Centrifugal pumps have substantial advantages over displacement pumps.
A disadvantage of centrifugal pumps is the difficulty to provide the required level of pressures in all flight modes and especially at low shaft speed.
Because of this, the use of centrifugal pumps, despite of their advantages, is quite limited as a high-pressure pump for the aircraft engine main fuel system.
Engine driven pumps for afterburner fuel supply represent one-stage high-speed centrifugal pumps. Fuel consumption through the afterburner fuel system can vary by more than 100 times. In addition, fuel flow from the pump must be shut-off when the engine is not using the afterburner.
As a result of large complex of R&D works performed by Kristall Design Bureau, the high-performance centrifugal pump units with adjustable hydrodynamic torque converter have been developed, which have original geometry of fuel-flow cavities, optimized energy, cavitation and mass characteristics.
These units have the torque converter pump wheel driven by the engine gearbox, while the turbine wheel is connected to the primary pump impeller.
Adjustable guide wheel within the torque converter allows for changing of the pump delivery rate. These pumps can serve as a single, unified fuel supply units for both main and afterburner engine fuel systems, featuring low fuel heating over the whole range of required flow rates.
Adoption of such pump units can significantly expand possibilities of engines for the new generation aircraft.
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