` [Project: High speed Train nose analysis] [MAE] [505] [Computer Modeling of Complex Thermal-Fluid System] [ 12 th May 2011]
`
[Project: High speed Train
nose analysis]
[MAE]
[505] [Computer Modeling of Complex Thermal-Fluid System]
[ 12th May 2011]
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Contents 1 Introduction of High Speed Train ............................................................................................... 3
1.1 Definition ........................................................................................................................... 3
1.2 History ............................................................................................................................... 3
1.3 Advantages ........................................................................................................................ 5
1.4 Objectives of the project ..................................................................................................... 5
1.5 Scope of work .................................................................................................................... 6
1.6 Computational fluid dynamics V/S Wind tunnel ................................................................. 6
1.7 Analysis of High Speed Train Nose using Different Geometry.............................................. 8
1.7.1 Input Parameters ...................................................................................................... 13
1.8 Results ............................................................................................................................. 14
1.8.1 Top view configurations ........................................................................................... 14
1.8.2 Side View Configuration .......................................................................................... 15
1.9 Appendix .......................................................................................................................... 22
1.9.1 CCL for Case A .......................................................................................................... 22
1.9.2 CCL for Case B........................................................................................................... 25
1.9.3 CCL for Case C........................................................................................................... 28
1.9.4 CCL for Case D .......................................................................................................... 32
1.9.5 Convergence Residual Plots ...................................................................................... 36
1.9.6 Dimensions for the Model ........................................................................................ 37
1.9.7 References : ............................................................................................................. 41
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1 Introduction of High Speed Train
1.1 Definition
The UIC (International Union of Railways) defines high speed rail as services which
regularly operate at or above 250 km/h on new tracks, or 200 km/h on existing tracks.
A number of characteristics are common to most high speed rail systems. Curve
radius will often be the ultimate limiting factor in a train's speed, with passenger
discomfort often more important than the danger of derailment. Magnetic levitation
trains fall under the category of high speed rail due to their association with track
oriented vehicles; however their inability to operate on conventional railroads often
leads to their classification in a separate category.
1.2 History
The first high speed train in the world was opened by the Japan, between Tokyo and
Osaka, in time for 1964 Olympics. Ref. by High speed train of Japan and France.
Figure 1.1
Figure 1 a) JR East Shinkansen trains (Japan) and b) TGV (France)
The maximum speed of first Shinkansen (new trunk line) service was 210 km/h (131
mph) and took four hours between the two cities. Later on improving the vehicles,
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with maximum speed of 277 km/h (172 mph) took less than three hours. Within
several years, the digit of speed reached to 443 km/h (275 mph) for test runs in 1996
and finally up to a world record 581 km/h (361 mph) for maglev (magnetic levitation)
train in 2003. With a brief view on other high speed line, some countries will be
found in the competition. The table mentioned below introduces the most friendly
high speed rail countries and their speed of rail.
Records in Trial Runs
From the beginning of high speed train, the continuous modification, improvement
and aid of latest technology reaches the speed to 581 km/h (Japan MLX01). The
survey for land speed record for railed vehicles focus on digit of speed of different
nations. Ref. by High speed Rail from Wikipedia.
Table 1 - Speed line of nations
Year Nation Speed records (km/h) Remarks
1963 Japan 256 1st nation to develop HSR
1965 West Germany 200 2nd nation to develop HSR
1967 France 318 3rd nation to develop HSR
1974 France 430 High speed monorail train
1979 Japan 319
1981 France 380
1988 Italy 319 4th nation to develop HSR
1993 Japan 425
1993 Germany 450
1994 Japan 431
1996 Japan 446
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2002 Spain 362 5th nation to develop HSR
2002 China 321 6th nation to develop HSR
2003 Japan 581 Current world record holder
2004 South Korea 352.4 7th nation to develop HSR
2007 France 574.8
2008 China 394.3
1.3 Advantages
1. Due to infrastructure design in many nations, highway and air travel systems
are constrained. It cannot expand and in many cases are overloaded. High
speed rail has the potential for high capacity on its fixed corridors and has the
potential relieve congestion on other transit systems.
2. High speed trains are also considered more energy efficient or equivalent to
other modes of transit per passenger mile.
3. In terms of possible passenger capacity, high speed trains can also reduce the
amount of land used per passenger when compared to cars on roads.
4. Well established high speed rail systems are more environmentally friendly
than air or road travel. This is due to lower energy consumption per passenger
kilometer.
5. Rail travel has considerably less weather dependency than does air travel.
1.4 Objectives of the project
On the increasing demand of high speed transportation vehicle it is necessary to have
a better design and good service that can be achieved only by continuous
improvement of high speed train nose. The purpose of this project is to address the
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need for an Aerodynamic nose shape which will help in using various types of
geometries used as the High speed train1, while running on a normal terrain. This is
not enough to specify whole domain but it is only the problem on which one can keep
idea to invent a new horizon.
The ultimate goal is to optimize the shape of the nose by providing the smooth and
gradual flow of air around the nose of the train. 3 D models are developed using CAD
tool with proper surfacing.
1.5 Scope of work
Decide the way to obtain different geometry based on mathematical curves.
Study of aerodynamics around streamlines.
