There are four main types of marine engine: the diesel engine, the steam turbine, the gas turbine and the marine nuclear plant. Each type of engine has its own particular application.

The diesel engine is a form of internal combustion engine similar to that used in a bus. Its power is expressed as brake horsepower (bhp). This is the power put out by the engine. Effective horsepower is the power developed by the piston in the cylinder but some of this is lost by friction within the engine. The power output of a modern marine diesel engine is about 40,000 brake horsepower. This is now expressed in kilowatts. By comparison the engine of a small family car has an output of about 80 bhp. Large diesel engines, which have cylinders nearly 3 ft in diameter, turn at the relatively slow speed of about 108 rpm. These are known as slow-speed diesel engines. They can be connected directly to the propeller without gearing. Although higher power could be produced by higher revolutions, this would reduce the efficiency of the propeller because a propeller is more efficient the larger it is and the slower it turns. These large slow running engines are used in the larger merchant ships, particularly in tankers and bulk carriers. The main reason is their low fuel consumption. More and more of the larger merchant vessels are being powered by medium-speed diesel engines. These operate between 150 and 450 rpm, therefore they are connected to the propeller by gearing. This type of engine was once restricted to smaller cargo ships but now they are used in fast cargo liners as well as in tankers and bulk carriers. They are cheaper than slow-speed diesel engines, and their smaller size and weight can result in a smaller cheaper ship.

In steam turbines high pressure steam is directed into a series of blades or vanes attached to a shaft, causing it to rotate. This rotary motion is transferred to the propeller shaft by gears. Steam is produced by boiling water in a boiler which is fired by oil. Recent developments in steam turbines which have reduced fuel consumption and raised power output have made them more attractive as an alternative to diesel power in ships. They are 50 per cent lighter and on very large tankers some of the steam can be used to drive the large cargo oil pumps. Turbines are often used on container ships which travel at high speeds.

Gas turbines differ from steam turbines in that gas rather than steam is used to turn a shaft. These have also become more suitable for use in ships. Many naval vessels are powered by gas turbines and some container ships are fitted with them. A gas turbine engine is very light and easily removed for maintenance. It is also suitable for complete automation.

Nuclear power in ships has mainly been confined to naval vessels, particularly submarines. But this form of power will be used more in merchant ships as oil fuels become more expensive. A nuclear-powered ship differs from a conventional turbine ship in that it uses the energy released by the decay of radioactive fuel to generate steam. The steam is used to turn a shaft via a turbine in the conventional way.

 

Exercise 1.

Find equivalents of these words in the text and learn them:

Морской двигатель; морская атомная установка; подходящий; радиоактивное топливо; особое применение; расход топлива; пар высокого давления; вращать вал; оснащать; тихоходный дизельный двигатель; редуктор; серия лопаток; большие грузовые масляные насосы; лошадиные силы; двигатель внутреннего сгорания; винт; торговые суда; подводная лодка; поршень; военные суда.

 

Exercise 2.

Answer the questions.

1. What is a diesel engine?
2. How is the diesel engine power expressed?
3. Why is some of the effective horsepower lost?
4. What are characteristics of a low-speed diesel engine (name the cylinder bore, rpm, power output)?
5. What is the main advantage of low-speed diesel engine?
6. What kind of engine is called a directly coupled engine?
7. What kind of ships are medium-speed diesel engines applied in? What are their particulars/characteristics?
8. How do steam turbines work?
9. What kind of ships are steam turbines used in for propulsion today?

• What has made turbines more attractive recently?
• How do gas turbines differ from steam turbines?
• What are the advantages of gas turbines over steam turbines?
• What kind of ships is nuclear power applied/used in?

 

Exercise 3.

Complete the following sentences:

1. Diesel engine power is expressed as … .
2. … develops power in the cylinder.
3. Some of effective horsepower is lost by … within the engine.
4. Slow-speed diesel engines can be connected to the … without … .
5. Large slow running engines are often used because of their low … … .
6. Medium-speed diesel engines are … to the propeller by … .
7. Steam is often used to drive … … .
8. … is used to … a shaft in gas turbines.
9. A gas turbine engine is very light and it is easily removed for … .

