analysis of aerodynamic design optimization of maglev trains
TRANSCRIPT
AERODYNAMIC DESIGN AND OPTIMIZATION OF
MAGLEV TRAINS
A Graduate Project Report submitted to Manipal University in partial fulfillment of the
requirements for the award of the degree of
BACHELOR OF TECHNOLOGY
in
Mechanical Engineering
by
Prateek Biswas
Nihaar Ponnanna
Apoorva Jain
under the guidance of
A. Amar Murthy
Assistant Professor (Sr. Scale)
Department of Mechanical and Manufacturing Engineering
MANIPAL INSTITUTE OF TECHNOLOGY
DEPARTMENT OF MECHANICAL AND MANUFACTURING ENGINEERING
MANIPAL INSTITUTE OF TECHNOLOGY
(A constituent Institute of Manipal University)
MANIPAL – 576104, KARNATAKA, INDIA
May, 2015
DEPARTMENT OF MECHANICAL AND MANUFACTURING ENGINEERING
MANIPAL INSTITUTE OF TECHNOLOGY
(A constituent Institute of Manipal University)
MANIPAL – 576104, KARNATAKA, INDIA
May, 2015
Manipal
/ / 2015
CERTIFICATE
This is to certify that the project titled AERODYNAMIC DESIGN AND
OPTIMIZATION OF MAGLEV TRAINS is a record of the bonafide work done by
PRATEEK BISWAS (110909600) submitted in partial fulfillment of the requirements for
the award of the degree of BACHELOR OF TECHNOLOGY in MECHANICAL
ENGINEERING of Manipal Institute of Technology, Manipal, Karnataka (A constituent
college of Manipal University) during the year 2014 – 2015.
A. AMAR MURTHY Dr. DIVAKARA SHETTY S
Project Guide Head of Department
iii
ACKNOWLEDGEMENTS
First and foremost, we would like to thank Manipal Institute of Technology for presenting
us with the opportunity to carry out a project work in our desired field of interest, the design
of future technology trains.
We express my gratitude and sincere thanks to our guide Prof. A. Amar Murthy, Assistant
Professor (Sr. Scale) in the Department of Mechanical and Manufacturing, MIT Manipal for
his constant guidance and patience throughout the length of our project.
We are indebted to the Department of Mechanical and Manufacturing in our Institute for
allowing us the use of their CAD Lab Systems for the running of necessary software which
otherwise would not have been possible without such heavy-duty systems. A special thanks
to Prof. Manjunath of the Department of Mechanical and Manufacturing who aided us in
solving the several issues encountered in the last stage of my project.
We would like to extend my regards to Dr. Vinod Thomas, the Director of the Institute and
Dr. Divakara Shetty S, the Head of Department for Mechanical and Manufacturing for
allowing us to undertake this project.
iv
ABSTRACT
After the 3 Modes of Transport – air, water and land, there was conceived a 4th
kind –
magnetic levitation travel. The idea of using magnets as the medium of levitating and
propelling a train across distances has been around for decades, yet it is only recently that
magnetic levitation has been considered as a viable commercial alternative for high speed
transportation. This project aims to understand the technology and science behind the
working of magnetic levitation, and focusses on its singular and foremost obstacle, the drag
force generated by the train passing through the air. Through understanding of the drag force
equation, it is possible to vary the related parameters namely dimensions of the train as well
as shape of the train to decrease the drag coefficient of the train and subsequently its drag
force. Several designs are conceptualized and then designed using design software after
which they are subject to fluid flow analysis using appropriate software. After the
optimization of the train shape, focus is shifted to the design of evacuated tubes/tunnels
whose shapes affect aerodynamics. Hypothetical conditions of pressure that can be
theoretically maintained in the tubes are used as the basis for the analysis of previously
designed trains in order to reduce fluid density and subsequently drag force to considerably
low levels.
v
CONTENTS
Page No.
