IC Engine Piston Design

THERMO
STRUCTURAL
DESIGN OF A FOUR
STROKE IC ENGINE
JJ Technical Solutions
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Presentation Outline
 Introduction
 Aim
 Literature Review
 Problem Formulation
 Scheme of Implementation
 Progress Made
 References
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AIM
The aim of the study is to understand the effect of the shape of an IC Engine
Piston on its structural strength and the fins parameters effect viz. shape,
material, heat transfer coefficient etc. on the rate of heat transfer from the fins,
using FEA package Ansys 14.0.
An existing 4 stroke, Spark Ignition, air cooled IC engine (Bajaj Pulsar 150cc)
is modeled and optimize its piston design & fin geometry by varying the
following design parameters:
 Effect of piston shape and material on the stresses developed in the piston.
 Optimization of piston crown design and comparison with analytical results.
 Study the effect of fin geometry, pitch and shape on the rate of heat transfer.
 Optimize the fin design for rate of heat transfer and weight of fin.
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LITERATURE REVIEW
S. No. Name of the Parts Materials of Construction
1. Cylinder head Cast iron, Cast Aluminium
2. Cylinder liner Cast steel, Cast iron
3. Engine block Cast iron, Cast aluminum, Welded steel
4. Piston Cast iron, Aluminium alloy
5. Piston Pin Forged steel, Case hardened steel.
6. Connecting rod Forged steel. Aluminium alloy.
7. Piston rings Cast iron, Pressed steel alloy.
8. Connecting rod bearings Bronze, White metal.
9. Main bearings White metal, Steel backed Babbitt base.
10. Crankshaft Forged steel, Cast steel
11. Camshaft Forged steel, Cast iron, cast steel,
12. Timing gears Cast iron, Fiber, Steel forging.
13. Push rods Forged steel.
14. Engine valves Forged steel, Steel, alloy.
15. Valve springs Carbon spring steel.
16. Manifolds Cast iron, Cast Aluminium.
17. Crankcase Cast iron, Welded steel
18. Flywheel Cast iron.
19. Studs and bolts Carbon steel.
20. Gaskets Cork, Copper, Asbestos.
Different materials used for IC engine construction
Components of a two stroke, Air Cooled, SI engine
IC ENGINE

LITERATURE REVIEW….
Pressure v/s crank angle for a SI engine
Temperature v/s crank angle for a SI Engine at
full loadWorking Principle and PV diagram of a SI Engine (Otto-
cycle)
IC ENGINE

Piston in an IC engine must possess the following
characteristics:
1. Strength to resist gas pressure and inertia forces.
2. Must have minimum weight to minimize the inertia
forces.
3. Must be able to reciprocate with minimum noise.
4. Must have sufficient bearing area to prevent wear.
5. Must seal the gas from top and oil from the bottom.
6. Must disperse the heat generated during
combustion.
7. Must have good resistance to distortion under heavy
forces and heavy temperature.
The piston assembly consists of the head or crown, piston rings, skirt and Piston Pins.
Piston cross sectional view
PISTON

PISTON DESIGN
The piston head or crown is designed keeping in view the following two
main considerations.
1. It should have adequate strength to withstand the straining action due
to pressure of explosion inside the engine cylinder , and
2. It should dissipate the heat of combustion on the cylinder walls as
quickly as possible.
tH = )(
16
3 2
inmm
pD
ts
tH = )(
)(56.12
inmm
TTK
H
EC -
When tH is 6mm or less, then no ribs are required to strengthen the piston head against gas loads . But
when tH is greater than 6mm then a suitable number of ribs at the centre line of the boss extending around
the skirt should be provided to distribute the side thrust from the connecting rod and thus to prevent
distortion of the skit .The thickness of the ribs may be takes as tH / 3 to tH /2.
For engines having length of stroke to cylinder bore (L/D) ratio upto 1.5 a cup is provide in the top of the
piston head with a radius equal to 0.7D. This is done to provide space for combustion chamber
CROWN THICKNESS-
STRUCTURAL
CROWN THICKNESS-
THERMALL

FIN DESIGN
Energy distribution in a Typical Spark Ignition Engine
Typical straight fin configuration
Fin Performance:
• Fin Effectiveness
• Fin Efficiency
Fin effectiveness is enhanced by:
a) Using material with high thermal conductivity like Copper,
Aluminum etc.
b) Increasing the ratio of perimeter to the cross-sectional area of the
fin; P/A. Therefore the use of thin, but closely spaced fins is
preferred to that of thick ones. For example during use a square
fin with a dimension of W×W: P=4W, AC=W2, P/AC=(4/W).
The smaller W, the higher the P/AC, and the higher f.
c) Lower value of heat transfer coefficient h. The fins are preferable
when the fluid is a gas rather than a liquid, particularly when the
heat transfer from surface is by natural convection. If fins are to
be used on surfaces separating gas and liquid. Fins are usually
placed on the gas side. Therefore, it is no coincidence that in
liquid-to-gas heat exchangers such as the car radiator, fins are
placed on the gas side.

