A COMPARISON STUDY OF LIQUID AND VAPOR PHASE DEVELOPMENT AT SPRAY BOUNDARY OF DIESEL SPRAY, BDF AND SVO SPRAY

ADAM MOHD IZHAN BIN NOOR AZAM

Report submitted in partial fulfillment of the requirement for the award of the degree of Bachelor of Mechanical Engineering with Automotive Engineering

Faculty of Mechanical Engineering

UNIVERSITY MALAYSIA PAHANG

June 2012

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ABSTRACT

The use of biodiesel as an alternative diesel engine fuel is preferred for fossil fuel substitution. However, due to technical deficiencies, they are rarely used purely or with high percentages in unmodified diesel engines. Therefore, this project is to study spray simulation of diesel, biodiesel fuel (BDF) and straight vegetable oil (SVO) in the diesel chamber. Two main components are focused on this paper. First, the relations between the viscosities of different fuels and the spray characteristics in achieving stoichiometric air-fuel mixture are investigated. Lastly the spray liquid-vapor phase in chamber is investigated. Good spray characteristics lead to the good drivability, high combustion efficiency and stoichiometric air-fuel mixture. Therefore, Computational Fluid Dynamics (CFD) method using ANSYS Fluent simulation software is used for this purpose. The simulation of injection spray in chamber is conducted by using three type of fuel that is diesel, biodiesel and palm oil with the one 0.2mm valve covered orifice (VCO) nozzle, injection pressure at 700 MPA, ambient pressure at 10 MPA, ambient temperature at 300 K and same iteration time. The results are shown by changing the type of fuel. The simulation results showed that the spray characteristics are better for diesel at the same time iteration compared to BDF and SVO by the penetration length, cone angle and liquid-vapor phase data.

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ABSTRAK

Penggunaan biodiesel sebagai alternatif minyak enjin diesel lebih disukai bagi penggantian bahan api fosil. Walau bagaimanapun, disebabkan oleh kekurangan teknikal, ia jarang digunakan tulen atau dengan peratusan yang tinggi dalam enjin diesel tanpa ubah suai. Oleh itu, projek ini adalah untuk mengkaji semburan simulasi diesel, minyak biodiesel (BDF) dan minyak sayuran terus (SVO) di dalam kebuk diesel. Dua komponen utama yang diberikan tumpuan di atas kertas ini. Pertama, hubungan antara kelikatan bahan api yang berbeza dan ciri-ciri semburan dalam mencapai stoikiometri udara-minyak campuran dikaji. Akhir sekali semburan fasa cecair-wap di dalam kebuk juga dikaji.Ciri-ciri semburan yang baik membawa kepada daya pemanduan yang baik, kecekapan pembakaran yang tinggi dan stoikiometri campuran udara-bahan api. Oleh itu, kaedah Computational Fluid Dynamics (CFD) menggunakan perisian simulasi ANSYS Fluent digunakan untuk tujuan ini. Simulasi semburan suntikan di dalam kebuk dijalankan dengan menggunakan tiga jenis bahan api iaitu diesel, biodiesel dan minyak sawit dengan muncung 0.2mm meliputi muncung orifis (VCO), tekanan suntikan pada 700 MPA, tekanan awal (ambient) pada 10 MPA, suhu awal (ambient) pada 300 K dan sama masa iterasi. Hasil yang diperolehi ditunjukkan dengan menukar jenis minyak. Keputusan simulasi menunjukkan bahawa ciri-ciri semburan adalah lebih baik bagi diesel pada iterasi masa yang sama yang berbanding BDF dan SVO melalui panjang penembusan, sudut kon dan data fasa cecair-wap.

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TABLE OF CONTENTS

Page

SUPERVISOR’S DECLARATION ii

STUDENT’S DECLARATION iii

ACKNOWLEDGEMENTS iv

ABSTRACT v

ABSTRAK vi

TABLE OF CONTENTS vii

LIST OF TABLES x

LIST OF FIGURES xi

LIST OF ABBREVIATIONS xiii

LIST OF APPENDICES xiv

CHAPTER 1 INTRODUCTION

1.1 Research Introduction 1

1.2 Problem Statement 2

1.2.1 Problem 2

1.2.2 Solution of the problem 3

1.3 Objectives of the paper 3

1.4 Scopes 3

1.5 Hypothesis 4

1.6 Methodology 4

CHAPTER 2 LITERATURE REVIEW

2.1 Introduction 5

2.2 Diesel Engine 5

2.3 Alternative Fuels 6

2.3.1 Viscosity 7

2.3.2 Diesel 7

2.3.3 Bio-Diesel Fuel (BDF) 9

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2.3.4 Straight Vegetable Oil (SVO) 10