Acknowledgements iii
Abstract iv
List of Notations and Abbreviations viii
List of Figures ix
List of Tables xi
Chapter 1 Introduction 1
1.1 Introduction to MAGLEV 1
1.2 Types and Working of MAGLEV Rail Technology 2
1.3 Advantages of MAGLEV over Conventional Rail 3
1.4 Introduction to Aerodynamic Drag 3
1.5 Drag Equation and its influence on Aerodynamic Designing 4
using CFD Software
Chapter 2 Literature review 5
2.1 Commercial (Presently Operating) MAGLEV Train Systems 5
2.1.1 Shanghai MAGLEV 5
2.1.2 Linimo, Japan 5
2.1.3 Incheon Airport MAGLEV 6
2.2 Commercial (Under Construction) MAGLEV Systems 6
2.2.1 Short Distance Commuter Metro Lines 6
2.2.2 Japan SCMAGLEV 7
2.3 Aerodynamically Efficient Train/Rolling Stock Designs 7
2.3.1 TransRapid TR09 7
2.3.2 Bombardier Zefiro 380 8
2.3.3 Automotrice à grande vitesse (AGV), Elettro Treno 8
Rapido 500
2.3.4 Japan Chuo-Shinkansen SCMAGLEV Trains 9
vi
Chapter 3 Objectives and methodology 10
3.1 Objectives of the Project 10
3.2 Methodology of Design 11
Chapter 4 Result Analysis 14
4.1 Design of train models 14
4.2 Analysis of all designed models under constant parameters 17
4.2.1 Drag coefficients of all models 18
4.2.2 Drag forces of all models 18
4.3 Analysis of all models under varying parameters 19
4.3.1 Variation of all models at 2 different lengths of train 19
100m and 315m (Standard train lengths)
4.3.2 Variation of 2 models at 2 different areas 21
4.3.3 Variation of all models at 3 different operating speeds 22
4.4 Analysis of all models with track introduced as part of enclosure 23
4.4.1 Variation of drag coefficients of all models 24
4.4.2 Variation of drag forces of all models 24
4.5 Analysis of 2 models with tunnel shape introduced for 26
enclosure design
4.5.1 Drag coefficients of model 6 and 7 under varying tunnel 26
enclosure shape
4.5.2 Drag forces of model 6 and 7 under varying tunnel 26
enclosure shape
4.6 Evacuated tube analysis of all models in curved head tunnel 27
enclosure at blockage ratio 0.17 at reduced density
4.6.1 Drag coefficients of all trains in low density, curved 28
head tunnel conditions
4.6.2 Drag forces of all trains in low density, curved head 28
tunnel conditions
vii
Chapter 5 Conclusions and Scope for Future Work 29
5.1 Conclusions 29
5.2 Scope for Future Work 30
References 31
viii
LIST OF NOTATIONS AND ABBREVIATIONS
LIST OF ABBREVIATIONS
MAGLEV Magnetic Levitation
EMS Electromagnetic Suspension
EDS Electrodynamic Suspension
LSM Linear Synchronous Motor
HS High Speed
KIMM Korea Institute of Machinery and Materials
SCMAGLEV Superconducting Magnetic Levitation
JRMAGLEV Japan Railway Magnetic Levitation
TR TransRapid
ATV Automotrice à Grande Vitesse
ETR Elettro Treno Rapido
Model V Model Version
CFD Computational Fluid Dynamics
LIST OF NOTATIONS
Fd Drag Force
ρ Mass Density of Fluid
u Flow Velocity relative to object
A Reference Area
Cd Drag Coefficient of a Shape
T Shear Stress
m Meter
kN Kilo Newton
m2 Meter Squared
kmph Kilometer per Hour
Pa Pascal
kg/m3 Kilogram per Meter Cubed
ix
LIST OF FIGURES
Fig. No. Title of the Figure Page No.
1.1 Forces Acting on MAGLEV Train 1
1.2 LSM generating a Travelling Field 2
2.1.1 Shanghai MAGLEV 5
2.1.2 Linimo MAGLEV 5
2.1.3 Incheon MAGLEV 6
2.2.1 Beijing MAGLEV 6
2.2.2 Japan SCMAGLEV 7
2.3.1 TransRapid TR09 Design 7
2.3.2 Bombardier Zefiro 380 8
2.3.3 AGV, France 8
2.3.4.1 MLX01 Train 9
2.3.4.2 L0 Train 9
3.2 (1) Mesh Sizing 11
3.2 (2) Mesh Statistics 11
3.2 (3) Simple Solution Method 12
3.2 (4) Coupled Solution Method 12
3.2 (5) Analysis using ANSYS 13
4.1 (1) Model V1 14
4.1 (2) Model V2 14
4.1 (3) Model V3 14
4.1 (4) Model V4 15
4.1 (5) Model V5 15
4.1 (6) Model V6 15
4.1 (7) Model V7 16
4.1 (8) Model V8 16
4.1 (9) Model V9 16
4.2 Train in regular enclosure 17
4.2.1 Drag coefficients of all models in regular enclosure 18
x
4.2.2 Drag forces of all models in regular enclosure 18
4.3.1.1 Drag coefficients of all models under varying length 19
4.3.1.2 Drag forces of all models under varying length 20
4.3.2.1 Drag coefficients of 2 models with varying area 21
4.3.2.2 Drag forces of 2 models with varying area 21
4.3.3.2 Drag forces of all models with varying speed 22
4.4 Track inclusion in enclosure 23
4.4.1 Drag coefficients of all models before and after track 24
inclusion
4.4.2 Drag Forces of all models before and after track 24
inclusion
4.5 Tunnel shapes 25
4.5.1 Drag coefficients of model 6 and 7 under varying tunnel 26
enclosure shape
4.5.2 Drag coefficients of model 6 and 7 under varying tunnel 26
enclosure shape
4.6 Curved head tunnel enclosure with ratio 0.17 27
4.6.1 Drag coefficients of all trains in low density, curved head 28
tunnel conditions
4.6.2 Drag forces of all trains in low density, curved head 28
tunnel conditions
xi
LIST OF TABLES
Table No. Title of the Table Page No.