• A gas turbine engine is suitable for complete … .

 

Exercise 4.

Translate the following sentences:

1. Турбины часто используются на контейнерных судах.
2. Часть мощности теряется из-за трения.
3. Мощность выражается в киловаттах.
4. Малооборотный дизельный двигатель соединяется прямо на винт без редуктора.
5. Он называется двигателем с прямым соединением на винт.
6. Все больше торговых судов оснащаются среднеоборотными двигателями. Они соединяются с винтом с помощью редуктора.
7. В паровых турбинах пар высокого давления направляется на ряд лопаток, прикрепленных к валу.
8. Вращательное движение (вала) передается на гребной вал с помощью редукторов.
9. Расход топлива в современных паровых турбинах уменьшен, а мощность увеличена.

• Газовая турбина очень легкая и легко вынимается (извлекается) для ремонта.
• На атомоходах пар производится энергией, выделяемой при распаде радиоактивного топлива.

 

 

Exercise 5.

Complete the following sentences with a preposition.

1. Horsepower is developed … the piston … the cylinder.
2. Water … a boiler is fired … oil.
3. Brake horsepower is expressed … kilowatts.
4. Gas turbines are often used … tankers.
5. A gas turbine engine is light and easily removed … maintenance.

 

Exercise 6.

Speak about different types of marine engines and their application.

 

 

WHAT HAPPENS INSIDE THE ENGINE

 

Learning how a diesel engine works, let’s see what happens inside the engine step by step.

First, air must be gotten into the cylinder because no fuel burns without air. Combustion is a chemical process uniting a fuel or combustible with the oxygen in the air. The fuel and oxygen, uniting, change into new substances.

Second, the air must be squeezed or compressed to a high pressure. There are two reasons for compressing the air. One reason is that if the combustible mixture has been compressed to a high pressure before it starts to burn, it will produce more power than if it hadn’t been compressed. The other reason is that when air is compressed, its temperature goes up – the higher the pressure, the higher the temperature. In a diesel engine the entering air is compressed so much that it becomes hot igniting oil that is sprayed into it.

This is a fundamental difference between a diesel engine and a gasoline engine where a spark is used to ignite the combustible mixture, while in a diesel engine the fuel ignites by itself contacting with air.

Third, the fuel must be squirted into the cylinder forming a fine spray. The oil is squirted in after the air has been compressed and thus heated to a high temperature. It must be in the form of a fine spray so that a cloud of oil droplets will spread throughout all of the air producing a thorough or ‘homogeneous’ mixture of oil and air which is needed for quick and complete combustion.

Fourth, combustion takes place immediately after the oil is sprayed into the cylinder. The gaseous mixture gets hotter trying to expand. It pushes on the sliding piston which in turn transmits the force through the connecting rod to the crank on the crankshaft making the crankshaft revolve and thus deliver power to whatever machine the engine is driving.

Fifth, the spent gases must be gotten rid of or exhausted.

Exercise 1.

Find equivalents of these words in the text and learn them.

Горение; смесь; коленчатый вал; шатун; разница; горючая смесь; сжимать; химический процесс; топливо; искра; воспламенять; кислород; вещество; высокое давление; впрыскивать; гореть; разница; передавать.

 

Exercise 2.

Answer the questions:

1. Why is air gotten into the cylinder?
2. What is combustion?
3. What do fuel and air form uniting?
4. Why does the entering air become hot?
5. What ignites oil in a diesel engine?
6. What is a combustible mixture ignited by in a gasoline engine?
7. How is fuel squirted into the cylinder?
8. When does combustion take place in the cylinder?
9. What does combustion generate?

• Where is power delivered to?

 

Exercise 3.

