IV .
1.Couplings provide for slight expansion of various parts. 2. There are solid and flexible couplings. 3. When reduction gears are used couplings are employed between the turbines and the gear sets. 4.
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Some misalignment is caused by pipe srains. 5. Some misalignment may be caused due to strains. 6.
Gears are used to transmit rotary motion from one shaft to another. 7. A double reduction gear provides the necessary speed reduction. 8.Conventional practice employs two compound turbines driving the propeller.
V. .
1. Toothed wheels transmit rotary motion from one shaft to another. 2. Most present day (up to date) marine turbines operate at speeds up to 10 000 r.p.m. 3. A double reduction gear is used to rovide speed reduction. 4. Couplings are used to provide thermal expansion of parts. 5. Turbine couplings are solid and flexible. 6. Solid couplings are used when the turbine and the driven member are mounted on the common shaft. 7. A turbine drives a propeller through a reduction gear. 8. A flexible coupling is employed when a propeller is driven through a reduction gear.
VI. .
1. Turbines drive propellers through mechanical reduction gears or by electrical transmission. 2. When reduction gears are used flexible couplings are employed between the turbines and the gear sets. 3. Gears are used to transmit rotary motion and toque from one shaft to another. 4. Shafts may have a different speed and direction of rotation or both. 5. Most present day merchant marine turbines operate at speeds ranging between 3000 and 10000 r.p.m. 6. Turbines are connected to propeller. 7. Large, slow turning propellers operate speed ranging from 80 to 100 r.p.m. 8. Double reduction gears provide the necessary speed reduction. 9. High pressure and low pressure turbines are connected through the gearing. 10. Turbine and pinion shafts are connected through couplings. 11. Couplings are used to minimize the effects of hull distortion and provide for slight thermal expansion of various parts. 12. Threr are solid and flexible couplings. 13. Solid couplings are used for small units. 14. The turbine and the driven member are mounted on a common bed or foundation in small units. 15. Driving and driven units have their own two bearings. 16. Flexible couplings permit some slight misalignment after installation. 17. Pipe srains, expansion due to heat and others cause misalignment.
VII. .
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As being produced by ;
This often being designed by - .
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1. the propeller is said to be right handed 2. that edge is known as the leading edge 3this edge is called the trailing edge 4. the area of this circle is called the disk area of the propeller 5. this retio is called the pitch retio 6. the phenomenon is known as cavitation .
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Starting a unit , to make sure , to measure clearances , turbine rotors , motor driven , turning gear , main steam pipe - , maneuvering valve , turbine casing , vacuum gauge , circulating water , oil cooler , to heat the oil , to flow freely , initial temperature , turbine warming up , running slowly , running ahead and astern , in this event , throttle valve , to avoid , unequal heating , it is essential
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, , rolling ahead and rolling astern , air ejectors
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3. ,
1. The unit is clean inside and outside. The unit was clean inside and outside. The unit will be clean inside and outside. 2. This clearance is measured. This clearance was measured. This clearance will be measured. 3. The oil in the system is cold and viscous. The oil in the system was cold and viscous. The oil in the system will be cold and viscous.
4. must should. . (must , ; should ().
1. Unequal heating of the rotor should be avoided.( ). 2. The turbine should be run alternately ahead and astern. ( ). 3. The temperature of the oil should not be lower than 90 degrees faringate. ( 90 ). 4. All valves and cocks for draining water should be opened. ( ).
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5. to be ought to. .
1. Some precautions ought to be taken this time. ( . ). 2. Indicators ought to be installed to measure clearances. ( . ). 3. The cocks to the pressure gauges ought to be opened. ( . .) 4. Steam valves at the turbine ought to be closed. ( . ).
6. , Make sure that ,
1. Make sure that the turbines are still warm. 2. Make sure that the first opening of the throttle valve starts the turbine turning at once. 3. Make sure that the lubricating system is in order.
7. , See that,
1. See that all parts are securely fastened. 2. See thst there is a supply of circulating water through the oil cooler. 3. See that the oil in the lubricating system is heated. 4. See that the warming operation is omitted.
8. .
It is important - , it is desirable , it is necessary , it is essential , it is preferable , it is sufficient .
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9. , .
Lose lost-lost (), break broke-broken (), drive-drove-driven ( / ), hold-held-held ( / ), keep-kept-kept (/ ), set-set-set (), burn burnt burnt (), shut shut shut (), run ran run (), take took taken (), become became become (), make made made ( / ), bring brought brought (), cast cast cast (), split split split (), build built built (), draw drew- drawn ().
10. .