4.2.1 Drag coefficients of all models in regular enclosure 18
4.2.2 Drag forces of all models in regular enclosure 18
4.3.1.1 Drag coefficients of all models under varying length 19
4.3.1.2 Drag forces of all models under varying length 20
4.3.2.1 Drag coefficients of 2 models with varying Area 21
4.3.2.2 Drag forces of 2 Models with varying area 21
4.3.3.2 Drag forces of all models with varying speed 22
4.4.1 Drag coefficients of all models before and after track 24
inclusion
4.4.2 Drag forces of all models before and after track 24
inclusion
4.5.1 Drag coefficients of model 6 and 7 under varying tunnel 26
enclosure shape
4.5.2 Drag coefficients of model 6 and 7 under varying tunnel 26
enclosure shape
4.6.1 Drag coefficients of all Trains in low density, curved head 28
tunnel conditions
4.6.2 Drag forces of all trains in low density, curved head 28
tunnel conditions
1
Chapter 1: INTRODUCTION
1.1 Introduction to MAGLEV
MAGLEV or Magnetic Levitation is a system of transport, which differs from standard
ground methods of transportation in a manner that it does not use friction as its means of
required driving force, instead using the attraction and repulsion properties of a simple
magnet to levitate the train over a steel track by a few millimeters and propel it forward.
Levitation of the train removes all forms of drag/friction apart from air drag and propulsion
using a motor with its basis being magnetic fields removes the necessity of fossil fuels or
overhead electric wiring for a conventional engine. Because of the non-reliance of traction for
propelling forward the train in this system, and the fact that MAGLEV trains levitate on a
cushion of air, the trains are capable of accelerating and decelerating much faster [1]
, and thus
are far more technologically advanced in this age.
Fig.1.1 Forces Acting on MAGLEV Train
2
1.2 Types and Working of MAGLEV Rail Technology
Currently, the only tested and in use/planned for commercial use MAGLEV systems are the
EMS (Electromagnetic Suspension) and EDS (Electrodynamic Suspension) [1]
.
Their primary difference is in the technology used to levitate the train.
In an EMS type MAGLEV, for levitation, the support and guidance electromagnets on the
train’s undercarriage are electronically turned off and on at high frequencies to make it attract
and hover from the simple steel track.
In an EDS type MAGLEV, levitation occurs due to the repulsion between the onboard
magnets on the train and the electric coils embedded in the track that have an induced
magnetic polarity due to magnetic field induction effect (from the perpendicularly crossing
train magnets) that oppose it.
Fig. 1.2 LSM generating a travelling field
Method of propulsion is same in both using the principle of a linear synchronous motor
(LSM), where the track acts the stator with Coils inside/on it given alternating magnetic
polarities to make a travelling magnetic field, and the magnets on the train act as the rotor,
catching onto that magnetic field. The frequency of alternating magnetic polarities given to
the track directly changes the effective speed of the MAGLEV train. Because of this, only the
section of the track over which the train will be passing needs to be powered.
3
1.3 Advantages of MAGLEV over conventional rail
MAGLEV Systems enjoy several advantages over conventional wheel-on-wheel railway
systems [2]
that are illustrated below:
1. MAGLEV being a non-contact type of transport between the train and the track is capable
of all-weather operations leading to dramatically lower maintenance costs.
2. Sound levels will be far lower considering the only sound will be from the expulsion of
air allowing for MAGLEV lines to be built closer to metropolitan areas.
3. A MAGLEV System is environmentally clean with its onboard train magnets powered by
batteries and LSM in the Track powered by individual substations using renewable
energy. There is no reliance on fossil fuels.
4. Power efficiency is far higher. The only resistance is air resistance.
5. Considering that there is no contact between the track and train, MAGLEV tracks can be
built in areas where the weight of the locomotive questions the structural stability of the
track.
1.4 Introduction to Aerodynamic Drag
Considering that aerodynamic drag is the primary and most important form of resistance that
a MAGLEV train encounters at high speeds, design and optimization of a Train with the least
drag coefficient and drag force at speeds greater than 400 kmph became paramount to
Improve the energy efficiency and reduce fuel costs
Optimizing safety focusing on stability in cross-winds [3]
and at high speeds
Pressure pulses leading to structural issues on trains and on trackside structures and
Preceding pressure waves created that bounce back to the train after hitting the open air have
been observed and studied by engineers, as critical to the structural safety of the trains as well
as the avoidance of unnecessary vibrations felt on the walls of the train. These pressure waves
are of particular importance in the case of trains travelling through evacuated tubes with air.
4
1.4 Drag Equation and its influence on aerodynamic designing using CFD
software
In aerodynamics, aerodynamic drag is the fluid drag force [4]
that acts on any moving solid
body in the direction of the fluid freestream flow.
= Drag force
= Mass density of the fluid
= Flow velocity relative to the object
= Reference area
= Dimensionless drag coefficient subject to the object's geometry
Therefore, our project is the aerodynamic design of MAGLEV trains using Creo as a design
software and Ansys Fluent as a fluid flow simulation software to minimize the
- Drag coefficient by streamlining the design of the Train
- Drag coefficient by optimizing the shape of tunnel in the case of an evacuated tube
- Drag force by lowering drag coefficient and varying the other parameters
Streamlining the design of the train involves introducing changes in the modelling of the train
itself such as curves, rounded ends and arrowhead-ends in the geometry, decreasing the drag
coefficient and subsequently the drag force. Aerodynamic designs have been studied from
shape effect papers [5]
and [6]
.
