A. bowl periphery B. bowl center C. upper surface D. lower surface
Lesson 7
The Gas Exchange Process
单项选择题：
1. __________ arrangements have low temperature air and high temperature exhaust gas passing through adjacent ports, causing temperature differential problem for the liner material. A. Loop scavenge B. Cross scavenge C. Uniflow scavenge D. Supercharge
2. _________ is the removal of exhaust gases by blowing in fresh air. A. Gas exchange B. Charging C. Scavenging D. Supercharging 3. According to the way the energy of the exhaust gases is utilized, pressure-charging can be divided into two main systems, namely, the constant-pressure system and _______. A. the pulse-phase system B. the pulse Doppler system C. the pulse system D. the pulse interval
4. All three systems have the ports _______ to swirl the incoming air and direct it in the appropriate path. A. angled B. rounded C. being angled D. being rounded 5. An electrically driven automatically operating auxiliary blower is provided for slow speed and _______ of a low speed diesel engine. A. manoeuvring operations B. bad combustion C. cooling D. mooring trial
6. Cross scavenging requires the fitting of _______ to prevent air or exhaust gas escape when the piston is at the top of the stroke. A. an exhaust valve B. a piston skirt C. a piston crown D. an air suction valve
7. If the flame from combustion in the cylinder of a four-stroke engine past the piston into the space below, the accumulation of flammable mixture would be ignited, thus resulting in _______. A. the crankcase explosion B. lifting of the cylinder safety valve
C. a scavenge fire D. opening of the manhole
8. If the flame from combustion in the cylinder of a two-stroke engine past the piston into the space between the piston and the stuffing box, the accumulation of flammable mixture would be ignited, thus resulting in _______. A. the crankcase explosion B. lifting of the cylinder safety valve
C. a scavenge fire D. opening of the manhole
9. In ________ scavenging the incoming air enters at the lower end of the cylinder and exhaust gases are forced out at the top. A. cross B. loop C. aspirate D. uniflow
10. In _______ scavenging the incoming air is directed upwards and the exhaust gases travel down and out of the exhaust ports at the opposite side of the cylinder. A. cross B. loop C. aspirate D. uniflow
11. On opposite ends of a single shaft of a turboblower are a gas driven ________ and an air compressor, which are sealed each other. A. charge air receiver B. scavenging air belt C. turbine D. air cooler
12. On two-stroke diesel ________ is usually provided because the exhaust gas driven turbo-blower cannot provide enough air at low engine speeds. A. a hydraulic governor B. an electrically auxiliary blower C. control valves D. electric motors
13. On two-stroke diesels an electrically auxiliary blower is usually provided because the exhaust gas driven turbo-blower cannot provide enough air at low engine speeds, and the pressurized air is usually cooled to _______. A. reduce the temperature of piston B. increase its density C. increase its temperature D. reduce the fuel viscosity 14. Once a scavenge fire is detected the engine ______. A. will be speeded up B. should be slowed down C. must slow down D. have to be slow down
15. Once a scavenge fire is detected, fuel should be shut off from the affected cylinders an cylinder lubrication increased _______ the risk of seizure. A. to protect B. to guard C. to maximize D. to minimize
16. The indications of a scavenge fire are excessive black smoke, _______ and peeling from scavenge trunking. A. turbo-chargers surge B. spark seen from the drains C. paint blistering D. all above are right
17. The process to remove exhaust gases by blowing in fresh air is called ______. A. charging B. supercharging C. starting D. scavenging
18. Turbocharging system may be designed to operate on either the _______ or the constant pressure exhaust system. A. pulse B. exhaust C. fluctuating D. hunting
19. Uniflow is the most efficient scavenging system but requires _______ an opposed piston arrangement _______ an exhaust valve in the cylinder head. A. neither / nor B. both / and C. either / or D. not only / but also 20. With supercharging is large mass of air is supplied to the cylinder by blowing it in under pressure, which is the best means to _______ of the engine. A. increase the exhaust temperature B. increase the power of C. reduce the speed D. increase the fuel consumption 21. With uniflow scavenging the incoming air enters _______ and leaves at the top. A. at the bottom of the cylinder B. at the lower end of the cylinder C. at the middle of the cylinder D. in the scavenging box
22. A centrifuge arranged to separate impurities and small amounts of water from oil is known as ________. A. an oily water separator B. a purifier
C. a centrifugal compressor D. a clarifier
23. Which of the two events listed occurs simultaneously in a two-stroke/cycle diesel engine?
A. Exhaust and scavenging. B. Scavenging and compression. C. Ignition and expansion. D. Exhaust and compression. 24. The pressurized air is usually cooled to increase the charge air ______. A. viscosity B. density C. velocity D. electricity
25. A dirty intercooler on the ship service air compressor will result in ______.
A. decreased compression ratio B. higher than normal power consumption
C. un-loader malfunction D. water in the lubricating oil 26. The ______stage air compressors are widely used on board the ship. A. single B. II C. III D. multiple
