Classification of Flows

1. Steady and unsteady flows:

A flow is said to be steady if the properties (P) of the fluid and flow do not change with time (t) at any section or point in a fluid flow.

A flow is said to be unsteady if the properties (P) of the fluid and flow change with time (t) at any section or point in a fluid flow.

Eg: Flow observed at a dam section during rainy season, wherein, there will be lot of inflow with which the flow properties like depth, velocity etc.. will change at the dam section over a period of time representing it as unsteady flow.

2. Uniform and non-uniform flows:

A flow is said to be uniform if the properties (P) of the fluid and flow do not change (with direction) over a length of flow considered along the flow at any instant.

A flow is said to be non-uniform if the properties (P) of the fluid and flow change (with direction) over a length of flow considered along the flow at any instant.

Eg: Flow observed at any instant, at the dam section during rainy season, wherein, the flow varies from the top of the overflow section to the foot of the dam and the flow properties like depth, velocity etc., will change at the dam section at any instant between two sections, representing it as non-uniform flow.

3. One, two and three dimensional flows:

Flow is said to be one-dimensional if the properties vary only along one axis / direction and will be constant with respect to other two directions of a three-dimensional axis system.

Flow is said to be two-dimensional if the properties vary only along two axes / directions and will be constant with respect to other direction of a three-dimensional axis system.

Flow is said to be three-dimensional if the properties vary along all the axes / directions of a three-dimensional axis system.

4. Laminar and Turbulent flows:

When the flow occurs like sheets or laminates and the fluid elements flowing in a layer does not mix with other layers, then the flow is said to be laminar. The Reynolds number (Re) for the flow will be less than 2000.

When the flow velocity increases, the sheet like flow gets mixed up and the fluid elements mix with other layers there by causing turbulence. There will be eddy currents generated and flow reversal takes place. This flow is said to be Turbulent. The Reynolds number for the flow will be greater than 4000.

For flows with Reynolds number between 2000 to 4000 is said to be transition flow.

5. Compressible and Incompressible flows:

Flow is said to be Incompressible if the fluid density does not change (constant) along the flow direction and is Compressible if the fluid density varies along the flow direction

r = Constant (incompressible) and r ¹ Constant (compressible)

6. Rotational and Irrotational flows:

Flow is said to be Rotational if the fluid elements does not rotate about their own axis as they move along the flow and is Rotational if the fluid elements rotate along their axis as they move along the flow direction

KINEMATICS OF FLUID FLOW

Fluid kinematics refers to the features of a fluid in motion. It only deals with the motion of fluid particles without taking into account the forces causing the motion. Considerations of velocity, acceleration, flow rate, nature of flow and flow visualization are taken up under fluid kinematics.

A fluid motion can be analyzed by one of the two alternative approaches, called Lagrangian and Eulerian.

In Lagrangian approach, a particle or a fluid element is identified and followed during the course of its motion with time.

Difficulty in tracing a fluid particle (s) makes it nearly impossible to apply the Lagrangian approach. The alternative approach, called Eulerian approach consists of observing the fluid by setting up fixed stations (sections) in the flow field.

Motion of the fluid is specified by velocity components as functions of space and time. This is considerably easier than the previous approach and is followed in Fluid Mechanics.

Eg: Observing the variation of flow properties in a channel like velocity, depth etc, at a section.

CATIA

CATIA (Computer Aided Three-dimensional Interactive Application) is a multi-platform CAD/CAM/CAE commercial software suite developed by the French company Dassault Systemes and marketed worldwide by IBM. Written in the C++ programming language, CATIA is the cornerstone of the Dassault Systemes product lifecycle management software suite.

The software was created in the late 1970s and early 1980s to develop Dassault's Mirage fighter jet, then was adopted in the aerospace, automotive, shipbuilding, and other industries.

CATIA competes in the CAD/CAM/CAE market with Siemens NX, Pro/ENGINEER, Autodesk Inventor and SolidEdge.

History

CATIA started as an in-house development in 1977 by French aircraft manufacturer Avions Marcel Dassault, at that time customer of the CADAM CAD software.

Initially named CATI (Conception Assistée Tridimensionnelle Interactive — French for Interactive Aided Three-dimensional Design ) — it was renamed CATIA in 1981, when Dassault created a subsidiary to develop and sell the software, and signed a non-exclusive distribution agreement with IBM.

