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11. What can vortexing allow?
12. What is the function of a positive expulsion mechanism?
Task 13. Translate the following sentences into English.
1. В ЖРД с двухкомпонентным топливом ракетное топливо находится в
одном или более баках окислителя, тогда как ЖРД с однокомпонентным
топливом имеют лишь один комплект топливных баков.
2. Топливные баки изготавливаются из алюминия, нержавеющей стали,
титана, легированной стали и армированная волокном пластмасса, имеющая
непроницаемую внутреннюю металлическую оболочку, препятствующую
утечке через поры армированных стенок.
3. Газовая подушка – это избыточный объем газа, находящийся над
поверхностью ракетного топлива в герметизированных баках.
4. После наполнения бака ракетным топливом объем газовой подушки, а в
случае герметизации бака и ее давление, будет изменяться по мере изменения
средней температуры ракетного топлива.
5. Коэффициент вытеснения компонентов ракетного топлива из бака и/или
топливной системы – это отношение количества вытесненного или доступного
ракетного топлива к общему количеству изначально имевшегося топлива.
6. Потери составляют недоступные компоненты ракетного топлива,
находящиеся в канавках или углах труб, соединениях и клапанах,
увлажняющие стенки, удерживаемые поверхностным натяжением или
задерживаемые приборными штуцерами.
7. Оптимальной формой топливного бака является сферическая форма.
8. Криогенное ракетное топливо охлаждает стенки топливного бака до
температуры ниже температуры окружающей среды, что приводит к
конденсации влаги на внешней стороне бака и образованию льда в период,
предшествующий запуску.
9. При длительном хранении баки с криогенным ракетным топливом
необходимо теплоизолировать, а пористые внешние изоляционные слои –
герметизировать, чтобы предотвратить появление конденсата внутри
изоляционного слоя.
10. Прежде, чем наполнять топливный бак очень холодным
криогенным топливом, необходимо удалить воздух во избежание образования
твердых воздушных частиц или конденсации влаги в виде льда, что может
привести к закупорке форсуночных отверстий, запиранию клапанов при
замерзании среды или к неполному запиранию клапанов.
11. Во избежание самогерметизиции баков с криогенным топливом во
время их длительного хранения на стартовой платформе необходимо
осуществлять вентиляцию баков и топливной системы.
12. Вибрации и боковое ускорение при полете ракеты может вызывать
плескание топлива в баке, что, в свою очередь, может вызвать смещение центра
тяжести летательного аппарата и затруднить управление полетом.
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Task 14. Find the Russian equivalents for the English terms.
1. cryogenic propellant
2. ambient air
3. moisture
4. launch
5. to malfunction
6. initial flight
7. orbiter vehicle
8. insulation layer
9. to liquify
10. to solidify
11. low-conductivity
12. evaporation
13. thermal insulation
14. particle
15. to plug up
16. injection hole
17. valve
18. to freeze shut
19. piping
20. to chill
21. bubbling
22. vent valve
23. to seal
24. hardware
25. strength
26. failure
27. leak
28. explosion
29. launch pad
30. pressure safety device
31. burst diaphragm
32. relief valve
33. evaporation losses
34. boiling point
35. rocket firing
36. pressurized feed system
37. turbopump feed system
38. pump cavitation
39. side acceleration
40. sloshing
41. antiaircraft missile
42. tank outlet
1. первый полет
2. герметически закрыть
3. частица
4. потери при испарении
5. дренажный клапан
6. топливопровод
7. боковое ускорение
8. предохранительное устройство
избыточного давления
9. влага
10. система управления (полетом)
11. форсунка
12. вытеснительная система подачи
13. завихрение
14. криогенное ракетное топливо
15. прочность
16. орбитальный летательный аппарат
17. взрыв
18. испарение
19. делать твердым
20. впускной клапан
21. пузырение
22. точка кипения
23. наружный воздух
24. неисправность, отказ
25. плескание
26. теплоизоляция
27. отводящий трубопровод
28. пуск
29. зенитная ракета
30. клапан
31. оборудование
32. низкая теплопроводность
33. турбонасосная система подачи
34. охлаждать
35. характеристики ЛА
36. работать неисправно
37. выходное отверстие бака
38. закупоривать
39. разрывная диафрагма, прорывная
мембрана
40. изоляционный слой
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43. discharge line
44. flight control
45. vortexing
46. vehicle performance
41. кавитация в насосе
42. запирать
43. пуск ракеты
44. течь, утечка
45. стартовая платформа
46. разжижать
Task 15. Look through the texts (Task 7, 11) and find key sentences in each
paragraph.
