View Factor Orientation (or View factor or shape factor) plays an important role in radiation heat transfer. View factor is defined as, "fraction of radiation leaving surface 'i' and strike 'j' ". Summation Rule (View Factor) If there is are similar surfaces 'i' and 'j' , then: Blackbody Radiation Exchange Radiation Exchange between Opaque, Diffuse, Gray surfaces in an Enclosure 1. Opaque 2. Surfaces 3. Two surface enclosure Radiation Shield It is used to protect surfaces from radiation act like a reflective surface. References: Material from Class Lectures + Book named Fundamentals of Heat and Mass Transfer by Theodore L. Bergman + My knowledge. Photoshoped pics are developed. Some pics and GIF from Google. Videos from YouTube ( Engineering Sights ).
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Friction
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Friction And it's Characteristics:
It is defined as;
A force which resists the movement of two contacting surface that slide relative to one another.
The force always acts tangent to the point of contact and is directed opposite to the existing motion between the surfaces.
Types of Dry Friction Problems:
There three types of problems of Dry Friction:
1. No Apparent Impending Motion:
The body is about to slip. For the body not to slip Fs ≥ Us N, otherwise the body may slip. Only equilibrium equations are used.
2. Impending Motion at all Points of Contact:
In this scenario, equilibrium equations as well as frictional motion equation are used.
3. Impending Motion at some Points of Contact:
The body might get slip. In this scenario, number of unknowns are less than the equilibrium and frictional motion equation.
Impending Motion:
Impending motion refers to the state just before the surfaces start to slip.
Tipping Effect:
The effect in which body rotate and fall on its side when the moment due to pushing force becomes greater than the moment due to the force of gravity.
Mpushing force ＞ Mgravity force
Difference Between Slipping and Tipping of a Body:
1. Slipping Effect:
When the pushing force will exceed the maximum static friction force and the box will begin to slide across the surface.
Fpushing force ＞ Ffrictional force
2. Tipping Effect:
When the pushing force and the friction force will create a strong enough couple that the box will rotate and fall on its side.
Mpushing force ＞ Mgravity force
Tipping Point:
When a body's center of gravity is above the area formed by the support base, the normal force can provide the necessary moment to remain in rotational equilibrium.
TAPING CORRECTIONS There are two types of corrections depending upon the type of errors in tape due to the different conditions. 1. Systematic Errors : Slope Erroneous tape length Temperature Tension Sag 2. Random Errors : Slope Alignment Marking & Plumbing Temperature Tension & Sag 1. Temperature Correction It is necessary to apply this correction, since the length of a tape is increased as its temperature is raised, and consequently, the measured distance is too small. It is given by the formula, C t = 𝛼 (T m – T o )L Where, C t = the correction for temperature, in m. 𝛼 = the coefficient of thermal expansion. T m = the mean temperature during measurement. T o = the tempe...
Advance High Strength Steel Conventional low carbon mild steel has simpler ferritic structure (α-iron) and good ductility. Common type of HSS is High Strength Low Alloy (HSLA) ⇥ has yield strength 550 - 690 N/sq.mm . Manganese ⇥ supporter (stabilizer) of ferrite. Conventional HSS : Is single-phase ferritic steel with a potential for some pearlite in C-Mn steel. Lower strain hardening capacity. Advance HSS : primarily steel with a microstructure containing a phase other than ferrite, pearlite, cementite. Higher strain hardening capacity. Case Study of Automobile There are three different zones in a car: Crumple Zone (Front & Back) Middle Compartment Safety Cage Some important points about these zones are: Crumple Zone ⇥ Made with those materials which absorb maximum amount of energy. Safety Cage ⇥ Multiple areas (like cabins, structural elements). Areas of Safety cage are described ahead: Cabins (Blue Areas) ⇥ Should have high streng...
Air-Standard Cycle Assumptions: The actual cycle is rather more complicated so we deduce it by considering following assumptions: The working fluid is air which continuously flow in a closed loop and act as ideal gas. All process are internally reversible . Combustion process is replaced by Heat addition process. Exhaust process is replaced by Heat rejection process. Here we are discussing 4 main cycles, namely: Otto Cycle or Constant Volume Heat Addition Cycle Diesel Cycle or Constant Pressure Heat Addition Cycle Dual Cycle Brayton Cycle 1. Otto Cycle or Constant Volume Heat Addition Cycle: The information about the diagram is given by: 1 ➤ 2: Isentropic Compression 2 ➤ 3: Constant Volume Heat Addition 3 ➤ 4: Isentropic Expansion 4 ➤ 1: Constant Volume Heat Rejection A. Efficiency of Otto Cycle: The efficiency of Otto Cycle is given by clicking the picture below: B. Work Output of Otto Cycle: The work output of ...
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