MODELING AND ANALYSIS OF AN

EXPERIMENTAL CERAMIC COATED

CYLINDER AIDING IMPROVEMENT IN

PERFORMANCE CHARACTERISTICS OF AN IC

ENGINE

A PROJECT REPORT

Submitted By

K.SREE PRANEETH [Reg.No: 1021010169]

KRISHNA ADITYA Y V [Reg.No:1021010171]

S.AVINASH REDDY [Reg.No: 1021010281]

Under the guidance of

V.G UMASEKAR, M.E (Asst. Professor, Department of Mechanical Engineering)

V.P HARIDASAN, M.E,(Ph.D) (Asst. Professor(Sr.G), Department of Mechanical Engineering)

In partial fulfilment for the award of the degree of

BACHELOR OF TECHNOLOGY

MECHANICAL ENGINEERING

FACULTY OF ENGINEERING & TECHNOLOGY

S.R.M Nagar, Kattankulathur, Kancheepuram District

May 2014

SRM UNIVERSITY (Under section 3 of UGC act, 1956)

BONAFIDE CERTIFICATE

Certified that this project report titled “MODELING AND

ANALYSIS OF AN EXPERIMENTAL CERAMIC COATED

CYLINDER AIDING IMPROVEMENT IN PERFORMANCE

CHARACTERISTICS OF AN IC ENGINE” is the bonafide work of

K.SreePraneeth(Reg.No:1021010169),KrishnaAdityaYV(Reg.No:102

1010171) & S.AvinashReddy(Reg.No:1021010281), who carried out the

project under my guidance. Certified further, to the best of my knowledge

the work reported herein does not form any other project report or

dissertation on the basis of which a degree or award was conferred on an

earlier occasion on this or any other candidate.

Mr. V.G UMASEKAR,M.E Head Of The Deparment

GUIDE Dept. Of Mechanical Engg.

Asst.Professor ( O.G)

Dept. of Mechanical Engg.

Signature of Internal Examiner Signature of External Examiner

ABSTRACT

As per second law of thermodynamics the efficiency of engine depends

upon the extraction of work against the heat supplied. Minimization of

heat rejection leads to increase in the work. With growing demand for

efficient usage of fuels, it is the need of the hour to increase the efficiency

of an I.C engine widely used in automobile and aerospace applications.

To achieve the same, it was proposed use high performance ceramics to

retain heat in the combustion chamber. High performance ceramics

include various materials like thermal barrier ceramics, wear resistant

ceramics, anti-friction ceramics etc. These ceramics are chosen according

to the availability, cost and coating techniques.

This project is carried to understand and analyse the effect of thermal

insulation of an experimental aluminium cylinder block using TBC

coating in between inner liner used in IC engine and engine block.

Experimental model is developed from a cylindrical aluminium block

performing necessary operations to check the thermal conductivity of the

composite wall of the cylinder. ANSYSR is used to understand the

thermal conduction virtually. Several iterations for required thickness of

the TBC coat are performed for too much insulation would raise cooling

and strength issues at elevated temperatures in an IC engine.

ACKNOWLEDGEMENT

We express our deep sense of gratitude and indebtedness to our

esteemed institute “SRM University, Kattankulathur”, which has

provided us an opportunity to fulfil the most cherished desire to reach our

goal.

We owe our project to Mr. V.G.UMASEKAR, Assistant

Professor, Department of Mechanical Engineering, who has been our

project guide and instructor. We sincerely thank him, for the support and

guidance which he has given to us, without which we would not have

made this effort of ours a success.

Our deep hearted thanks to Mr. V.P.Haridasan, Assistant

Professor (Sr.G), Department of Mechanical Engineering, for being so

helpful in providing his valuable advice and guidance.

We are thankful to the people out of the college who have helped

us kick-start the project with their timely help and valuable suggestions

through e-mails and online support.

Our deep hearted thanks to all the faculty members of our

department for their value based imparting of theory and practical

subjects, which we have put into use in our project.

We are also indebted to the non-teaching staff for their

cooperation.

We would like to thank our friends for their help and support in

making our project a success.