5
Chapter 2: LITERATURE REVIEW
2.1 Commercial (Presently Operating) MAGLEV Train Systems
2.1.1 Shanghai MAGLEV
Fig. 2.1.1 Shanghai MAGLEV
Shanghai MAGLEV is an EMS MAGLEV developed in Germany by Transrapid
International (joint venture of Siemens and ThyssenKrupp) and built commercially to connect
a 40 km track between Pudong Airport and the center of the Shanghai, operating at a top
speed of 430 kmph and a cruising speed of 300 kmph.
2.1.2 Linimo, Japan
Fig. 2.1.2 Linimo MAGLEV
Built in 2005 in Aichi, Japan by the Chubu High Speed Train Development Corporation, this
Maglev System is built only for a short distance of 9 km with a maximum operating velocity
of 100 kmph. With its cruising velocity not sufficiently high to affect air drag, the train is
built flat to the front with very little aerodynamic capabilities.
6
2.1.3 Incheon Airport MAGLEV
Fig 2.1.3 Incheon MAGLEV
Incheon Airport Maglev, built in South Korea is the third commercial Maglev line to be built,
by Korea Institute of Machinery and Materials (KIMM) and Hyundai Rotem in 2014 for a
track distance of 6 km and an operating speed of 110 kmph. The design of Incheon Maglev
Trains is similar to that of the Shanghai Maglev Train built 14 years prior to it.
2.2 Commercial (Under Construction) MAGLEV Systems
2.2.1 Short Distance Commuter Metro Lines
Fig. 2.2.1 Beijing MAGLEV
Maglev trains are being built for short distance commuter metro lines in Georgia, Beijing,
Changsha (China) and Tel Aviv. All these train lines will have trains operating at 100 kmph
or below, not utilizing the entire potential of capability of MAGLEV’s aerodynamic
capabilities.
7
2.2.2 Japan SCMAGLEV
Fig. 2.2.2 Japan SCMAGLEV
Japan SC Maglev or Super-cooled Maglev is the first of its kind prototype and commercial
model of an EDS Maglev System with onboard magnets on the train cooled to subzero
temperatures using liquid nitrogen to maximize electrical conductivity. It has a track distance
of 286 km connecting Tokyo, Nagoya and Osaka with trains averaging almost 500 kmph. It is
built by the Central Japan Railway Company and will be completed by 2045.
2.3 Aerodynamically Efficient Train/Rolling Stock Designs
2.3.1 TransRapid TR09
Fig. 2.3.1 TransRapid TR09 Design
TransRapid TR09 is the current train design that is running on the 40 km long Shanghai
Maglev track. Designed for speeds in excess of 300 kmph, this train has a drag coefficient of
0.26. Tests conducted in Germany [7]
certified that the air flow velocity 1 m from this train
moving at 350 kmph was less than 10 kmph, relatively safe.
8
2.3.2 Bombardier Zefiro 380
Fig. 2.3.2 Bombardier Zefiro 380
The Bombardier Zefiro 380 train [8]
is a Canadian train design project result, aimed at
improving 60 different design parameters, taking account of the train’s outer shell, cab, crash
structure and ergonomic constraints using CFD and CAD. The result is a train with the lowest
drag coefficient of any previous train: 0.13.
2.3.3 Automotrice à grande vitesse (AGV), Elettro Treno Rapido 500
Fig. 2.3.3 AGV, France
The AGV (built by Alstom) and ETR trains are Euro rail trains built in 2008. Both were
designed by supervising the outlining of the matrix in its tiniest detail, limiting the
aerodynamic drag. The high pressures on the front doors and lags on the side doors were also
minimized. Despite being a conventional railway train with no added advantage of levitation,
these trains are capable of travelling at speeds over 350 kmph, owing to their AeroEfficient
designs.
9
2.3.4 Japan Chuo-Shinkansen SCMAGLEV Trains
2.3.4.1 Model MLX01
Fig 2.3.4.1 MLX01
The MLX 01 built in 2003 by Japan Railway Central was the first designed and tested
SCMAGLEV train, capable of travelling at a maximum of 581 kmph [9]
using its arrow-
wedge head as its primary aerodynamic feature. This design was discarded in 2013 for future
commercial use for a newer and more advanced shaped train, the L0.
2.3.4.2 Model L0 Series
Fig. 2.3.4.2 L0 Train
The L0 Series Train built in 2013 by Mitsubishi Heavy Industries and Nippon Sharyo
specifically for commercial usage in the proposed 250km Chuo-Shinkansen line is currently
undergoing testing. The L0 Series train design has a characteristic long nose, which is
purportedly designed to reduce aerodynamic drag and noise. This train very recently broke
the land speed record at 601kmph in its test track.
10
Chapter 3: OBJECTIVES AND METHODOLOGY
3.1 Objectives of the Project
Design of Maglev trains to obtain a low value of drag coefficient and drag force.
