Lesson – 03 UAV Terminology

Includes

a. Propulsion

b. Control

Propulsion

BEC Battery Eliminator Circuit“: a voltage regulator built into the ESC which can provide regulated 5V DC power to any electronics which need it.
Blades Propeller blades are the aerodynamic surface which generates lift. A propeller normally has two to four blades which can be fixed or folding.
CW / CCW CW indicates Clockwise rotation and CCW indicates Counter-Clockwise rotation. On a multi-rotor aircraft, you would normally use pairs of counter-rotating propellers.
ESC Electronic Speed Controller” is the device which connects to the battery, motor and flight controller and controls the speed at which the motor rotates
LiPo Lithium Polymer” is the most common battery used in drones and UAVs because of its light weight (versus storage capacity) and high current discharge rates.
There are other types of Lithium-based batteries available on the market as well (LiFe, LiMn, LiOn etc)
Motor The motor is what is used to rotate the propellers; in small UAVs, a brushed motor is most often used, whereas for larger UAVs, a “brushless” motor is much more common
PCB A “Printed Circuit Board” is the flat fiberglass part with many components soldered to it. Many electronic products have a PCB.
PowerDistribution
In order to power so many different devices used in a UAV, the battery must be split, which is where the Power Distribution (board or cable) comes into play.
It takes the single positive and negative terminals of the battery and provides many different terminals / connection points to which other devices (operating at the same voltage) can receive power.
Propeller The propellers are what provides the thrust and are more similar to those used in airplanes rather than on helicopters.
Prop Adapter A device used to connect the propeller to the motor.
Prop Saver A type of hub which mounts on top of your motor and replaces the prop adapter. In he event of a crash, a part of the prop saver is lost in an attempt to save the propeller.
Servo A servo is a type of actuator which, provided the right signal, can move to a specific angular position
Thrust The “thrust” is the force which a specific motor and propeller can provide (at a certain voltage). Usually measured in kilograms (Kg) or pounds (Lbs)

Control

base-station.jpg

Base / ground /
Control Station
Instead of (or in addition to) a hand held transmitter, a station (normally in a case or mounted to a tripod) is used to house / integrate the necessary components used to control a UAV.
This can include the transmitter, antenna(e), video receiver, monitor, battery, computer and other devices.
Binding The term “binding” refers to configuring a handheld transmitter so it can communicate with a receiver; if a transmitter came with a receiver, it should have been done at the factory.
Channel The number of channels on a transmitter relates to the number of separate signals it can send
Flight Controller The “Flight Controller” is what would be considered the “brain” of a UAV and handles all of the data processing, calculations and signals.
The core of a flight controller is often a programmable “microcontroller”. The flight controller may have multiple sensors onboard, including an accelerometer, gyroscope, barometer, compass, GPS etc.
If the flight controller has the ability to control the aircraft on its own (for example to navigate to specific GPS coordinates), it may be considered to be an “autopilot”.
Harness This usually refers to the “Wiring Harness” which are the wires that connect the receiver to the flight controller (and sometimes other devices).
HF/ UHF / VHF High Frequency“; “Very High Frequency” and “Ultra High Frequency” radio waves. Units are in Hz (Hertz)
Receiver This is what processes the information received wirelessly
Sketch / Code This is the program which is uploaded to your UAV’s flight controller (similar to a “thought process”)
Transmitter / Radio
The “transmitter” is what generates the control signal(s) wirelessly to the receiver

 

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Propelling Nozzle

A propelling nozzle is the component of a jet engine that operates to constrict the flow, to form an exhaust jet and to maximise the velocity of propelling gases from the engine.

Propelling nozzles can be subsonic, sonic, or supersonic.Physically the nozzles can be convergent, or convergent-divergent. Convergent-divergent nozzles can give supersonic jet velocity within the divergent section, whereas in a convergent nozzle the exhaust fluid cannot exceed the speed of sound within the nozzle.

Propelling nozzles can be fixed geometry, or they can have variable geometry, to give different throat and exit diameters so as to deal with differences in ambient pressure, flow and engine pressure; thus permitting improvement of thrust and efficiency.