CONTENTS

Chapter No Title Page No

ABSTRACT iv

LIST OF TABLES v

LIST OF FIGURES vi

LIST OF SYMBOLS viii

1. Introduction 1

2. Literature Review 5

2.1 Advanced technology ceramics 5

2.2 Heat transfer in an IC engine 5

2.3 Choosing a ceramic for coating 6

2.3.1 Thermal conductivities of various TBCs 8

2.4 Ceramic coating 8

2.4.1 Layers of coating 8

2.4.2 Coating techniques 11

3. Modeling and Finite element analysis of the specimen 14

3.1 Modeling 14

3.1.1 Cast iron liner 14

3.1.2 Aluminium sleeve 15

3.1.3 Thermal Barrier Coat (TBC) 15

3.1.4 Cylinder 16

3.1.5 The experimental specimen 17

3.2 Finite Element Analysis 18

3.2.1 Thermal analysis 18

3.2.2 Structural analysis 19

4. Results and Discussions 22

4.1 Specimen with no TBC 22

4.2 Specimen with 1cm thick TBC 25

4.3 Specimen with optimum TBC thickness 28

4.4 Conclusion 33

4.4.1 Choosing optimum coat thickness 33

4.4.2 Scope of improvement in efficiency of IC engine 33

5. Future Scope of the Project 34

Appendix1 35

Appendix2 36

References 37

LIST OF TABLES

Fig. No Title Page No

1.1 Advanced technology ceramics’ properties 6

4.1 Results of thermal analysis 32

4.2 Results of structural analysis 32

LIST OF FIGURES

Fig.No Title Page no

1.1. Energy balance illustration for conventional engine and ceramic 1

coated Engine

2.1. Various structures of zirconia 6

2.2. Thermal conductivity of various TBCs 8

2.3. TBC Coating over a material 9

2.4. Schematic diagram of Plasma spray gun 12

3.1. Cast Iron Liner 14

3.2. Aluminium sleeve 15

3.3. TBC layer 16

3.4. Cylinder 16

3.5. Experimental setup 17

3.6. Meshing for thermal analysis 19

3.7. Thermal loads 19

3.8. Interlinking thermal and structural analysis 20

3.9. Meshing for structural analysis 20

3.10. Defining supports 21

3.11. Defining structural loads 21

4.1. Thermal gradient of the specimen with no TBC 22

4.2. Total heat flux of the specimen with no TBC 23

4.3. Directional heat flux of the specimen with no TBC 23

4.4. Total deformation of the specimen with no TBC 24

4.5. Directional deformation of the specimen with no TBC 24

4.6. Equivalent stresses of the specimen with no TBC 25

4.7. Temperature gradient of the specimen with 10mm thick TBC 25

4.8. Total heat flux of the specimen with 10mm thick TBC 26

4.9. Directional heat flux of the specimen with 10mm thick TBC 26

4.10. Total deformation of the specimen with 10mm thick TBC 27

4.11. Directional deformation of the specimen with 10mm thick TBC 27

4.12. Equivalent stresses of the specimen with 10mm thick TBC 28

4.13. Temperature gradient of the specimen with optimum TBC thickness 28

4.14. Total heat flux of the specimen with optimum TBC thickness 29

4.15. Directional heat flux of the specimen with optimum TBC thickness 29

4.16. Total deformation of the specimen with optimum TBC thickness 30

4.17. Directional deformation of the specimen with optimum TBC 30

thickness

4.18. Equivalent stresses of the specimen with optimum TBC thickness 31

LIST OF SYMBOLS

PROPERTY SYMBOL UNITS

Thermal conductivity k W/mK

Convective heat transfer co-efficient h W/m2K

Degree Of Freedom D.O.F _

Heat transfer rate Q W

Temperature T K

Radius r m

Chapter 1

INTRODUCTION

Energy conservation and efficiency have always been the quest of engineers

concerned with internal combustion engines. J.Rajasekharan et al..,2013[1]; says

even the petrol engine rejects about two thirds of the heat energy of the fuel, one-third

to the coolant, and one third to the exhaust, leaving only about one-third as useful

power output as shown in fig 1.1. Theoretically if the heat rejected could be reduced,

then the thermal efficiency would be improved. Low Heat Rejection engines aim to

do this, by reducing the heat lost to the coolant.

Bryzik and Kamo et al..,1983; reported 35% reduction in engine dimensions and 17%

reduction in fuel consumption with a thermal barrier coated engine design in a

military tank.

Fig. 1.1 Energy balance illustration for conventional engine and ceramic coated

engine

Thermal Barrier Coatings (TBCs) in petrol engines lead to advantages including

higher power density, fuel efficiency, and multi fuel capacity due to higher

combustion chamber temperature. Using TBC can increase engine power and

decrease the specific fuel consumption and increase the exhaust gas temperature.

Aravinth et al..,2012[2]; Although several systems have been used as TBC for

different purposes, yttria stabilized zirconia has received the most attention. Several

factors play important roles in TBC lifetimes including thermal conductivity, thermal,

chemical stability at the service temperature, high thermo mechanical stability to the

maximum service temperature and the thermal expansion coefficient. Some

advantages of TBC coated engines are:

1. Low cetane fuels can be burnt

2. Improvements occurs at emissions except NOx

3. Waste exhaust gases are used to produce useful shaft work

4. Increased effective efficiency

5. Increased thermal efficiency

6. Using lower-quality fuels within a wider distillation range

7. The ignition delay of the fuel is considerably reduced

8. The faster vaporization and the better mixing of the fuel

9. Reduced specific fuel consumption

10. Multi-Fuel capability

11. Improved reliability

12. Smaller size

13. Lighter weight

14. Decreased the heat removed by the cooling system

The petrol engine with its combustion chamber walls insulated by ceramics is referred

to as Low Heat-Rejection (LHR) engine. The LHR engine has been conceived

basically to improve fuel economy by eliminating the conventional cooling system

and converting part of the increased exhaust energy into shaft work using the

turbocharged system. This study presents effect of Zirconia coating on the cylinder

bore on the performance of the modified four stroke engine

Heat can only be transferred by:

conduction

radiation

Convection is conduction in a moving medium, energy is transferred by fluid

motion which is not heat transfer.