Observation of the effects of track shape on the value of drag coefficient and drag force.
Design and observations of the effects of density change and tunneling effect on the
values of drag coefficient and drag force.
11
3.2 Methodology of Design
In Creo, the model of Maglev is prepared using extrude, blend and related options and saved
with the extension .IGES. Streamlining the shape by introducing curves, rounded ends and
arrowhead-ends in the geometry are manipulated using the existing modification tools of
Creo. Design cues are borrowed from existing designs such as the TransRapid and
Bombardier round-end design.
In the Ansys workbench, Ansys Fluent option is selected from the Menu. Geometry is
double-clicked to open the ‘Design Modeler’ where the design is imported, using the ‘Import
External Geometry File’ option in the ‘File’ menu. Next, an enclosure is produced of a
required shape and dimensions using the ‘Enclosure’ option in the ‘Tool’ menu. During
analysis in evacuated tube conditions, enclosure is produced of particular dimensions of
tunnels as well as keeping distance of train from track base and guide walls into
consideration.
‘Boolean Operation’ is used to subtract the train from the enclosure for meshing. The
progress is saved and the window is closed.
Next, in the workbench, the meshing option is updated and a meshing window is opened
using ‘Edit for Meshing’ where the different zones are named to distinguish each other later.
Meshing quality options and values are entered e.g. minimum size, growth rate, tessellation
values, inflation options, assembly method etc.
Next, meshing is performed as shown in Fig. 3.2.1 and Fig. 3.2.2, after which meshing is
executed by clicking on ‘Update’ or ‘Generate Meshing’.
Fig. 3.2 (1) Mesh Sizing Fig. 3.2 (2) Mesh Statistics
12
Next, in the workbench, the Setup Command where conditions like ‘Models (Standard k-e,
non-equilibrium wall’, ‘Material (Air)’, ‘Boundary Conditions (Inlet Velocity)’ and
‘Reference Values’ are chosen as per standard rules. Reference values include the reference
area which signifies the frontal area of the train designed.
During analysis in evacuated tube conditions, mesh quality is checked and when asked for a
report, ‘Pressure Based Solver’ is chosen. ‘Viscous laminar’ is chosen in the model tab, as
well as ‘k-epsilon’, ‘Enhanced wall treatment’ and ‘Realizable’. After this, fluid properties
are changed to decrease air density to 1/1000th
of its original value and materials needed are
selected in the ‘Cell Zone condition’ too. Inlet and outlet boundary conditions are chosen. In
inlet boundary conditions, ‘Turbulent Intensity’ and ‘Hydraulic Diameter’ are used as solving
parameters. Reference is selected as inlet.
Fig. 3.2 (3) Simple Solution Method
Fig. 3.2 (4) Coupled Solution Method
13
Next, the solution methods are chosen, which are either simple (Fig. 3.2.3) or coupled (Fig
3.2.4). Coupled Solution method is chosen for velocities in the range of 100 to 800 kmph [10]
.
Next, in the monitor, the Parameters such as drag and lift are selected.
Using hybrid initialization for accelerating the solution [11]
, the solution is initialized for
obtaining the range of solution values.
In the ‘Run Calculation’ option, the number of iterations to be performed is chosen for
obtaining a result. When the calculations are completed, the results are obtained from the
‘Graphics and Animation’, with Plots and Report Option given under the heading ‘Results’.
The progress is saved as a .WBPJ file.
Fig. 3.2 (5) Analysis using ANSYS
14
Chapter 4: RESULT ANALYSIS
4.1 Design of Train Models
A total of 9 Train Models were designed using Creo with subsequent modifications being
made to decrease the drag coefficient. The models are:
Fig. 4.1 (1) Model V1
Fig 4.1 (2) Model V2
Fig. 4.1 (3) Model V3
15
Fig 4.1 (4) Model V4
Fig 4.1 (5) Model V5
Fig. 4.1 (6) Model V6
16
Fig. 4.1 (7) Model V7
Fig. 4.1 (8) Model V8
Fig. 4.1 (9) Model V9
17
4.2 Analysis of all designed models under constant parameters
o Common length of train 100 m
o Common front area 3.7m x 4.02 m
o Common speed 402 kmph
Fig. 4.2 Train in a regular enclosure
Fig. 4.2 is a front cross-sectional view of the train during analysis. The dashed line represents
the enclosure surrounding the train (in red). These dimensions are standard enclosure
dimensions to simulate fluid flow analysis of an object in free air conditions.
