Text a Water Turbines

Turbines are rotary engines that have the ability for converting the energy of a moving stream of water, steam, or gas into mechanical energy. The basic element in a turbine is a wheel or rotor with blades arranged on its circumference in such a way that the moving fluid exerts a force that turns the wheel and imparts energy to it. It is this turbine element that is responsible for creating the mechanical energy. This mechanical energy is then transferred through a drive shaft to operate a machine, compressor, electric generator. Turbines are classified as hydraulic turbines, steam turbines, or gas turbines. They are of great importance in the business of electric power generation. Today turbine-powered generators produce most of the world's electrical energy.

Rapid developing the water turbines occurred in the nineteenth century, during the Industrial revolution, with using scientific principles and manufacturing methods. The first modern water turbine was designed by James B. Francis in 1849. It is the Frencis turbine that is still the most widely used water turbine in the world today. The Francis turbine is also called a radial flow turbine, since water flows from the outer circumference towards the centre of runner.

Around 1913, Viktor Kaplan created the Kaplan turbine, a propeller-type water turbine which has adjustable blades. It was an evolution of the Francis turbine. Its invention allowed efficient power production by installing it in low-head applications that was not possible with Francis turbines. Kaplan turbines are now widely used throughout the world in high-flow, low-head power production.

All water turbines can be divided into two groups: reaction turbines and impulse turbines. In reaction turbines water changes its pressure on moving through the turbine and gives up its energy to the turbine’s rotor. Newton’s third law describes the transfer of energy for reaction turbines. Most water turbines in use, including the Francis turbine and the Kaplan turbine, are reaction turbines and are used in low (<30m) and medium (30-300m) head applications. In reaction turbine pressure drop occurs in both fixed and moving blades.

Impulse turbines acts on the principle of changing the velocity of a water jet. The jet impinges on the turbine's curved blades which change the direction of the flow. The resulting change in momentum (impulse) leads to appearing a force on the turbine blades. Newton’s second law describes the rules for transferring energy for impulse turbines. Impulse turbines are of great significance in very high (>300m) head applications .

Large modern water turbines operate at mechanical efficiencies greater than 90%.

Задания к тексту A:

I. Прочитайте и переведите следующие выражения:

the energy of a moving stream of water, steam, or gas; a wheel or rotor with blades arranged on its circumference; a drive shaft; the business of electric power generation; turbine-powered generators; the Industrial revolution; the first modern water turbine; a radial flow turbine; a propeller-type water turbine; low-head applications; high-flow, low-head power production; reaction turbines; impulse turbines; the principle of changing the velocity of a water jet;

II. Найдите в предыдущем упражнении английские эквиваленты следующих русских выражений:

первая современная водяная турбина; водяная турбина пропеллерного типа; приводной вал; промышленная революция; энергия движущегося потока воды, пара или газа; турбина с радиальным потоком; импульсные турбины; турбинные генераторы; реактивные турбины; производство энергии на реках с сильным течением, но низким напором; принцип изменения скорости водяной струи; колесо или ротор с лопастями расположенными на его окружности; применение турбин на реках с низким напором; дело выработки электрической энергии;

III Прочитайте предложения, найдите в них герундий, определите его функцию:

1. Turbines are rotary engines that have the ability for converting the energy of a moving stream of water, steam, or gas into mechanical energy. 2. Rapid developing the water turbines occurred in the nineteenth century, during the Industrial revolution, with using scientific principles and manufacturing methods. 3. In reaction turbines water changes its pressure on moving through the turbine and gives up its energy to the turbine’s rotor. 4. Impulse turbines acts on the principle of changing the velocity of a water jet. 5. The resulting change in momentum (impulse) leads to appearing a force on the turbine blades. 6. Newton’s second law describes the rules for transferring energy for impulse turbines.

IV. Определите тип придаточных предложений, сделайте грамматический разбор и переведите предложения:

1. Its invention allowed efficient power production by installing it in low-head applications that was not possible with Francis turbines. 2. The Francis turbine is also called a radial flow turbine, since water flows from the outer circumference towards the centre of runner.

V. Ответьте письменно на следующие вопросы:

1. What is a turbine?

2. What is the basic element in a turbine?

3. What is the principle of the turbine working?

4. What element is responsible for creating the mechanical energy?

5. Where is the mechanical energy transferred?

6. How are turbines classified?

7. When was the first modern water turbine designed and by whom?

8. What is a radial turbine?

9. When did the Kaplan turbine appear?

10. What did its invention allow?

11. How many classes can all water turbines be divided into?

12. Which Newton’s law describes the transfer of energy for reaction turbines?

13. Which Newton’s law describes the rules for transferring energy for impulse turbines?

14. Large modern water turbines operate at mechanical efficiencies greater than 90%, don’t they?

VI. Переведите текст А письменно.