Impact of Engine Heat Transfer on various parameters of performance:

1) Efficiency and Power: Heat transfer in the inlet decrease volumetric efficiency. In

the cylinder, heat losses to the wall is a loss of availability.

2) Exhaust temperature: Heat losses to exhaust influence the turbocharger

performance. In-cylinder and exhaust system heat transfer has impact on catalyst light

up.

3) Friction: Heat transfer governs liner, piston/ ring, and oil temperatures. It also

affects piston and bore distortion. All of these effects influence friction. Thermal

loading determined fan, oil and water cooler capacities and pumping power.

4) Component design: The operating temperatures of critical engine components

affects their durability; e.g. via mechanical stress, lubricant behaviour.

5) Mixture preparation in SI engines: Heat transfer to the fuel significantly affect

fuel evaporation and cold start calibration

6) Cold start of diesel engines: The compression ratio of diesel engines are often

governed by cold start requirement

7) SI engine octane requirement: Heat transfer influences inlet mixture temperature,

chamber, cylinder head, liner, piston and valve temperatures, and therefore end-gas

temperatures, which affect knock. Heat transfer also affects build up of in-cylinder

deposit which affects knock.

Proper use of ANSYS requires that you understand heat transfer sufficiently to:

Identify analytical solutions for verification

Identify approximate solutions for sanity checks

Some effects of heat transfer

• Higher heat transfer (HT) to combustion wall will lower the average combustion gas

temperature and pressure: reduces the work per cycle

• HT between unburned charge and cylinder wall in SI engines: affects onset of

knock, by limiting the compression ratio

• HT from exhaust valves and piston to mixture in SI engines: affects onset of knock,

by limiting the compression ratio

• Piston and liner distortion due to non‐uniformities have a significant impact on the

piston component of engine friction

• HT to inflowing charge reduces the volumetric efficiency (in SI engines the intake

mixture is heated to aid in vaporizing the fuel)

This project aims at modeling and analysis of the cylinder bore replica to understand

performance parameters like conduction of side walls and strength of the cylinder to

validate the design. ANSYSR

14.5 is used to conduct the analysis. Various stages of

the project involve selection of TBC, modelling of the cylinder, static thermal

analysis, structural analysis of the bore, iterating for optimum thickness and

conclusion.

Chapter 2

LITERATURE REVIEW

Many research activities are carried in the field of Ceramic coated IC engines. Several

published papers and journals are referred to understand the scope of the project.

2.1 Advanced technology ceramics

Ceramics have been used since nearly at the beginning of low heat rejection engines.

These materials have lower weight and heat conduction coefficient comparing with

materials in conventional engines (Gataowski, 1990). Nowadays, important

developments have been achieved in quantity and quality of ceramic materials. Also

new materials named as “advanced technology ceramics” have been produced in the

last quarter of 20th century from Murat et al..,2102[3];. Advantages of advanced

technology ceramics can be listed as below;

1. Resistant to high temperatures.

2. High chemical stability

3. High hardness values

4. Low densities

5. Can be found as raw material form in environment

6. Resistant to wear

7. Low heat conduction coefficient

8. High compression strength

2.2 Heat transfer in an IC engine

Three means of heat transfer are namely conduction, convection and radiation.

Internal combustion engines use heat to convert the energy of fuel to power. Not all of

the fuel energy is converted to power. Excess heat must be removed from the engine.

In engines, heat is moved to the atmosphere by fluids water and air. If excess heat is

not removed, engine components fail due to excessive temperature. Engine

temperature is not consistent throughout the cycle from Krisztina uzuneanu et

al..,;2008[4] . Heat moves from areas of high temperature to areas of low

temperature. Heat transfer parameters are further studied to understand the actual

thermal scenario in the engine.

2.3 Choosing a Ceramic for coating

Advanced technology ceramics consist of pure oxides such as alumina (Al2O3),

Zirconia (ZrO2), Magnesia (MgO), Berillya (BeO) and non oxide ones. Some

advanced technology ceramic properties are given below in table 1.1. Several

ceramics like Nikasil, zirconia are studied comparatively to choose the best among

them Murat et al..,2102[3].

Table 1.1: Advanced technology ceramics’ properties

Zirconia (ZrO2):

Zirconia can be found in three crystal structure as it can be seen in Fig 2.1. These are

monolithic (m), tetragonal (t) and cubic (c) structures. Monolithic structure is stable

between room temperature and 1170oC while it turns to tetragonal structure above

1170oC. Tetragonal structure is stable up to 2379

oC and above this temperature, the

structure turns to cubic structure.

Figure 2.1: Various structures of zirconia

Yttria (Y2O3):

Melting point of yttria is 2410oC. It is very stable in the air and cannot be reduced

easily. It can be dissolved in acids and absorbs CO2. It is used in Nerst lambs as

filament by alloyed with zirconia and thoria in small quantities. When added to

zirconia, it stabilizes the material in cubic structure. Primary yttria minerals are

gadolinite, xenotime and fergusonite. Its structure is cubic very refractory.