3.7 m
4.02 m
50 m
50 m
50 m
18
4.2.1 Drag coefficients of all models Table 4.2.1
Drag coefficients of all models
in regular enclosure
Train Model
Version
Drag
Coefficient
1 0.68
2 0.653
3 0.6
4 0.55
5 0.423
6 0.37
7 0.275
8 0.17
9 0.22
Fig 4.2.1 Drag coefficients of all models in regular enclosure
4.2.2 Drag forces of all models Table 4.2.2
Drag forces of all models in
regular enclosure
Train Model
Version
Drag Force
(kN)
1 75
2 71.96
3 66.123
4 60.61
5 46.61
6 40.77
7 30.306
8 18.73
9 24.3
Fig. 4.2.2 Drag forces of all models in regular enclosure
19
4.3 Analysis of all models under varying parameters
4.3.1 Variation of all models at 2 different lengths of train 100 m and 315 m (Standard
train lengths)
4.3.1.1 Variation of drag coefficients of all models
Table 4.3.1.1 Drag coefficients of all models under varying length
Length
(m)
Cd
(V1)
Cd
(V2)
Cd
(V3)
Cd
(V4)
Cd
(V5)
Cd
(V6)
Cd
(V7)
Cd
(V8)
Cd
(V9)
100 0.68 0.653 0.6 0.55 0.423 0.37 0.275 0.17 0.22
315 0.92 0.798 0.785 0.786 0.647 0.566 0.543 0.38 0.43
Fig. 4.3.1.1 Drag coefficients of all models under varying length
20
4.3.1.2 Variation of drag forces of all models
Table 4.3.1.2 Drag forces of all models under varying length
Length
(m)
Fd
(V1)
(kN)
Fd
(V2)
(kN)
Fd
(V3)
(kN)
Fd
(V4)
(kN)
Fd
(V5)
(kN)
Fd
(V6)
(kN)
Fd
(V7)
(kN)
Fd
(V8)
(kN)
Fd
(V9)
(kN)
100 75 71.76 66.12 60.61 46.61 40.77 30.3 18.73 24.3
315 110.2 84.46 83.1 83.11 64 62.89 41.68 38.69 40.11
Fig. 4.3.1.2 Drag forces of all models under varying length
21
4.3.2 Variation of 2 models at 2 different areas
Areas chosen are based on dimensions of width and height of train model designed
A1 = 2.8 m x 2.65 m = 7.42 m2
A2 = 4.2 m x 4 m = 16.7 m2
(Dimensions multiplied by 1.5)
A3 = 6.3 m x 6 m = 37.56 m2
(Dimensions multiplied by 1.5)
4.3.2.1 Variation of drag coefficients of 2 models Table 4.3.2.1
Fig. 4.3.2.1 Drag coefficients of 2 models with varying area
4.3.2.2 Variation of drag forces of 2 models Table 4.3.2.2
Drag forces of with varying area
Fig. 4.3.2.2 Drag forces of 2 models with varying area
Area
(m2)
Drag
Coefficient
(V1)
Drag
Coefficient
(V4)
7.42 0.926 0.786
16.7 0.664 0.532
37.56 0.533 0.463
Area
(m2)
Drag
Force (V1)
(kN)
Drag
Force (V4)
(kN)
7.42 43.32 53.34
16.7 176.48 106.74
37.56 318.66 208.82
Drag coefficients with varying area
22
4.3.3 Variation of all models at 3 different operating speeds
Speeds chosen vary from regular intra-city rapid transit to very high speed inter-city travel
Speed 1 = 100 kmph (Rapid transport speed)
Speed 2 = 300 kmph (High speed railway speed)
Speed 3 = 500 kmph (Theoretical very high speed)
4.3.3.1 Variation of drag coefficients of all models
Drag coefficient is subject only to the geometry of the train, and is unaffected by the speed,
with changes being in the order of 0.0x (negligible).
4.3.3.2 Variation of drag forces of all models
Table 4.3.3.2 Drag forces of all models with varying speed
Speed
(kmph)
Fd
(V1)
(kN)
Fd
(V2)
(kN)
Fd
(V3)
(kN)
Fd
(V4)
(kN)
Fd
(V5)
(kN)
Fd
(V6)
(kN)
Fd
(V7)
(kN)
Fd
(V8)
(kN)
Fd
(V9)
(kN)
100 4.32 4.23 3.91 3.409 2.53 2.17 1.36 1.18 1.27
300 37.22 38.73 35.56 29.89 16.84 17.86 11.97 9.85 10.91
500 106.74 106.87 97.95 81.37 46.61 40.77 32.25 26.35 29.41
Fig. 4.3.3.2 Drag forces of all models with varying speed
23
4.4 Analysis of all models with track introduced as part of enclosure
The track designed as part of the enclosure is meant to represent the aerodynamics of the train
travelling above a set track, elevated by a certain distance, and between 2 guide walls, with
certain clearances. This approach of narrowing the passage of air between the train and its
surroundings on 3 of its sides is an attempt at showing the fluid flow as realistic as possible.
Fig. 4.4 Track inclusion in enclosure
As can been seen in Fig. 4.4, the train (marked in red), is surrounded by the track (marked in
purple) whose guide walls have a clearance of 150 mm as per dimensions used for Japan
Maglev, and the elevation from the base being 100 mm, the maximum elevation of track
possible. The total height of the guide wall is 1.44 m, out of which 1.34 m lies above the base
of the train. This portion is 1/3rd
of the height of the train itself to align with the magnets in
the base of the train.
Because of the change in the flow of air, the drag coefficient of the train changes and
correspondingly the drag force.