Nozzle Shapes

1. Convergent Nozzle
2. Divergent Nozzle
3. Convergent – Divergent Nozzle (C-D) Nozzle
Convergent-divergent nozzle
 Types of Nozzle
1.Fixed Area Nozzle
2.Afterburner Nozzle or Variable  Area Nozzle
3.Ejector Nozzle
4. Variable – geometry C- D Nozzle
5. Thrust Vectoring Nozzle
6.Rocket Nozzle
7.Low Ratio Nozzle
8.Thrust Reversing Nozzle
9.Nozzle with noise-reducing features
LOW RATIO NOZZLE – is predominantly used on the civil aircrafts and also some low speed reconnaissance airplanes, and is convergent-divergent de Laval nozzle with an extremely low inlet-outlet area pressure ratio that prevents choking at low air speeds, reduces generated noise, and is as reliable as they come:

       Boeing ecoDemonstrator

Boeing ecoDemonstrator tested on American Airlines airplane

  • Ejector nozzle is the simpler of the variable exhaust nozzles, and is more commonly used on jet propelled aircrafts than the iris nozzles due to its simpler design of spring-loaded petals and are thus more reliable, but do produce more secondary airflow drag and are less efficient than some other, more advanced designs:

Variable Exhaust Nozzle, on the GE F404-400 low-bypass turbofan installed on a Boeing F/A-18 Hornet

Variable Exhaust Nozzle, on the GE F404-400 low-bypass turbofan installed on a Boeing F/A-18 Hornet

  • Iris nozzle is a variable exhaust nozzle commonly used on jet fighter airplanes and bombers and can adjust its contour by iris like petal design to maximize performance and avoid uneven pressure distribution (oblique shock). In some designs, they can also change the thrust vector (angle to aircraft), or add air brakes (e.g.: MiG-23 afterburner exhaust air brakes)

Iris nozzle afterburners on the F-15 "Eagle" fighter

Iris nozzle afterburners on the F-15 Eagle fighter

The nozzle types used in astronautics, hypersonic experimental airplanes

  • Bell nozzle is possibly the most commonly used nozzle type on rocket engines, for its simplicity, relatively low weight with advanced materials and in some designs even adjustability (see iris nozzle below) of the volume of its exhaust / expansion chamber:Rocket nozzle on V2 showing the classic shape Rocket nozzle on V2 showing the classic shape
  • Expansion-deflection nozzle (or Pintle Injector) is a type of propellant injection device for a rocket engine that was first used on a flight vehicle during the Apollo Program in the Lunar Excursion Module’s descent engine. Pintle injectors are currently used in SpaceX’s Merlin engines:

Patent application cross-section schematic diagram of the pintle injector

Patent application cross-section schematic diagram of the pintle injector

  • Plug nozzle “Aerospike” (or Spike Nozzle) is an altitude compensating nozzle with the ideal contour a long, gradual pressure reducing ‘spike’, often with a wide (large volume) annular type combustion chamber at the base. This nozzle is self-compensating for atmospheric pressure, and the plug and the combustion chamber can vary in size for different applications (shorter convex shaped “spike plugs” are used also on civil aviation jet engines, and truncated/non-truncated or full-length concave spikes usually used for supersonic aircraft, rockets,…). Among main advantages is up to 30% reduction in propellant required at lower altitudes due to their self-compensating nature:

3D model of the Aerospike engine

3D model of the components of the Aerospike engine with a slightly convex shaped “spike”

  • Annular and Linear aerospike are variants on the truncated aerospike nozzle design, commonly with several turbine combustion exhausts placed linearly, or annularly over exhaust nozzle. Spike nozzle is truncated and allows for additional thrust with subsonic recirculating flow field forming at the truncated part, as the gases expand over the nozzle’s surface. Dynamics of a linear aerospike engine are explained in detail in this Linear Aerospike Engine video:

XRS-2200 linear aerospike engine for the X-33 program being tested

XRS-2200 linear aerospike engine for the X-33 program being tested

  • SERN (Single Expansion Ramp Nozzle) is essentially a single side linear aerospike nozzle, but can be accompanied by more complex pitch and elevation control systems due to momentum transfer that can be angular to the aircraft / spacecraft due to throttling:

    Many designs for space planes with scramjet engines make use of SERNs because of the weight reduction at large expansion ratios, or the additional lift at under-expansion. The X-43, a test vehicle in NASA’s Hyper-X programme, is a flying example.

Aurora Mach 5 and SR-71 Mach 3 reconnaissance aircraft flying in formation

Aurora Mach 5 (below) and SR-71 Mach 3 (above) reconnaissance aircraft flying in formation

Composite Material Categories

Composite Material:

A typical composite material is a system of materials composing of two or more materials (mixed and bonded) on a macroscopic scale. For example, concrete is made up of cement, sand, stones, and water. If the composition occurs on a microscopic scale (molecular level), the new material is then called an alloy for metals or a polymer for plastics.

