough UniversityLanguage
- en