Task 16. Write a summary to the text (Task 7)
Task 17. Sum up the text (Task 11).
Task 18. Skim the text and try to understand its subject matter.
In the gravity-free environment of space, the stored liquid will float around in a
partly emptied tank and may not always cover the tank outlet, thus allowing gas to
enter the tank outlet or discharge pipe. Various devices have been developed to solve
this problem: namely, positive expulsion devices and surface tension devices. The
positive expulsion tank design include movable pistons, inflatable flexible bladders,
or thin movable, flexible metal diaphragms. Surface tension devices rely on surface
tension forces to keep the outlet covered with liquid.
Several basic types of positive expulsion devices have been used successfully in
propellant tanks of pressurized feed systems. These devices mechanically separate the
pressurizing gas from the liquid propellant in the propellant tank. Separation is
needed for these reasons:
1. It prevents pressurizing gas from dissolving in the propellant. Dissolved
pressurizing gas dilutes the propellant, reduces its density as well as its specific
impulse, and makes the pressurization inefficient.
2. It allows hot and reactive gases (generated by gas generators) to be used for
pressurization, and this permits a reduction in pressurizing system mass and volume.
The mechanical separation prevents a chemical reaction between the hot gas and the
propellant, prevents gas from being dissolved in the propellant, and reduces the heat
transfer to the liquid.
3. In some cases tanks containing toxic propellant must be vented without spilling
any toxic liquid propellant or its vapor. For example, in servicing a reusable rocket,
the tank pressure needs to be relieved without venting or spilling potentially
hazardous material.
A piston expulsion device permits the center of gravity (CG) to be accurately
controlled and its location to be known. This is important in rockets with high side
accelerations such as antiaircraft missiles or space defense missiles, where the thrust
vector needs to go through the CG; if the CG is not well known, unpredictable
turning moments may be imposed on the vehicle. A piston also prevents sloshing or
Propellant Tanks
(Part III)
63
vortexing.
Surface tension devices use capillary attraction for supplying liquid propellant to
the tank outlet pipe. These devices are often made of very fine (300 mesh) stainless
steel wire woven into a screen and formed into tunnels or other shapes. These screens
are located near the tank outlet and, in some tanks, the tubular galleries are designed
to connect various parts of the tank volume to the outlet pipe sump. These devices
work best in a relatively low-acceleration environment, when surface tension forces
can overcome the inertia forces. The combination of surface tension screens, baffles,
sumps, and traps is called a propellant management device.
High forces can be imposed on the tanks and thus on the vehicle by strong
sloshing motions of the liquid and also by sudden changes in position of liquid mass
in a partly empty tank during a gravity-free flight when suddenly accelerated by a
relatively large thrust. These forces can be large and can cause tank failure. The
forces will depend on the tank geometry, baffles, ullage volume, and its initial
location and the acceleration magnitude and direction.
(Sutton, George P. & Biblarz, Oscar Rocket Propulsion Elements: an introduction to
the engineering of rockets)
Task 19. Choose the right variant to fill in the gap.
1. In the gravity-free environment of space, the stored __________will float
around in a partly emptied tank and may not always cover the tank outlet.
a) propellant
b) liquid
c) oxidant
2. Several basic types of positive expulsion devices have been used successfully
in propellant tanks of ___________feed systems.
a) turbopump
b) pressurized
c) high-pressure gas
3. Positive expulsion devices _________separate the pressurizing gas from the
liquid propellant in the propellant tank.
a) automatically
b) mechanically
c) don’t
4. Separation permits a reduction in pressurizing system____________.
a) volume
b) mass
c) mass and volume
5. A piston prevents___________.
a) sloshing or vortexing
b) either sloshing or vortexing
c) neither sloshing or vortexing
6. _____________devices use capillary attraction for supplying liquid propellant
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to the tank outlet pipe.
Function
Form
Expresses a realizable supposition
If the high-pressure gas expands rapidly,
then the gas remaining in the tank
undergoes essentially an isentropic
expansion.