2.4 Spray Combustion Process 11

2.5 Spray Regimes 13

2.6 Spray Penetration 14

2.7 Computational Fluid Dynamic (CFD) 14

CHAPTER 3 METHODOLOGY

3.1 General Methodology 17

3.2 Literature Study 17

3.3 Flow Chart/Project Flow 18

3.4 3D Design Modeling 19

3.5 ANSYS Fluent Simulation Setup 19

3.5.1 Geometry 19

3.5.2 Computational Meshing Setting 20

3.5.3 Simulation Setup 20

3.5.4 Solution Setup 31

CHAPTER 4 RESULTS AND DISCUSSIONS

4.1 Introduction 33

4.2 Spray Image 33

4.3 Spray Penetration 36

4.4 Spray Cone Angle 38

4.5 Liquid-Vapor Area 40

CHAPTER 5 CONCLUSIONS AND RECOMMENDATIONS

5.1 Conclusions 42

5.2 Recommendations 43

REFERENCES 44

APPENDICES 46

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LIST OF TABLES

Table No.

Title Page

2.1 Comparison of Viscosity among Diesel, Biodiesel and Vegetable

Oils.

7

2.2 Hydrocarbon contents in Crude Oil 8

2.3 Physical Properties of Petroleum Products 8

4.1 Spray penetration length 36

4.2 Cone angle size 39

4.3 Liquid-vapor phase area 41

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LIST OF FIGURES

Figure No.

Title Page

2.1 Overall mechanism of Transesterification 10

2.2 SVO and BDF process. 11

2.3 The consecutive phase’s during the operation of a Diesel engine. 12

3.1 Flow Chart 18

3.2 3D Design of Injection Chamber 19

3.3 Injection Chamber mesh 20

3.4 General setup 21

3.5 Progress report 21

3.6 Model setup 22

3.7 Energy setup 22

3.8 Viscous model 23

3.9 Species model 24

3.10 Discrete phase physical model 25

3.11 Discrete phase tracking model 26

3.12 Setting injection point properties 27

3.13 Setting injection turbulent dispersion 27

3.14 Species mixture materials 28

3.15 Species droplet materials 29

3.16 Pressure outlet setting 30

3.17 Operating conditions setting 31

3.18 Solution control setting 32

4.1 Contours spray image 34

4.2 Particle track spray image 35

4.3 Spray penetration measure method 36

4.4 Penetration vs. Iteration 37

4.5 Spray cone angle measure method 38

4.6 Cone angle vs. Iteration 40

4.7 Liquid-vapor phase measure method 41

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LIST OF ABBREVIATIONS

BDF Biodiesel Fuels

SVO Straight Vegetable Oils

CAD Computer-aided Design

CFD Computational Fluid Dynamics

VCO Valve Covered Orifice

DPM Discrete Phase Model

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LIST OF APPENDICES

Appendix A Gantt Chart / Project Schedule for FYP1

Appendix B Gantt Chart / Project Schedule for FYP 2

 

CHAPTER 1

INTRODUCTION

1.1 Research Introduction

Nowadays, the depleting reserves of fossil fuel, increasing demands for diesels

and uncertainty in their availability have been a matter of global concern. This is

considered to be the important trigger for many initiatives to search for the alternative

source of energy, which can supplement or replace fossil fuels. The concern over

automotive pollution also been important aspects as it been environmental, medical and

philosophical, leading to strict emission requirement. These are effort around the world

to protect the environment from further deterioration.

From the automotive view, to minimize the fuel consumption rate in the diesel

engine is by improve the engine performance to reduce the energy lose in the

combustion. In the diesel engine, combustion and emission characteristics are

influenced by the fuel atomization, nozzle geometry, injection pressure, shape of inlet

port and other factors. So, in order to improve the fuel-air mixing, it is important to

understand the fuel atomization and spray formation process. So far, to improve the

combustion performance and particulate emissions, many researchers have investigated

the characteristics of the spray behavior by experimental and theoretical approaches.

