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, "a passage through which heat energy of steam is converted to kinetic energy by producing a high velocity jet of steam which is used to drive a steam turbine".
Nozzle ↣ Increase velocity at the expense of pressure drop.
Throat ↣ Produce steam jet with high velocity to drive steam turbine.
Types of Nozzles:
Convergent Nozzle ↣ Cross-section decreases continuously from entrance to exit.
Divergent Nozzle ↣ Cross-section increases continuously from entrance to exit.
Convergent-Divergent Nozzle ↣ Cross-section first decreases from entrance to throat, then increase from its throat to exit.
Stagnation State
For a high speed flows (in jet engines), P.e. is negligible but K.e. is not. It is convenient t combine enthalpy and K.e. of the fluid into a single term called Stagnation or Total Enthalpy.
ho = h + 0.5 V^2
Total or Stagnation State ↣ state in which flow is brought to rest isentropically in steady flow, zero adiabatic work output.
Dynamic Temperature ↣ temperature change when molecules are moving.
Velocity of Sound & Mach Number
Sound wave is defined as, "a small pressure disturbance that propagates through a states (gas, liquid, solid)".
Velocity of wave depends on properties of the medium.
Mach Number ↣ the ratio of actual velocity and the velocity of sound.
If M < 1 ↣ Subsonic Flow.
If M = 1 ↣ Sonic Flow.
If M > 1 ↣ Supersonic Flow.
Variation of Fluid Velocity with Flow Area
The last equation concludes that:
Stagnation Property Relations (Critical Pressure Ratio & Choked Flow)
Effect of Back Pressure in Convergent Nozzle
Back Pressure is defined as, "the pressure applied at the nozzle discharge region".
Condition of Flow ↣ pressure difference between inlet and outlet.
Choked Flow ↣ when nozzle operates with maximum mass flow (done by reducing back Pressure to critical pressure).
Critical Pressure ↣ pressure of fluid at a location in the nozzle where M=1 (at throat).
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 designe...
Projection: The term Projection is defined as: Presentation of an image or an object on a surface. The principles used to graphically represent 3-D objects and structures on 2-D media and it based on two variables: Line of Sight. Plane of Projection. Line of Sight & Plane of Projection: Line of sight is divided into 2 types: Parallel Projection Converging Projection & A plane of projection is an imaginary flat plane upon which the image created by the lines of sight is projected. Orthographic Projection: When the projectors are parallel to each other and perpendicular to the plane of projection. The lines pf sight of the observer create a view on the screen. The screen is referred to as the Plane of Projection (POP). The lines of sight are called Projection lines or projectors. Rules of Orthographic Projection: Edges that are parallel to a plane of projection appear as lines. Edges that are incl...
Gear Forming by Machining Formation of gear through machining consists of following methods: Form Milling by Disc Cutter Form Milling by End Mill Cutter Shaper, Planner and Slotter Broaching 1. Form Milling by Disc Cutter It is defined as, " Tooth is cut one by one by plunging the rotating cutter into the blank " . Each gear needs a separate cutter. 8 - 10 standard cutters are available for producing 12 - 120 teeth gears. Used for big spur gears of large pitch. 2. Form Milling by End Mill Cutter It includes the cutting of tooth at a time and then indexed for the next tooth space for cutting. For a small volume production of low precision gears. Set of 10 cutters ↠ 12 - 120 teeth gears . Used for teeth of large gears/module. To reduce cost, same cutter is often used for multiple sized gears resulting in profile errors . Characteristics: Use of Hardened stainless steels (HSS) form milling cutters. Use of Ordinary milling machines. Low production rate (need of indexing...
Comments
Post a Comment
HI, we wI'll contact you later