Generally, a composite material is composed of reinforcement (fibers, particles, flakes, and/or fillers) embedded in a matrix (polymers, metals, or seramics). The matrix holds the reinforcement to form the desired shape while the reinforcement improves the overall mechanical properties of the matrix. When designed properly, the new combined material exhibits better strength than would each individual material.

gallery-areospace-uavwing2 (1).jpg

Classification of Composite Materials

Based on the form of reinforcement, common composite materials can be classified as follows:

1. Fibers as the reinforcement (Fibrous Composites):
a. Random fiber (short fiber) reinforced composites

b. Continuous fiber (long fiber) reinforced composites

2. Particles as the reinforcement (Particulate composites):

3. Flat flakes as the reinforcement (Flake composites):

4. Fillers as the reinforcement (Filler composites):

Benefits of Composites

Different materials are suitable for different applications. When composites are selected over traditional materials such as metal alloys or woods, it is usually because of one or more of the following advantages:

  • Cost:
    • Prototypes
    • Mass production
    • Part consolidation
    • Maintenance
    • Long term durability
    • Production time
    • Maturity of technology
  • Weight:
    • Light weight
    • Weight distribution
  • Strength and Stiffness:
    • High strength-to-weight ratio
    • Directional strength and/or stiffness
  • Dimension:
    • Large parts
    • Special geometry
  • Surface Properties:
    • Corrosion resistance
    • Weather resistance
    • Tailored surface finish
  • Thermal Properties:
    • Low thermal conductivity
    • Low coefficient of thermal expansion
  • Electric Property:
    • High dielectric strength
    • Non-magnetic
    • Radar transparency

Note that there is no one-material-fits-all solution in the engineering world. Also, the above factors may not always be positive in all applications. An engineer has to weigh all the factors and make the best decision in selecting the most suitable material(s) for the project at hand.

SOURCE : EFUNDA

Lesson 1 – UAV Terminology – Mechanics & Types

shell.jpg

Mechanics

CG Center of Gravity“; this is the point on the aircraft where there is equal weight distributed on all sides.
Clamp A “tube clamp” is a device normally used on a round tube in order to connect it to another device (such as a motor mount or a UAV’s body).
Connectors In order to plug and unplug wires, connectors are used at the ends of wires. Common connectors for batteries are Deans & XT60, while connectors for the flight controller and sensors are 0.1″ spaced
Dampeners These are molded rubber parts used to minimize vibration transmitted throughout a UAV
Frame The frame is like the “skeleton” of the aircraft and holds all of the parts together. Simple frames have motors connected to aluminum or other lightweight extrusions (“arm”) which then connect to a central body.
G10 This is a material commonly used instead of carbon fiber to make a UAV’s frame since it is very rigid and lightweight, but significantly less expensive
Landing Gear
Multirotor landing gear normally does not have wheels as you might find on an airplane – this is to prevent it from moving when on the ground and reduce overall weight.
LED Light Emitting Diode“. These are used to make the UAV visible, primarily at night or low lighting conditions.
Prop Guards “Propeller guards” are material which curround a propeller to prevent the propeller from contacting other objects. They are implemented as a safety feature and a way to minimize damage to the UAV
Retract “Retractable” normally refers to landing gear which has two positions: one for landing and takeoff, and another, which takes up less room or improves visibility, during flight.
Shell This is an aesthetic / functional cover used to improve resistance to the elements and sometimes improve aerodynamics. Some production UAVs only have a plastic shell which also acts as the “frame”.

Types

ARF Almost Ready to Fly“: a UAV which comes assembled with almost all parts necessary to fly. Components like the controller and receiver may not be included.
BNF Bind and Fly“; the UAV comes fully assembled and includes a receiver. You only need to choose a compatible transmitter and “bind” it to the receiver.
DIY Do It Yourself“, which is now commonly used to mean “custom”. This normally involves using parts from a variety of different suppliers and creating or modifying parts.
Drone This is synonymous with UAV. The term “drone” seems to be more common for military use whereas “UAV” is more common for hobby use
Hexacopter
A UAV which has six motors / propellers.
Multirotor “Multirotor” simply means an aircraft with multiple rotors
Octocopter A UAV which has eight motors / propellers.
Quadcopter A UAV which has four motors / propellers and four support arms. Configurations are normally “+” (the front of the UAV faces one of the arms) or “X” (the front of the aircraft faces between two arms).
RTF Ready To Fly“: a UAV which comes fully assembled with all necessary parts. Simply charge the battery and fly!
Size (mm) “Size” is normally provided in millimeters (ex 450mm) and represents the greatest point to point distance between two motors on a UAV. Size can also determine the “class” of UAV (micro, mini etc)
Spyder A “Spyder” type UAV (normally quad or hex) is one where the supporting arms are not symmetric in bot haxes when looked at from the top.
Tricopter A UAV which has three motors / propellers, and usually three support arms
UAV Unmanned Aerial Vehicle” (of any kind)
V-Tail A UAV which has four arms, of which the rear two are at an angle to form a ‘V’
X4 / X8  X4 and X8 are UAV configurations with four support arms; X4 configurations have one motor at the end of each arm, whereas X8 have two motors per arm (one facing up, the other facing down)
Y3 / Y6 Y3 and Y6 are UAV configurations with three support arms; Y3 configurations have one motor at the end of each arm, whereas Y6 have two motors per arm (one facing up, the other facing down)

FLUENT – LAMINAR PIPE FLOW

Laminar Pipe Flow

Created using ANSYS 13.0. Tutorial instructions work with ANSYS 14.0 and 15.0. There are minor layout changes in ANSYS 15.0.