Therefore, there is substantial emphasis on improving the fuel economy without

sacrificing the engine performance, while adhering to stringent emission regulation. As

a result, biodiesel fuel have becomes main focus of alternative fuel research and become

popular worldwide especially in Europe for its cleaner combustion than diesel.

2  

Biodiesel fuel is made by processing vegetable oil, animal fat, or recycled cooking

grease with alcohols or other chemical.

Biodiesel fuel is a renewable, biodegrable and oxygenous fuel with similar

physical and chemical characteristics to diesel. Not only that, it also produce lower

combustion emission and fewer greenhouse gas emission than fossil diesel.

However, there are some differences in fuel properties parameters especially the

kinematic viscosity between biodiesel fuel and diesel. In a diesel engine, the fuel

development and atomization characteristics play an important role in improvement of

combustion and engine performance, because they influence the fuel-air mixing in the

cylinder. Therefore, it is necessary to study and analyze the spray development and

atomization characteristics of various fuels in relation to its application in internal

combustion engines, mainly effect the spray behavior and spray characteristics inside

spray chamber. Among the various alternative fuels, biodiesel fuel (BDF) and straight

vegetable oil (SVO) fuels are the most popular. This is because biodiesel fuel can be

used in conventional diesel engine without modification of the engine and a diesel

engine fueled with BDF or SVO can be operated with only a partial modification of the

fuel supply system. In this project, the effect of kinematic viscosity of diesel, BDF and

SVO on liquid phase and vapor phase development at spray boundary will be

investigated.

1.2 Problem Statement

1.2.1 Problem

In the simulation software, there is no database of biodiesel fuel and straight

vegetable oil available for the flow injection simulation. It is very important to know the

spray characteristic for the diesel engine which is being operated with biodiesel fuel and

straight vegetable oil.

3  

1.2.2 Solution of the problem

ANSYS Fluent is a user friendly and very suitable for every engine simulation

and being used in most fluid flow simulation research. Therefore there is an alternative

for the problem in defining fuel for the simulation. ANSYS Fluent allows the users to

create their own fuel files. Referring to the biodiesel fuel and straight vegetable oil

properties table, the biodiesel fuel and straight vegetable oil can be created. The results

gain by simulation can give overview on how the fuel properties affect the spray

characteristic.

1.3 Objectives of the paper

Generally, the objectives to be achieved in this project are stated below:

i. To observe the development of “structures like branches” inside spray

boundary.

ii. To measure the liquid and vapor phase area.

iii. To investigate the relationship between kinematic viscosity of fuel and,

liquid and vapor phase development at spray boundary.

iv. To measure the spray penetration and cone angle.

1.4 Scopes

The project is focused on:

i. Literature review

ii. Simulate the model by using FLUENT ANSYS software

iii. Result comparing with different fuel and the spray development

4  

1.5 Hypothesis

The low viscosities of fuels cause good fuel atomization and increasing in spray

penetration, which leads to complete fuel combustion. This was mainly because the

increase in fuel viscosity prevented the breaking of the spray jet, resulting in an increase

in the size of the spray droplets. The larger size of the spray droplets will increase the

momentum of droplet but the resistance also increases that preventing forward

movement.

1.6 Methodology

i. Stage 1 : Literature study

Make review on literature study involving project title.

ii. Stage 2 : 3D modeling

3D modeling of the injector and engine geometry.

iii. Stage 3 : Boundary condition setting simulation

Set up boundary condition for simulation analysis.

iv. Stage 4 : Simulating analysis by using FLUENT software

Simulation analysis using FLUENT ANSYS software.

v. Stage 4 : Analysis of simulation result

Analyze result from simulation.

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CHAPTER 2

LITERATURE REVIEW

2.1 Introduction

This chapter covers the recent review of diesel engine powered with diesel,

biodiesel fuel and straight vegetable oil research activities are presented here. All the

studies are mainly focus on the spray characteristic and liquid-vapor phase development

for the diesel engine operating with diesel, biodiesel fuel and straight vegetable oil.

2.2 Diesel Engine

The history of diesel engine was started by Dr. Rudolf Diesel (1858 to 1913). In

1892, he present his diesel engine which the ignition of fuel by compression process.