In 1984, the Boeing Company chose CATIA as its main 3D CAD tool, becoming its largest customer.

In 1988, CATIA version 3 was ported from mainframe computers to UNIX.

In 1990, General Dynamics Electric Boat Corp chose CATIA as its main 3D CAD tool, to design the U.S. Navy's Virginia class submarine.

In 1992, CADAM was purchased from IBM and the next year CATIA CADAM V4 was published. In 1996, it was ported from one to four Unix operating systems, including IBM AIX, Silicon Graphics IRIX, Sun Microsystems SunOS and Hewlett-Packard HP-UX.

In 1998, an entirely rewritten version of CATIA, CATIA V5 was released, with support for UNIX, Windows NT and Windows XP since 2001.

In 2008, Dassault announced and released CATIA V6. While the server can run on Microsoft Windows, Linux or AIX, client support for any operating system other than Microsoft Windows is dropped.

Features

Commonly referred to as a 3D Product Lifecycle Management software suite, CATIA supports multiple stages of product development (CAx), from conceptualization, design (CAD), manufacturing (CAM), and engineering (CAE).

CATIA can be customized via application programming interfaces (API). V4 can be adapted in the Fortran and C programming languages under an API called CAA. V5 can be adapted via the Visual Basic and C++ programming languages, an API called CAA2 or CAA V5 that is a component object model (COM)-like interface.

Although later versions of CATIA V4 implemented NURBS, V4 principally used piecewise polynomial surfaces. CATIA V4 uses a non-manifold solid engine.

Catia V5 features a parametric solid/surface-based package which uses NURBS as the core surface representation and has several workbenches that provide KBE support.

V5 can work with other applications, including Enovia, Smarteam, and various CAE Analysis applications.

Supported operating systems and platforms

CATIA V6 runs only on Microsoft Windows.

CATIA V5 runs on Microsoft Windows (both 32-bit and 64-bit), and as of Release 18 Service Pack 4 on Windows Vista 64. IBM AIX, Hewlett Packard HP-UX and Sun Microsystems Solaris are supported.

CATIA V4 is supported for those Unixes and IBM MVS and VM/CMS mainframe platforms up to release 1.7.

CATIA V3 and earlier run on the mainframe platforms.

Notable industries using CATIA

CATIA is widely used throughout the engineering industry, especially in the automotive and aerospace sectors. CATIA V4, CATIA V5, Pro/ENGINEER, NX (formerly Unigraphics), and SolidWorks are the dominant systems.

Aerospace

The Boeing Company used CATIA V3 to develop its 777 airliner, and is currently using CATIA V5 for the 787 series aircraft. They have employed the full range of Dassault Systemes' 3D PLM products — CATIA, DELMIA, and ENOVIA LCA — supplemented by Boeing developed applications.

European aerospace giant Airbus has been using CATIA since 2001.

Canadian aircraft maker Bombardier Aerospace has done all of its aircraft design on CATIA.

Automotive

Many automotive companies use CATIA to varying degrees, including BMW, Porsche, Daimler Chrysler, Audi, Volkswagen, Bentley Motors Limited, Volvo, Fiat, Benteler AG, PSA Peugeot Citroën, Renault, Toyota, Ford, Scania, Hyundai, Škoda Auto, Tesla Motors, Proton, Tata motors and Mahindra & Mahindra Limited. Goodyear uses it in making tires for automotive and aerospace and also uses a customized CATIA for its design and development. Many automotive companies use CATIA for car structures — door beams, IP supports, bumper beams, roof rails, side rails, body components — because CATIA is very good in surface creation and Computer representation of surfaces.

Shipbuilding

Dassault Systems has begun serving shipbuilders with CATIA V5 release 8, which includes special features useful to shipbuilders. GD Electric Boat used CATIA to design the latest fast attack submarine class for the United States Navy, the Virginia class. Northrop Grumman Newport News also used CATIA to design the Gerald R. Ford class of supercarriers for the US Navy.

Other

Architect Frank Gehry has used the software, through the C-Cubed Virtual Architecture company, now Virtual Build Team, to design his award-winning curvilinear buildings. His technology arm, Gehry Technologies, has been developing software based on CATIA V5 named Digital Project. Digital Project has been used to design buildings and has successfully completed a handful of projects.