Put the sentences in the right order according to the processes inside the engine:

1. The gases in the cylinder have lost their pressure.
2. The fuel forms a fine spray.
3. A combustible unites with the oxygen in the air.
4. The fuel contacts with air.
5. The gases expand.
6. The entering air becomes hot.
7. The gaseous mixture pushes on the piston.
8. The fuel and oxygen changes into new substances.
9. The process of combustion produces power.

• The spent gases are gotten rid of.

 

Exercise 4.

Complete the sentences:

1. Air is gotten into… .
2. The fuel and oxygen unite in … .
3. The combustible mixture is squeezed to a high … .
4. The combustible mixture is squeezed to produce more … .
5. The hot air ignites … .
6. The fuel oil is squirted into the cylinder in a fine … .
7. Combustion takes place after the oil … .
8. Combustion generates a great … .
9. The gaseous mixture expands and pushes on … .

• The piston makes the crankshaft … .
• The crankshaft delivers power to the driven … .
• The spent gases after work are … .

 

Exercise 5.

Fill in the proper Participle 1:

1. Combustion is a chemical process … a combustible with the oxygen in the air.
2. The piston slides down the cylinder … the force through the connecting rod to the crank on the crankshaft.
3. The crankshaft revolves … power to the driven machine.
4. … a fine spray the oil is squirted into the cylinder.
5. … a homogeneous mixture oil droplets spread throughout the air.
6. … the gaseous mixture pushes the piston.
7. A spark … the combustible mixture is used to start combustion in a gasoline engine.
8. Fuel … with air ignites.
9. In a diesel engine air … the cylinder is compressed to a high pressure.

 

Exercise 6.

Translate into Russian:

1. The combustible mixture has been compressed to a high pressure before it starts to burn.
2. After the air has been heated to a high temperature, the oil is squirted in.
3. When the piston has finished its power stroke, the spent gases are exhausted.
4. When the gases in the cylinder have lost their pressure, the gases must be gotten rid of.
5. After the air has been squeezed, the oil is sprayed into the cylinder.
6. Before the fuel and oxygen change into new substances in the process of combustion, they have been united.

 

Exercise 7.

Describe what happens inside the engine.

 

 

CYCLES OF DIESEL ENGINES

 

Any internal combustion engine, regardless of principle it operates in, is said to have a four-stroke cycle or a two-stroke cycle. The engines of either type may be single or double acting, trunk-piston type, crosshead type, opposed-piston type.

The four-stroke cycle consists of the suction stroke, compression stroke, combustion and expansion stroke and exhaust stroke. The piston starts a downward, suction stroke. The air inlet valve is open and air is being drawn into the cylinder through the air inlet pipe. The exhaust valve, fuel valve are all closed. As the piston reaches the end of the suction stroke the air inlet valve closes and as the piston rises on the second, or compression, stroke the air in the cylinder is compressed. At the end of this stroke the air has been compressed to about 480 pounds and its temperature has risen to about 1,000 degrees F. the fuel injection valve now opens and the fuel oil is sprayed into the cylinder under a pressure of 3,550 p.s.i. the high temperature of the compressed air in the cylinder ignites the fuel, and it continues to burn as long as injection is maintained. This burning raises the temperature of the gas to approximately 3,000 degrees F. in the meantime, the piston has started down on the third, or expansion, stroke with the gas expanding behind it. The injection valve closes shortly after the piston has started down on this stroke. At the end of this stroke the exhaust valve opens and the burned gases in the cylinder, now reduced to about 40 pounds pressure, and correspondingly reduced in temperature, start to flow out through the exhaust pipe. Retuning on the fourth, of exhaust, stroke the piston pushes the remaining gas out of the cylinder. At the end of this stroke the exhaust valve closes, the air inlet valve opens and the cycle of operation starts again.

It is thus seen that one complete cycle requires four strokes of the piston; the four strokes comprise two complete revolutions of the crankshaft.

The majority of medium and high speed diesel engines for main and auxiliary drive operate on the four-stroke cycle.