Study of CFD and its method for flow analysis.
Comparison of the results.
1.6 Computational fluid dynamics V/S Wind tunnel
The wind tunnel has played a leading role in aerodynamic performance analysis since
the first days of powered flight when the Wright brothers used a wind tunnel to
evaluate the lift and drag of the airfoil profiles. A wind tunnel simulates the
movement of an object (e.g. an aircraft, a train nose or a car) through air by placing a
stationary scale model of the object within a duct and either blowing or sucking air
through the duct. Mounting the model on a force balance allows measurement of
forces, such as drag and lift or downforce, as the air interacts with the scale model.
Later, wind tunnel testing was applied to automobiles to determine ways to reduce the
power required to move the vehicles on a roadways at a given speed. Ref. from
Wikipedia, NASA wind tunnel.
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Figure 2 (NASA wind tunnel with the model of plane)
Air is blown or sucked through a duct equipped with a viewing port and instruments
where models and geometrical shapes are mounted for testing. Typically the air is
moved through the tunnel using a series of fans. For large wind tunnels a single large
fan is not practical so an array of multiple fans is used in parallel to provide sufficient
airflow.
Wind tunnel classification
a) Low speed wind tunnel: Low speed wind tunnels are used for operations at very low
mach number, with speeds in the test section up to 400 km/h (M = 0.3).
b) High speed wind tunnel: High subsonic wind tunnels (0.4 < M < 0.75) or transonic
wind tunnels (0.75 < M < 1.2) are designed on the same principles as the subsonic
wind tunnels. Transonic wind tunnels are able to achieve speeds close to the speeds of
sound.
c) Supersonic wind tunnel: A supersonic wind tunnel is a wind tunnel that produces
supersonic speeds (1.2<M<5) .
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d) Hypersonic wind tunnel: A hypersonic wind tunnel is designed to generate a
hypersonic flow field in the working section. The speed of these tunnels varies from
Mach 5 to 15.
1.7 Analysis of High Speed Train Nose using Different Geometry
In this project we analyzed the following 4 models of the train nose to understand the
pressure acting on the face of the high speed train. The described side sectional views
are obtained from different curves. Mainly ellipse and parabola curves are taken to
develop sections. The various shapes are derived from general high speed train
geometry of different countries.
Figure 3 Model A: Section of straight edge, Model B: Section of elliptical curves, Model C: Section of
parabolic segment, Model D: Section of parabola curves – for dimensions refer appendix
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Table 2 (Input Parameters)
STAGNATION PROPERTIES OF HIGH SPEED TRAIN NOSE
INPUT PARAMETERS
Train speed (Km/h) 320
Air pressure (Pa) 101325
Temperature (K) 300
Gas const (J/kg K) 287
Cp/Cv 1.4
For generating the mesh , we used the mesh enhancement features like inflation.
Figure 4 (Mesh for Model A)
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Mesh Statistics for Model A
Total number of nodes 397885
Total number of tetrahedral 2212594
Total number of pyramids 1618
Total number of prisms 8904
Total number of elements 2223116
Figure 5 (Mesh for Model B)
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Mesh Statistics for Model B
Total number of nodes 374669
Total number of tetrahedral 2094037
Total number of faces 64054
Total number of elements 2094037
Figure 6(Mesh for Model C)
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Mesh Statistics for Model C
Total number of nodes 599010
Total number of tetrahedral 3391588
Total number of pyramids 443
Total number of prisms 2137
Total number of elements 3394168
Figure 7(Mesh for Model D)
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Mesh Statistics for Model D
Total number of nodes 109989
Total number of tetrahedral 591303
Total number of pyramids 1600
Total number of prisms 8088
Total number of elements 600991
1.7.1 Input Parameters
Component Feature Details
CFX-Pre User Mode General Mode
Analysis Type Steady State
Fluid Type Ideal Gas
Domain Type Single Domain
Turbulence Model Shear Stress Transport
Heat Transfer Isothermal
Boundary Conditions Inlet (Subsonic)
Outlet (Subsonic)
Side Wall: Free-Slip
Body: No-Slip
Timestep Physical Time Scale
CFX-Solver Manager Parallel processing
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1.8 Results
1.8.1 Top view configurations
The design for top sections is made on basis of smoother flow around the nose body,
less pressure gradient and relatively low stagnation area. The main criterion to adopt
for optimum design is drag and minimum static pressure.
When considering the top view (Fig 8.), we can see that the peak pressure is achieved
in the Model D with the maximum value of 4995 Pa. At the same time Model B has
the least pressure of 4851 Pa. The rectangular portion of the Model D is the reason for
having the maximum drag stagnation area. Model B appears to be the optimum shape
to have minimum value of the pressure.
Figure 8 (Figure showing the pressure distribution for the four geometries - Top view)
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Smoother streamlines on side wall plays a vital role to keep train system with track.
This face can be seen in the Model B which have smooth transition without any
stagnation area being created on the sidewalls.
1.8.2 Side View Configuration
In this view as shown in fig 9 we can see that the Model C offers a large resistance to
speed with quite large stagnation area.