3.7 m
4.02 m
50 m
50 m
150 mm
100 mm 1.44 m
24
4.4.1 Variation of drag coefficients of all models Table 4.4.1
Fig. 4.4.1 Drag coefficients of all models before and after track
4.4.2 Variation of drag forces of all models
Fig. 4.4.2 Drag forces of all models before and after track
Train
Model
Version
Cd
(Original)
Cd
(Track
Include)
1 0.68 0.62
2 0.65 0.61
3 0.6 0.57
4 0.55 0.57
5 0.42 0.59
6 0.37 0.59
7 0.27 0.3
8 0.17 0.23
9 0.22 0.27
Train
Model
Version
Fd
(Original)
(kN)
Fd
(Track
Include)
(kN)
1 75 67.9
2 71.96 65.27
3 66.1 61.4
4 60.61 61.4
5 46.61 63.1
6 40.77 63.1
7 30.3 28.4
8 18.7 23.7
9 24.3 31.8
Table 4.4.2
Drag forces before and after track
Table 4.4.1
Drag coefficients before and after track
25
4.5 Analysis of 2 models with tunnel shape introduced for enclosure design
Before the analysis of the designed trains in evacuated tubes at low pressure/density values, it
is necessary to compare the variation of drag values of a train in constant conditions of area,
speed and length but varying tunnel/tube shape. To address this, 3 tunnel shapes were
designed as part of the enclosure surrounding the trains. The illustrations along with accurate
dimensions used for designing are as follows:
Circular Rectangular Curved Head
Fig. 4.5 Tunnel Shapes
Therefore, the 3 tunnel shapes are
- Circular
- Rectangular
- Curved Head
Cross-sectional area of the enclosures was drastically reduced to simulate an actual tunnel
with capabilities of being constructed over long distances. All tunnel shapes are designed
with a constant blockage ratio of 0.17 based on the values used for proposed Swiss
Underground Maglev Metro [12]
, with the resulting cross-sectional area of the tunnel being
87.5 m2. Parameters kept constant were speed at 402 kmph, dimensions of the train at 3.7 m x
4.02 m, length at 100 m.
Models 6 and 7 were chosen to be tested on, after which the tunnel design whose enclosure
results in the lowest drag for the analyzed train, would be chosen for the final evacuated tube
analysis.
7 m
10 m
8.2
m
7.9 m
10.6 m
26
4.5.1 Drag coefficients of model 6 and 7 under varying tunnel enclosure shape
Fig. 4.5.1 Drag coefficients varying enclosure shape
4.5.2 Drag forces of model 6 and 7 under varying tunnel enclosure shape
Fig 4.5.2 Drag forces varying enclosure shape
As can be seen, curved head tunnel shape generates least drag values out of 3, and hence is
chosen as the tunnel for the evacuated tube analysis of all train models in low
pressure/density conditions.
Train
Model
Version
Cd
(Circular)
Cd
(Rectangular)
Cd
(Curved
Head)
6 0.87 0.91 0.72
7 0.67 0.68 0.63
Train
Model
Version
Fd
(Circular)
kN
Fd
(Rectangular)
kN
Fd
(Curved
Head)
KN
6 96.7 101.2 80
7 74.5 75.6 70
Table 4.5.2
Table 4.5.1
Drag coefficients varying enclosure shape
Table 4.5.2
Drag forces varying enclosure shape
27
4.6 Evacuated tube analysis of all models in curved head tunnel enclosure
at blockage ratio 0.17 at reduced density
Fig. 4.6 Curved Head Tunnel Enclosure with Ratio 0.17
Evacuated tube analysis is necessary to simulate a maglev train travelling in conditions that
drastically reduce its primary form of friction – air drag. As exemplified in SpaceX’s paper
‘Hyperloop Alpha’ [13]
, while it is impossible to create and maintain vacuum conditions in
large tubes, it is quite possible to implement a low pressure system that can be maintained by
standard commercial pumps as well as overcome any leaks. Pressure of air inside the
evacuated tube is hypothesized to be feasibly reduced upto 100 Pa, 1/1000th
of the sea level
air pressure. The pressure is equivalent to an airplane travelling at 150,000 ft. Since Ansys
Fluent does not allow change of operating pressure, we can simulate this low pressure by
changing the density of the air inside the tube in the reference values. By Ideal Gas Law,
density is directly proportional to air pressure. By changing the air pressure to 100 Pa, the
density inside the tube will be 1.225 x 10-3
kg/m3. This is the value that we use for the
analysis of all trains in low density conditions in realistic fluid flow simulations. Changing
the density changes the drag coefficient and drag force values.