In the 2-cycle, single acting Diesel engine instead of an exhaust valve there is a ring of exhaust ports around the bottom of the cylinder, communicating with the exhaust pipe. The spray valve and starting valve are the same as in the 4-cycle. In place of air inlet valves there are scavenging ports, in place of exhaust valves there are exhaust ports, in uniflow scavenging engines there are exhaust valves. The scavenging ports are in communication with a passage leading to a low pressure scavenging air compressor, operated from the engine.

When the piston on its downward stroke uncovers the exhaust ports and the cylinder pressure drops to atmospheric, the scavenging ports open and the air, under the pressure, flows into the cylinder and pushes the exhaust gases out through these ports. As the piston on its up stroke covers the scavenging ports, the exhaust ports close leaving the cylinder full of fresh air. The piston moving upward on its compression fuel injection occurs, just as previously described for the 4-cycle. It is thus seen that the complete series of operations, including fuel injection and combustion, expansion, exhaust, filling cylinder with fresh air and compression, occurs in two strokes of the piston, or one revolution of the crankshaft.

Practically all large slow-speed, direct drive marine diesel engines operate in the two-stroke cycle.

 

Exercise 1.

Find the equivalents of these words in the text and learn them.

Впускной патрубок; выхлопной ход; топливо впрыскивающий клапан; продувочное окно; выхлопное окно; выхлопные газы; простого или двойного действия; ход сжатия; поршень; ход всасывания; впрыскивающий клапан; давление; коленчатый вал; пусковой клапан; оборот коленчатого вала; впускной клапан; выхлопной клапан; ход горения и расширения.

 

Exercise 2.

Ask question as if you want to know the time of the action.

Look at the model and do the same.

Model 1.

The inlet valve closes at the end of the suction stroke.

When does the inlet valve close?

1. The fuel injection valve opens after the compression stroke.
2. The oil gets into the cylinder at the end of the compression stroke.
3. The gas expands during the combustion and expansion strokes.
4. The gas exhausts during the exhaust stroke.
5. The exhaust valve opens during the exhaust stroke.
6. The gas reduces in pressure and temperature during the expansion stroke.

 

Exercise 3.

Ask questions as if you want to find out the place of Diesel engine parts.

Model 1.

The exhaust valve is placed in the cylinder head.

Where is the exhaust valve placed?

1. There is an exhaust pipe connected to the cylinder.
2. The fuel is ignited in the cylinder.
3. The inlet valve is placed in the cylinder head.

 

Exercise 4.

Complete the sentences:

1. The four-stroke cycle includes … .
2. When air is being drawn into the cylinder through the …, the … and … are all closed.
3. At the end of the … the air has been compressed to about four hundred eighty pounds.
4. … of the compressed air in the cylinder … the fuel.
5. When the piston returns on the exhaust stroke, it pushes … out of the cylinder.
6. There is a ring of exhaust ports around the bottom of the cylinder in place of … .
7. There are scavenging ports instead of … .
8. There are exhaust ports instead of … .
9. A low pressure scavenging air compressor is operated from the … .

• The complete series of operations occurs in one revolution of the … .

 

Exercise 5.

Translate extending the sentences gradually.

a)

1. Впрыскивается топливо.
2. Топливо впрыскивается в цилиндр.
3. Топливо впрыскивается в цилиндр двигателя.
4. Топливо впрыскивается в цилиндр двигателя под давлением.
5. Топливо впрыскивается в цилиндр двигателя под давлением 3500 фунтов на В. дюйм.

 

b)

1. Поршень движется вверх.
2. Поршень движется вверх на выхлопной ход, на ход «выпуск».
3. Поршень движется вверх на выхлопной ход, выталкивая газы.
4. Поршень движется вверх на выхлопной ход, выталкивая газы через окна.
5. Поршень движется вверх на выхлопной ход, выталкивая газы через открытые выхлопные окна.

 

Exercise 6.

Questions on the text and problems.

Test your comprehension.