CATIA V4 to V5/V6 Conversion

CATIA V5 and V6 can directly use the CATIA V4 models, but changes in the CATIA data structure requires data conversion from CATIA V4 to V5/V6. This is due to both a change in geometric kernel between CATIA V4 and CATIA V5, and changes in the CAD data structure between CATIA V5 and CATIA V6.

Dassault Systemes provides utilities to convert CATIA V4 data to CATIA V5 with a one-to-one mapping. Still, cases show that there can be issues in the data conversion from CATIA V4 to V5, from either differences in the geometric kernel between CATIA V4 and CATIA V5, or by the modelling methods employed by end users. Experiment results show that there can be data loss during the conversion (from 0% to 90%). The percentage loss can be minimized by using the appropriate pre-conversion clean-up, choosing the appropriate conversion options, and clean-up activities after conversion.

Engineering service providers have solutions, but mostly they are unique to a particular company and its processes / standard of modeling method. A common solution for 100% data conversion has yet to be devised. It is important to note that ANY change from one modeling kernel to another would cause similar problems; this issue is not unique to CATIA.

SolidWorks

SolidWorks is a 3D mechanical CAD (computer-aided design) program that runs on Microsoft Windows and was developed by Dassault Systèmes SolidWorks Corp., a subsidiary of Dassault Systèmes, S. A. (Vélizy, France). SolidWorks is currently used by over 3.4 million engineers and designers at more than 100,000 companies worldwide.

History

SolidWorks was introduced in 1995 as a competitor to CAD programs such as Pro/ENGINEER, I-DEAS, Unigraphics, and CATIA. SolidWorks Corporation was founded in 1993 by Jon Hirschtick, who recruited a team of engineers to build a company that developed 3D CAD software, with its headquarters at Concord, Massachusetts, and released its first product, SolidWorks 95, in 1995. In 1997 Dassault Systèmes, best known for its CATIA CAD software, acquired the company and currently owns 100% of its shares. SolidWorks was headed by John McEleney from 2001 to July 2007, and is now headed by Jeff Ray.

Modeling Methodology

SolidWorks is a parasolid-based solid modeler, and utilizes a parametric feature-based approach to create models and assemblies.

Parameters refer to constraints whose values determine the shape or geometry of the model or assembly. Parameters can be either numeric parameters, such as line lengths or circle diameters, or geometric parameters, such as tangent, parallel, concentric, horizontal or vertical, etc. Numeric parameters can be associated with each other through the use of relations, which allows them to capture design intent.

Design intent is how the creator of the part wants it to respond to changes and updates. For example, you would want the hole at the top of a beverage can to stay at the top surface, regardless of the height or size of the can. SolidWorks allows you to specify that the hole is a feature on the top surface, and will then honor your design intent no matter what the height you later gave to the can

Features refer to the building blocks of the part. They are the shapes and operations that construct the part. Shape-based features typically begin with a 2D or 3D sketch of shapes such as bosses, holes, slots, etc. This shape is then extruded or cut to add or remove material from the part. Operation-based features are not sketch-based, and include features such fillets, chamfers, shells, applying draft to the faces of a part, etc.

Building a model in SolidWorks usually starts with a 2D sketch (although 3D sketches are available for power users). The sketch consists of geometry such as points, lines, arcs, conics (except the hyperbola), and splines. Dimensions are added to the sketch to define the size and location of the geometry. Relations are used to define attributes such as tangency, parallelism, perpendicularity, and concentricity. The parametric nature of SolidWorks means that the dimensions and relations drive the geometry, not the other way around. The dimensions in the sketch can be controlled independently, or by relationships to other parameters inside or outside of the sketch.

SolidWorks pioneered the ability of a user to roll back through the history of the part in order to make changes, add additional features, or change the sequence in which operations are performed. Later feature-based solid modeling software has copied this idea.

In an assembly, the analog to sketch relations are mates. Just as sketch relations define conditions such as tangency, parallelism, and concentricity with respect to sketch geometry, assembly mates define equivalent relations with respect to the individual parts or components, allowing the easy construction of assemblies. SolidWorks also includes additional advanced mating features such as gear and cam follower mates, which allow modeled gear assemblies to accurately reproduce the rotational movement of an actual gear train.

