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AUGMENTED SPARK IGNITER

Posted by admin in Apollo Saturn V News Reference on November 3, 2015

The augmented spark igniter (ASI) is mounted to the injector face. It provides the flame to ignite the propellants in the thrust chamber. When engine start is initiated, the spark exciters energize two spark plugs mounted in the side of the igniter cham­ber. Simultaneously, the control system starts the initial flow of oxidizer and fuel to the spark igniter. As the oxidizer and fuel enter the combustion cham­ber of the ASI, they mix and are ignited.

Mounted in the ASI is an ignition monitor which in­dicates that proper ignition has taken place. The ASI operates continuously during entire engine fir­ing, is uncooled, and is capable of multiple reigni­tions under all environmental conditions.

Propellant Feed System

The propellant feed system consists of separate fuel and oxidizer turbopumps, main fuel valve, main oxidizer valve, propellant utilization valve, fuel and oxidizer flowmeters, fuel and oxidizer bleed valves, and interconnecting lines.

FUEL TURBOPUMP

The fuel turbopump, mounted on the thrust cham-

image125

6-2

 

Подпись: turbine drive. The oxidizer turbopump increases the pressure of the liquid oxygen and pumps it through high-pressure ducts to the thrust chamber. The pump operates at 8,600 rpm at a discharge pressure of 1,080 psia and develops 2,200 brake horsepower. The pump and its two turbine wheels are mounted on a common shaft. Power for operating the oxidizer turbopump is provided by a high-speed, two-stage turbine which is driven by the exhaust gases from the gas generator. The turbines of the oxidizer and fuel turbopumps are connected in a series by exhaust ducting that directs the discharged exhaust gas from the fuel turbopump turbine to the inlet of the oxidizer turbopump turbine manifold. One static and two dynamic seals in series prevent the turbopump oxidizer fluid and turbine gas from mixing. Beginning the turbopump operation, hot gas enters the nozzles and, in turn, the first stage turbine wheel. After passing through the first stage turbine wheel, the gas is redirected by the stator blades and enters the second stage turbine wheel. The gas then leaves the turbine through exhaust ducting, passes through the heat exchanger, and exhausts into the thrust chamber through a manifold directly SATURN V NEWS REFERENCE

ber, is a turbine-driven, axial flow pumping unit consisting of an inducer, a seven-stage rotor, and a stator assembly. It is a high-speed pump operating at 27,000 rpm, and is designed to increase hydrogen pressure from 30 psia to 1,225 psia through high – pressure ducting at a flowrate which develops 7,800 brake horsepower.

Power for operating the turbopump is provided by

a high-speed, two-stage turbine. Hot gas from the gas generator is routed to the turbine inlet mani­fold which distributes the gas to the inlet nozzles where it is expanded and directed at a high velocity into the first stage turbine wheel.

After passing through the first stage turbine wheel, the gas is redirected through a ring of stator blades and enters the second stage turbine wheel. The gas leaves the turbine through the exhaust ducting.

Three dynamic seals in series prevent the pump fluid and turbine gas from mixing. Power from the turbine is transmitted to the pump by means of a one-piece shaft.

OXIDIZER TURBOPUMP

The oxidizer turbopump is mounted on the thrust chamber diametrically opposite the fuel turbopump.

image126,image127,image128

It. is a single-stage centrifugal pump with direct

J-2 Major Component Breakdown

Подпись: REFERENCE transfer valve and is located at the oxidizer turbopump outlet volute. The propellant utilization valve ensures the simultaneous exhaustion of the contents of the propellant tanks. During engine operation, propellant level sensing devices in the vehicle propellant tanks control the valve gate position for adjusting the oxidizer flow to ensure simultaneous exhaustion of fuel and oxidizer. An additional function of the PU valve is to provide thrust variations in order to maximize payload. The second stage, for example, operates with the PU valve in the closed position for more than 70 per cent of the firing duration. This valve position provides 225,000 pounds of thrust at a 5.5:1 propellant (oxidizer to fuel by weight) mixture ratio. During the latter portion of the flight, the PU valve position is varied to provide simultaneous emptying of the propellant tanks. The third stage also operates at the high-thrust level for the majority of the burning time in order to realize the high thrust benefits. The exact period of time at which the engine will operate with the PU valve closed will vary with individual mission requirements and propellant tanking levels. When the PU valve is fully open, the mixture ratio is 4.5:1 and the thrust level is 175,000 pounds. The propellant utilization valve and its servomotor are supplied with the engine. A position feedback potentiometer is also supplied as a part of the PU valve assembly. The PU valve assembly and a stage or a facility-mounted control system make up the propellant utilization system. FUEL AND OXIDIZER FLOWMETERS The fuel and oxidizer flowmeters are helical-vaned, rotor-type flowmeters. They are located in the fuel and oxidizer high-pressure ducts. The flowmeters measure propellant flowrates in the high-pressure propellant ducts. The four-vane rotor in the hydrogen system produces four electrical impulses per revolution and turns approximately 3,700 revolutions per minute at nominal flow. The six-vane rotor in the liquid oxygen system produces six electrical impulses per revolution and turns at approximately 2,600 revolutions per minute at nominal flow. PROPELLANT BLEED VALVES The propellant bleed valves used in both the fuel and oxidizer systems are poppet-type which are spring-loaded to the normally open position and

SATURN V NEWS

above the fuel inlet manifold. Power from the tur­bine is transmitted by means of a one-piece shaft to the pump. The velocity of the liquid oxygen is increased through the inducer and impeller. As the liquid oxygen enters the outlet volute, velocity is converted to pressure and the liquid oxygen is dis­charged into the outlet duct at high pressure.

Bearings in the liquid hydrogen and liquid oxygen turbopumps are lubricated by the fluid being pumped because the extremely low operating temperature of the engine precludes use of lubricants or other fluids.