Figure 9 (Figure showing the pressure distribution for the four geometries - side view)
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The main reason to analyze the side section is to observe the negative pressure,
control vortex generation and minimizing the coefficient of moment. Because the
coefficient of moment must be less for the stability of the train on the track and this is
done by keeping the coefficient of lift to be minimum. The coefficient of drag is
calculated later in the project.
Figure 10 (Velocity Streamlines)
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Velocity Streamlines :
In Fig. 11 we can see that velocity streamlines travel smoothly over the streamline
bodies. We can observe in the plot, the red regions in the velocity field , where the
velocity is maximum. Pressure reduces in those regions since velocity in high. If such
regions are more at the top, it can lead to lift. We can see in the vortex formation on
the backside of the body. The motion of the fluid swirls rapidly around a center. The
speed and rate of rotation of the fluid are greatest at the center and progressively
decrease with distance from the center. Generally in High speed trains the back end is
made similar in geometry like the front. Hence these wakes are minimized.
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Figure 11 (Pressure Contour)
In the figure 12, we can see the pressure contour. Here the highest pressure is
same in all the models but the area of the contour of not same. The smaller the
area of the contour, smaller is the force. We can see in the figure that the area for
the top two figure has relatively large area for the highest pressure. These area are
relatively small in the lower ones. Also we can observe the negative pressure
regions on the surface. For configuration Model A and Model C the stagnation
pressure as well as drag co-efficient is greater because for both configurations
portion on tip of nose may be affected due to larger surface area. The main
drawbacks for such type of shape are no smoother streamlines exists due to
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straight edge rather than curved one. So the next target is to gain some side wall
of nose inclined to get smooth streamline and reduced drag as well as pressure.
1. DRAG
The force that oppose the relative motion of an object through a fluid. Also it is
called an air resistance which acts in a direction opposite to the oncoming flow
velocity. In an open air condition, the aerodynamic drag of the train is sum of the
normal force (pressure drag) and tangential force (skin friction drag). The
reference area A is defined as the area of the orthographic projection of the object
on a plane perpendicular to the direction of motion.
The drag force due to wind (air) acting on an object can be found by:
AVCF DD
2
2
1 (1)
where: FD = drag force (N)
CD = drag coefficient (no units)
V = velocity of object (m/s)
A = projected area (m2)
ρ = density of air (kg/m3) {1.2 kg/m
3}
Here we will calculate the CD which is a number that is used to model all of the
complex dependencies of shape and flow conditions and this factor decides the
geometrical changes required to generate a better aero-dynamical shape.
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With the help of CFX solver, we are able to calculate the force Fd in the direction
opposite to the velocity of the train.
Using the relation mentioned above we generated the following table to compare
the drag coefficient for the different geometries.
S. No. Force FD Area A CD
Model A 14128.5 [N] 8.55 0.34
Model B 17058.8 [N] 11.822 0.30
Model C 14748.3 [N] 8.87 0.35
Model D 11895.9 [N] 8.55 0.29
From the results we can see that the value of CD for the Model B and Model D are
almost similar with the least value of the coefficient of Drag. These two profiles
had the elliptical and the parabolic curve which provides a better aerodynamic
shape to the train nose.
2. LIFT
A fluid flowing past the surface of a body exerts force on it. The component of
this force that is perpendicular to the oncoming flow direction.
AVCF LL
2
2
1 (2)
where: FL = drag force (N)
CL = drag coefficient (no units)
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V = velocity of object (m/s)
A = projected area (m2)
ρ = density of air (kg/m3) {1.2 kg/m
3}
S. No. Force FD Area A CD
Model A 2355.09 31.01 0.016
Model B 3960.55 25.09 0.033
Model C 3177.34 10.3 0.065
Model D 5235.74 18 0.061
4.8 Closure
The guidelines set up for shape optimization of high speed train nose is very good
approach to have the best geometrical shape. The commercial CFX package for
flow simulation is one of the best tools to investigate the flow without having the
real wind tunnel. The study has been done in direction of shape optimization is
not limited to geometry but can also be extended to analyze the behavior of front
cab in storm and cross wind.
I would like to thanks Prof. Vanslooten, for the guidance and his presence during
executing the project.I would also like to thank him for giving a good
understanding of the mesh element in this classes.