1. I ought to take precautions to make sure that the unit is ready in operation. 2. The unit should be absolutely clean inside and out. 3. Yes a certain procedure should be observed for starting the unit. 4. Clearances should be measured where indicators are installed. 5. The turbine rotors and gears must move freely. 6. The turbine rotor and gear movement is checked by means of motor driven turning gear. 7. All valves and cocks for draining water, manoeuvring valves should be opened. 8. Wnen starting all steam valves at the manoeuvtring gear and about the turbines should be closed. 9. The cocks to the pressure and vacuum gauges on the turbine and condenser should be open. 10. A supply of circulating water is determined by turning on the water and then turning it out. 11. It is important to inspect the lubricating system carefully because sometimes oil in the system become cold and viscous.
12. Oil shoul be heated to allow it to flow freely. The minimum initial temperature of the iol should not be lower than 90 degrees Faringate. 13. The turbine is warmed up by running it slowly. 14. The warming operation should be omitted entirely if conditions are such as to preclude alternate running ahead and astern. 15. If the turnine is still warm, it is essential thet the rolling alternately ahead and astern be carried uot before bringing the unit up to speed.
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Starting under way , the procedure should be observed , recirculating line , combination of nozzles , lubricationg oil system - , bearing temperatures and pressures , to record data , clearance indicators , thrust bearings , shut down the ejectors , main circulating pump- , turning gear , to force a fresh supply of oil .
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3. to be should. . .
1.Wear in the bearings should be determined once a week. ( . ). 2. Bearing temperatures should be observed all the time. ( . ). 3. The turnbine should be thoroughl drained. ( . ). 4. The turning gear should be disconnected. ( . ).
4. .
1. How long was the condenser pump wrking? 2. How long was the air ejector running? 3. How long was the main circulating pump operating?
5. at least once every watch
1. The location of turbine rotors is checked at least once every watch. 2. The clearance of the bearings is checked at least once every watch. 3. The main bearing pressure is checked at least once every watch.
6. :
1.When underway close recirculating line when the load is sufficient to provide the necessary condensate for the air ejector condensers. 2. Proper combination of nozzles should be opened to obtain designed steam pressure. 3. The bearing temperatures should be controlled every watch to avoid their overheating. 4. Shut off the main steam stop valve, shut down the air ejectors, shut off the gland- sealing system. Shut down the main circulating pump. 5. The air pumps and ejectors should be run every second day after stopping to keep the turbine interiors dry. 6. The lubricating pumps can be shut after the turning gear disconnection. 7. Oil pumps are started every day to force a fresh supply of clean oil through all bearings. 8. Turbine rotors are turned through 1 ½ revolutions of the propeller to oil all the gear teeth in order to let the rotors come to rest in a new position..
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Lack of balance , rotating parts , a source of trouble (), excessive wear , exact point of unbalance- ,its difficult to locate - , building up speed , to slow down immediately , vibration ceases , it may be assumed , unequal heating , steps should be taken , to remedy the trouble , faulty boiler operation () , in case of emergency , the blading is damaged , accurate alignment ,
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smooth operation , eccentric loading , the causes of vibration , worn gears , disturbing forces , severe vibration will result .
3. . .
1.The blading has been damaged. . 2. The point of unbalance has been found. . 3. Rumbling has been heared from the turbine. . 4. The turbine has been shut down. .
4. , .
1.The trouble was due to an accummulation of water in the turbine. - . 2. The shocks were due to the eccentric loading. - 3. The troubles were often due to unequal heating of the rotor. - . 4. Turbine vibration was due to many different reasons. . 5. The vibration this time was due to some foreign matter in the turbine. - - , .
5. , if - - it may be assumed that -. .
1.If the turbine starts to vibrate, it may be assumed that there is unequal heating of parts . , , . 2. If the vibration ceases at a lower speed, it may be assumed that the unit should run at that speed. , , 3. If the vibration does not cease at a lower speed, it may be assumed that the trouble is quite serious. , , .
6. .
1.Yes, the wear of bearings causes vibration. 2. It is difficult to locate the disbalance. 3. I should immediately slow the turbine down if in building up speed a turbine starts to vibrate. If the vibration does not cease at a lower speed I should run it at this speed for some minutes and then build up the speed again. If no vibration is noted the trouble was probably due to unequal heating of rotor. 4. If the vibration does not cease at a lower speed it is necessary immediately locate and remedy the trouble. 5. Rumbling in the turbine may occur due to water or other foreign matter in the turbine.
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Marine propultion , gas turbine , thermo dynamic cycle , oil engine , burning fuel , to represent the pressure and volume , suction stroke , return stroke , to expand adiabatically , to finally exhaust , power output , combustion chamber , heat exchanger , axial flow compressor or turbo-compressor ,