Magnesia (MgO):

Magnesia is the most abundant one in refractory oxides and its melting point is

2800oC. Its thermal expansion rate is very high. It can be reduced easily at high

temperatures and evaporate at 2300-2400oC. At high temperature levels, magnesia has

resistance to mineral acids, acid gases, neutral salts and moisture. When contacted to

carbon, it is stable up to 1800oC. It rapidly reacts with carbons and carbides over

2000oC. The most important minerals of magnesia are magnesite, asbestos, talc,

dolomite and spinel.

Alumina (Al2O3):

Melting point of alumina is about 2000oC. It is the most durable refractory material to

mechanical loads and chemical materials at middle temperature levels. Relatively low

melting point limits its application. It doesn’t dissolve in water and mineral acids and

basis if adequately calcined. Raw alumina can be found as corundum with silicates as

well as compounds of bauxide, diaspore, cryolit, silimanite, kyanite, nephelite and

many other minerals. As its purity rises, it becomes resistant to temperature, wear and

electricity.

Beryllia:

Beryllia has a high resistance to reduction and thermal stability and its melting point

is 2250oC. It is the most resistant oxide to reduction with carbon at higher

temperatures. Thermal resistance is very high though its electrical conductivity is very

low. Mechanical properties of beryllia are steady till 1600oC and it is one of the

oxides that has high compression strength at this temperature. An important amount

of beryllium oxide acquired from beryl. It is a favourable refractory material for

molten metals owing to its resistance to chemical materials (Geçkinli, 1992).

2.3.1 THERMAL CONDUCTIVITIES OF VARIOUS TBCs:

Since the project aims at retaining the heat in combustion chamber of an IC engine, it

is necessary that our selection of ceramic should be conductivity based. Direct contact

to the moving parts is avoided and hence need for structural rigidity is of lesser

priority. Conductivities of various TBCs are shown in the fig 2.2 graph below

A.G.Evans et al..,2007[5];.

Fig 2.2: Thermal conductivity of various TBCs

2.4 Ceramic coating:

2.4.1 Layers of coating:

A typical TBC system consists of (i) the top coat (TC), a porous ceramic layer that

acts as the insulator, (ii) the bond coat (BC), an oxidation-resistant metallic layer

between the substrate and the TC and (iii) the super alloy or other material substrate

that carries the structural load J.Rajasekharan et al..,2013[1].

Fig 2.3: TBC Coating over a material

THE TOP COAT:

The top coat provides thermal insulation for the underlying substrate as shown in fig

2.3. The specifications for this coating require a material that combines low thermal

conductivity and a coefficient of thermal expansion (CTE) that it is as similar as

possible to that of the substrate, so that generation of stresses during thermal cycling

can be minimized. The preferred material for this application is zirconia. Zirconia

may exist as three solid phases, which are stable at different temperatures. At

temperatures up to 1200°C, the monoclinic phase (m) is stable.

Zirconia transforms from the monoclinic to the tetragonal phase (t) above 1200°C

and above 2370°C to the cubic phase (c). Transformation from m to the t phase has an

associated volume decrease of 4% . To prevent catastrophic cracking as a result of the

volume changes accompanying the t→m transformation, which occurs at

temperatures within the range of the working environment in gas turbines, stabilizers

are added to the zirconia. These stabilize zirconia into its cubic or tetragonal phases.

Early attempts used MgO to stabilize zirconia in its cubic state, by adding 25 wt%

MgO. However, during heat treatment the zirconia reverts to its monoclinic form and

the stabilizing oxide precipitates out from solid solution, affecting the thermal

conductivity. Zirconia can be fully stabilised to its cubic phase by adding 20% yttria

by weight. However, such fully stabilised zirconia coatings perform very poorly in

thermal cycling tests. Typically 7-9wt% yttria is used to partially stabilise zirconia,

although other stabilizers have been used as well. Other stabilizers include CaO,

MgO, CeO2 Sc2O3.

The basic criteria for the selection of a suitable stabiliser include a suitable cation

radius, similar to that of zirconium, and a cubic crystal structure. Inspite of the

addition of a stabilizer in order to ensure phase stability of the top coat, phase changes

in the top coat might still be induced during service. An important aspect of the

performance of top coat material is its sintering behaviour. After prolonged heating

during service, sintering of the top coat can occur. This will result in healing of the

micro cracks and pores that will in turn reduce the strain tolerance of the coating and

increase the likelihood for spallation.

BOND COAT:

The bond coat protects the underlying substrate from oxidation and improves

adhesion between the ceramic and the metal. Oxidation occurs due to oxygen

reaching the bond coat by diffusion through the lattice of the top coat and permeation

through the pores. The yield and creep characteristics of the bond coat are thought to

be significant for the performance of the TBC system.

Commonly used bond coats can be divided in two categories: MCrAlY (where M= Co

or Ni or both) and Pt-modified aluminides. These coatings were developed for use as

protective coatings against oxidation and hot corrosion. When exposed to an oxidizing

environment, they form a stable dense alumina layer in preference to other oxides.

This alumina, often termed the thermally grown oxide (TGO) prevents further attack

of the underlying material, due to its low oxygen diffusivity and its good adherence.

MCrAlY bond coats are usually deposited by low –pressure plasma spraying and

consist of two phases (β-NiAl and either γ-Ni solid solution or γ’Ni3Al).