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1.9 Appendix
1.9.1 CCL for Case A
+---------------------------------------------+ | | | CFX Command Language for Run | | | +------------------------------------------------------+ LIBRARY: MATERIAL: Air Ideal Gas Material Description = Air Ideal Gas (constant Cp) Material Group = Air Data, Calorically Perfect Ideal Gases Option = Pure Substance Thermodynamic State = Gas PROPERTIES: Option = General Material EQUATION OF STATE: Molar Mass = 28.96 [kg kmol^-1] Option = Ideal Gas END SPECIFIC HEAT CAPACITY: Option = Value Specific Heat Capacity = 1.0044E+03 [J kg^-1 K^-1] Specific Heat Type = Constant Pressure END REFERENCE STATE: Option = Specified Point Reference Pressure = 1 [atm] Reference Specific Enthalpy = 0. [J/kg] Reference Specific Entropy = 0. [J/kg/K] Reference Temperature = 25 [C] END DYNAMIC VISCOSITY: Dynamic Viscosity = 1.831E-05 [kg m^-1 s^-1] Option = Value
END THERMAL CONDUCTIVITY: Option = Value Thermal Conductivity = 2.61E-2 [W m^-1 K^-1] END ABSORPTION COEFFICIENT: Absorption Coefficient = 0.01 [m^-1] Option = Value END SCATTERING COEFFICIENT: Option = Value Scattering Coefficient = 0.0 [m^-1] END REFRACTIVE INDEX: Option = Value Refractive Index = 1.0 [m m^-1] END END END END FLOW: Flow Analysis 1 SOLUTION UNITS: Angle Units = [rad] Length Units = [m] Mass Units = [kg] Solid Angle Units = [sr] Temperature Units = [K] Time Units = [s] END ANALYSIS TYPE: Option = Steady State EXTERNAL SOLVER COUPLING: Option = None END END DOMAIN: Default Domain Modified Coord Frame = Coord 0
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Domain Type = Fluid Location = B110 BOUNDARY: body Boundary Type = WALL Location = Default 2D Region BOUNDARY CONDITIONS: MASS AND MOMENTUM: Option = No Slip Wall END WALL ROUGHNESS: Option = Smooth Wall END END END BOUNDARY: inlet Boundary Type = INLET Location = inlet BOUNDARY CONDITIONS: FLOW REGIME: Option = Subsonic END MASS AND MOMENTUM: Normal Speed = 320 [km hr^-1] Option = Normal Speed END TURBULENCE: Option = Medium Intensity and Eddy Viscosity Ratio END END END BOUNDARY: outlet Boundary Type = OUTLET Location = outlet BOUNDARY CONDITIONS: FLOW REGIME: Option = Subsonic END MASS AND MOMENTUM: Option = Average Static Pressure Pressure Profile Blend = 0.05 Relative Pressure = 0 [Pa] END PRESSURE AVERAGING: Option = Average Over Whole Outlet END
END END BOUNDARY: wall Boundary Type = WALL Location = free1,free2,free3,free4 BOUNDARY CONDITIONS: MASS AND MOMENTUM: Option = Free Slip Wall END END END DOMAIN MODELS: BUOYANCY MODEL: Option = Non Buoyant END DOMAIN MOTION: Option = Stationary END MESH DEFORMATION: Option = None END REFERENCE PRESSURE: Reference Pressure = 1 [atm] END END FLUID DEFINITION: Fluid 1 Material = Air Ideal Gas Option = Material Library MORPHOLOGY: Option = Continuous Fluid END END FLUID MODELS: COMBUSTION MODEL: Option = None END HEAT TRANSFER MODEL: Fluid Temperature = 25 [C] Option = Isothermal END THERMAL RADIATION MODEL: Option = None END TURBULENCE MODEL: Option = SST END
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TURBULENT WALL FUNCTIONS: Option = Automatic END END END OUTPUT CONTROL: RESULTS: File Compression Level = Default Option = Standard END END SOLVER CONTROL: Turbulence Numerics = First Order ADVECTION SCHEME: Option = High Resolution END CONVERGENCE CONTROL: Length Scale Option = Conservative Maximum Number of Iterations = 100 Minimum Number of Iterations = 1 Timescale Control = Auto Timescale Timescale Factor = 1.0 END CONVERGENCE CRITERIA: Residual Target = 0.00001 Residual Type = RMS END DYNAMIC MODEL CONTROL: Global Dynamic Model Control = On END END END COMMAND FILE: Results Version = 13.0 Version = 13.0 END SIMULATION CONTROL: EXECUTION CONTROL: EXECUTABLE SELECTION: Double Precision = Off END INTERPOLATOR STEP CONTROL: Runtime Priority = Standard MEMORY CONTROL: Memory Allocation Factor = 1.0 END
END PARALLEL HOST LIBRARY: HOST DEFINITION: edge.ccr.buffalo.edu Host Architecture String = linux-amd64 Installation Root = /util/cfx/ansys-13.0/ansys_inc/v%v/CFX END END PARTITIONER STEP CONTROL: Multidomain Option = Independent Partitioning Runtime Priority = Standard EXECUTABLE SELECTION: Use Large Problem Partitioner = Off END MEMORY CONTROL: Memory Allocation Factor = 1.0 END PARTITIONING TYPE: MeTiS Type = k-way Option = MeTiS Partition Size Rule = Automatic Partition Weight Factors = 0.25000, 0.25000, 0.25000, 0.25000 END END RUN DEFINITION: Run Mode = Full Solver Input File = /ifs/user/mandeeps/final_002.res.def END SOLVER STEP CONTROL: Runtime Priority = Standard MEMORY CONTROL: Memory Allocation Factor = 1.0 END PARALLEL ENVIRONMENT: Number of Processes = 4 Start Method = HP MPI Local Parallel Parallel Host List = edge.ccr.buffalo.edu*4 END END END END