Compared to gasoline engines and steam engines, this engine had number of

advantages. It is less fuel consumptions and could be dimensioned for higher power

outputs. In 1922, Robert Bosch decided to develop a fuel-injection system for diesel

engines. Those Bosch fuel-injection pumps were a stepping stone in achieving higher

running speeds in diesel engine. In 1936, Mercedes-Benz 260D (2580 cc, 50 hp) was

the first volume-production car to be fitted with a diesel engine. In diesel engines, the

spark plug and carburettor are replaced by a fuel injector. This due to the air when being

compressed to a temperature that is above the auto-ignition temperature of the fuel, and

combustion creates on contact as the fuel is injected into this hot air.

6  

In diesel engines, only air is compressed during the compression stroke, which

can eliminate the possibility of auto-ignition. (Yunus and Michael, 2007). Therefore the

diesel engines can operate on much higher compression ratios, between 12 and 24. The

principle operation of Diesel engines relies on the heat within the compressed air to

cause an ignition of the fuel charge. The chemical energy stored in the fuel is then

converted into mechanical energy, which can be used to power tractors, locomotives

and freight trucks. The diesel engines also burn fuel more completely compared to

gasoline engines since they work on lower revolutions per minute (rpm) and having

higher air-fuel mass ratio. It is more efficient than spark ignition engine (gasoline)

because they operate at much higher compression ratios (Yunus and Michael, 2007).

Lower fuel cost and higher efficiency become the reason why they have been used in

large ships and emergency power generation units.

2.3 Alternative Fuels

The concept of using alternative fuels is not contemporary in its nature; it has

existed for many years. Alternative diesel engine fuels that have been researched over

the years range from coal to peanut oil. During the 1900 Paris World Fair, the French

Otto Company ran the Diesel Engine on peanut oil at the request of the French

government. A Belgian patent granted in 1937 to G. Chavanne displays the early

existence of the use of ethyl esters extracted from palm oil (Knothe et al., 1997).

However, inexpensive petroleum-based fuels prevented biodiesel fuels from

receiving much consideration, resulting in adoption of a diesel engine to specifically

burn petroleum diesel. Interruption of cheap oil supplies resulting from the 1973 oil

embargo as well as the 1990 Gulf War sparked a renewed interest and research in using

domestically grown and renewable sources for fuel production. Although the use of

biodiesel did not receive much attention in the United States until the late 1990s, it has

been used extensively in Europe for nearly a quarter of a century.

In this project, alternative fuel properties been study and research because fuel

characteristics play an important part as it effect the spray characteristics, spray

penetration, atomization, droplet size drop distribution.

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2.3.1 Viscosity

Viscosity is a measure of a fuel’s adhesive or cohesive property and is the key

factor in estimating the required temperature for pumping, injection, storage, and

transfer of the fuel. A viscosity comparison of diesel, biodiesel, and vegetable oils is

shown in Table 2.1.

Table 2.1: Comparison of Viscosity among Diesel, Biodiesel and Vegetable Oils

[Source: Knothe et al., 1997]

2.3.2 Diesel

Diesel is processed from crude oil, a fossil fuel with broad variations in colour,

from clear to tar-black, and viscosity, from that of water to almost a solid. Crude oil

contains a complex mixture of hydrocarbons comprised of differing chain lengths and

physical and chemical properties. Hydrocarbons containing up to four carbon atoms are

gaseous in nature, those with 5 to 19 carbon atoms are usually found in liquid form, and

those with a carbon composition greater than 19 are found as solids as shown in Table

2.2.

8  

Table 2.2: Hydrocarbon Contents in Crude Oil

[Source: ATSDR, 1995; OTM, 1999]

Products resulting from fractional distillation that undergo further processing

(cracking, unification and alternation) in order to acquire desired compounds are shown

in Table 2.3.

Table 2.3: Physical Properties of Petroleum Products

[Source: Freudenrich, 2001]

9  

2.3.3 Bio-Diesel Fuel (BDF)

Biodiesel is defined as a fuel comprised of mono-alkyl esters of long chain fatty

acids derived from vegetable oils or animal fats. Biodiesel is typically created by

reacting fatty acids with an alcohol in the presence of a catalyst to produce the desired

mono-alkyl esters and glycerin. After reaction, the glycerin, catalyst, and any remaining

alcohol or fatty acids are removed from the mixture. The alcohol used in the reaction is

typically methanol, although ethanol and higher alcohols also have been used.

