29-12-2012, 06:40 PM
THERMO-MECHANICAL ANALYSIS OF PISTON IN HIGH SPEED DIESEL ENGINE
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INTRODUCTION
CVRDE
Combat Vehicle Research and Development
Establishment (CVRDE) has taken up the project of
upgrading a supercharged engine of power 580 kW
(780 HP) to 735 kW (1000 HP) turbocharged engine by
employing suitable modifications in the form of a
conversion kit consisting of high performance fuel
injection system, pulse type exhaust driven
turbochargers, piston jet cooling, charged air cooler,
enhanced capacity water pump and a lubrication oil
pump for achieving
•High Power
•High Torque
•High power to weight ratio
•Compactness and Reliability
These factors contribute to the increase
in stress in the engine components engine
head, cylinder block with liner, piston,
piston rings, connecting rod, crank shaft,
and crank case.
PISTON, PISTON PIN & PISTON RINGS
Piston is a cylindrical shaped mass that
reciprocates inside the cylinder. It is attached to
the connecting rod that forms a swivel joint at
each end.
When the combustion pressure builds up in
combustion chamber it pushes on the piston.
The piston, in turn, pushes on the piston pin or
wrist pin that connects the piston to the upper end
of the connecting rod.
CYLINDER HEAD
In an internal combustion diesel engine, the
cylinder head sits atop the cylinders and consists
of a platform containing part of the combustion
chamber and the location of the valves.
The top half of the cylinder head contains the
camshaft in an overhead cam engine, or another
mechanism (such as rocker arms and pushrods)
to transfer rotational motion from the crankshaft
to linear motion to operate the valves.
CYLINDER BLOCK WITH LINER
A cylinder is the central working part of a
reciprocating engine, the space in which a
piston travels. Multiple cylinders are
commonly arranged side by side in a bank
and called as engine block.
The cylinder block or engine block is a
machined casting containing cylindrically
bored holes for the pistons of a multi-cylinder
reciprocating internal combustion engine.
CRANK CASE
The crankcase supports the cylinders and the
crankshaft and also functions like a housing and
protects the engine parts against dust, water and
splashing mud.
The crankcase stores lubricating oil required for
lubricating the engine parts.
The size of a crankcase is sufficiently large so that
it accommodates the revolving crankshaft with the
connecting rod.
PROBLEM DEFINITION & SOLUTION APPROACH
ENGINE UPRATING
CVRDE has taken up the project of uprating the
existing heavy duty engine to high power capacity,
without modifying the basic configuration of the
engine.
The power output can be increased by modifying
the parameters of an engine:
•Mean effective pressure
•Stroke length
•Cross section area of the cylinder
•Number of cylinders
CONCLUSION
•The analysis results show the stress obtained is within
the limit of yield stress.
•The stress and deformation patterns show how they
are varying through the Piston. These distribution
patterns, give the idea for design modifications.
•The heat transfer coefficients are approximations, as
there are transient effects on Piston loads, there may
be deviation in the results.