Text Hydraulic power units

· What do you know about space shuttles? Share your knowledge with your groupmates. Have you got any idea about the semblance between rocket hydraulics and aircraft hydraulics?

Words and phrases:

solid rocket booster ускоритель ракеты на твердом топливе

stage ступень (ракеты)

thrust реактивная сила

propulsion движущая сила, импульс, толчок, тяга

hydraulic fluid manifold assembly система труб, заполненная рабочей жидкостью

aft end кормовая часть

aft skirt полый цилиндр, юбка

tilt actuator механизм наклона кузова в кривой

servoactuator сервопривод; серводвигатель

attach ring примыкающее кольцо

fuel isolation valve запорный топливный клапан

startup пуск, запуск; ввод в эксплуатацию

startup bypass line перепускное устройство при запуске

fuel pump outlet pressure давление на выходе топливного насоса

lube oil pump насос системы смазки

exhaust duct сопло

to assume допускать, предполагать

to switch включать

high pressure relief valve предохранительный клапан

 

· Guess the meanings of these words by their prefixes. Then look through the text and find these words in the sentences. Do they have the same meanings?

 

overpressure, overboard external, self-contained, to decompose, reusable.

· Do you know the meanings of these words? What are they? Find these words in the text and compare the meanings. Do they differ?

rock, skirt, power, tank, nozzle, chamber, relief

 

· Translate into Russian

most powerful single-chamber liquid fueled rocket engine, solid-fuel rocket motors, aft integrated electronic assemblies, the aft external tank attach rings, auxiliary power unit turbine assembly, high pressure relief valve, overpressure protection.

 

The Space Shuttle Solid Rocket Boosters (SRBs) are the pair of large solid rockets used by the Space Shuttle during the first two minutes of powered flight. 1. _____ The SRBs are the largest solid-fuel rocket motors ever flown, and the first to be used for primary propulsion on human spaceflight missions.

There are two self-contained, independent Hydraulic Power Units (HPUs) on each SRB. 2. _____. The APUs are fueled by hydrazine and generate mechanical shaft power to a hydraulic pump that produces hydraulic pressure for the SRB hydraulic system. The two separate HPUs and two hydraulic systems are located on the aft end of each SRB between the SRB nozzle and aft skirt. The HPU components are mounted on the aft skirt between the rock and tilt actuators. The two independent hydraulic systems are connected to the rock and tilt servoactuators.

The HPU controller electronics are located in the SRB aft integrated electronic assemblies on the aft external tank attach rings.

The HPUs and their fuel systems are isolated from each other. The fuel tank is pressurized with gaseous nitrogen at 2.8 MPa, which provides the force to expel (positive expulsion) the fuel from the tank to the fuel distribution line, maintaining a positive fuel supply to the APU throughout its operation.

The fuel isolation valve is opened at APU startup to allow fuel to flow to the APU fuel pump and control valves and then to the gas generator. 3. ______. It feeds the hot gas exhaust product to the APU two-stage gas turbine. Fuel flows primarily through the startup bypass line until the APU speed is such that the fuel pump outlet pressure is greater than the bypass line's. Then all the fuel is supplied to the fuel pump.

The APU turbine assembly provides mechanical power to the APU gearbox. The gearbox drives the APU fuel pump, hydraulic pump and lube oil pump. 4. ______. The turbine exhaust of each APU flows over the exterior of the gas generator, cooling it, and is then directed overboard through an exhaust duct.

When the APU speed reaches 100%, the APU primary control valve closes, and the APU speed is controlled by the APU controller electronics. If the primary control valve logic fails to the open state, the secondary control valve assumes control of the APU at 112% speed.

Each HPU on an SRB is connected to both servoactuators on that SRB. One HPU serves as the primary hydraulic source for the servoactuator, and the other HPU serves as the secondary hydraulics for the servoactuator. Each servoactuator has a switching valve that allows the secondary hydraulics to power the actuator if the primary hydraulic pressure drops below 14 MPa. 5. _____. When the valve is closed, a signal is sent to the APU controller that inhibits the 100% APU speed control logic and enables the 112% APU speed control logic. The 100-percent APU speed enables one APU/HPU to supply sufficient operating hydraulic pressure to both servoactuators of that SRB.

The hydraulic pump speed is 3,600 rpm and supplies hydraulic pressure of 21 MPa, plus or minus 345 kPa. A high pressure relief valve provides overpressure protection to the hydraulic system and relieves at 26 MPa.