1.9.2 CCL for Case B
+---------------------------------------------------------+ | | | CFX Command Language for Run | | | +---------------------------------------------------------+ LIBRARY: MATERIAL: Air at 25 C Material Description = Air at 25 C and 1 atm (dry) Material Group = Air Data, Constant Property Gases Option = Pure Substance Thermodynamic State = Gas PROPERTIES: Option = General Material EQUATION OF STATE: Density = 1.185 [kg m^-3] Molar Mass = 28.96 [kg kmol^-1] Option = Value END SPECIFIC HEAT CAPACITY: Option = Value Specific Heat Capacity = 1.0044E+03 [J kg^-1 K^-1] Specific Heat Type = Constant Pressure END REFERENCE STATE: Option = Specified Point Reference Pressure = 1 [atm] Reference Specific Enthalpy = 0. [J/kg] Reference Specific Entropy = 0. [J/kg/K] Reference Temperature = 25 [C] END
DYNAMIC VISCOSITY: Dynamic Viscosity = 1.831E-05 [kg m^-1 s^-1] Option = Value END THERMAL CONDUCTIVITY: Option = Value Thermal Conductivity = 2.61E-02 [W m^-1 K^-1] END ABSORPTION COEFFICIENT: Absorption Coefficient = 0.01 [m^-1] Option = Value END SCATTERING COEFFICIENT: Option = Value Scattering Coefficient = 0.0 [m^-1] END REFRACTIVE INDEX: Option = Value Refractive Index = 1.0 [m m^-1] END THERMAL EXPANSIVITY: Option = Value Thermal Expansivity = 0.003356 [K^-1] END END END END FLOW: Flow Analysis 1 SOLUTION UNITS: Angle Units = [rad] Length Units = [m] Mass Units = [kg] Solid Angle Units = [sr] Temperature Units = [K]
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Time Units = [s] END ANALYSIS TYPE: Option = Steady State EXTERNAL SOLVER COUPLING: Option = None END END DOMAIN: Default Domain Modified Coord Frame = Coord 0 Domain Type = Fluid Location = B39 BOUNDARY: Default Domain Modified Default Boundary Type = WALL Location = \ F47.39,F48.39,F49.39,F50.39,F51.39,F52.39,F53.39,F54.39,F55.39,F56.39\ ,F57.39 BOUNDARY CONDITIONS: MASS AND MOMENTUM: Option = No Slip Wall END WALL ROUGHNESS: Option = Smooth Wall END END END BOUNDARY: free Boundary Type = WALL Location = free1,free2,free3,free4 BOUNDARY CONDITIONS: MASS AND MOMENTUM: Option = Free Slip Wall END END END BOUNDARY: inlet Boundary Type = INLET Location = inlet BOUNDARY CONDITIONS: FLOW REGIME: Option = Subsonic END MASS AND MOMENTUM:
Normal Speed = 320 [km hr^-1] Option = Normal Speed END TURBULENCE: Option = Medium Intensity and Eddy Viscosity Ratio END END END BOUNDARY: outlet Boundary Type = OUTLET Location = outlet BOUNDARY CONDITIONS: FLOW REGIME: Option = Subsonic END MASS AND MOMENTUM: Option = Average Static Pressure Pressure Profile Blend = 0.05 Relative Pressure = 0 [Pa] END PRESSURE AVERAGING: Option = Average Over Whole Outlet END END END DOMAIN MODELS: BUOYANCY MODEL: Option = Non Buoyant END DOMAIN MOTION: Option = Stationary END MESH DEFORMATION: Option = None END REFERENCE PRESSURE: Reference Pressure = 1 [atm] END END FLUID DEFINITION: Fluid 1 Material = Air at 25 C Option = Material Library MORPHOLOGY: Option = Continuous Fluid END
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END FLUID MODELS: COMBUSTION MODEL: Option = None END HEAT TRANSFER MODEL: Fluid Temperature = 300 [K] Option = Isothermal END THERMAL RADIATION MODEL: Option = None END TURBULENCE MODEL: Option = SST END TURBULENT WALL FUNCTIONS: Option = Automatic END END END OUTPUT CONTROL: RESULTS: File Compression Level = Default Option = Standard END END SOLVER CONTROL: Turbulence Numerics = First Order ADVECTION SCHEME: Option = High Resolution END CONVERGENCE CONTROL: Length Scale Option = Conservative Maximum Number of Iterations = 200 Minimum Number of Iterations = 1 Timescale Control = Auto Timescale Timescale Factor = 1.0 END CONVERGENCE CRITERIA: Residual Target = 0.00001 Residual Type = RMS END DYNAMIC MODEL CONTROL: Global Dynamic Model Control = On END END
