CAVITATION ITS EFFECTS AND PRECAUTION

CAVITATION ITS EFFECTS AND PRECAUTION

Cavitation:

Cavitation is defined the phenomenon of formation of vapour bubbles of a flowing liquid in a region where the pressure of the liquid falls below its vapour pressure and sudden collapsing of these vapour bubbles in a region of higher pressure . When the vapour bubbles collapse, a very high pressure is created. The metallic surfaces, above which these vapour bubbles collapse, is subjected to these high pressures, which cause pitting action on the surface. Thus cavities are formed on the metallic surface and also considerable noise and vibrations are produced.

Effects:-

1. The metallic surfaces are damaged and cavities are formed on the surfaces.

2. Due to sudden collapse of vapour bubble, considerable noise and vibrations are produced.

3. The efficiency of a turbine decreases due to cavitation.

Precaution:-

1. The pressure of the flowing liquid in any part of the hydraulic system should not be allowed to fall below its vapour pressure. If the flowing liquid is water, then the absolute pressure head should not be below 2.5m of water.

2. The special materials or coatings such as aluminium-bronze and stainless steel, which are cavitation resistant materials, should be used.

REFERRED BY :- GOOGLE SEARCH ENGINE

Comments

APRON MECHANISM IN LATHE

APRON MECHANISM IN LATHE Apron Mechanism: Apron is attached to the carriage and hangs over the front side of the lathe bed. It is useful in providing power and hand feed to both carriage and cross-slide. It is also used to provide power feed to the carriage during thread cutting through two half nuts. The construction of apron is shown in Fig. Fig - Apron Mechanism Construction Power is transmitted from the spindle to the lead screw and feed rod through the spindle gear and tumbler gear arrangement. A worm is mounted on the feed rod by a sliding key. The worm meshes with a worm gear on whose axis another gear G1 is attached. Gear G1 is attached to a small gear G2 by a bracket as shown in the diagram. Gear G4 is positioned to be in mesh with the rack gear always. Another gear G3 is mounted on the same axis of gear G4. The carriage hand wheel meant for longitudinal feed is attached to the gear G5 on the same axis. The gears G3 and G5 are always in mesh. The gear G

Boiler Mountings - Dead Weight Safety Valve

DEAD WEIGHT SAFETY VALVE Function:- A valve is placed upon a valve seat that is fixed upon a long vertical pipe having a flange at the bottom for fixing at the top of the boiler. Suspended at the top of the valve is the weight carrier that carries cast iron rings. The total weight must be sufficient to keep the valve on its seat against the normal working pressure. When the steam pressure exceeds the normal limit, it lifts the valve with its weight & the excess steam escape through the pipe to the outside. This valve is used only with stationary type of boilers. It is the most elementary type of safety valve. The objection to dead weight safety valve is the heavy weight that has to be carried. Image - Dead Weight Safety Valve Figure - Dead Weight Safety Valve

DOM MANUAL / B-TECH / MECHANICAL / KUK - TO FIND THE SPEED AND TORQUE OF DIFFERENT GEARS IN AN EPICYCLIC GEAR TRAIN.

OBJECTIVE: TO FIND THE SPEED AND TORQUE OF DIFFERENT GEARS IN AN EPICYCLIC GEAR TRAIN. SPECIFICATIONS : 1. GEAR TRAIN : SUN GEAR : 14 TEETH 2. PLANT GEAR: 21 TEETH (2 NOS.) 3. INTERNAL GEAR WITH : 56 TEETH TORQUE MEASUREMENT · INPUT TORQUE – MOTOR CURRENT CALIBRATED FOR MOTOR TORQUE. · PLANT CARRIER - PULLEY OF 50 MM DIA AND SPRING BALANCE. · INTERNAL GEAR - PULLEY, 120 MM DIA AND SPRING BALANCES. Ø BOTH PULLEYS ARE PROVIDED WITH ROPE OF 12 Ø MM DIA Ø DRIVE MOTOR - 1HP DC MOTOR RPM MOTOR OPERATING ON 220 VOLTS Ø 50 HZ SUPLLY, DRIVING THE SUN GEAR. CURRENT(AMPS) TORQUE 1.00 0.5 1.20 1.5 1.40 2.5 1.60 3.0 1.80 4.0 2.00 5.0 2.20 6.0 MOTOR CALIBRATION CHART THEORY : WHENEVER THE DISTANCE BETWEEN THE DRIVING AND DRIVEN MEMBER, (BOTH SHAFTS ARE NOT OPERATING ON THE SAME A

Mechanical Guru's

Search This Blog