27. All three systems have the ports____ to swirl the incoming air and direct it in the appropriate path.
A. angled B. rounded C. being angled D. being rounded 28. Scavenging in a four-stroke/cycle diesel engine occurs during the ______. A. last part of the exhaust stroke, and the first part of the intake stroke B. last part of the intake stroke only C. early part of the injection stroke only D. early part of the power stroke
29. The process to remove exhaust gases by blowing in fresh air is called ______. A. charging B. supercharging C. starting D. scavenging
30. Which of the diesel engine components listed increases air density and helps to improve engine operating efficiency?
A. Impeller B. Compressor C. After-cooler D. Exhaust diffuser
Lesson 8
Lubricating System
单项选择题：
1. ________ is arranged for cleaning the lubricating oil in the system and clean oil can be provided from a storage tank. A. A filter B. A centrifuge C. A distiller D. A generator 2. The function of lubricating oil is to ________. A. reduce friction between moving surface B. provide even distribution of bearing wear
C. reduce the accumulation of harmful detergents
D. maintain a constant oil temperature output at each bearing
3. In a general oil cooler circulated by sea water, the oil is at a higher pressure, the result being that any leak in the cooler will mean a loss of ______. A. oil B. sea water C. air D. fresh water
4. In an engine with a pot-shaped piston, some lubricating oil from the main bearing will pass along a drilled passage in the crankshaft to the bottom end bearing and
then up a connection rod to the ________. A. crosshead B. crankpin C. crank journal D. gudgeon pin
5. In large marine diesel engines cylinder oils usually contain additives formulated to impart the _______ to clean the rings and grooves. A. inefficiency B. oiliness C. detergency D. purity 6. In some designs the cylinder oil is timed so that the oil injects only on the _______.
A. piston crown B. piston groove C. piston skirt D. piston ring belt
7. Oil is supplied to the cylinder wall and _______ by means of mechanical lubricators.
A. the cylinder cover B. the piston rings C. the piston crown D. the piston skirt
8. The development of _______ has kept pace with the increasing demands made by the steady rise in power produced by modern marine diesels. A. water B. fresh air C. oils D. gases
9. The lube oil in the bearings is drawn from a _______, usually located in the bedplate. A. tank B. sump C. vessel D. bottle
10. The oil is drawn from a drain tank through _______, one of a pair of pumps, into one of fine filters. A. a strain tank B. a head tank C. a service tank D. a strainer 11. The oil lubricating diesel engine cylinders usually contain additives formulated to impart a high degree of alkalinity to _______ the acid conditions. A. invade B. provide C. detergent D. neutralize
12. The selection of a lubricating oil depends to a great extent on the operating conditions, _______. A. the type of coolant B. the design of the engine C. the type of fuel to be burned D. B and C
13. The successful operation of any engine or machine and ________ depend on effective lubrication. A. their no trouble period B. their freely trouble period} C. its free trouble life D. its trouble-free life
14. The use of a poor quality piston cooling oil can lead to rapid deterioration of its properties with the resultant formation of deposits in the piston crown which in turn results in a considerable _______ in heat transfer. A. advantage B. superior C. increase D. reduction
15. To counteract these undesirable effects cylinder oils usually contain additives formulated to impart a high degree of _______ and detergency. A. salinity B. alkalinity C. acid D. sanitary
16. Large marine diesels of crosshead construction generally two systems of lubrication, _______ for cylinders and ________ for the running gear and cooling the pistons.
A. a circulating system / a total loss system
B. a total loss system / a circulating system C. an opened system / a closed system D. a closed system / an opened system
17. An additive used to improve the ability of a lube oil to reduce friction is known as a/an ______.
A. suppressant additive B. dispersant additive C. extreme pressure additive D. viscosity improver additive
18. Although lube oils used in the main lubricating service systems should have a relatively high flash point to avoid ignition, they can create smoke and fire hazards when they ______. A. are exposed to a vacuum
B. come in contact with extremely hot surfaces
C. are reduced in temperature to just above the pour point D. become extremely agitated or aerated
19. A lube oil filter can be used to remove most contaminants from lube oil. A contaminant which will remain in the lube oil after filtering is ______. A. abrasive B. fuel oil C. sediment D. impurities
Lesson 9 Starting System
单项选择题：
1. The total starting air capacity required for reversible main engines is to be sufficient for a least ________. A. six consecutive starts B. eight consecutive starts C. ten consecutive starts D. twelve consecutive starts
2. In the event of the cylinder starting valve leakage _______ would pass into the air pipes and ignite the oil deposited. A. cooling water B. vapor from the boiler C. starting air D. hot gases
3. Rotating flyweights acting against spring pressure make a simple type of ______. A. governor B. safety valve C. reducing valve D. feed water regulator
4. The loss of ________ from an air compressor could lead to an overheated air discharge and possibly an explosion in the pipelines leading to the air reservoir. A. lubricating oil B. compressed air C. cooling water D. sealing ring 5. The starting air system usually has ______ to prevent starting if anything is not in order.
A. drain cocks B. vent valves C. counteracts D. interlocks
6. When the starting air valve closes on one cylinder, another starting air valve has _______ opened on another cylinder whose piston has just commenced its downward stroke. A. just B. nearly C. merely D. already
7. __________ are commonly used in mechanical-hydraulic governor to sense