If the high-pressure gas expands rapidly,
then the gas remaining in the tank will
undergo essentially an isentropic
expansion.
Expresses an improbable supposition
If the high-pressure gas expanded
slowly, then the gas remaining in the tank
would not undergo essentially an
isentropic expansion.
Expresses an impossible supposition
If the high-pressure gas had not
expanded rapidly, then the gas remaining
in the tank would not have undergone
essentially an isentropic expansion.
a) Surface tension
b) Positive expulsion
c) Propellant management
Task 20. Collect all the possible supplementary information on the theme of Unit
6 and present it to your groupmates.
UNIT 7. Tank Pressurization
TEXT: TANK PRESSURIZATION
Grammar: Conditional Sentences
Task 1. Study the forms and functions of the Conditional sentences in the English
sentences and translate them into Russian.
Task 2. Study conditional sentences of realizable supposition and translate them
into Russian. Make the supposition improbable and impossible.
1. In general, about 2,5 times as much nitrogen mass is needed for pressurizing
liquid oxygen if compared to the nitrogen needed for displacing an equivalent volume
of water at the same pressure.
2. The heat transfer to the liquid cools the gas and that increases the density;
therefore a larger mass of gas is needed for pressurization even if none of the gas
dissolves in the liquid propellant.
3. If there is major sloshing and splashing in the tank during flight, the gas
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temperature can drop quickly, causing irregularities in the tank pressure.
ambient temperature – температура
окружающей среды
density – плотность
to dilute – разжижать
discharge – выходящий поток (струя)
to dissolve – растворять, растворяться
erratic pressure – неустойчивое
давление, беспорядочно
изменяющееся давление
flexible bladder – мягкая мембрана,
мягкая уплотнительная манжета
heat transfer – теплопередача
isentropic expansion –
изэнотропическое
(изоэнотропийное) расширение
moderate – средний, умеренный
piston – поршень, клапан pressurant –
газ наддува
pressurization – вытеснение (топлива),
наддув бака
psi – фунт на квадратный дюйм
psig – фунт на квадратный дюйм-
индикаторный
pump cavitation – кавитация в насосе
soluble – растворимый
splashing – разбрызгивание, барботаж
to suppress – подавлять, сдерживать
4. If hot gas from a solid propellant gas generator or from the decomposition of a
monopropellant is used (instead of a high-pressure gas supply), a substantial
reduction in the gas and inert mass of the pressurizing system can be achieved.
5. If the high-pressure gas expands rapidly, then the gas remaining in the tank
undergoes essentially an isentropic expansion.
Task 3. Study the following words and word combinations and learn them by heart.
Task 4. Translate the words into Russian. Mind suffixes and prefixes.
System – subsystem, regular – irregular – irregularity, to compose – to
decompose, composition – decomposition, name – namely, to pressurize –
pressurization, to charge – to discharge, to solve – to dissolve – soluble, great –
greatly, to oxidize – oxidizer, to place – to displace, slight – slightly, to ignite –
ignitable, to reproduce – reproducible, success – successful, to store – storage, to
expand - expansion
Task 5. Read and translate the following international words.
Helium, nitrogen, method, inert, positive, cryogenic, cavitation, portion, tetroxide,
oxygen, temperature, injection, maneuver, problem, reactive, generator, hydrazine,
catalytic, function, operation, to absorb, effect, to condense, concentration
Task 6. Translate the sentences into Russian using the terms from Task 3.
1. In pump feed systems a small positive pressure in the tank is needed to
66
suppress pump cavitation.
2. The pressurizing gas must not condense, or be soluble in the liquid propellant,
for this can greatly increase the mass of required pressurant and the inert mass of its
pressurization system hardware.
3. Nitrogen pressurizing gas will dissolve in nitrogen tetroxide or in liquid
oxygen and reduce the concentration and density of the oxidizer.
4. The problem of erratic tank pressure changes can be avoided by physically
separating the hot reactive gas from the liquid propellant by a piston or a flexible
bladder.
5. The first part of the gas leaving the high-pressure-gas storage tank is at ambient
temperature.
Task 7. Read the following text carefully paying attention to the words in bold
type. Try to understand the subject matter of the text and be ready to answer the
following questions.
1. Where are subsystems for pressurizing tanks used?
2. What is the most common method of pressurization?
3. How could pump cavitation be suppressed in pump feed systems and for
cryogenic propellants?