Problem Specification



Consider fluid flowing through a circular pipe of constant radius as illustrated above. The figure is not to scale. The pipe diameter D = 0.2 m and length L = 8 m Consider the inlet velocity to be constant over the cross-section and equal to 1 m/s. The pressure at the pipe outlet is 1 atm. Take density ρ = 1 kg/ m 3and coefficient of viscosity µ = 2 x 10 -3 kg/(m s). These parameters have been chosen to get a desired Reynolds number of 100 and don’t correspond to any real fluid.

Solve this problem numerically using ANSYS FLUENT. Present the following results:

  • Velocity vectors
  • Velocity magnitude contours
  • Pressure contours
  • Velocity profile at the outlet
  • Skin friction coefficient along the wall

Provide comparisons of the results with the full-developed analytical solution. Verify your results.

Geometry

Fluid Flow (FLUENT) Project Selection

On the left hand side of the workbench window, you will see a toolbox full of various analysis systems. To the right, you see an empty work space. This is the place where you will organize your project. At the bottom of the window, you see messages from ANSYS.

Left click (and hold) on Fluid Flow (FLUENT) , and drag the icon into the empty space in the Project Schematic. Your ANSYS window should now look comparable to the image below.

Since we selected Fluid Flow (FLUENT), each cell of the system corresponds to a step in the process of performing CFD analysis using FLUENT. Rename the project to Laminar Pipe.
We will work through each step from top down to obtain the solution to our problem.

Analysis Type

In the Project Schematic of the Workbench window, right click on Geometry and select Properties , as shown below.



The properties menu will then appear to the right of the Workbench window. Under Advance Geometry Options , change the Analysis Type to 2D as shown in the image below.

Launch Design Modeler

In the Project Schematic, double click on Geometry to start preparing the geometry.
At this point, a new window, ANSYS Design Modeler will be opened. You will be asked to select desired length unit. Use the default meter unit and clickOK .

Creating a Sketch

Start by creating a sketch on the XYPlane. Under Tree Outline, select XYPlane, then click on Sketching right before Details View. This will bring up theSketching Toolboxes.
Click Here for Select Sketching Toolboxes Demo
Click on the +Z axis on the bottom right corner of the Graphics window to have a normal look of the XY Plane.
Click Here for Select Normal View Demo
In the Sketching toolboxes, select Rectangle. In the Graphics window, create a rough Rectangle by clicking once on the origin and then by clicking once somewhere in the positive XY plane. (Make sure that you see a letter P at the origin before you click. The P implies that the cursor is directly over a point of intersection.) At this point you should have something comparable to the image below.

Dimensions

At this point the rectangle will be properly dimensioned.

Under Sketching Toolboxes, select Dimensions tab, use the default dimensioning tools. Dimension the geometry as shown in the following image.


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Under the Details View table (located in the lower left corner), set V1 = 0.1m and set H2 = 8m, as shown in the image below.


Click Here for Higher Resolution

Surface Body Creation

In order to create the surface body, first (Click) Concept > Surface From Sketches as shown in the image below.

This will create a new surface SurfaceSK1. Under Details View, select Sketch1 as the Base Objects  by selecting one of the lines of the sketch and by clicking apply.  Then select the thickness to be 0.1m and click Generate to generate the surface.

Saving

At this point, you can close the Design Modeler and go back to Workbench Project Page .

Save the project by clicking on the “Save As..” button, , which is located on the top of the Workbench Project Page . Save the project as “LaminarPipeFlow” in your working directory. When you save in ANSYS a file and a folder will be created. For instance if you save as “LaminarPipeFlow”, a “LaminarPipeFlow” file and a folder called “LaminarPipeFlow_files” will appear. In order to reopen the ANSYS files in the future you will need both the “.wbpj” file and the folder. If you do not have BOTH, you will not be able to access your project.

Fluid Flow (FLUENT) Project Selection

On the left hand side of the workbench window, you will see a toolbox full of various analysis systems. To the right, you see an empty work space. This is the place where you will organize your project. At the bottom of the window, you see messages from ANSYS.