1. Enumerate all types of Diesel engines you know.
2. Name the strokes of a four-stroke cycle. What valves are there on the cylinder head? When is the air inlet valve open? What valves should be closed during the comprehension. Under what pressure is the fuel injected into the cylinder? When does the gas expand? What is its action? When do the gases flow out of the cylinder? How many revolutions of the crank dot he four piston strokes require? Where are the four-stroke cycle engines used?
3. Name the strokes of a two-stroke cycle.
4. Show the principal difference in construction.
5. Speak about location of exhaust and scavenging ports. On what stroke does the piston uncover the exhaust ports? When do scavenging ports open during operation? When is the cylinder full of fresh air? When does fuel injection occur? How many revolutions of the crankshaft are required in a 2-cycle engine? Where are these engines used?

 

Exercise 7.

Read and translate the dialogues and learn them by heart.

BEFORE THE EXAM

• Do you know the types of Diesel engines?
• Certainly, I do. They are four-stroke and two-stroke engines.
• As to the principle of operation, what are they?
• Single-acting and double-acting.
• And what about their construction?
• I know it too. They are crosshead, trunk-piston and opposed-piston types.
• Oh, I see, you’re preparing for the exam.
• Yes, I am.

 

 

• During the compression stroke, all the valves should be closed, shouldn’t they?
• What valves do you mean?
• Air inlet valve, fuel valve and exhaust.
• Yes, naturally. Otherwise there will be no compression.
• What is the pressure and temperature of compression?
• It’s about 500 pounds and about 1,000 deg. F, i.e. about 100 kg/cm² and 500º C.
• Fuel is injected under pressure, isn’t it?
• Yes, it’s quite high. 3,500 pounds per square inch.
• Does the burning raise the temperature of the gas?
• Up to 3,000ºF, i.e. about 1,500º.
• At the end of the expansion stroke the pressure of gases drops to about 40 pounds and they start to flow out, don’t they?
• Yes, they do. So we see now the whole cycle of operation. It’s quite simple.
• I think I’ll be able to explain everything in English. Besides I’ll use the scheme.

 

 

• We go on with our talk. Now we have to revise the principles of a two-cycle engine operation.
• Is there any difference in construction between the four- and two-cycle engine?
• Yes, a principal one. In a four-stroke cycle there are valves in the cylinder head, and in the two-cycle Diesel there are ports. There are exhaust ports and scavenging ports.
• What is their location?
• It’s very important. As far as I know the scavenging ports are always lower than exhaust ones.
• Why so?
• To provide scavenging of the cylinder. The working processes are absolutely the same as in the four-stroke cycle, but they occur during the two cycles.
• I see that you know this material.

 

Exercise 8.

Describe the four-cycle and two-cycle internal combustion engines and all the processes occurring in them.

While speaking, use the following plan.

1. Types of engines as to their construction and principle of operation.
2. The four-stroke cycle (every stroke separately).
3. The two-stroke cycle. Principal changes in construction with the same processes.
4. Number of revolutions of the crankshaft in both types.

 

 

LUBRICATING OIL SYSTEM

A lubricating oil system for a large main engine includes pressure pumps, strainers and fine filters which are in duplicate, one set being used while the other acts as standby. Fine filters should be capable of being cleaned without interruption of the oil flow. Mesh size will depend on the bearing materials and clearances: in most large engines it is 50 microns. Capacity of the system must be adequate for the type of installation. If the engine has oil-cooled pistons the capacity and throughput will be increased accordingly.

Lubricating oil pressure pumps draw oil from the engine drain tank through suction strainers, the tank suction being clear of the lowest point to avoid picking up any water or sludge which may have settled.

The pumps discharge at pressure through the oil cooler, ensuring that sea water at its lower pressure can not leak into the oil system in the event of a fault in the cooler. The oil then passes through the fine filters to the engine. It will be distributed to all bearings, piston cooling, sprayers, exhaust valve actuators, control systems etc.

Various sections of the lubricating system may require different pressures and to accommodate this engine driven booster pumps may raise the supply pressure while pressure reducing valves and restricted orifices may reduce or flow to other parts.