LITERATURE REVIEW…. www.mechieprojects.com

PROBLEM
FORMULATION
There are three scope of study for this dissertation of
thermo structural design of an IC engine:
1. Modeling in 3D of piston and fin configuration
using Cad Software’s SolidWorks
2. Finite Element Modeling and mesh
optimization using Ansys14.0 & Fluent
3. Using linear static stress and thermal analysis
under static loading method
Axis-symmetric models will be made in SolidWorks
and imported to Ansys/Gambit for Meshing. The
meshed geometries will be imported to Fluent for
problem solving
After the solution of first iteration, a new model
based on the case considered will be drafted and
subjected to the same process.
The results of all these iterations will be tabulated
and documented.Project Flow Chart

INITIAL STUDY
 To study the effect of piston geometry on stress generated due to
combustion pressure, three shapes of piston is drawn namely flat, concave
and convex and the same is modeled in solid works. Also to study the
effect of fin shape for the total heat dissipated different fin configurations
are drawn to be solved in Ansys.
 The Spark Ignition engine considered for this study is Bajaj Pulsar DTSI
150 cc engine. The engine and fin specifications is as follows:
Engine 4 Stroke, Single Cylinder, Air Cooled
Max. Power 14.5 PS @ 8500rpm
Max. Torque 12.76 Nm @ 6500rpm
Displacement 149.01 cc
Bore and Stroke 56 × 58.8 mm
Piston Al. alloy, flat top Piston
Idling speed 1400 RPM
Compression Ratio 9.5:1
Fin Material Al. Alloy
No. of fins 12
Fin Pitch 10
Fin Thickness 2mm
Fin Profile Rectangular (uniform cross section) with curved edges
Max. Fin Height 35mm
Min. Fin Height 10mm
Sl.No
PARAMETERS
Al. alloy
A4032
1
Elastic Modulus (GPa)
79
2
Ultimate Tensile Strength (MPa)
380
3
0.2% Yield Strength (MPa)
315
4 Poisson’s Ratio 0.33
5 Thermal Conductivity (W/m/
o
C) 154
6 Coefficient of Thermal Expansion
(1/K)
79.2
7
Density (Kg/m3
)
2684
The Properties of Aluminum Alloy
The Engine and Fin Specifications for Modeling and Meshing

REFERENCES
[1] Heat and Mass Transfer by R.K. Rajput (2007)
[2] Isam Jasim Jaber and Ajeet Kumar Rai, “Design and Analysis of IC
Engine Piston and Piston-Ring Using CATIA and ANSYS Software”,
IJMET, Vol.5, 2014.
[3] J.C.Sanders, et al. (1942). Cooling test of an air-cooled engine cylinder
with copper fins on the barrel, NACA Report E-103
[4] Thermal Engineering by Rudramoorthy.
[5] P. Agarwal, et al. (2011). Heat Transfer Simulation by CFD from Fins of
an Air Cooled Motorcycle Engine under Varying Climatic Conditions.
Proceedings of the World Congress on Engineering.
[6] J.A. Paul, et al. (2012). "Experimental and Parametric Study of Extended
Fins in the Optimization of Internal Combustion Engine Cooling Using
CFD." International Journal of Applied Research in Mechanical
Engineering (IJARME) 2(1).
[7] Heat Transfer by PK Nag.
[8] D.G.Kumbhar, et al. (2009). Finite Element Analysis and Experimental
Study of Convective Heat Transfer Augmentation from Horizontal
Rectangular Fin by Triangular Perforations. Proc. of the International
Conference on Advances in Mechanical Engineering.
[9] Denpong Soodphakdee, et al. (2001). "A Comparison of Fin Geometries for
Heatsinks in Laminar Forced Convection Part 1 - Round, Elliptical, and
Plate Fins in Staggered and In-Line Configurations." The International
Journal of Microcircuits and Electronic Packaging 24(1).
[10] Biermann, A. E. and B. Pinkel (1934). Heat Transfer from finned metal
cylinders in an air stream, NACA Report No.488
[11] Shigley, Mechanical Engineering Design, 9
th
editions, McGraw-Hill.
[12] Ajay Raj Singh et al. (2014) “ Design Analysis and Optimisation of three
Aluminium piston alloy using FEA”. IJERA Vol. 4, Issue 1, 2014.
[13] Aditya Kumar Gupta et. al. (2014) “ Design Analysis and Optimisation of IC
engine piston using CAE tool ANSYS”. IJERA, Vol4, Issue 11, 2014.

IC Engine Piston Design

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IC Engine Piston Design