Biodiesel fuel is now mainly being produced from soybean, rapeseed and palm

oils. Its properties are close to diesel fuels that can usually be used in diesel engines

without modification and have reduced emissions from a cleaner burn due to their

higher Oxygen content and therefore biodiesel becomes a strong candidate to replace

the diesel. It probably has better efficiency than petrol-oil. Due to the increment of

crude oil prices, limited resources of fossil oil, environmental concerns, population

increase and higher energy demand, biodiesel represents a promising alternative fuel for

use in compression ignition (diesel) engines.

In order for vegetable oils and fats to be compatible with the diesel engine, it is

necessary to reduce their viscosity. This can be accomplished by breaking down

triglyceride bonds, with the final product being referred as biodiesel. There are at least

four ways in which oils and fats can be converted into biodiesel:

i) Transesterification

ii) Blending

iii) Microemulsions

iv) Pyrolysis

Among these processes, transesterification is the most commonly used method.

The transesterification process is achieved by reaction of a triacylglycerol molecule

with an excess of alcohol in the presence of a catalyst to produce glycerol and fatty

esters as shown in Figure 2.1. Currently, the preferred alcohol is methanol (R = CH3)

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Figure 2.1: Overall mechanism of Transesterification

[Source: Gerpen, 2005]

2.3.4 Straight Vegetable Oil (SVO)

SVO is a biodiesel fuel obtained from plant seed oil pressing. It can be used in a

non modified diesel engine just by adding a small heat exchanger in conjunction with

other minor modifications in the fuel intake system. The production of SVO with

respect to BDF is much easier because it includes fewer processes and less energy

consumption. The production process for BDF and SVO is shown in Figure 2.2.

However, the disadvantage of straight vegetable oil (SVO) was too viscous for

the fuel injectors to handle properly. Prolonged use of vegetable oil in a stock diesel

engine will lead to carbon deposits in the combustion chamber, valve sticking on seats

and stems and eventual leakage of fuel into the lubricating oil causing irreparable

engine damage. This viscosity problem left two options: modify the vegetable oil fuels

or modify the diesel engine. Early experimentation focused on reducing the viscosity of

the vegetable oil fuels by convert the vegetable oil to biodiesel.

11  

Figure 2.2: SVO and BDF process.

[Source: Bernat Esteban, 2011]

2.4 Spray Combustion Process

The combustion performance and emissions are mainly influenced by the

atomization of the liquid fuel, the motion and evaporation of the fuel droplets and

mixing of fuel with air. The dynamics of spray and its combustion characteristics are

extremely important in determining, for instance, the flame stability behavior at widely

varying loads, the safe and efficient utilization of energy, as well as the mechanisms of

pollutants formation and destruction. Figure 2.3 show the consecutive phase’s occurring

during the operation of a diesel engine.

12  

Figure 2.3: The consecutive phase’s during the operation of a Diesel engine.

[Source: Olga WOJDAS, 2010]

Understanding and controlling atomization and spray combustion is becoming

an essential part of the industrial applications, which have been driven by increasingly

urgent demands to improve fuel and energy efficiencies, and to drastically reduce the

emission of pollutants. The spray combustion process may be divided into several

elements, such as atomization, liquid transport, vaporization, and combustion. In

general, liquid fuel is injected through a nozzle system into the combustor chamber and

is atomized to form a spray of droplets before gas-phase combustion takes place in the

vaporized fuel. In the atomization region, the liquid dominates the flow and the liquid

fuel disintegrates into ligaments and droplets. Large liquid blobs which are bulks of

continuous liquids present in the atomization region.

13  

The dense spray region has lower but still significant liquid volume fraction and

includes secondary breakup of drops and ligaments as well as drop interactions, such as

collisions and coalescence. Liquid ligaments normally present in the atomization and

dense spray regions, which are non-spherical liquid sheets, sheared off the liquid jet

column. In the dilute spray region, spherical droplets are well formed and have a strong

interaction with the turbulent airflow. In general, the spray structure depends on the

injection pressure difference, injector size, fuel viscosity and fuel density. (X. Jiang,

G.A. Siamas, K. Jagus, T.G. Karayiannis, 2010)

2.5 Spray Regimes

Diesel engine sprays are usually of the full-cone type. This means that in the idle

mode the fuel is blocked from the upstream side of the nozzle and during injection the

core of the spray is denser than the outer regions. The liquid spray can be characterized

by distinguishing spatial regimes. Starting from the nozzle exit there is an intact liquid

core. A few nozzle diameters further downstream in the so-called churning the liquid

consists of ligaments (blobs). These liquid parts are like large droplets with sizes

comparable to the nozzle diameter. Then the ligaments are breakup into many smaller

droplets in the thick zone where the volume and mass fraction of the liquid phase is

high. Further downstream the breakup process of droplets goes on and in the same time

more and more of the surrounding gas is entrained into the spray area.