Small amounts of Y are added in order to improve TGO adherence .Yttrium additions

have been found to inhibit void formation at the TGO/BC interface. In addition, Y-

rich oxide protrusions are formed in the oxide that mechanically pegs the oxide to the

alloy. Furthermore, yttrium has the effect of decreasing the grain size of the TGO and

thus raising its mechanical strength. Pt-modified aluminides are usually fabricated by

electroplating a thin Pt layer on the super alloy and then aluminizing by chemical

vapour deposition or pack cementation. These coatings usually consist of a single

phase- β with Pt in solid solution. Platinum additions improve the spallation resistance

of conventional aluminide coatings. However, the mechanisms by which this occurs

are not fully understood. Optimum adhesion between the bond coat and the top coat is

attained differently in plasma sprayed and EB-PVD coatings. In plasma sprayed

coatings, it is achieved by mechanical interlocking of the two interfaces, so the

surface roughness of the bond coat is an important parameter.

In contrast, EB-PVD coatings achieve maximum durability when applied to a smooth

(preferably polished) surface, free of absorbed gases or loose oxides. Asperities in the

BC/TGO interface are thought to serve as nucleation sites for cracks that cause

coating spallation when they coalesce. MCrAlY bond coats creep at temperatures

above 800°C. At this temperature, stresses in the BC are relieved and it is non load

bearing. The creep behaviour of the BC can have a significant influence on the stress

state of the TBC and thus on the failure mechanisms.

2.4.2. Coating techniques:

Plasma Sprayed Coatings: A characteristic of all thermal spray processes is a highly

concentrated power source, to which the coating material is fed in the form of powder,

wire or rod. The coating material is melted and accelerated to the substrate, forming

the coating. The coating is formed of many overlapping splats, solidifying one after

another and locking one to another. Due to the high kinetic energy of the droplets, the

splats spread over the substrate, forming a pancake. It is widely used for the

production of TBCs. PS-TBCs have the necessary strain tolerance required for most

of the applications in which such coatings are currently applied A.G.evans et

al..,2008[5];. This is largely a consequence of the presence of many fine micro cracks

and pores in the microstructure, which results in low stiffness.

This low stiffness prevents large stresses from being generated in the top coat. The

thermal conductivity of plasma sprayed coatings range from 0.5-1.4W/mK, which is

lower than corresponding values for EB-PVD coatings.The microstructure of PS

TBCs exhibits pores and grain boundaries aligned perpendicular to the direction of

heat flux. Grain boundaries and pores hinder heat transfer. The shape and orientation

of porosity with respect to the heat flux are more critical factors than the total amount

of porosity for the thermal conductivity of PS coating. EB-PVD coatings offer

benefits over PS coatings in terms of the erosion resistance. In PS coatings, the

erosion occurs in the form of removal of the mechanically bonded splats by the

erosive material. Since inters plat porosity is already present, the energy required for

this process is low. The low cost associated with the PS process compared to EBPVD

makes PS TBCs is the more attractive. However, applications that require excellent

strain tolerance, good surface finish and erosion resistance, such as in aerofoils and

aero-gas turbines, EB-PVD coatings will be favoured.

THE PLASMA SPRAYING PROCESS:

The Plasma Jet: Plasma Spraying, first conducted by Reinecke in 1939, was

advanced in the late 50´s by several other scientists. Since then, it has become

increasingly sophisticated and is nowadays widely used in surface technology.

The plasma spraying gun consists principally of two electrodes.

Fig 2.4: Schematic diagram of Plasma spray gun

Fig 2.4 shows a schematic of the plasma spray gun, with the thoriated tungsten

cathode inside the water-cooled copper anode. A gas, commonly a mixture of argon

and hydrogen, is injected into the annular space between the two. To start the process,

a DC electric arc is stuck between the two electrodes. The electric arc produces gas

ionisation, i.e. gas atoms lose electrons and become positive ions. Electrons move

with high velocity to the anode, while ions move to the cathode. On their way,

electrons and atoms collide with neutral gas atoms and molecules. Hence, the electric

arc continuously converts the gas into plasma (a mixture of ions and electron of high

energy).

The plasma is on average, electrically neutral and characterized by a very high

temperature. The kinetic energy of the plasma (mostly carried by free electrons) is

converted into thermal energy during collisions between ions, electrons and atoms. In

this way, the plasma is capable of producing temperatures up to approximately 104K.

The hot gas exits the nozzle of the gun with high velocity. Powder material is fed into

the plasma plume. The powder particles are melted and propelled by the hot gas onto

the surface of the substrate.

When individual molten particles hit the substrate surface, they form splats by

spreading, cooling and solidifying. These splats then incrementally build the coating.

Plasma plumes exhibit radial temperature gradients. Whereas particles that pass

through the central core of the plasma tend to be melted, superheated or even

vaporised, particles that flow near the periphery may not melt at all. This will affect

the final structure of the coating, which may contain partially molten or unmelted

particles. Voids, oxidised particles and unmelted particles can appear in the coating.

These effects may be desirable, or they may be unwanted, depending on the

requirements of the coating.

