This paper relates the advantages of centrifugal, mechanically-driven fuel pumps and quotes their ability to operate with hot contaminated fuel. It also shows the substantial weight saving when compared with positive displacement pumps. The poor part load efficiency of the conventional centrifugal pump at its design speed, giving considerable temperature rise in the fuel, has resulted in the development of the vapour core principle where flow regulation is effected by a throttle at the eye of the impeller.

Reference is made to the associated control and distribution equipment which, although not peculiar to the vapour core pump must be made compatible with a pump having an inherent pressure-raising capability which decreases with engine speed. The inlet throttle feature permits adequate control of the temperature rise to be maintained over the whole working range of the gas-turbine fuel systems.

The fundamentals of the pump are explained and the development progress reviewed for application to main and reheat fuel systems. Reference is also made to control methods that are being currently developed for combined engine and reheat systems supplied from a common pump.

The spill nozzle, which was developed specifically for use with hot contaminated fuel, possesses satisfactory characteristics for use with the vapour core pump. The temperature rise data associated with combination of vapour core pump and spill nozzle are quoted, and temperature rise data are also given where the pump is used either for reheat supply or for both combined reheat and main engine fuel systems.