Left click (and hold) on Fluid Flow (FLUENT) , and drag the icon into the empty space in the Project Schematic. Your ANSYS window should now look comparable to the image below.

Since we selected Fluid Flow (FLUENT), each cell of the system corresponds to a step in the process of performing CFD analysis using FLUENT. Rename the project to Laminar Pipe.
We will work through each step from top down to obtain the solution to our problem.

Analysis Type

In the Project Schematic of the Workbench window, right click on Geometry and select Properties , as shown below.



The properties menu will then appear to the right of the Workbench window. Under Advance Geometry Options , change the Analysis Type to 2D as shown in the image below.

Launch Design Modeler

In the Project Schematic, double click on Geometry to start preparing the geometry.
At this point, a new window, ANSYS Design Modeler will be opened. You will be asked to select desired length unit. Use the default meter unit and clickOK .

Creating a Sketch

Start by creating a sketch on the XYPlane. Under Tree Outline, select XYPlane, then click on Sketching right before Details View. This will bring up theSketching Toolboxes.
Click Here for Select Sketching Toolboxes Demo
Click on the +Z axis on the bottom right corner of the Graphics window to have a normal look of the XY Plane.
Click Here for Select Normal View Demo
In the Sketching toolboxes, select Rectangle. In the Graphics window, create a rough Rectangle by clicking once on the origin and then by clicking once somewhere in the positive XY plane. (Make sure that you see a letter P at the origin before you click. The P implies that the cursor is directly over a point of intersection.) At this point you should have something comparable to the image below.

Dimensions

At this point the rectangle will be properly dimensioned.

Under Sketching Toolboxes, select Dimensions tab, use the default dimensioning tools. Dimension the geometry as shown in the following image.


Click Here for Higher Resolution
Under the Details View table (located in the lower left corner), set V1 = 0.1m and set H2 = 8m, as shown in the image below.


Click Here for Higher Resolution

Surface Body Creation

In order to create the surface body, first (Click) Concept > Surface From Sketches as shown in the image below.

This will create a new surface SurfaceSK1. Under Details View, select Sketch1 as the Base Objects  by selecting one of the lines of the sketch and by clicking apply.  Then select the thickness to be 0.1m and click Generate to generate the surface.

Saving

At this point, you can close the Design Modeler and go back to Workbench Project Page .

Save the project by clicking on the “Save As..” button, , which is located on the top of the Workbench Project Page . Save the project as “LaminarPipeFlow” in your working directory. When you save in ANSYS a file and a folder will be created. For instance if you save as “LaminarPipeFlow”, a “LaminarPipeFlow” file and a folder called “LaminarPipeFlow_files” will appear. In order to reopen the ANSYS files in the future you will need both the “.wbpj” file and the folder. If you do not have BOTH, you will not be able to access your project.

Mesh

In this section the geometry will be meshed with 500 elements. That is, the pipe will be divided into 100 elements in the axial direction and 5 elements in the radial direction.

Launch Mesher

In order to begin the meshing process, go to the Workbench Project Page, then (Double Click) Mesh.

Default Mesh

In this section the default mesh will be generated. This can be carried out two ways. The first way is to (Right Click) Mesh > Generate Mesh, as shown in the image below.


The second way in which the default mesh can be generated is to (Click) Mesh > Generate Mesh as can be seen below.


Either method should give you the same results. The default mesh that you generate should look comparable to the image below.

Note that in Workbench there is generally at least two ways to implement actions as has been shown above. For, simplicity’s sake the “menu” method of implementing actions will be solely used for the rest of the tutorial.

Mapped Face Meshing

As can be seen above, the default mesh has irregular elements. We are interested in creating a grid style of mesh that can be mapped to a rectangular domain. This meshing style is called Mapped Face Meshing. In order to incorporate this meshing style (Click) Mesh Control > Mapped Face Meshingas can be seen below.


Now, the Mapped Face Meshing still must be applied to the pipe geometry. In order to do so, first click on the pipe body which should then highlight green. Next, (Click) Apply in the Details of Mapped Face Meshing table, as shown below.


This process is shown here
Now, generate the mesh by using either method from the “Default Mesh” section above. You should obtain a mesh comparable to the following image.

 

Edge Sizing

The desired mesh has specific number of divisions along the radial and the axial direction. In order to obtain the specified number of divisions Edge Sizingmust be used. The divisions along the axial direction will be specified first. Now, an Edge Sizing needs to be inserted. First, (Click) Mesh Control > Sizing as shown below.

Now, the geometry and the number of divisions need to be specified. First (Click) Edge Selection Filter, . Then hold down the “Control” button and then click the bottom and top edge of the rectangle. Both sides should highlight green. Next, hit Apply under the Details of Sizing table as shown below.

