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1. Various types of power source:
- (^) DIESEL ENGINE PROPULSION.
- GAS TURBINE PROPULSION.
- (^) NUCLEAR POWERED PROPULSION.
- WIND POWERED PROPULSION.
- (^) WAVE POWERED PROPULSION.
- (^) HUMAN PROPULSION.
- STEAM TURBINE.
- (^) FUEL CELL.
- SOLAR.
- (^) ELECTROMAGNETIC PROPULSION.
- (^) ELECTRICAL PROPULSION
3. Forces acting on ship while
cruising?
- Total weight acting down at centre of gravity
- Total buoyancy( up thrust) acting up at centre of buoyancy
- Resistance acting against the direction of motion.
- Thrust acting along the direction of motion when trying to push forward.
4. Types of propulsion systems used
in ships?
- (^) PADDLE WHEEL
- (^) VANE WHEEL
- (^) SCREW PROPELLERS
- (^) CYCLOIDAL PROPELLER
- (^) OSCILATING FOIL PROPELLER
- (^) PODDED PROPELLER
- (^) DUCTED PROPELLER
- (^) WATER JET
- (^) JET PROPULSION
- (^) CONTRA ROTATING PROPELLER
- (^) CONTROLLABLE PITCH PROPELLER
- (^) AZIMUTHING PROPELLER.
- (^) DIVER PROPUSION.
5. Define pitch of propeller?
- (^) Propeller blades are made up of hydrofoil sections. Propeller blades
are given some angle of attack to the incoming flow and rotated.
When blades rotates high pressure is created on back side and low
pressure is created on front face of propeller. Both these pressure
forces cancel and resultant force will be acting in forward direction,
pushing the ship forward.
7. Define resistance, thrust ,
effective power?
9. Ship correlation factor?
- (^) The total resistance value obtained by ship model correlation will be
slightly lesser than the real time values. Because the model doesn’t
have appendages, the model surface is smooth whereas the ship
surface is rough due to fouling, sea margin etc.
- (^) So by experience, ship correlation factor is multiplied with naked
effective power to obtain true effective power.
True effective power= naked effective power X SCF.
10. Wake fraction and wake speed?
w T & w F, ( wake factors) are determined by the measurements made in a model test (near a hull’s stern) or in a real ship test. Nominal wake : wake measured near the stern of a hull in the absence of the propeller (using pilot tubes). Effective wake : wake measured in the presence of propeller. The measurements show that a propeller at a rotating speed n behind a hull advancing at velocity, V s , delivers thrust T. By comparing it to the results of the same propeller in the open- water tests, we will find that at the same revolutions n, the propeller will develop the thrust T but at a different speed (usually lower), known as effective speed of advance, V A
. The difference between V s & V A is considered as the effective wake.
- Relation between nominal wake & effective wake. Since propellers induce an inflow velocity which reduces the positive wake to some extent, the effective wake factor usually is 0.03~0.04 lower than the corresponding nominal wake.
Wake factor of a
single screw ship
Averaged Wake Fraction
12. Real slip and apparent slip?
13. Why the propeller is not fitted
forward of ship?
- (^) Propeller produces turbulent flow, if this flows around the ship hull, it
will increase frictional resistance of ship.
- (^) Probability of propeller damage will increase due to collision.
- (^) Rudder effectiveness increases if kept behind propeller.
15. Difference between right handed
and left handed propeller?
- (^) If you look the propeller from behind the ship,
- (^) If the direction of rotation of propeller is in clockwise direction it is
called Right hand propeller.
- (^) If the direction of rotation is in Anticlockwise direction, it is called left
hand propeller.
16. What is augment of resistance
and thrust deduction factor?
