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In the Kaveri engine development program of the Government of India, a
newly developed fuel control system has been incorporated which has been tested by
HAL, Lucknow. But the existing facility in India does not support the full operational
testing of the individual components of Aircraft Fuel Control System (AFCS) under
various aircraft acceleration conditions. Theoretical analyses were carried out to check
the flow distribution through First Stage Pump (FSP) under various aircraft accelerations
( forces).
The FSP is a two stage centrifugal pump consisting of a first stage variable
lead inducer and a second stage radial impeller rotating within a volute. A low flow
warning switch is also incorporated in the pump. This provides a warning signal in case
of reduced main engine gear pump inlet pressure due to FSP failure.
An effort has been made to find out Head (H)-Discharge (Q) characteristics
under various aircraft acceleration conditions and to compare the calculated H-Q with
the operational test data to check whether there is any significant change in
the characteristics.For energy transfer in a rotodynamic machine, Euler's equation expresses
the total head developed in the case of an inviscid fluid as the summation of: 1) change
in absolute kinetic energy or dynamic head developed due to flow through the
rotor; 2) a change in fluid energy due to the movement of the rotating fluid from one
radius to another; and 3) change in the static head due to a change in fluid velocity
relative to the rotor. For axial flow machines, the main direction of the flow is parallel to
the axis of the rotor, and hence the inlet and outlet points of the flow do not vary in
their radial locations from the axis of rotation (Som and Biswas, 2002).
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