Used oil drains to the bottom of the crankcase and passes through strainers by gravity to the drain tank. Drain returns are kept remote from the pump suction and must be submerged to reduce aeration and to make a safe seat. With oil-cooled pistons each piston oil return has its temperature monitored and it then passes through a sight glass before returning to the crankcase.

The oil drain tank is usually built into the ship’s double bottom but it must be surrounded by a cofferdam to prevent any contamination from leakages. It is fitted with an air vent, level measuring gauge and sounding pipe. Central positioning of the level gauge will reduce fluctuation in readings due to pitching and rolling at sea. The tank must be of sufficient size to accommodate the full charge of oil. Its interior surfaces may be coated to prevent rusting due to condensation on its non-flooded surfaces. The system should also have low pressure, high temperature and low tank level alarms fitted.

A bypass centrifuge system is fitted to purify oil from the drain tank to remove water, sludge and insolubles. This should be operated continuously at with a slow throughput, the oil being preheated to 70-90ºC to assist separation.

When the engine is not in use batch purification of the whole charge may be carried out. It is most important that water content in the oil is eliminated or kept to a minimum.

 

Exercise 1.

Find equivalents of these words in the text and learn them:

Масляные насосы высокого давления; междудонное пространство; фильтры грубой отчистки; сливная цистерна; картер; поток масла; система управления; зазор; масляные клапаны; форсунки; редукционные клапана; маслоохладители; подшипник; фильтры тонкой отчистки; поддон картера; масляное охлаждение поршней; тип установки.

 

Exercise 2.

Answer the following questions:

1. What filters does a lubricating oil system include?
2. Why are they in duplicate?
3. How do lubricating oil pressure pumps draw oil from the engine drain tank?
4. Where can water and sludge settle?
5. Where is the oil distributed to all bearings, piston cooling, control systems etc?
6. What pumps increase the supply pressure?
7. What pumps reduce pressure?
8. Where does used oil go?
9. What filters does it go through?

• Where is the oil drain tank usually located?
• Why is it surrounded by a cofferdam?
• What is every tank fitted with?
• What is important to do when the engine is not in use for a long time?

 

Exercise 3.

Find these sentences in the text:

1. Масляные насосы, фильтры грубой и тонкой очистки обязательно должны дублироваться.
2. Когда один насос в работе, то другой должен быть в состоянии немедленной готовности.
3. Производительность и общий объем системы смазки должны быть соответственно увеличены, если двигатель имеет масляное охлаждение поршней.
4. Фильтры грубой отчистки должны быть расположены достаточно удаленно от наинизших точек.
5. Масло через фильтры тонкой отчистки поступает к двигателю.
6. Масло распределяется для смазки всех подшипников, охлаждения поршней, форсунок, привода выпускных клапанов, систем управления и др.
7. Различные секции системы смазки могут использовать масло при различных давлениях.
8. Для предотвращения загрязнений вследствие течи танк окружают коффердамом.
9. Система должна быть оборудована аварийной сигнализацией понижения давления, высокой температуры и низкого уровня масла в танке.

• Центрифуги постоянно работают во время рейса, обеспечивая качественную сепарацию части потока масла.

 

Exercise 4.

Agree with the statements, completing the main idea with the words given in brackets.

Model 1:

A: Pressure pumps, strainers are in duplicate (fine filters).

B: Fine filters are in duplicate as well.

1. The oil will be distributed to all bearings, piston cooling, sprayers, exhaust valve actuators (control system).
2. The oil drain tank is fitted with an air vent, level measuring gauge (sounding pipe).
3. Central positioning of the level gauge will reduce fluctuation in readings due to pitching at sea (rolling).
4. The system should also have low pressure, high temperature alarms fitted (low tank level alarm).
5. A bypass centrifuge system is fitted to purify oil from the drain tank to remove water, sludge (insolubles).

 

Exercise 5.

Speak about the lubricating oil system.