END COMMAND FILE: Results Version = 13.0 Version = 13.0 END SIMULATION CONTROL: EXECUTION CONTROL: EXECUTABLE SELECTION: Double Precision = Off END INTERPOLATOR STEP CONTROL: Runtime Priority = Standard MEMORY CONTROL: Memory Allocation Factor = 1.0 END END PARALLEL HOST LIBRARY: HOST DEFINITION: edge.ccr.buffalo.edu Host Architecture String = linux-amd64 Installation Root = /util/cfx/ansys-13.0/ansys_inc/v%v/CFX END END PARTITIONER STEP CONTROL: Multidomain Option = Independent Partitioning Runtime Priority = Standard EXECUTABLE SELECTION: Use Large Problem Partitioner = Off END MEMORY CONTROL: Memory Allocation Factor = 1.0 END PARTITIONING TYPE: MeTiS Type = k-way Option = MeTiS Partition Size Rule = Automatic Partition Weight Factors = 0.25000, 0.25000, 0.25000, 0.25000 END END RUN DEFINITION: Run Mode = Full Solver Input File = /ifs/user/mandeeps/model2.def INITIAL VALUES SPECIFICATION:
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INITIAL VALUES CONTROL: Continue History From = Initial Values 1 Use Mesh From = Solver Input File END INITIAL VALUES: Initial Values 1 File Name = /ifs/user/mandeeps/model2_012.res Option = Results File END END END SOLVER STEP CONTROL: Runtime Priority = Standard MEMORY CONTROL: Memory Allocation Factor = 1.0 END PARALLEL ENVIRONMENT: Number of Processes = 4 Start Method = HP MPI Local Parallel Parallel Host List = edge.ccr.buffalo.edu*4 END END END END
1.9.3 CCL for Case C
+--------------------------------------------------------+ | | | CFX Command Language for Run | | | +--------------------------------------------------------+ LIBRARY: MATERIAL: Air Ideal Gas Material Description = Air Ideal Gas (constant Cp) Material Group = Air Data, Calorically Perfect Ideal Gases Option = Pure Substance
Thermodynamic State = Gas PROPERTIES: Option = General Material EQUATION OF STATE: Molar Mass = 28.96 [kg kmol^-1] Option = Ideal Gas END SPECIFIC HEAT CAPACITY: Option = Value Specific Heat Capacity = 1.0044E+03 [J kg^-1 K^-1] Specific Heat Type = Constant Pressure END REFERENCE STATE: Option = Specified Point Reference Pressure = 1 [atm]
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Reference Specific Enthalpy = 0. [J/kg] Reference Specific Entropy = 0. [J/kg/K] Reference Temperature = 25 [C] END DYNAMIC VISCOSITY: Dynamic Viscosity = 1.831E-05 [kg m^-1 s^-1] Option = Value END THERMAL CONDUCTIVITY: Option = Value Thermal Conductivity = 2.61E-2 [W m^-1 K^-1] END ABSORPTION COEFFICIENT: Absorption Coefficient = 0.01 [m^-1] Option = Value END SCATTERING COEFFICIENT: Option = Value Scattering Coefficient = 0.0 [m^-1] END REFRACTIVE INDEX: Option = Value Refractive Index = 1.0 [m m^-1] END END END END FLOW: Flow Analysis 1 SOLUTION UNITS: Angle Units = [rad] Length Units = [m] Mass Units = [kg] Solid Angle Units = [sr] Temperature Units = [K] Time Units = [s] END ANALYSIS TYPE: Option = Steady State EXTERNAL SOLVER COUPLING: Option = None END END DOMAIN: Default Domain Modified Coord Frame = Coord 0
Domain Type = Fluid Location = B73 BOUNDARY: Default Domain Modified Default Boundary Type = WALL Location = \ F100.73,F101.73,F102.73,F103.73,F80.73,F81.73,F82.73,F83.73,F84.73,F8\ 5.73,F86.73,F87.73,F88.73,F89.73,F90.73,F91.73,F92.73,F93.73,F94.73,F\ 95.73,F96.73,F97.73,F98.73,F99.73 BOUNDARY CONDITIONS: MASS AND MOMENTUM: Option = No Slip Wall END WALL ROUGHNESS: Option = Smooth Wall END END END BOUNDARY: free Boundary Type = WALL Location = free1,free2,free3,free4 BOUNDARY CONDITIONS: MASS AND MOMENTUM: Option = Free Slip Wall END END END BOUNDARY: inlet Boundary Type = INLET Location = inlet BOUNDARY CONDITIONS: FLOW REGIME: Option = Subsonic END MASS AND MOMENTUM: Normal Speed = 320 [km hr^-1] Option = Normal Speed END TURBULENCE: Option = Medium Intensity and Eddy Viscosity Ratio END
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END END BOUNDARY: outlet Boundary Type = OUTLET Location = outlet BOUNDARY CONDITIONS: FLOW REGIME: Option = Subsonic END MASS AND MOMENTUM: Option = Average Static Pressure Pressure Profile Blend = 0.05 Relative Pressure = 0 [Pa] END PRESSURE AVERAGING: Option = Average Over Whole Outlet END END END DOMAIN MODELS: BUOYANCY MODEL: Option = Non Buoyant END DOMAIN MOTION: Option = Stationary END MESH DEFORMATION: Option = None END REFERENCE PRESSURE: Reference Pressure = 1 [atm] END END FLUID DEFINITION: Fluid 1 Material = Air Ideal Gas Option = Material Library MORPHOLOGY: Option = Continuous Fluid END END FLUID MODELS: COMBUSTION MODEL: Option = None END HEAT TRANSFER MODEL: Fluid Temperature = 25 [C]