4. What properties must the pressurizing gas obtain?
5. Why is a larger mass of the pressurizing gas needed for cryogenic propellant?
6. What is chemical pressurization?
7. What is the main problem with chemical pressurization and how could it be
solved?
8. What are the functions of the pressurizing gas?
TEXT
TANK PRESSURIZATION
Subsystems for pressurizing tanks are needed for both of the two types of feed
systems, namely pressure feed systems and pump feed systems. The tank pressures
for the first type are usually between 200 and 1800 psi (pound-force per square inch)
and for the second between 10 and 50 psig. Inert gases such as helium or nitrogen are
the most common method of pressurization. In pump feed systems a small positive
pressure in the tank is needed to suppress pump cavitation. For cryogenic
propellants this has been accomplished by heating and vaporizing a small portion of
the propellant taken from the high-pressure discharge of the pump and feeding it into
the propellant tank. This is a type of low-pressure gas feed system.
The pressurizing gas must not condense, or be soluble in the liquid propellant, for
this can greatly increase the mass of required pressurant and the inert mass of its
pressurization system hardware. For example, nitrogen pressurizing gas will dissolve
in nitrogen tetroxide or in liquid oxygen and reduce the concentration and density of
67
the oxidizer. In general, about 2,5 times as much nitrogen mass is needed for
pressurizing liquid oxygen if compared to the nitrogen needed for displacing an
equivalent volume of water at the same pressure. Oxygen and nitrogen tetroxide are
therefore usually pressurized with helium gas, which dissolves only slightly. The
pressurizing gas must not react chemically with the liquid propellant. Also, the gas
must be dry, since moisture can react with some propellants or dilute them.
The pressurizing gas above a cryogenic liquid is usually warmer than the liquid.
The heat transfer to the liquid cools the gas and that increases the density; therefore
a larger mass of gas is needed for pressurization even if none of the gas dissolves in
the liquid propellant. If there is major sloshing and splashing in the tank during
flight, the gas temperature can drop quickly, causing irregularities in the tank
pressure.
Chemical pressurization permits the injection of a small amount of fuel or other
suitable spontaneously ignitable chemical into the oxidizer tank (or vice versa) which
creates the pressurizing gas by combustion inside the propellant tank. While ideally
this type of pressurization system is very small and light, in practice it has not usually
given reproducible tank pressures, because of irregular combustion the sloshing of
propellant in the tank during vehicle maneuvers has caused sudden cooling of the hot
pressurizing gas and thus some erratic tank pressure changes. This problem can be
avoided by physically separating the hot reactive gas from the liquid propellant by a
piston or a flexible bladder. If hot gas from a solid propellant gas generator or from
the decomposition of a monopropellant is used (instead of a high-pressure gas
supply), a substantial reduction in the gas and inert mass of the pressurizing system
can be achieved. For example, the pressurizing of hydrazine monopropellant by warm
gas (from the catalytic decomposition of hydrazine) has been successful for
moderate durations.
The major function of the pressurizing gas is to expel the propellants from their
tanks. In some propulsion system installations, a small amount of the pressurized gas
also performs other functions such as the operation of valves and controls. The first
part of the gas leaving the high-pressure-gas storage tank is at ambient temperature.
If the high-pressure gas expands rapidly, then the gas remaining in the tank
undergoes essentially an isentropic expansion, causing the temperature of the gas to
decrease steadily; the last portions of the pressurizing gas leaving the tank are very
much colder than the ambient temperature and readily absorb heat from the piping
and the tank walls. The Joule-Thomson effect causes a further small temperature
change.
(Sutton, George P. & Biblarz, Oscar Rocket Propulsion Elements: an introduction to
the engineering of rockets)
Task 8. Find in the text the English equivalents for the following words and word
combinations.
Вытеснительная система подачи, насосная система подачи, общепринятый
метод, подавлять кавитацию в насосе, нагрев и превращение в пар, горючее,
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выходящая из насоса струя под высоким давлением, топливный бак, газ
the liquid propellant, the pressurizing gas, hydrazine monopropellant, a cryogenic
liquid, to expel, pressurizing tanks, helium gas, inert gases, nitrogen tetroxide, the
high-pressure-gas storage tank
In pump feed systems a small positive
pressure in the tank is needed …
therefore a larger mass of gas is needed
for pressurization even if none of the gas
dissolves in the liquid propellant.
