Page 129 - The Jet Engine

Fuel system

tures, whereas a wide-cut fuel wilt boil at a much 117. For sustained supersonic flight, some measure
lower altitude. of tank insulation is necessary to reduce kinetic
heating effects, even when lower volatility fuels are
115. The fuel temperature during flight depends used.
upon altitude, rate of climb, duration at altitude and
kinetic heating due to forward speed. When boiling Fuel contamination control
does occur, the vapour loss can be very high, 118. Fuel can be maintained in good condition by
especially with wide-cut fuels, and this may cause well planned storage and by making routine aircraft
vapour locking with consequent malfunctions of the tank drain checks. The use of suitable filters,
engine fuel system and fuel metering equipment. fuel/water separators and selected additives will
restrict the contamination level, e.g. free water and
116. To obviate or reduce the risk of boiling, it is solid matter, to a practical minimum. Keeping the fuel
usual to pressurize the fuel tanks. This involves free of undissolved water will prevent serious icing
maintaining an absolute pressure above the fuel in problems, reduce the microbiological growth and
excess of its vapour pressure at any specific minimize corrosion. Reducing the solid matter will
temperature. This may be accomplished by using an prevent undue wear in the fuel pumps, reduce
inert gas or by using the fuel vapour pressure with a corrosion and lessen the possibility of blockage
controlled venting system. occurring within the fuel system.

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