Finally, drawings can be created either from parts or assemblies. Views are automatically generated from the solid model, and notes, dimensions and tolerances can then be easily added to the drawing as needed. The drawing module includes most paper sizes and standards (ANSI, ISO, DIN, GOST, JIS, BSI and GB).

Market

Solidworks Corp. has sold over a million licenses of Solidworks worldwide. The Sheffield Telegraph comments that Solidworks is the world's most popular CAD software. Its user base ranges from individuals to large companies, and covers a very wide cross-section of manufacturing market segments. Commercial sales are made through an indirect channel, which includes dealers and partners throughout the world. Directly competitive products to SolidWorks include Pro/ENGINEER, Solid Edge, and Autodesk Inventor.

Fluid Mechanics Basic Definitions

• Mechanics : Deals with action of forces on bodies at rest or in motion.

• Velocity and Speed: Rate of displacement is called velocity and Rate and distance traveled is called Speed.

Unit: m/s

• Acceleration: Rate of change of velocity is called acceleration. Negative acceleration is called retardation.

• Momentum: The capacity of a body to impart motion to other bodies is called momentum.

The momentum of a moving body is measured by the product of mass and velocity the moving body

Momentum = Mass x Velocity

Unit: Kg m/s

• Newton’s first law of motion: Every body continues to be in its state of rest or uniform motion unless compelled by an external agency.

• Inertia: It is the inherent property the body to retain its state of rest or uniform motion.

• Force: It is an external agency which overcomes or tends to overcome the inertia of a body.

• Newton’s second law of motion: The rate of change of momentum of a body is directly proportional to the magnitudes of the applied force and takes place in the direction of the applied force.

• Mass: Measure of amount of matter contained by the body it is a scale of quantity.

Unit: Kg.

• Weight: Gravitational force on the body. It is a vector quantity.

F = ma

W = mg

Unit: newton (N) g = 9.81 m/s2

• Volume: Measure of space occupied by the body.

Unit: m3

1 m3 = 1000 litres

• Work: Work done = Force x Displacement  Linear motion.

Work done = Torques x Angular displacement  Rotatory motion.

Unit: Nm or J

• Energy: Capacity of doing work is called energy.

Unit: Nm or J

Potential energy = mgh

Kinetic energy = ½ mv2 or ½ mrw2

Power: Rate of doing work is called Power.

• Matter: Anything which possess mass and requires space to occupy is called matter.

• States of matter:

Matter can exist in the following states

• Solid state.

• Fluid state.

• Solid state: In case of solids intermolecular force is very large and hence molecules are not free to move. Solids exhibit definite shape and volume. Solids undergo certain amount of deformation and then attain state of equilibrium when subjected to tensile, compressive and shear forces.

• Fluid State: Liquids and gases together are called fluids. Incase of liquids Intermolecular force is comparatively small. Therefore liquids exhibit definite volume. But they assume the shape of the container Liquids offer very little resistance against tensile force. Liquids offer maximum resistance against compressive forces. Therefore, liquids are also called incompressible fluids. Liquids undergo continuous or prolonged angular deformation or shear strain when subjected to tangential force or shear force. This property of the liquid is called flow of liquid. Any substance which exhibits the property of flow is called fluid. Therefore liquids are considered as fluids.

In case of gases intermolecular force is very small. Therefore the molecules are free to move along any direction. Therefore gases will occupy or assume the shape as well as the volume of the container.

Gases offer little resistance against compressive forces. Therefore gases are called compressible fluids. When subjected to shear force gases undergo continuous or prolonged angular deformation or shear strain. This property of gas is called flow of gases. Any substance which exhibits the property of flow is called fluid. Therefore gases are considered as fluids.