Chapter 3

Modeling and Finite Element Analysis of the Specimen

3.1Modeling:

Modeling of the components was done using Creo Elements. The experimental setup

consists of four components. Four major elements or components are used to analyse

the insulation performance of the experimental setup decided. They are:

1. Cast iron liner

2. Aluminium sleeve

3. Thermal Barrier coating

4. Cylinder

3.1.1. Cast Iron liner:

This is the inner most part of the experimental setup. The dimensions of the liner were

taken from the Royal Enfield Bullet 350cc engine specifications as shown in fig 3.1.

Cast iron has thermal conductivity of 22W/mK and a thermal expansion co-efficient

of 0.0000105/oC.

It has a Poisson’s ratio of 0.26 & Young’s modulus of 70326.52MPa.

Fig 3.1: Cast Iron Liner

3.1.2. Aluminium Sleeve:

A sleeve of aluminium given in fig 3.2 forms the next layer over the cast iron liner.

The thickness of the sleeve was taken to be 5mm.

Al 356 T6 is the aluminium alloy chosen for the aluminium sleeve.

It has a thermal conductivity of 151 W/mK and thermal expansion coefficient of

0.0000214/oC. It has a Poisson’s ratio of 0.33.

Al 356 T6 has a young’s modulus of 72.4GPa.

Fig 3.2: Aluminium sleeve

3.1.3. Thermal Barrier Coat (TBC):

This is the third layer from inside as shown in the fig 3.3 below. A thickness of 1mm

is taken for the first iteration and is increased by 0.5mm upto 10mm thickness.

Zirconia is selected as the TBC. It has a thermal conductivity of 2W/mK and a

thermal expansion co-efficient of 0.00001/oC.

Young’s Modulus of zirconia is 205GPa. It has a Poisson’s ratio of 0.3.

Fig 3.3: TBC layer

3.1.4. Cylinder:

This forms the outer most part of the experimental specimen. The outer diameter of

the cylinder is fixed at 128mm where as the inner diameter of the cylinder changes

according to the outer diameter of the TBC from fig 3.4.

Fig 3.4: Cylinder

The above four parts were modelled separately as individual units. These four are then

assembled together to form the experimental specimen.

3.1.5. The Experimental Specimen:

At first, cast iron liner was brought into the assembly and is given a fixed constraint.

Secondly, the aluminium sleeve is called into the assembly and then its inner surface

is mated (insert) with the outer surface of the cast iron liner as well as its top and

bottom surfaces are aligned with those of cast iron liner. The TBC is then called into

the assembly and its inner surface is mated (insert) with the outer surface of the

aluminium sleeve as well as its top and bottom surfaces are aligned with those of the

cast iron liner. The next component called in to the assembly is the cylinder. The

inner surface of the cylinder is mated (insert) with the outer surface of the TBC as

well as its top and bottom surfaces are aligned with those of the cast iron liner. This

completes the experimental specimen as shown in fig 3.5.

Fig 3.5: Experimental setup

3.2 Finite Element Analysis:

The finite element analysis of the experimental specimen is done using ANSYSR14.5

software. The assembly created in the Creo Elements, is saved in a parasolid (x t)

format and then imported in the ANSYSR14.5. The analysis consists of two stages for

the required task. One is the thermal analysis and the other is the structural analysis.

3.2.1 Thermal Analysis:

The aim of thermal analysis is to find out the temperature gradient (Appendix3)

across the composite cylindered specimen and also to find the total heat flux and

directional heat flux across it (Appendix 2). Firstly, the thermal properties (thermal

conductivity) of the materials are defined in the Engineering Data tab.

Then, the geometry is imported in the parasolid format from Ravindra R et

al..,2012[6]; . As the geometry consists of four different parts, it is clubbed together

to a form a new part in ANSYSR14.5. Then, the properties of the materials are added

to the respective part in the geometry. The next step is of great importance. It is

meshing the part geometry. It divides the geometry into small elements.

The meshing element chosen was SOLID278 which has a 3-D thermal conduction

capability as shown in fig 3.6. The element has 8 nodes with a single degree of

freedom, temperature at each node. The meshing element size is set as fine. The

relevance centre and also the span angle centre are also set as fine. The next step is to

define the thermal loads (Appendix1). Here, thermal loads are the respective

convective heat transfer co-efficients and the temperatures inside the cast iron liner

and outside the cylinder. The convective heat transfer co-efficient (hi) inside the liner

is derived from the Woschni’s equation. This can be seen from fig 3.7.

Fig 3.6: Meshing for thermal analysis

Fig 3.7: Thermal loads

3.2.2 Structural Analysis:

After performing the thermal analysis, its results are transferred to the

structural analysis domain as shown in fig. Other mechanical and thermal properties

such as density, Young’s modulus, Poisson’s ratio and co-efficient of thermal

expansion are defined for all the materials of the specimen in the engineering data tab

of the structural domain. The geometry taken for the thermal analysis is transferred to

the structural domain evident from fig 3.8.

Fig 3.8: Interlinking thermal and structural analysis

It is followed by meshing. The meshing element chosen was SOLID185. It is defined

by 8nodes having 3degrees of freedom at each node; translations in the nodal x, y & z

directions. The element has plasticity, hyper elasticity, stress stiffening, creep, large

deflection and large strain capabilities. The mesh element size is set as fine as can be

seen from fig 3.9. The relevance centre and the span angle centre are also set as fine.

