Quiz #1: Q. 1-50 Flashcards
The process of supplying a diesel engine cylinder with air at a pressure greater than atmospheric is called __________.
supercharging
Forcing the exhaust gases from the cylinder of an operating two cycle diesel engine with the aid of a blower is known as __________.
scavenging
Which of the listed types of superchargers will NOT have a volumetric capacity proportional to engine speed? A Exhaust gas turbocharger B Roots blower C Piston type blower D Vane type blower
A Exhaust gas turbocharger
The relative air pressure in the inlet manifold of a turbocharged diesel engine is usually __________.
greater than the average exhaust manifold pressure
The process of scavenging a two-stroke/cycle diesel engine serves to __________.
cool the exhaust valves
After cooling of a turbocharged diesel engine will result in __________.
higher torque and higher brake horsepower
Why will a turbocharged diesel engine produce black smoke if excessive additional load is applied too quickly?
The inertia of the turbocharger rotor causes a time lag which delays the turbocharger speed increase.
Which of the following devices will increase the power output of a diesel engine without increasing its frictional load? A Positive displacement blower B Roots-type rotary blower C Gear-driven centrifugal blower D Turbine-driven centrifugal blower
D Turbine-driven centrifugal blower
[aka a turbocharger]
Some diesel engines are supercharged with a __________.
turbocharger
The device shown in the illustration is commonly used to __________. Illustration MO-0080
utilize the flow of exhaust gases to supercharge the engine
At rated engine load and RPM, the diesel engine turbocharger is powered by __________.
exhaust gases
The operating speed of a turbocharger is directly dependent upon __________.
engine load
What statement is true concerning the charge air system of a modern turbocharged slow- speed two-stroke cycle diesel engine?
A A mechanically driven auxiliary blower is usually provided because the turbocharger cannot provide enough air at low engine speeds and loads.
B An electrically driven auxiliary blower is usually provided because the turbocharger cannot provide enough air at low engine speeds and loads.
C An electrically driven auxiliary blower is usually provided because the turbocharger cannot provide enough air at high engine speeds and loads.
D A mechanically driven auxiliary blower is usually provided because the turbocharger cannot provide enough air at high engine speeds and loads.
B An electrically driven auxiliary blower is usually provided because the turbocharger cannot provide enough air at low engine speeds and loads.
What statement is true concerning the charge air system of a modern turbocharged slow- speed two-stroke cycle diesel engine?
A A charge air cooler is usually provided to increase the charge air density.
B A charge air heater is usually provided to decrease the charge air density.
C A charge air heater is usually provided to increase the charge air density.
D A charge air cooler is usually provided to decrease the charge air density.
A A charge air cooler is usually provided to increase the charge air density.
On a typical turbo-charged marine diesel engine, what type of blower/compressor is used within the turbocharger?
Centrifugal
During the valve overlap period, the exhaust pressure of a turbocharged, four- stroke/cycle diesel engine must be less than the intake manifold pressure to ensure __________.
effective cylinder scavenging and cooling
The power consumed during the scavenging process of a diesel engine is known as the __________.
pumping loss
Corrosion inhibitors and/or soluble oils are added to diesel engine cooling systems to __________.
form a protective film on metal surfaces
Ethylene glycol, when used as a coolant in a closed cooling system for a diesel engine, is more advantageous than untreated raw water because it __________.
has a lower freezing point and higher boiling point
The expansion tank for a diesel engine closed cooling system is designed to maintain a constant head on the system and __________.
allow for an increase in water volume as the engine warms up
The highest pressure in any closed diesel engine freshwater cooling system is at the __________.
cooling water pump outlet
The expansion tank in a diesel engine closed freshwater cooling system is located at __________.
the highest point in the system
A closed freshwater cooling system is commonly used with marine diesel engines because the __________.
jacket water temperature is more easily controlled
Cooling water pumps driven by direct-reversing diesel engines are usually __________.
straight impeller vane with concentric housing
Sacrificial zinc anodes are used on the saltwater side of diesel engine heat exchangers to __________.
reduce electrolytic action on heat exchanger metals
When checking zincs in a saltwater cooled heat exchanger, you should __________.
replace the zincs if they are approximately 50% consumed
In a diesel engine jacket water cooler, with seawater cooling the fresh water, the __________.
jacket water pressure should always be greater than the sea water pressure
A three-way thermostatic control valve regulates the diesel engine cooling water temperature by passing a portion of the water __________.
around the cooler
What would be considered a normal temperature increase between the inlet and outlet jacket cooling water of a medium or high-speed diesel engine operating at normal load?
10 to 20 degrees Fahrenheit
An electric heater built into some smaller diesel engines is used to __________.
increase jacket water temperature for easier starting in cold weather
In a diesel engine closed freshwater cooling system employing a radiator, proper water temperature can be obtained by __________.
adjusting the radiator louvers
The temperature at which an adjustable bellows type thermostatic valve operates is determined by __________.
changing the spring compression opposing the bellows
The theoretical minimum compression ratio necessary to ensure compression ignition in a direct injection diesel engine is __________.
12:1
Which of the following reasons represents why the designed compression ratio of a gasoline engine is lower than that of a diesel engine?
A Compression must be low for smooth operation.
B The heat of compression is not used as an ignition source of the fuel.
C Compression must be low to have effective pre-ignition.
D Compression must be low for effective spark ignition.
B The heat of compression is not used as an ignition source of the fuel.
In the starting process of a diesel engine, the main object is to attain the compression conditions sufficient to __________.
ignite the fuel
The thermal energy produced by an internal combustion engine is transformed into __________.
mechanical energy
Diesel engines are classified as reciprocating internal combustion engines because they __________.
burn fuel in a closed chamber which imparts linear motion to pistons
The highest pressure in a diesel engine cylinder normally occurs __________.
after TDC
The load is always placed on the lower half of the main bearings in a/an __________.
two-stroke/cycle engine
Which of the terms listed below represents the operational speed at which excessive engine vibration is created? A Non-harmonic speed. B Critical speed. C Maximum speed. D Design maximum speed.
B Critical speed.
The cubic inch (or liter) displacement of a cylinder is determined by the diameter of the piston and the __________.
length of the stroke
If the compression ratio is increased on any diesel engine, __________.
thermal efficiency will increase
In the illustrated diesel engine, which label points to the piston? MO-0122
4
The diesel engine wrist pin in the illustration is indicated by the component labeled __________. MO-0122
7
Which of the following is an example of a solid bearing?
Piston pin bushing
The proper location for journal bearing oil grooves is __________.
as a side relief where the two shells meet
Which of the bearings listed below is most widely used for the main and connecting rod bearings of a modern high-speed diesel engine?
Precision insert
Component āUā of the diesel engine shown in the illustration is called the __________. MO-0122
crankshaft counterweight
The linear motion of a diesel engine piston is converted into the rotary motion required to drive gears, propeller shafts, and generators by the __________.
crankshaft
Connecting rods in a diesel engine are used to connect the __________.
piston to the crankshaft
