The light and medium fuels utilized in internal combustion engines provide a source of ________./food for microbiological organisms What is to be installed on an internal combustion engine if its cylinder bore exceeds eight inches?/Explosion relief valves Which statement regarding the arrangement and location of explosion relief valves used on an internal combustion engines is true_____________?/Minimizing the danger from emission of flame is a key consideration Which of the following listed construction details of internal combustion engines is required?/A warning notice to caution against the opening of a hot crankcase for a specified period of time after shut down. At what pressure should a cylinder relief valve of an internal combustion engine be set to relieve?/The device should be set to relieve at a pressure not more than 40 percent in excess of the maximum firing pressure. Successful combustion inside the cylinders of a diesel engine is dependent upon _____________./all of the above Which of the combustion parameters listed is used in a diesel engine, but NOT related to the injection system?/Effective stroke Precombustion chambers, air cells, and energy cells in high- speed, small bore diesel engines all serve to increase _____________./turbulence Which statement about diesel engine combustion is true?/Maximum cylinder firing pressure is not developed until the piston passes TDC. Proper atomization of fuel in diesel engine combustion chambers will _____________./improve combustion The ability of a fuel particle to travel into the combustion chamber before burning is called _____________./penetration Theoretical perfect combustion in a diesel engine yields by-products of _____________./water vapor and carbon dioxide What is the term given to the process of breaking up fuel oil into very fine particles for better combustion?/Atomizing Turbulence in a diesel engine cylinder is of major importance in providing _____________./complete fuel/air mixing Poor combustion in a diesel engine can be caused by ______________./low intake air temperature Which of the following conditions will tend to increase the ignition delay period of combustion in a compression ignition engine?/Decreasing the air charge temperature. Combustion gas venting through the expansion tank can be caused by a _____________./cracked cylinder head Combustion knock can occur in the cylinders of a diesel engine under any condition permitting _____________./excess fuel in the combustion chamber Turbulence of the compressed air charge in a diesel engine cylinder increases _____________./the efficiency of the engine Combustion knock occurring in a diesel engine can be caused by _____________./prolonged ignition lag Which of the following statements is a description of the combustion cycle?/The heat process which produces the force to initiate the movement of the engine parts. An exhaust pipe from a internal combustion engine may not need to be insulated when _________./it is of the water jacketed type Combustion knock occurring in a diesel engine can be caused by ________________./low coolant temperature In a diesel engine, the time taken to heat the fuel particles, turn them into vapor, and bring about combustion is called _____________./ignition delay Diesel engines are classified as reciprocating internal combustion engines because they ______________./burn fuel in a chamber where its energy moves a piston back and forth The thermal energy produced by an internal combustion engine is transformed into ______________./mechanical energy Which of the listed designs is effectively used to provide the turbulence necessary for proper combustion in a diesel engine cylinder?/Precombustion chamber Which of the following statements represents the advantage of a precombustion chamber used in an auxiliary diesel engine?/Timing of injection does not need to be exact. One advantage obtained from the use of a precombustion chamber in a diesel engine is _____________./smoother combustion Precombustion chambers differ from turbulence chambers in that precombustion chambers _____________./contain a smaller portion of the total clearance volume What is commonly used to create turbulence in a diesel engine combustion system?/Shape of the piston crowns. Turbulence is created in the cylinders of a diesel engine to _____________./help mix fuel and air The main operating characteristic of diesel engines which distinguishes them from other internal combustion engines is the _____________./method of igniting fuel What determines the number of events occurring in a cycle of operation in an internal combustion engine?/Type of engine (diesel or gasoline) Which of the following statements describes the operating characteristics of a precombustion chamber?/When fuel oil is injected into the precombustion chamber, it does not need to be as finely atomized as the fuel oil in diesel engines having direct injection. Modern marine diesel engines using mechanical fuel injection, operate on a combustion cycle which is _________./a combination of constant volume and constant pressure Modern marine diesel engines equipped with mechanical fuel injection operate on a combustion phase within the cycle which is _________./a combination of constant volume and constant pressure A multi-orifice fuel injection nozzle is usually used with which of the listed types of combustion chamber?/Open combustion chamber Black smoke exhausting from an operating diesel engine is an indication of poor combustion which may be caused by _____________./clogged air intake passages In a modern internal combustion diesel engine, the load carrying part of the engine is referred to as the _________./bedplate or base According to U. S. Coast Guard Regulations (46 CFR), internal combustion engine driven emergency generators shall be operated under load for at least two hours at least once ____________./a month According to Coast Guard Regulations (46 CFR), how often shall internal combustion engine driven emergency generators be operated under load?/Once a month for two hours Which of the following conditions is likely to develop if the thermocouple element of a pyrometer becomes coated with excessive amounts of combustion by-products?/Pyrometer responses will be retarded. In a diesel engine, what is the advantage of precombustionchambers over the open type of combustion chamber? I. Precombustion chambers permit coarser fuel atomization. II. Precombustion chambers allow lower fuel injection pressure./both I and II Modern marine diesel engines equipped with mechanical fuel injection operate on a combustion cycle which is _________./a combination of constant volume and constant pressure Which internal combustion engine starting system uses avane type fluid motor?/Compressed air Which of the following relationships should occur between the temperature developed in a combustion space, and the compression ratio of the engine?