Fig 3.9: Meshing for structural analysis

After the meshing is done, the structural loads are defined. The specimen is given a

fixed support on the four top faces and the four bottom faces as shown in fig 3.10.

Fig 3.10: Defining supports

Then, a pressure is applied on the internal surface of the cast iron liner shown in fig

3.11. Now, we are interested to find out the total deformation, directional deformation

and the equivalent stresses (Von-Mises Stresses) for the applied loads.

Fig 3.11: Structural loads

Chapter 4

RESULTS AND DISCUSSIONS

As stated in the previous chapter, the analysis was begun with the thermal analysis

followed by the structural analysis. Several iterations starting from the specimen with

no TBC to the specimen with a TBC of 1cm thickness were done. The deciding

criterion was to have heat insulation as much as possible but at the same time the

equivalent stresses in the specimen should be less than the permissible stress for the

material with a factor of safety 1.25.

Shown below are the results of few iterations with no TBC, 1cm thick TBC and the

specimen with the optimum TBC thickness.

4.1 Specimen without TBC:

Fig 4.1: Thermal gradient with no TBC.

Observation: FEA of experimental cylinder with no TBC coating showed a

temperature of 1190.2oc at the inner liner and 1179.5

oC at the outer surface of the

cylinder. It can be seen in fig 4.1.

Fig 4.2: Total heat flux of specimen with no TBC

Observtion: From fig 4.2, it is evident that total heat flux at the inner liner is 42,466

W/m2. Total heat flux at the outer cylinder is 23060 W/m

2

Fig 4.3: Directional heat flux of specimen with no TBC

Observation: From fig 4.3, it can be seen that maximum directional heat flux of the

inner liner is 42,340 W/m2

and minimum of -42,329W/m2

Fig 4.4: Total deformation of specimen with no TBC

Observation: From fig 4.4 it is evident that total deformation at the inner liner is

1.0552e-5

m and 0m at the outer surface.

Fig 4.5: Directional deformation of specimen with no TBC

Obseravation: From fig 4.5, it can be seen that directional deformation of the inner

liner is 1.0551e-5 m and -1.0551e-5 m.

Fig 4.6: Equivalent stresses of specimen with no TBC

Observation: From fig 4.6 it is shown that equivalent stress at the inner liner is

4.3638e7 Pa and 2.8805e7

Pa.

4.2 Specimen with 1cm thick TBC:

Fig 4.7: Temperature gradient of specimen with 1cm thick TBC

Observation: From fig 4.7, it is observed that temperature at inner liner is 1194.3oC

and the temperature at the outer surface of the cylinder is 1049.2oC.

Fig 4.8: Total heat flux of specimen with 1cm thick TBC

Observation: From fig 4.8 it is evident that Total heat flux at the liner is 37686W/m2

and at the outer cylinder is 20475W/m2.

Fig 4.9: Directional heat flux of specimen with 1cm thick TBC

Observation: From fig 4.9 it can be seen that maximum directional heat flux is

37575W/m2

and minimum is -375563W/m2.

Fig 4.10: Total deformation of the specimen with 1cm thick TBC

Observation: From fig 4.10, it can be seen that total deformation is 6.2779e-5m and

the minimum deformation is 0m at the outer surface.

Fig 4.11: Directional deformation of the specimen with 1cm thick TBC

Observation: From fig 4.11, it is evident that maximum directional deformation

6.2774e-5 m and a minimum of -6.2774e-5

m

Fig 4.12: Equivalent stresses of the specimen with 1cm thick TBC

Observation: From fig 4.12, it can be seen that max equivalent stress at the inner

liner is 3.0169e8 and minimum at the outer surface of 1.8084e7.

4.3 Specimen with optimum TBC thickness:

Fig 4.13: Temperature gradient of the specimen with optimum TBC thickness

Observation: From fig 4.13, it is evident that temperature in the liner is 1193.3oC and

1082.5oC

Fig 4.14: Total heat flux of the specimen with optimum TBC thickness

Observation: From fig it can be seen that total flux at the liner is 38,906 W/m2

and

21,081 W/m2

at the outer surface.

Fig 4.15: Directional heat flux of the specimen with optimum TBC thickness

Observation: From fig 4.15, it can be seen that maximum directional heat flux is

38791 W/m2

and minimum of -38780 W/m2

Fig 4.16: Total deformation of the specimen with optimum TBC thickness

Observation: From fig 4.16, it can be seen that maximum total deformation is

4.0837e-5m and minimum is 0m.

Fig 4.17: Directional deformation of the specimen with optimum TBC thickness

Observation: From fig 4.17, it is evident that max directional deformation is

4.0831e-5m and minimum is -4.0831e-5.

Fig 4.18: Equivalent stresses of the specimen with optimum TBC thickness

Observation: From fig 4.18, it can be seen that maximum equivalent stress of

1.8933e8 Pa is at liner and minimum of 1.1751e7 Pa is at outer surface.

List of iterations and their results are as listed below. Table 2 gives Total heat flux,

temperature at the inner and outer sections and, directional heat flux of the specimen

at various thickness of TBC coating. Table 3 gives structural deformation and von

mises stresses of the entire specimen at various thickness of TBC. A pressure of

100bar is applied at the core of the cylinder to simulate the engine combustion

characteristics.