Now, change Type to Number of Divisions as shown in the image below.


Then, set Number of Divisions to 100 as shown below.


Follow the same procedure as for the edge sizing in the radial direction, except select the left and right side instead of the top and bottom and set theNumber of Division to 5. Then, generate the mesh by using either method from the “Default Mesh” section above. You should obtain the following mesh.


As it turns out, in the mesh above there are 540 elements, when there should be only 500. Mesh statistics can be found by clicking on Mesh in the Tree and then by expanding Statistics under the Details of Mesh table. In order to get the desired 500 element mesh the Behavior needs to be changed fromSoft to Hard for both Edge Sizing’s. In order to carry this out first Expand Mesh in the tree outline then click Edge Sizing and then change Behavior toHard under the Details of Edge Sizing table, as shown below.


Then set the Behavior to Hard for Edge Sizing 2. Next, generate the mesh using either method from the “Default Mesh” section above. You should then obtain the following 500 element mesh.



Radial Sizing

Create Named Selections

Here, the edges of the geometry will be given names so one can assign boundary conditions in Fluent in later steps. The left side of the pipe will be called “Inlet” and the right side will be called “Outlet”. The top side of the rectangle will be called “PipeWall” and the bottom side of the rectangle will be called “CenterLine” as shown in the image below.


In order to create a named selections first (Click) Edge Selection Filter, . Then click on the left side of the rectangle and it should highlight green. Next, right click the left side of the rectangle and choose Create Named Selection as shown below.

Enter Inlet and click OK, as shown below.




Now, create named selections for the remaining three sides and name them according to the diagram.

Save, Exit & Update

First save the project. Next, close the Mesher window. Then, go to the Workbench Project Page and click the Update Project button, .

Physics Setup

Your current Workbench Project Page should look comparable to the following image. You should have checkmarks to the right of Geometry and Mesh.



Next, the mesh and geometry data need to be read into FLUENT. To read in the data (Right Click) Setup > Refresh in the Workbench Project Page as shown in the image below. If the refresh option is not available, simply omit this step. 



After you click Update, a question mark should appear to the right of the Setup cell. This indicates that the Setup process has not yet been completed.

Launch Fluent

Double click on Setup in the Workbench Project Page which will bring up the FLUENT Launcher. When the FLUENT Launcher appears change the options to “Double Precision”, and then click OK as shown below.The Double Precision option is used to select the double-precision solver. In the double-precision solver, each floating point number is represented using 64 bits in contrast to the single-precision solver which uses 32 bits. The extra bits increase not only the precision, but also the range of magnitudes that can be represented. The downside of using double precision is that it requires more memory.


Click Here for Higher Resolution
Twiddle your thumbs a bit while the FLUENT interface starts up. This is where we’ll specify the governing equations and boundary conditions for our boundary-value problem. On the left-hand side of the FLUENT interface, we see various items listed under Problem Setup. We will work from top to bottom of the Problem Setup items to setup the physics of our boundary-value problem. On the right hand side, we have the Graphics pane and, below that, the Command pane.

Check and Display Mesh

First, the mesh will be checked to verify that it has been properly imported from Workbench. In order to obtain the statistics about the mesh (Click) Mesh > Info > Size, as shown in the image below.



Then, you should obtain the following output in the Command pane.



The mesh that was created earlier has 500 elements(5 Radial x 100 Axial). Note that in FLUENT elements are called cells. The output states that there are 500 cells, which is a good sign. Next, FLUENT will be asked to check the mesh for errors. In order to carry out the mesh checking procedure (Click) Mesh > Check as shown in the image below.



You should see no errors in the Command Pane. Now, that the mesh has been verified, the mesh display options will be discussed. In order to bring up the display options (Click) General > Mesh > Display as shown in the image below.



The previous step should cause the Mesh Display window to open, as shown below. Note that the Named Selections created in the meshing steps now appear.


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You should have all the surfaces shown in the above snapshot. Clicking on a surface name in the Mesh Display menu will toggle between select and unselect. Clicking Display will show all the currently selected surface entities in the graphics pane. Unselect all surfaces and then select each one in turn to see which part of the domain or boundary the particular surface entity corresponds to (you will need to zoom in/out and translate the model as you do this). For instance, if you select wall, outlet, and centerline and then click Display you should then obtain the following output in the graphics window.



Now, make sure all 5 items under Surfaces are selected. The button next to Surfaces selects all of the boundaries while the button deselects all of the boundaries at once. Once, all the 5 boundaries have been selected click Display, then close the Mesh Display window. The long, skinny rectangle displayed in the graphics window corresponds to our solution domain. Some of the operations available in the graphics window to interrogate the geometry and mesh are:

Translation: The model can be translated in any direction by holding down the Left Mouse Button and then moving the mouse in the desired direction.