/Higher compression ratios create higher temperature. Diesel engine blow-by is the leakage of combustion gases past the _____________./compression and scraper rings In accordance with Coast Guard Regulations (46 CFR) regarding internal combustion engine exhaust manifold installations, which of the following statements is true?/They may be water-jacketed and cooled by the discharge from a pump which operates only when the engine is running. Open combustion chambers are designed to _____________./provide proper fuel/air mixing The primary purpose of the open combustion chamber used in diesel engines is to _____________./provide a place for combustion Turbulence in the combustion chamber of a diesel engine can be induced by _____________./directional intake ports The greatest turbulence in a diesel engine cylinder is created by the _____________./shape of the combustion chamber Combustion knock will most likely occur as a result of using a fuel with _____________./low ignition quality Coast Guard Regulations (46 CFR) require a trial for ignition period must not exceed ____________./15 seconds The air supplied to a diesel engine is compressed to___________.I. provide heat for the ignition of the fuelII. decrease injection delay/I only is correct For a given fuel, a change in the compression ratio will affect the ignition lag by which of the listed means?/An increase in compression ratio will decrease the ignition lag. The longer the ignition delay period occurs in a diesel engine, the _____________./more rapid will be the rise in combustion pressure Which of the following conditions will tend to increase the ignition delay period of combustion in a compression ignition engine?/Decreasing the air charge temperature. The rate of pressure rise during the period following fuel ignition process in a diesel engine, is influenced chiefly by the ____________./length of the ignition delay period Which of the following statements concerning the factors affecting ignition delay is correct?/An increase in coolant temperature will decrease ignition delay. The time between injection and ignition of the fuel is known as _____________./ignition delay The minimum speed an engine must attain before ignition can occur depends upon __________./all of the above In a diesel engine, the time period between fuel injection and ignition is usually defined as _____________./ignition delay The theoretical minimum compression ratio necessary to ensure compression ignition in a direct injection diesel engine is _____________./0.50069444 In an operating diesel engine, preignition can be caused by _____________./oil in the air charge The rate of pressure rise during the period following fuel ignition in a diesel engine is influenced by the length of the ignition delay period due to the ______./turbulence of the air change The ignition quality of diesel fuel becomes less critical as ______________./engine speeds decrease One cause of diesel engine fuel ignition delay is _______./ignition quality of the fuel oil If fuel injection in a diesel engine begins earlier than the design start of injection, ignition may be delayed because the _____________./cylinder compression pressure may not be high enough In diesel engineering practice, the term used to express the ignition quality of a particular fuel is _____________./cetane number The ignition quality of diesel fuel is indicated by its ______________./cetane number The ignition quality of diesel fuel oil is indicated by the ______________./cetane number The ignition quality of a diesel fuel is indicated by the _____________./cetane number The ignition quality of a fuel oil is an important operational consideration because it _____________./affects the starting ability of a cold engine The longer the ignition delay period resulting from improper use of low cetane fuel, the ____________./more rapid the rise in combustion pressure A mixture of 45% cetane and 55% alpha-methyl-naphthalene is found to have the same ignition delay as a sample of diesel oil. The sample can be described as having a/an __________./cetane number of 45 When comparing different fuels for different engines, the ignition quality of diesel fuel oils becomes a less critical consideration as ______________./engine speeds decrease Most practical diesel engines today operate on a cycle which is a combination of the Diesel and Otto cycles. In this process, compression ignition _____________./begins on a constant volume basis A diesel engine is turned at normal cranking speed and no ignition occurs. This could be the result of _____________./air bubbles in the fuel oil system The amount of oil consumed by a return flow-type fuel atomization system, fitted with both supply and return meters, can be determined by the ____________./difference between the supply and return meter readings A sprayer plate used in a return flow fuel oil atomizer is correctly installed if the oil __________./passes through the tangential slots before passing through the whirling chamber The amount of fuel oil atomized by a return flow oil burner is directly controlled by the ____________./fuel oil back pressure In comparison to straight flow mechanical atomizers, return flow atomizers provide relatively uniform atomization over a wide firing range due to the ____________./oil supply pressure not having to be reduced at low loads to the point where poor atomization occurs Fuel droplets injected into a diesel engine cylinder must have adequate penetration to _____________./thoroughly utilize the air charge Fuel injection systems meter fuel, atomize fuel, and _____________./inject fuel at the proper time A variable capacity, pressure atomizing, fuel oil burner functions to ____________./provide a wide range of combustion The firing range of a variable capacity, return flow-type fuel atomizer is regulated to meet steam demand by varying the ____________./fuel oil return pressure Fuel oil penetration into the cylinder of a diesel engine is _____________./reduced by finer atomization Proper atomization of fuel in diesel engine combustion chambers will _____________./improve combustion A change in the degree of fuel atomization in a diesel engine would most greatly affect _____________./fuel penetration Fuel oil discharged to the diesel engine cylinder is atomized at the _____________./injector nozzle tip A change in the degree of fuel atomization in a diesel engine cylinder has the greatest effect on the ____________./combustion in that cylinder In a diesel engine, what is the advantage of precombustion chambers over the open type of combustion chamber? I. Precombustion chambers permit coarser fuel atomization. II. Precombustion chambers allow lower fuel injection pressure./both I and II A change in the degree of fuel atomization in a diesel engine greatly affects the _______________./fuel penetration Which of the following statements concerning fuel atomization in a diesel engine cylinder is correct?/The greater the atomization, the lesser the penetration. | |||