3.7 m
4.02 m
3 m
10.6 m
7.9 m
28
4.6.1 Drag coefficients of all trains in low density, curved head tunnel conditions
Fig. 4.6.1 Drag coefficients in low density, tunnel
4.6.2 Drag forces of all trains in low density, curved head tunnel conditions
Fig. 4.6.2 Drag forces in low density, tunnel
Train
Model
Version
Cd
(Original)
Cd
(Tunnel)
1 0.68 1.7
2 0.65 1.59
3 0.6 1.52
4 0.55 1.33
5 0.42 1.34
6 0.37 1.3
7 0.27 1.06
8 0.17 0.67
9 0.22 1.19
Train
Model
Version
Fd
(Original)
(kN)
Fd
(Tunnel)
(kN)
1 75 0.2
2 71.96 0.17
3 66.123 0.16
4 60.61 0.146
5 46.61 0.147
6 40.77 0.143
7 30.306 0.09
8 18.73 0.07
9 24.3 0.14
Table 4.6.2
Table 4.6.1
Drag coefficients in low density, tunnel
Table 4.6.2
Drag forces in low density, tunnel
29
Chapter 5: CONCLUSIONS AND SCOPE FOR FUTURE
WORK
5.1 Conclusions
Levitation of a MAGLEV train allows the removal of all other forms of drag except air
drag, which becomes significant at high speeds. Aerodynamic modelling of trains directly
influences power consumption and fuel efficiency.
AeroEfficient shaping of trains is carried out in design software and tested out using wind
tunnel analysis to determine drag coefficients and drag forces.
We have used Creo as our design software and Ansys Fluent for the fluid (air) flow
analysis with varying parameters.
Streamlining the front end of the train lowers the drag coefficient of the train, allowing us
to achieve the lowest drag coefficient of 0.17 with a train length of 100 m, front area
dimensions of 3.7 m x 4.02 m, and a speed of 402 kmph.
With increase in length of train, drag coefficient and drag force increases greatly. Trains
with shorter lengths, such as shuttles are optimum.
With increase in speed of air flow inside enclosure, drag force increases exponentially.
With increase in front-end cross-sectional area of the train, drag force increases. Trains
with relatively smaller frontal areas are optimum.
Guide walls as part of the Maglev track narrow the passage of air flow around the train,
increasing the drag coefficient and drag force.
Curved head tunnel as an enclosure allows least drag for a Maglev train passing through it
as compared to a circular and rectangular design.
Simulating a Maglev train travelling in an evacuated tube by its fluid flow analysis in a
tunnel with a blockage ratio of 0.17 and reducing the density to 1/1000th
of its regular
value will increase the drag coefficient of the train slightly but drastically decrease its
drag force to negligible values.
30
5.2 Scope for Future Work
Our project has solely focused on the design and analysis of EDS maglev trains modelled
after the Japan SCMaglev. Design of EMS Maglev trains and tracks, analysis and
comparison of drag values could be of paramount importance to understand which system
is better/more efficient.
Design of Maglev trains with dimensions capable of running on existing Indian Rails
(using the steel tracks as guide walls and sleepers as bases for installing levitation wiring)
could be done as a hypothetical case to reduce costs of not building a brand new
infrastructure.
Aerodynamic simulation of Maglev trains to understand nature and damage capabilities
of shock waves induced from the opposite direction crossing of 2 Maglev trains at an
excess of 600 kmph can be assessed using different software.
Simulation of a train in a closed evacuated tube can help understand the syringe-effect of
a train pushing air till it reaches the Kantrowitz limit [13]
of maximum speed and the
phenomenon’s variation with diameter of the tube.
Analysis of drag encountered by trains in the evacuated tubes proposed at super-sonic
speeds could be of importance when considering possibility of inter-continental travel at
3000 kmph.
31
REFERENCES
1. Wikipedia Articles on Maglev, EMS, EDS, SCMaglev, Shanghai Maglev
2. Dispelling the Top Ten Myths of Maglev by Laurence E. Blow President,
MaglevTransport, Inc. - High Speed Rail 2010 Conference: White Paper
3. Aerodynamic Aspects of Maglev Systems by Th. Tielkes, Deutsche Bahn AG, DB
Systemtechnik, Dep. of Aerodynamics and Air Conditioning, Munich, Germany, 2014
4. A review of Train Aerodynamics Fundamentals by Baker, Christopher, University of
Birmingham - Citation for published version (Harvard): Baker, C 2014, The Aeronautical
Journal, Vol. 118, no.1201.
5. Rocket Aerodynamics – ScienceLearn.ORG Website
6. Shape Effects on Drag – Glenn Research Centre, NASA Website
7. High Tech for “Flying on the Ground” – TransRapid International, Summary Article
published on website, Published 2013
8. AeroEfficient Optimized Train Shaping – Bombardier, EcoActive Technologies
9. Superconducting Maglev Developed by RTRI and JR Central – Kazuo Sawad, published
in Railway Technology Today, October 2000
10. A coupled finite volume solver for the solution of incompressible flows on unstructured
grids - M. Darwish, I. Sraj, F. Moukalled, published 2009, Department of Mechanical
Engineering, American University of Beirut, P.O. Box 11-0236, Riad El Solh, Beirut
1107 2020, Lebanon
11. Accelerating CFD Solutions - Mark Keating, Principal Engineer, ANSYS, Inc. published
in ANSYS Advantage • Volume V, Issue 1, 2011
12. Feasibility and Economic Aspects of Vactrains - Worcester Polytechnic Institute,
Professor Oleg Pavlov, SSPS, published October 11, 2007
13. Hyperloop Alpha – Space Exploration Technologies Corporation, Open Paper published
2013