Some of Mechanical Engineering Question for Interviews

1. even though LPG is economical than petrol,why we are not promoting LPG usage?
2. explain bearing nomenclature with example.
3. Explain Why Nozzles are made convergent and Divergent?
4. Funtion of cluch
5. How a Diesel Engine Works in Generators?Explain with Labelled Diagram.
6. how can u increase the efficiency of power plant without changeing in effort?
7. How cooling Tower height selected E
8. how gravity filling machine is designed
9. How hydrulic power stearin @ lutch works plz explain?
10. How Hydrulic Power Stering & Clutch works plz explain ?
11. how much efficiency loss will took place in a steam turbine due to low vacuumWhat is Auto Dosing?
12. What is fuel oil viscosity, specific gravity?
13. What causes damage to impellers?
14. What are the causes of damage to propellers?
15. What are the causes of main engine black smoke?
16. How is a factor of safety used in design?
17. Interpret a Stress vs. Strain Curve.
18. What types of equations or theories would be used in Static Failure?
19. What types of equations would be used in Fatigue Failure?
20. Which one is more efficient– a four stroke engine or a two stroke? Why?
21. What causes crankcase explosion?
22. What are the defects in exhaust valve?
23. In auto mobile industry for any type of vehicle how can we differentiate 2 stroke and 4 stroke engine....
24. In hydroulic clutch mechanism can i adjust clutch play? if it is possible plz explain ?
25. increase in unit speed increases the discharge of impulse turbine how?
26. Name fuels used in nuclear power plant?
27. On what property u can distinguish material as brittle or ductile?
28. On what thermodynamic cycle nuclear power plant works?
29. Pipe. Whats The Concept Behind It?
30. Purpose of centrifugal pump casing wear ring and impeller wear ring what is back plate in centrifugal pumps and its purpose?
31. Suppose a steel bar of cross sectional area A is subjected to load P at one end and 2P at the other end ,what will be the induced
32. waht is vaily gap in welding?
33. what are engines that use carburetor and that use inductor ? difference between them
34. What are the conditions considered while evaluvating MARGIN OF SAFETY for newly designed mechanical components....? or
35. what are the types of welding machine?
36. What are your significant functional achievements in the present company? How did they contribute to the total process
37. What do you mean gy "Clausius inequality"?
38. What does a pump develops? Flow or Pressure. Give the Answer with Proper Logic.
39. what for orifice using in liquid flow line
40. what is bearing? how many types of bearing
41. What is difference between sand blasting and grit blasting ? What is its purpose and how is it done ?
42. what is drive speed & what is driven speed
43. What is Dry Bulb Temperature and Wet Bulb temperature?
44. what is electronically operated pneumatic valves? give one example
45. What is FEED?
46. What happens when too much oil is injected in the working cylinder
47. What is the seal packing gland for turbine?
48. How to prevent back fire of boiler?
49. What is the tolerance allowable for ISMC 150(c-channel) as per IS 2062?
50. why the reaction turbines are not exposed to atmosphere? and why the impulse turbines are exposed to?
51. Where can you find the feed check valve and feed stop valve and give the purpose of it?
52. What s gland sealing steam?
53. What type of pump use in boiler F.O. system?
54. A bearing is designated as 6205 , what is it’s bore diameter?
55. advantages and disadvamtges of using lpg in car?
56. All Rector or Exchanger have spherical/hemispherical end Why?
57. Compare Brayton and Otto cycle.
58. current rating of a 3 phase DG set is 20 Amps, but what will be the per phase current for single phase supply.
59. Define Overall Heat transfer coefficient.
60. do any one have an idea,of saipem engineering interviw?
61. Does Is 2062 Specifies Only Seamless Pipes Or Erw Pipe Is Also Covered Under Is 2062
62. Explain about power technology?
63. How is SAP useful for mechanical engineers?
64. What are the different types of bearings? What are different types of rivets?
65. What is the applicability of mechanical engineering in the industry?
66. Explain Newton’s Laws.

Mechanical engineering

Mechanical Engineering is an engineering discipline that was developed from the application of principles from physics and materials science. Mechanical engineering involves the analysis, design, manufacturing, and maintenance of various systems. It is one of the oldest and broadest engineering disciplines.

The field requires a solid understanding of core concepts including mechanics, kinematics, thermodynamics, fluid mechanics, heat transfer, materials science, and energy. Mechanical engineers use the core principles as well as other knowledge in the field to design and analyze manufacturing plants, industrial equipment and machinery, heating and cooling systems, motor vehicles, aircraft, watercraft, robotics, medical devices and more.