Table 4.1: Results of thermal analysis

Table 4.2: Results of structural analysis

4.4 CONCLUSION:

4.4.1 Choosing optimum coat thickness:

• Von-Mises or equivalent stresses of the cylinder are compared with maximum

allowable stress of the material at respective points

• From analysis we can see cast iron liner is the maximum stress region for

every iteration.

• With a factor of safety of 1.25 S.Srikanth Reddy et al..,2013[7]; maximum

allowable stress is 248 Mpa.

• Cylinder with coat thickness not satisfying the maximum allowable stress

criterion does not suit our need

• Hence 7mm thickness is the optimum thickness of the TBC we can use in this

experiment.

4.4.2 Scope of improvement in efficiency of IC engine:

• Consider Qw is the amount of heat lost to the coolant in an IC engine.

• We know that Qw = mwcpdT

Where m= mass flow rate of coolant, kg/s

cp = specific heat capacity of water, KJ/kg-K

dt = difference in temperature from initial to final state of the coolant.,K

1. Now consider the cylinder without ceramic coating, from the iterations,

external temperature at the coolant is 1179 deg.C

i.e Qw = mwcp(1179-27) watts

2. Consider the cylinder with optimum TBC coat thickness 7mm, from the

iterations, external temperature is 1082.5 deg.C

i.e (QW)TBC = mwcp(1082.5-27) watts

3. Improvement in heat recovery from uncoated block to TBC coated block is

given by

(QW)TBC - Qw / Qw

i.e substituting the values, it is 9.78 %

Chapter 5

FUTURE SCOPE OF THE PROJECT

1. With proper information fatigue, creep cycle analysis of both thermal and

structural performance of the TBC coated cylinder can be done.

2. This project can be extended to perform practical experimental analysis given

the proper resources.

3. Practical experimental analysis requires TBC coating on the working engine

model.

4. Coating adhesion to the bore material is pretty difficult and costly process

5. To measure working parameters of the ceramic coated bore cylinder of the

engine an engine dynamometer is essential.

6. Fabrication of the ceramic layer in between the aluminum block is also equally

challenging.

7. Rare and costly equipment like honing might be required for adhering surface

finish.

8. TBC choosing can be made on fatigue basis in case of complete replacement

of the iron liner.

9. It requires an internal coating manipulator specially designed to coat the

internal surfaces of the bore of the cylinder. This is a challenging task too.

Appendix-1

CALCULATION OF INTERNAL CONVECTIVE HEAT

TRANSFER CO-EFFICIENT

The convective heat transfer co-efficient (hi) inside the combustion chamber of an IC

engine is calculated from the Woschni’s correlation, which is

hc(W/m2K) = 3.26B(m)

-0.2p(kPa)

0.8T(K)

-0.55w(m/s)

0.8

Where

B = bore of the cylinder = 70mm

p = pressure inside the combustion chamber = 100bar = 104kPa

T = temperature inside the combustion chamber = 1500K

w = linear speed of the piston = 2LN

L = length of the stroke = 90mm

N = speed of crankshaft = 4000rpm = 66.6667rps

Hence, w = 12m/s

hc = hi = 3.26.(0.07)-0.2

.(104)0.8

.(1500)-0.55

.(12)0.8

i.e; hi = 1149.99W/m2K

Appendix-2

THEORETICAL CALCULATION OF THERMAL

GRADIENT

Parameters Considered (for optimum thickness specimen):

Inner radius of cast iron liner, r1 = 35mm

Outer radius of cast iron liner = inner radius of aluminium sleeve, r2 = 38mm

Outer radius of aluminium sleeve = inner radius of TBC, r3 = 43mm

Outer radius of TBC = inner radius of cylinder, r4 = 50mm

Outer radius of cylinder, r5 = 64mm

Length of the specimen, L = 150mm

Internal ambient temperature, Ti = 1500K

External ambient temperature, To = 295K

Internal convective heat transfer co-efficient, hi = 1150W/m2K

External convective heat transfer coefficient, ho = 20W/m2K

Calculation of Heat Transfer Rate:

Heat transfer rate, Q = -kAdT/dx

Or Q/A = -dT/R

Where R = [ (1/hi.r1) + ln(r2/r1) + ln(r3/r2) + ln(r4/r3) + ln(r5/r4) + (1/ho.r5) ]

k1 k2 k3 k4

-dT = (Ti - To) and A = 2πL

By substituting the above values in these formulae, we have Q = 1279.361083W

....(i)

Let temperature at the inner surface of the cast iron liner be T1.

Let temperature at the outer surface of the cylinder be T5.

Now, calculate –dT = Ti – T1 and R = (1/hi) and equate it to the value Q of eq(i) and

find T1.

Hence, T1 = 1466.2746K = 1193.274oC

Now, calculate –dT = T1 – T5 and

R = [ ln(r2/r1) + ln(r3/r2) + ln(r4/r3) + ln(r5/r4) ]

k1 k2 k3 k4

Equate it to the value Q/A of eq(i) and find T5. Hence, T5 = 1355.108K = 1082.1oC

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