Zoom In: Hold down the Middle Mouse Button and drag a box from the Upper Left Hand Corner to the Lower Right Hand Corner over the area you want to zoom in on.

Zoom Out: Hold down the Middle Mouse Button and drag a box anywhere from the Lower Right Hand Corner to the Upper Left Hand Corner.

Use these operations to zoom in and interrogate the mesh.

Define Solver Properties

In this section the various solver properties will be specified in order to obtain the proper solution for the laminar pipe flow. First, the axisymmetric nature of the geometry must be specified. Under General > Solver > 2D Space select Axisymmetric as shown in the image below.


Click Here for Higher Resolution
Next, the Viscous Model parameters will be specified. In order to open the Viscous Model Options Models > Viscous – Laminar > Edit…. By default, the Viscous Model options are set to laminar, so no changes are needed. Click Cancel to exit the menu.
Now, the Energy Model parameters will be specified. In order to open the Energy Model Options Models > Energy-Off > Edit…. For incompressible flow, the energy equation is decoupled from the continuity and momentum equations. We need to solve the energy equation only if we are interested in determining the temperature distribution. We will not deal with temperature in this example. So leave the Energy Equation set to off and click Cancel to exit the menu.

Define Material Properties

Now, the properties of the fluid that is being modeled will be specified. The properties of the fluid were specified in the Problem Specification section. In order to create a new fluid (Click) Materials > Fluid > Create/Edit… as shown in the image below.



In the Create/Edit Materials menu set the Density to 1kg/m^3 (constant) and set the Viscosity to 2e-3 kg/(ms) (constant) as shown in the image below.


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Click Change/Create. Close the window.

Define Boundary Conditions

At this point the boundary conditions for the four Named Selections will be specified. The boundary condition for the inlet will be specified first.

Inlet Boundary Condition

In order to start the process (Click) Boundary Conditions > inlet > Edit… as shown in the following image.


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Note that the Boundary Condition Type should have been automatically set to velocity-inlet. Now, the velocity at the inlet will be specified. In theVelocity Inlet menu set the Velocity Specification Method to Components, and set the Axial-Velocity (m/s) to 1 m/s, as shown below.


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Then, click OK to close the Velocity Inlet menu.

Outlet Boundary Condition

First, select outlet in the Boundary Conditions menu, as shown below.


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As can be seen in the image above the Type should have been automatically set to pressure-outlet. If the Type is not set to pressure-outlet, then set it to pressure-outlet. Now, no further changes are needed for the outlet boundary condition.

Centerline Boundary Condition

Select centerline in the Boundary Conditions menu, as shown below.


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As can be seen in the image above the Type has been automatically set to wall which is not correct. Change the Type to axis, as shown below.


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When the dialog boxes appear click Yes to change the boundary type. Then click OK to accept “centerline” as the zone name.

Pipe Wall Boundary Condition

First, select pipe_wall in the Boundary Conditions menu, as shown below.


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As can be seen in the image above the Type should have been automatically set to wall. If the Type is not set to wall, then set it to wall. Now, no further changes are needed for the pipe_wall boundary condition.

Save

In order to save your work (Click)File > Save Project as shown in the image below.

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Different Types of Aircraft Takeoff and Landing

Takeoff is the phase of flight in which an aerospace vehicle goes from the ground to flying in the air.

For aircraft that take off horizontally, this usually involves starting with a transition from moving along the ground on a runway. For balloons,helicopters and some specialized fixed-wing aircraft (VTOL aircraft such as the Harrier), no runway is needed. Takeoff is the opposite of Landing.

Landing is the last part of a flight, where a flying aircraft or spacecraft (or animals) returns to the ground. When the flying object returns to water, the process is called alighting, although it is commonly called “landing” and “touchdown” as well. A normal aircraft flight would include several parts of flight including taxi, takeoff, climb, cruise, descent and landing.

The Different Types of Takeoff & Landing

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1.Horizontal Takeoff & Landing                                                                     

HOTOL, for Horizontal Take-Off and Landing, was a British design for an Airbreathing jet engine spaceplane by Rolls-Royce and British Aerospace.

Designed as a single-stage-to-orbit (SSTO) reusable winged launch vehicle, it was to be fitted with a unique air-breathing engine, the RB545 or Swallow, to be developed by the Rolls-Royce company. The engine was technically a liquid hydrogen/liquid oxygen design, but dramatically reduced the amount of oxidizer needed to be carried on board by utilising atmospheric oxygen as the spacecraft climbed through the lower atmosphere.