Option = Isothermal END THERMAL RADIATION MODEL: Option = None END TURBULENCE MODEL: Option = SST END TURBULENT WALL FUNCTIONS: Option = Automatic END END END OUTPUT CONTROL: RESULTS: File Compression Level = Default Option = Standard END END SOLVER CONTROL: Turbulence Numerics = First Order ADVECTION SCHEME: Option = High Resolution END CONVERGENCE CONTROL: Length Scale Option = Conservative Maximum Number of Iterations = 200 Minimum Number of Iterations = 1 Timescale Control = Auto Timescale Timescale Factor = 1.0 END CONVERGENCE CRITERIA: Residual Target = 0.00001 Residual Type = RMS END DYNAMIC MODEL CONTROL: Global Dynamic Model Control = On END END END COMMAND FILE: Results Version = 13.0 Version = 13.0 END SIMULATION CONTROL: EXECUTION CONTROL:
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EXECUTABLE SELECTION: Double Precision = Off END INTERPOLATOR STEP CONTROL: Runtime Priority = Standard MEMORY CONTROL: Memory Allocation Factor = 1.0 END END PARALLEL HOST LIBRARY: HOST DEFINITION: edge.ccr.buffalo.edu Host Architecture String = linux-amd64 Installation Root = /util/cfx/ansys-13.0/ansys_inc/v%v/CFX END END PARTITIONER STEP CONTROL: Multidomain Option = Independent Partitioning Runtime Priority = Standard EXECUTABLE SELECTION: Use Large Problem Partitioner = Off END MEMORY CONTROL: Memory Allocation Factor = 1.0 END PARTITIONING TYPE: MeTiS Type = k-way Option = MeTiS Partition Size Rule = Automatic Partition Weight Factors = 0.12500, 0.12500, 0.12500, 0.12500, \ 0.12500, 0.12500, 0.12500, 0.12500 END END RUN DEFINITION: Run Mode = Full Solver Input File = /ifs/user/mandeeps/model3revised.def INITIAL VALUES SPECIFICATION: INITIAL VALUES CONTROL: Continue History From = Initial Values 1 Use Mesh From = Solver Input File END INITIAL VALUES: Initial Values 1 File Name =
/ifs/user/mandeeps/model3revised_006.res Option = Results File END END END SOLVER STEP CONTROL: Runtime Priority = Standard MEMORY CONTROL: Memory Allocation Factor = 1.0 END PARALLEL ENVIRONMENT: Number of Processes = 8 Start Method = HP MPI Local Parallel Parallel Host List = edge.ccr.buffalo.edu*8 END END END END
1.9.4 CCL for Case D
+--------------------------------------------------------+ | | | CFX Command Language for Run | | | +--------------------------------------------------------+ LIBRARY: MATERIAL: Air Ideal Gas Material Description = Air Ideal Gas (constant Cp) Material Group = Air Data, Calorically Perfect Ideal Gases Option = Pure Substance Thermodynamic State = Gas PROPERTIES: Option = General Material EQUATION OF STATE: Molar Mass = 28.96 [kg kmol^-1] Option = Ideal Gas END SPECIFIC HEAT CAPACITY: Option = Value Specific Heat Capacity = 1.0044E+03 [J kg^-1 K^-1] Specific Heat Type = Constant Pressure END REFERENCE STATE: Option = Specified Point Reference Pressure = 1 [atm] Reference Specific Enthalpy = 0. [J/kg] Reference Specific Entropy = 0. [J/kg/K] Reference Temperature = 25 [C] END DYNAMIC VISCOSITY: Dynamic Viscosity = 1.831E-05 [kg m^-1 s^-1] Option = Value END
THERMAL CONDUCTIVITY: Option = Value Thermal Conductivity = 2.61E-2 [W m^-1 K^-1] END ABSORPTION COEFFICIENT: Absorption Coefficient = 0.01 [m^-1] Option = Value END SCATTERING COEFFICIENT: Option = Value Scattering Coefficient = 0.0 [m^-1] END REFRACTIVE INDEX: Option = Value Refractive Index = 1.0 [m m^-1] END END END END FLOW: Flow Analysis 1 SOLUTION UNITS: Angle Units = [rad] Length Units = [m] Mass Units = [kg] Solid Angle Units = [sr] Temperature Units = [K] Time Units = [s] END ANALYSIS TYPE: Option = Steady State EXTERNAL SOLVER COUPLING: Option = None END END DOMAIN: Default Domain Modified Coord Frame = Coord 0 Domain Type = Fluid Location = B153 BOUNDARY: Default Domain Modified
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Default Boundary Type = WALL Location = \ F160.153,F161.153,F162.153,F163.153,F164.153,F165.153,F166.153,F167.1\ 53,F168.153,F169.153,F170.153,F171.153,F172.153,F173.153,F174.153,F17\ 5.153,F176.153,F177.153,F178.153,F179.153,F180.153,F181.153,F182.153,\ F183.153,F184.153,F185.153,F186.153,F187.153,F188.153,F189.153,F190.1\ 53,F191.153,F192.153,F193.153,F194.153,F195.153,F196.153,F197.153,F19\ 8.153,F199.153,F200.153,F201.153,F202.153,F203.153,F204.153,F205.153,\ F206.153,F207.153,F208.153,F209.153,F210.153,F211.153,F212.153,F213.1\ 53,F214.153,F215.153,F216.153,F217.153 BOUNDARY CONDITIONS: MASS AND MOMENTUM: Option = No Slip Wall END WALL ROUGHNESS: Option = Smooth Wall END END END BOUNDARY: free Boundary Type = WALL Location = free1,free2,free3,free4 BOUNDARY CONDITIONS: MASS AND MOMENTUM: Option = Free Slip Wall END END END BOUNDARY: inlet Boundary Type = INLET