The pressurizing gas must not condense,
or be soluble in the liquid propellant, …
then the gas remaining in the tank
undergoes essentially an isentropic
expansion, causing the temperature of the
gas to decrease steadily.
наддува, конденсироваться, жидкое ракетное топливо, сжатый азот для
наддува, жидкий, сухой, влага, вытеснение, снижаться, давление в топливном
баке, химически активный газ, твердое ракетное топливо, однокомпонентное
ракетное топливо, подача газа под высоким давлением, каталитическое
разложение, вытеснить, двигательная система, клапаны и системы управления,
бак для хранения газа высокого давления, топливопровод
Task 9. Fill in the gaps with appropriate words from the box.
1. The pressurizing gas must not condense, or be soluble in____________, for
this can greatly increase the mass of required pressurant and the inert mass of its
pressurization system hardware.
2. The major function of the pressurizing gas is __________the propellants from
their tanks.
3. Nitrogen pressurizing gas will dissolve in __________or in liquid oxygen and
reduce the concentration and density of the oxidizer.
4. _________such as helium or nitrogen are the most common method of
pressurization.
5. The pressurizing of ___________by warm gas (from the catalytic
decomposition of hydrazine) has been successful for moderate durations.
6. Oxygen and nitrogen tetroxide are therefore usually pressurized
with__________, which dissolves only slightly.
7. The first part of the gas leaving ____________is at ambient temperature.
8. The pressurizing gas above ___________is usually warmer than the liquid.
9. Subsystems for __________are needed for both of the two types of feed
systems, namely pressure feed systems and pump feed systems.
10. Chemical pressurization permits the injection of a small amount of fuel
or other suitable spontaneously ignitable chemical into the oxidizer tank (or vice
versa) which creates ____________by combustion inside the propellant tank.
Task 10. Complete the sentences with appropriate endings.
69
The pressurizing gas must not …
for this can greatly increase the mass of
required pressurant and the inert mass of
its pressurization system hardware.
The heat transfer to the liquid cools the
gas and that increases the density; …
other functions such as the operation of
valves and controls.
Chemical pressurization permits …
to suppress pump cavitation.
In some propulsion system installations, a
small amount of the pressurized gas also
performs …
react chemically with the liquid
propellant.
If the high-pressure gas expands rapidly,
…
the injection of a small amount of fuel or
other suitable spontaneously ignitable
chemical into the oxidizer tank.
Task 11. Read the following text and try to understand its subject matter.
Translate the text into Russian. Use the dictionary if necessary.
Design of Propellant Tanks
Liquid-propellant rocket engines and propellant-feed systems form the propulsion
system. Propellant tankage and its arrangement have a large effect upon liquid
propellant rocket engine design and propulsion systems integration.
The configuration of propellant tanks depends largely on vehicle mission and size.
In many designs, the tanks form an integral part of the vehicle structure. According to
vehicle application, propellant tanks can be categorized as prepackaged storable-
liquid (хранимая в заправленном состоянии двигательная установка), boosterstage (стартовая ступень), and upper-stage (верхняя ступень) systems.
In prepackaged storable-liquid system, the tanks, arranged in tandem, have a
common bulkhead (перегородка). This system is designed for long storage periods,
perhaps 5 to 10 years. A main characteristic of these systems: propellants will be
loaded and contained in the tanks by burst disks (разрушающиеся мембраны) or
isolation valves (клапаны отсечки). Both the tank and containment (оболочка)
component construction materials must be compatible with the propellants for the
storage duration. The tank walls form an integral part of the vehicle structure and are
designed to withstand the internal pressure loads (внутренние нагрузки от
давления) as well as the vehicle dynamic loads. In some designs the tanks are further
stabilized by the internal pressure against buckling (потеря устойчивости); i.e., the
walls are always kept under tension loads (растягивающие нагрузки) by a specified
pressure level (заданный уровень давления) maintained during storage and
handling. In smaller units, the walls are usually capable of taking external loads
without being pressurized internally. Operational tank pressures range from 400 to
2000 psia (фунт на квадратный дюйм-полный). Prepackaged storable-liquid
systems are usually employed in relatively short-duration, low-thrust applications.
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