Since propellant typically represents the majority of the takeoff weight of a rocket, HOTOL was to be considerably smaller than normal pure-rocket designs, roughly the size of a medium-haul airliner such as the McDonnell Douglas DC-9/MD-80. Ultimately, comparison with a rocket vehicle using similar construction techniques failed to show much advantage, and funding for the vehicle ceased.

CTOL is an acronym for conventional take-off and landing,and is the process whereby conventional aircraft (such as passenger aircraft) take off and land, involving the use of runways.

 STOL is an acronym for short take-off and landing, aircraft with very short runway requirements.

RTOL is an acronym for Reduced take-off and landing.

CATOBAR (Catapult Assisted Take-Off But Arrested Recovery or Catapult Assisted Take-Off Barrier Arrested Recovery) is a system used for the launch and recovery of aircraft from the deck of an aircraft carrier. Under this technique, aircraft launch using a catapult-assisted take-off and land on the ship (the recovery phase) using arrestor wires.

STOBAR (Short Take-Off But Arrested Recovery) is a system used for the launch and recovery of aircraft from the deck of an aircraft carrier, combining elements of both short take-off and vertical landing (STOVL) with catapult-assisted take-off but with arrested recovery (CATOBAR).

2.Vertical Take-Off and Landing

VTOL is an acronym for vertical take-off and landing aircraft. This classification includes fixed-wing aircraft that can hover, take off and land vertically as well as helicopters and other aircraft with powered rotors, such as tiltrotors.The terminology for spacecraft and rockets is VTVL(vertical takeoff with vertical landing).Some VTOL aircraft can operate in other modes as well, such as CTOL (conventional take-off and landing),STOL (short take-off and landing), and/or STOVL (short take-off and vertical landing). Others, such as some helicopters, can only operate by VTOL, due to the aircraft lacking landing gear that can handle horizontal motion. VTOL is a subset of V/STOL (vertical and/or short take-off and landing).

A short take-off and vertical landing aircraft (STOVL aircraft) is a fixed-wing aircraft that is able to take off from a short runway (or take off vertically if it does not have a heavy payload) and land vertically (i.e. with no runway).

VTOHL Vertical Take-Off and Horizontal Landing as well as several VTOHL aviation-specific subtypes: VTOCL,VTOSL, VTOBAR exist.

Launch and Recovery Cycle

Vertical takeoff, vertical landing (VTVL) is a form of takeoff and landing for rockets. Multiple VTVL craft have flown. As of 2012, at least six VTVL rocket vehicles are currently under development at four different aerospace companies. VTVL is often proposed as a viable technology for reusable rockets. VTVL rockets are not to be confused with aircraft, where that class of aircraft which takeoff and land vertically (helicopters, etc.) are known as VTOL aircraft.

Horizontal Takeoff , Horizontal Landing (HTHL) – is the mode of operation for the first private commercial spaceplane, the two-stage-to -space Scaled Composite Tier One from the Ansari X – Prize SpaceShipOne/WhiteKnightOne combination.

HTVL or horizontal takeoff and vertical landing is the spaceflight equivalent of aviation HTOVL (and its subtypes CTOVL, STOVL, CATOVL). This mode of operation has not been used, but has been proposed for some systems that use a two-stage to orbit launch system with a plane based first stage, and a capsule return vehicle.

SOURCE : WIKIPEDIA

India’s Home made Super Sonic Interceptor Missile TestFire

Balasore: As part of efforts to develop a full fledged multi-layer Ballistic Missile Defence system, India on Sunday test-fired its indigenously developed supersonic interceptor missile, capable of destroying any incoming ballistic missile, from a test range off Odisha coast.

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“The test was conducted to validate various parameters of the interceptor in flight mode,” said defence sources.

The interceptor, known as Advanced Air Defence (AAD) missile, was engaged against an electronically prepared target which simulated the trajectory of a hostile ballistic missile.

After getting signals from tracking radars, the interceptor, positioned at Abdul Kalam Island (Wheeler Island), roared through its trajectory at around 9.46 am to destroy the incoming missile mid-air, in an endo-atmospheric altitude, defence sources said.

The ‘kill’ effect of the interceptor was being ascertained by analysing data from multiple tracking sources,” a Defence Research Development Organisation (DRDO) scientist said soon after the test was carried out.

The interceptor is a 7.5-meter long single stage solid rocket propelled guided missile equipped with a navigation system, a hi-tech computer and an electro-mechanical activator, the sources said.

The interceptor missile had its own mobile launcher, secure data link for interception, independent tracking andhoming capabilities and sophisticated radars, the sources said.

SOURCE : FIRSTPOST