Posted tagged ‘equilibrium’

Introduction | Fluid Mechanics | Fluid properties

September 16, 2011

Fluid Mechanics – Introduction

01-Fluid Mechanics example - Static and Turbulent Flow - Analysis -Dynamic  analysis - CFD

Fluid Mechanics is that section of applied mechanics, concerned with the statics and dynamics of liquids and gases.

A knowledge of fluid mechanics is essential for the Mechanical engineer, because the majority of Mechanical processing operations are conducted either partially or totally in the fluid phase.

The handling of liquids is much simpler, much cheaper, and much less troublesome than handling solids.

Even in many operations a solid is handled in a finely divided state so that it stays in suspension in a fluid.

Fluid Statics: Which treats fluids in the equilibrium state of no shear stress

 02-Fluid Mechanics example - Static and Turbulent Flow - Analysis -Dynamic  analysis - CFD

Fluid Mechanics: Which treats when portions of fluid are in motion relative to other parts.

03-Fluid Mechanics example - Static and Turbulent Flow - Analysis -Dynamic  analysis - CFD

Fluids and their Properties

Fluids

In everyday life, we recognize three states of matter:

  • solid,
  • liquid and
  • gas.

Although different in many respects, liquids and gases have a common characteristic in which they differ from solids: they are fluids, lacking the ability of solids to offer a permanent resistance to a deforming force.

fluid is a substance which deforms continuously under the action of shearing forces, however small they may be.Conversely, it follows that:
If a fluid is at rest, there can be no shearing forces acting and, therefore, all forces in the fluid must be perpendicular to the planes upon which they act.

Shear stress in a moving fluid

Although there can be no shear stress in a fluid at rest, shear stresses are developed when the fluid is in motion, if the particles of the fluid move relative to each other so that they have different velocities, causing the original shape of the fluid to become distorted. If, on the other hand, the velocity of the fluid is same at every point, no shear stresses will be produced, since the fluid particles are at rest relative to each other.

MECHANICAL ENGG QUESTIONS

August 22, 2011

1. What is the importance of the Thermodynamics in the field of Mechanical Engineering?
All the mechanical engineering systems are studied with the help of thermodynamics. Hence it is very important for the mechanical engineers.

2. How many Laws of Thermodynamics are there?
There are three laws of the thermodynamics.

First Law: Energy can be neither created nor destroyed. It can only change forms.In any process in an isolated system, the total energy remains the same.


Second Law: When two isolated systems in separate but nearby regions of space, each in thermodynamic equilibrium in itself, but not in equilibrium with each other at first, are at some time allowed to interact, breaking the isolation that separates the two systems, and they exchange matter or energy, they will eventually reach a mutual thermodynamic equilibrium. The sum of the entropies of the initial, isolated systems is less than or equal to the entropy of the final exchanging systems. In the process of reaching a new thermodynamic equilibrium, entropy has increased, or at least has not decreased.

Third Law: As temperature approaches absolute zero, the entropy of a system approaches a minimum.

3. State Laws of conservation of energy?
According to the laws of conservation of energy, “energy can neither be created nor be destroyed. It can only be transformed from one form to another.”

4. Is the boiler a closed system?
Yes definitely the boiler is a closed system.

5. What is Carnot engine?
It was being designed by Carnot and let me tell you that Carnot engine is an imaginary engine which follows the Carnot cycle and provides 100% efficiency.

6. Which formula forms a link between the Thermodynamics and Electro chemistry?
Gibbs Helmholtz formula is the formula which forms the link between the thermodynamics and electromagnetism.

∆Hs/R = [∂ lnp /∂ (1/T)]x

where: x – mole fraction of CO2 in the liquid phase
p – CO2 partial pressure (kPa)
T – temperature (K)
R – universal gas constant
α – mole ratio in the liquid phase (mole CO2 per mole of amine)

7. Which is the hardest compound known?
Diamond.

8. What is Hess Law?
According to the Hess law the energy transfer is simply independent of the path being followed. If the reactant and the product of the whole process are the same then same amount of energy will be dissipated or absorbed.


9. Which has more efficiency: Diesel engine or Petrol engines?
Off course Diesel engine has the better efficiency out of two.