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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Joints and Fasteners
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Welded Joints
A permanent joint which is obtained by the friction of edges of two parts to be joined, with or without the application of pressure and a filler material.
Used in fabrication as an alternative method for casting and forging.
Used as a repair medium.
If filler material is used ↠ Strength of Joint > Base metal strength.
If filler not used ↠ Joint strength < Base metal strength.
Grinding Finish ↠ Welding at top and bottom off the plate.
Machining Finish ↠ Welding at bottom surface after welding machining operation.
Want to learn more about welded joint, click here.
Designing of Butt Joint
Design of Lap Joint or Fillet Joint
Lap or Fillet joint is "formed by the overlapping of plates and then welding the edges of plates". There are two types of fillet joints:
Single and Double Transverse Fillet Joints ↣ are designed for tensile loading.
Parallel Fillet Joints ↣ are designed for shear loading.
Screw Joints
Screw Threads are formed by "Cutting the continuous helical groove on a cylindrical surface or rod".
Pitch is the reciprocal of the number of threads forms per inch 'N'.
Lead 'l' is the distance the nut moves parallel to the screw axis when the nut is given one turn.
For a single thread ↠ Lead = Pitch.
Thread Standards
1. American National Thread Standard
Thread size is specified by the number of threads per inch 'N'.
Thread angle is 60-degrees.
Crests of thread may be either Flat or Rounded.
There are two series of American National Thread Standard:
UN Series ↠ we have sharp edges at root (no radius).
UNR Series ↠ we add root radius which increases its thread and fatigue strength.
2. Metric Thread Standard
Specified by writing the nominal major diameter and pitch in millimetres.
Thread angle is 60-degrees.
If we add pitch with M12 ↠ it is Fine-pitch thread otherwise it is Coarse-pitch thread.
There are two series of Metric Thread Standard
Without Root Radius ↠ denoted by 'M'.
With Root Radius ↠ denoted by 'MJ'.
Square and Acme Threads
Square and Acme threads are used on screw when power is to be transmitted.
Square Threads ↠ thread angle is 0-degrees, interlocking of threads is good but have wear.
Acme Threads ↠ thread angle is 29-degrees, high load carrying capacity.
Power Screw
It is defined as, "a device used in machinery to change angular motion into linear motion to transmit power".
Bolt Preload or Pretension ↠ Clamping force which stretches the bolt when nut gets tighten (or assembly force which nut apply to bolt).
Spring Rate ↠ Ratio between the force applied to the member and the deflection produced by that force.
Grip ↠ Total thickness of clamped material (including both member and both washers).
Self-locking Screw ↠ which requires a positive torque to lower the load.
Over-hauling Screw ↠ in which friction is too low so that load lower itself by causing the screw to spin without external effort.
Rankine Cycle Rankine cycle is an ideal cycle for Vapour Power Cycles and is normally used for Electricity Generation. The Rankine cycle consist of following steps: 1 ↝ 2 : Isentropic Compression in Pump. 2 ↝ 3 : Constant Pressure Heat Addition in Boiler. 3 ↝ 4 : IsentropicExpansion in Turbine. 4 ↝ 1 : Constant Pressure Heat Rejection in Condenser. Energy Balance: Since, all the devices which Rankine Cycle posses are steady flow devices, so the energy balance for Rankine cycle is: 》For Pump ( q = 0 ): 》For Boiler ( w = 0 ): 》For Turbine ( q = 0 ): 》For condenser ( w = 0 ): The thermal efficiency of Rankine Cycle is: How can we Increase the Efficiency of A Rankine Cycle: The efficiency of a Rankine cycle can be increased: Increasing the avg. temperate at which heat is added Decreasing the avg. Temperature at which heat is rejected. The above two objectives can be achieved by following three methods: 1. By
Cotter Joints A temporary fastener used to connect rigidly two co-axial rods (or bars) which are subjected to axial tensile or compressive forces. Cotter ↣ A flat wedge shaped piece of rectangular cross-section of uniform thickness and its width is tapered for an easy adjustment.It is made of steel . Used in connecting piston rod to cross-head of reciprocating steam engine. Inserted ⊥ to the axis of shaft. Strength of key < Cotter strength ↣ because of removing material . We add taper on top of key while we add taper on top, bottom but along width side of cotter. Types of Cotter Joint 1. Sleeve and Cotter Joints Simplest of all cotter joints and is used to fasten two round rods/bars . Rectangular cross-section area, tapered both sides along width. We add cotter pin ⊥ to the axis of shaft and add sleeve to shaft and then add pin. It has better strength than Socket and Spigot Cotter joint . Taper in cotter is 1 in 24 . 2. Gib and Cotter Joints It is used to join two square rod
Principle Of Linear Impulse And Momentum : The basis of principle of linear impulse and momentum is given by: The above equation can be written as: The above equation is called Principle of Linear and Momentum. Impulse measures the effect of force during small time period 'dt'. Momentum (is the strength of motion ) is associated with the states of process. Impulse are associated with process caused by external force. For System Of Particles: For system of particles, the principle of linear impulse and momentum is written as the summation for number of particles: Here, Individual Particle Velocity (Vi) = Velocity of center of mass (Vg). Summation Of individual particle (mi) = Total mass of body (m). Conservation Of Linear Momentum For System Of Particles : If the sum of external impulse of the system of particles is zero, then Principle of linear momentum and impulse becomes: There are two types of force on the basis of Impulse whic
Need some info about Allen Nuts and Bolts like its sizes, prices, how to assemble any part using these nuts and bolts.
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