Location = inlet BOUNDARY CONDITIONS: FLOW REGIME: Option = Subsonic END MASS AND MOMENTUM: Normal Speed = 320 [km hr^-1] Option = Normal Speed END TURBULENCE: Eddy Length Scale = 1 [m] Fractional Intensity = 0.05 Option = Intensity and Length Scale END END END BOUNDARY: outlet Boundary Type = OUTLET Location = outlet BOUNDARY CONDITIONS: FLOW REGIME: Option = Subsonic END MASS AND MOMENTUM: Option = Average Static Pressure Pressure Profile Blend = 0.05 Relative Pressure = 0 [Pa] END PRESSURE AVERAGING: Option = Average Over Whole Outlet END END END DOMAIN MODELS: BUOYANCY MODEL: Option = Non Buoyant END DOMAIN MOTION: Option = Stationary END MESH DEFORMATION: Option = None END REFERENCE PRESSURE: Reference Pressure = 1 [atm] END
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END FLUID DEFINITION: Fluid 1 Material = Air Ideal Gas Option = Material Library MORPHOLOGY: Option = Continuous Fluid END END FLUID MODELS: COMBUSTION MODEL: Option = None END HEAT TRANSFER MODEL: Fluid Temperature = 25 [C] Option = Isothermal END THERMAL RADIATION MODEL: Option = None END TURBULENCE MODEL: Option = SST END TURBULENT WALL FUNCTIONS: Option = Automatic END END END OUTPUT CONTROL: RESULTS: File Compression Level = Default Option = Standard END END SOLVER CONTROL: Turbulence Numerics = First Order ADVECTION SCHEME: Option = High Resolution END CONVERGENCE CONTROL: Length Scale Option = Conservative Maximum Number of Iterations = 200 Minimum Number of Iterations = 1 Timescale Control = Auto Timescale Timescale Factor = 1.0 END CONVERGENCE CRITERIA:
Residual Target = 0.00001 Residual Type = RMS END DYNAMIC MODEL CONTROL: Global Dynamic Model Control = On END END END COMMAND FILE: Results Version = 13.0 Version = 13.0 END SIMULATION CONTROL: EXECUTION CONTROL: EXECUTABLE SELECTION: Double Precision = Off END INTERPOLATOR STEP CONTROL: Runtime Priority = Standard MEMORY CONTROL: Memory Allocation Factor = 1.0 END END PARALLEL HOST LIBRARY: HOST DEFINITION: edge.ccr.buffalo.edu Host Architecture String = linux-amd64 Installation Root = /util/cfx/ansys-13.0/ansys_inc/v%v/CFX END END PARTITIONER STEP CONTROL: Multidomain Option = Independent Partitioning Runtime Priority = Standard EXECUTABLE SELECTION: Use Large Problem Partitioner = Off END MEMORY CONTROL: Memory Allocation Factor = 1.0 END PARTITIONING TYPE: MeTiS Type = k-way Option = MeTiS Partition Size Rule = Automatic Partition Weight Factors = 0.25000, 0.25000, 0.25000, 0.25000
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END END RUN DEFINITION: Run Mode = Full Solver Input File = /ifs/user/mandeeps/model4.def END SOLVER STEP CONTROL: Runtime Priority = Standard MEMORY CONTROL: Memory Allocation Factor = 1.0 END PARALLEL ENVIRONMENT: Number of Processes = 4 Start Method = HP MPI Local Parallel Parallel Host List = edge.ccr.buffalo.edu*4 END END END END
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1.9.5 Convergence Residual Plots
Figure 12(Model A)
Figure 13(Model B)
Figure 14(Model C)
Figure 15(Model D)
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1.9.6 Dimensions for the Model
MODEL A
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MODEL B
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MODEL C
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MODEL D
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1.9.7 References :
1. TIAN HONG-qi “Formation mechanisms of aerodynamic drag of high-speed train
and some reduction measures” J.Cent. South Univ. Technol. (2009) 16:0166- 0171.
2. E. Lorriaux, N. Bourabaa and F. Monnoyer “Aerodynamic optimization of railway
motor coaches” University of Valenciennes, France.
3. Samuel Holmes, Martin Schroder, Elton Toma “High Speed passanger and intercity
train aerodynamic computer modeling”, The 2000 International Mechanical
Engineering Congress & Exposition November 5-10, 2000, Florida.
4. Milan Schuster “CFD Methods in industrial applications – Vehicle external
aerodynamics and aerodynamic interaction of moving vehicles” XXI ICTAM, 15-21
August 2004, Poland.
5. Jongsoo Lee and Junghui Kim “Approximate optimization of high-speed train nose
shape for reducing micropressure wave”, Struct Multidisc Optim (2008).
6. Charles-Andre LEMARIE, Nachida BOURABAA and Francois MONNOYER
“Aerodynamic optimization in railway transportation:numerical and experimental
approach”
7. CFX Tutorials - Bluntbody
8. Wikipedia.com