This results in a diverging behavior with a characteristic spray angle. The

regimes after the thick zone are the thin zone (low volume but still high mass fraction of

liquid) and the dilute zone (negligible volume and low mass fraction of liquid),

respectively.

In a hot environment the position at which all liquid droplets are evaporated is

called the liquid length. From (automotive) experiments this liquid length is found to be

approximately constant after a short development time. From that point on the

evaporated fuel continues to penetrate the surrounding gas and is denoted as vapor

length. In a typical diesel injection timeframe (few milliseconds) the vapor length does

not reach a steady state.

14  

2.6 Spray Penetration

The spray penetration is defined as the maximum distance from the nozzle to the

tip of the spray at any given time and is one of the most important characteristics of the

combustion process. If the spray penetration is too long, there is a risk of impingement

on the wall of the combustion chamber, which may lead to fuel wastage and the

formation of soot. This normally occurs when the chamber wall is cold and where there

is limited air motion. However, a short penetration will reduce mixing efficiency hence

resulting in poor combustion. Hence the information of spray tip penetration would be

useful for the design of the engine combustion chamber.

2.7 Computational Fluid Dynamic (CFD)

Computational fluid dynamics or known as CFD is defined as the process and

set of methodologies that enables the computer to provide numerical simulation of

fluids flows. Computational fluid dynamics is a technology that is used to analyze the

dynamics of anything that can flow regardless in liquid or gaseous state. It is also a

software tool that can model or simulate a flow or phenomena of any system or device

under analysis (Hirsh. 2007). CFD is computed using a set of partial different equations

to predict the flow behavior. Besides that, it is also used for analyzing heat transfer

model, mass flow rate, phase change, chemical reaction such as combustion, turbulence

model, mechanical movement, deformation of solid structure and many more.

The word simulation is to indicate that the usage of computer in solving

numerically the laws that govern the movement of fluids in or around a material system,

where its geometry is also modeled on the computer. Hence, the whole system is

transformed into virtual environment or virtual product. This can be opposed to an

experimental investigation, characterized by a material model or prototype of a system

in measuring the flow properties in a prototype of an engine.

15  

Simulations used nowadays are mostly 3D simulation and 2D simulation. Both

simulations differ a lot in generating data and analysis of material. 3D simulation gives

the higher ability in drawing the geometrical complexity by offering un-uniform surface

of a material to be simulated. This ability gives a more real-time data by creating a near

real-time scenario (Hirsch, 2007). The data generated are more reliable for analysis. In

contrast, 2D simulation which offers less geometrical complexities are mostly used to

simulate a general overview of the scenario.

The creation of the product is definition phase, which covers the specification

and geometrical definition. It is based on Computer-Aided Design (CAD) software,

which allows creating, and defining the geometry of the system, in or its details. The

CAD definition of the geometry is required an unavoidable input to the CFD simulation

task.

CFD always preferred method over the conventional design method because it is

cheaper and save a lot of time. Before, there is such technology, usually engineers need

to build a real model for testing and redo the model again until optimum result is

obtained. Such a long procedure would consume more money and time. With the aid of

CFD software, engineer can simulate different set of parameters for testing to get the

optimum result before working on the real prototype without any additional cost (Lim,

2004).

In automotive industry for instance the time required for the design and

production of new car and engine model has been reduce from 6 to 8 years in the 1970’s

to roughly 36 months in 2005, with the announced objective of 24 to 18 months in the

new future. This is driven by the method known as CFD with the help of fast growing

computer hardware performance (Hirsch, 2007).

Air was used as fluid media, which was assumed to be steady and

incompressible. High Reynolds number k-epsilon turbulence model was used in the

CFD model. This turbulence model is widely used in industrial applications. The

equations of mass and momentum were solved using SIMPLE algorithm to get velocity

and pressure in the fluid domain. The assumption of an isotropic turbulence field used

in this turbulence model was valid for the current application.