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 ).
It is defined as, "Laminar flow of viscous fluid in the space between two parallel plates (one of which is moving relative to the other)".
Flow is driven by:
Viscous drag force acting at the fluid.
Applied pressure gradient parallel to the plates.
Application are:
Hydro-static lubrication
Viscosity pumps
Turbine
Applied to Journal bearings (used in mechanical systems).
3. Steady, Incompressible & Laminar Flow in a Circular Tube
It is defined as, "Steady, incompressible and laminar flow through a straight circular tube of constant cross-section". It is also called Hagen-Poiseuille Flow.
Lubrication
Navier-stokes equation used to find out the velocity profile inside a bearing. There are 3 types of lubrication:
Full Film Lubrication ↦ Bearing surfaces are fully separated by a film of lubricant.
Boundary Lubrication ↦ Bearing surfaces physically come into contact.
Mixed Film Lubrication ↦ Combination of partial lubricant films and some asperity (roughness/difficult to endure) contact between the surfaces.
Full film lubrication is further divided into the following:
Hydrostatic ↦ Surfaces are separated by an externally pressurized lubricant.
Hydrodynamics ↦ Surfaces are separated by a dynamic film of lubricant.
Elastohydrodynamic ↦ Characterized by elastic deflections of the surfaces under very high pressures within the contact zone with an increase in viscosity of the fluid.
Hydrodynamic Lubrication
It is governed by Reynold's equation of Classical Lubrication Theory which came into existence by assuming:
Liquid flowing through thin region separated by 2 moving surfaces.
Pressure does not vary across the film.
Appropriate boundary conditions required for Reynold's equation solution.
Reynold's Equation
It is defined as, "Analysis of Momentum Transport and Continuity equations leads to a single elliptic DE".
Analysis served as a basis of designing hydrodynamically lubricated bearings.
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...
Solid Mechanics OR Mechanics of Materials OR Strength of Materials: It is the study of mechanics of body i.e. forces and their effects on deformable solids under different loading conditions. Deformable Body Mechanics: It is the study of non-rigid solid structures which deform under load. Deformation/Distortion ⇾ change of shape and size OR have some relative displacement or rotation of particles. It happens when we apply combined load. Rigid Body Motion ⇾ Translation or rotation of particles but having constant distance between particles. Since deformation occur at particular load. Below this load, every body is considered as rigid body . Types of Load: Point Load ⇾ Load apply on a single point i.e. concentrated load. Uniformly Distributed Load (UDL) ⇾ Load remains uniform throughout an area of element like beam. Varying Distributed Load (VDL) ⇾ Load varies with length with constant rate. Moment ⇾ It measures the tend...
Strain Transformation Principal Strain and stresses can occur in the same directions. Material Properties Relation (Young, bulk Rigidity Modulus) ⇼ Hooke's Law General State of Strain ⇼ Є X , Є Y , Є Z and ૪ X , ૪ Y , ૪ Z . Stress (normal or shear)/ Strain (normal or shear) ⇼ vary with element orientation. Transformation equations for Plane strain derived from: Interpretation of Experimental measurements Represent in graphical form for plane strain (Mohr's Circle). Geometry and independent of material properties. Mohr's Circle It is defined as., " A graphical method for determining normal and shear Shear stresses without using the stress transformation equations " . While considering the circle CCW ⇼ Shear strain positive upward & Normal strain positive towards right. The construction of Mohr's circle (with normal and shear stresses are known) is quite easy which include following steps: Draw a set o...
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