Development

Applications of mechanical engineering are found in the records of many ancient and medieval societies throughout the globe. In ancient Greece, the works of Archimedes (287 BC–212 BC) and Heron of Alexandria (c. 10–70 AD) deeply influenced mechanics in the Western tradition. In China, Zhang Heng (78–139 AD) improved a water clock and invented a seismometer, and Ma Jun (200–265 AD) invented a chariot with differential gears. The medieval Chinese horologist and engineer Su Song (1020–1101 AD) incorporated an escapement mechanism into his astronomical clock tower two centuries before any escapement could be found in clocks of medieval Europe, as well as the world's first known endless power-transmitting chain drive.

During the early 19th century in England and Scotland, the development of machine tools led mechanical engineering to develop as a separate field within engineering, providing manufacturing machines and the engines to power them. The first British professional society of mechanical engineers was formed in 1847, thirty years after civil engineers formed the first such professional society.In the United States, the American Society of Mechanical Engineers (ASME) was formed in 1880, becoming the third such professional engineering society, after the American Society of Civil Engineers (1852) and the American Institute of Mining Engineers (1871). The first schools in the United States to offer an engineering education were the United States Military Academy in 1817, an institution now known as Norwich University in 1819, and Rensselaer Polytechnic Institute in 1825. Education in mechanical engineering has historically been based on a strong foundation in mathematics and science.

The field of mechanical engineering is considered among the broadest of engineering disciplines. The work of mechanical engineering ranges from the depths of the ocean to outer space.

Fundamental subjects of mechanical engineering usually include:

* Statics and dynamics
* Strength of materials and solid mechanics
* Instrumentation and measurement
* Thermodynamics, heat transfer, energy conversion, and HVAC
* Fluid mechanics and fluid dynamics
* Mechanism design (including kinematics and dynamics)
* Manufacturing technology or processes
* Hydraulics and pneumatics
* Engineering design
* Mechatronics and control theory
* Material Engineering
* Drafting, CAD (including solid modeling), and CAM.

Mechanical engineers are also expected to understand and be able to apply basic concepts from chemistry, chemical engineering, electrical engineering, civil engineering, and physics. Most mechanical engineering programs include several semesters of calculus, as well as advanced mathematical concepts which may include differential equations and partial differential equations, linear and modern algebra, and differential geometry, among others.

In addition to the core mechanical engineering curriculum, many mechanical engineering programs offer more specialized programs and classes, such as robotics, transport and logistics, cryogenics, fuel technology, automotive engineering, biomechanics, vibration, optics and others, if a separate department does not exist for these subjects.

Most mechanical engineering programs also require varying amounts of research or community projects to gain practical problem-solving experience. Mechanical engineering students usually hold one or more internships while studying, though this is not typically mandated by the university.

Modern tools

Many mechanical engineering companies, especially those in industrialized nations, have begun to incorporate computer-aided engineering (CAE) programs into their existing design and analysis processes, including 2D and 3D solid modeling computer-aided design (CAD). This method has many benefits, including easier and more exhaustive visualization of products, the ability to create virtual assemblies of parts, and the ease of use in designing mating interfaces and tolerances.

Other CAE programs commonly used by mechanical engineers include product lifecycle management (PLM) tools and analysis tools used to perform complex simulations. Analysis tools may be used to predict product response to expected loads, including fatigue life and manufacturability. These tools include finite element analysis (FEA), computational fluid dynamics (CFD), and computer-aided manufacturing (CAM).

Using CAE programs, a mechanical design team can quickly and cheaply iterate the design process to develop a product that better meets cost, performance, and other constraints. No physical prototype need be created until the design nears completion, allowing hundreds or thousands of designs to be evaluated, instead of a relative few. In addition, CAE analysis programs can model complicated physical phenomena which cannot be solved by hand, such as viscoelasticity, complex contact between mating parts, or non-Newtonian flows

As mechanical engineering begins to merge with other disciplines, as seen in mechatronics, multidisciplinary design optimization (MDO) is being used with other CAE programs to automate and improve the iterative design process. MDO tools wrap around existing CAE processes, allowing product evaluation to continue even after the analyst goes home for the day. They also utilize sophisticated optimization algorithms to more intelligently explore possible designs, often finding better, innovative solutions to difficult multidisciplinary design problems.