(from http://en.wikipedia.org/wiki/Space_Shuttle_Solid_Rocket_Booster)

· The following sentences have been removed from the text. Look through the text and decide which sentence should be in the gap.

1. Each SRB produces 1.8 times more liftoff thrust than one F-1 engine – the all-time most powerful single-chamber liquid fueled rocket engine ever flown.

2. Each HPU consists of an auxiliary power unit (APU), fuel supply module, hydraulic pump, hydraulic reservoir and hydraulic fluid manifold assembly.

3. The gas generator's catalytic action decomposes the fuel and creates a hot gas.

4. The APU lube oil pump lubricates the gearbox.

5. A switch contact on the switching valve will close when the valve is in the secondary position.

 

· Read the text quickly again and answer the following questions about the text in your own words:

1. How can you describe the space shuttle solid rocket boosters?

2. How many hydraulic power units are there on a solid rocket booster?

3. What does a hydraulic power unit consist of?

4. Where are the HPU components placed?

5. What happens when the fuel decomposes?

6. What drives the APU fuel pump?

7. What are the functions of each HPU?

8. What does a servoactuator do?

 

· Comment the underlined grammar phenomena in the following sentences:

1. The SRBs are the largest solid-fuel rocket motors ever flown, and the first to be used for primary propulsion on human spaceflight missions.

2. The turbine exhaust of each APU flows over the exterior of the gas generator, cooling it, and is then directed overboard through an exhaust duct.

 

· Compose the sentences using the following words:

1. Hydraulic machinery are machines and tools which use fluid power to do work.

2. High pressure hydraulic fluid is transmitted throughout the machine to various hydraulic motors and hydraulic cylinders.

3. The control valve is one of the most expensive and sensitive parts of a hydraulic circuit.

4. Sequence valves control the sequence of hydraulic circuits.

5. They are available in many configurations.

 

· There is one unnecessary word in each sentence below. Cross it out:

1. SRBs they are located on either side of the orange external propellant tank.

2. During are launch they provide 83% of its liftoff thrust.

3. Each SRB has have two hydraulic gimbal servoactuators: one for rock and one for tilt.

4. The spent SRBs are recovered from the ocean, refurbished, reloaded with propellant, and reused for several the missions.

5. Each SRB servoactuator consists of four independent, two-stage servovalves that receive which signals from the drivers.

6. Failure monitors are provided for each is channel to indicate which channel has been bypassed.

7. Each actuator ram is equipped with transducers are for position feedback to the thrust vector control system.

· Put the verbs in brackets into the correct form:

1. To keep up pressure on the low pressure side, the circuits (to have)a charge pump (a small gearpump) that supplies cooled and filtered oil to the low pressure side.

2. Closed-loop circuits (to use) for hydrostatic transmissions in mobile applications.

3. The pump (can/to utilize) for any other hydraulic function and cooling can be a problem due to the limited exchange of oil flow.

4. Closed loop systems generally have a 'flush-valve' (to assemble) in the hydraulic motor in order to exchange more flow than the basic leakage flow from the pump and the motor.

5. The leakage (to flow) as well as the extra flush flow (must/to supply) by the charge pump.

6. Closed loop systems in mobile equipment (to use) for the transmission as an alternative to mechanical and hydrodynamic (converter) transmissions.

 

 

· Translate from Russian into English:

Для самолетов, ракет и космических летательных аппаратов требуются специальные высокоэнергетические топлива. Существуют два основных типа двигателей для летательных аппаратов, используемых в авиации и космонавтике.

Топливо для воздушно-реактивных двигателей, в которых в качестве окислителя используется кислород атмосферного воздуха, должно иметь высокую удельную теплоту сгорания. Кроме того, такое топливо должно быть термически устойчивым. Для достижения наивысших технических показателей летательного аппарата такое топливо должно иметь также высокую плотность.

Таким образом, в авиационной технике проблема состоит в нахождении топлива, которое характеризуется большой плотностью и высокой удельной теплотой сгорания. В настоящее время большинство реактивных двигателей работает на керосине или на бензине в качестве топлива. Однако ведутся исследования смесей специальных углеводородных соединений, которые обладали бы более высокой плотностью. Значительное внимание уделяется также поиску других видов топлив.

(with the help of http://www.bigpi.biysk.ru/encicl/articles/11/1001193/1001193A.htm)

 

 

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