Fuel provides a convenient and effective means of cooling engine and airframe equipment and it is important that its coolant capability is maximized for present and projected aircraft. The Spill Control and Recovery Valve (SCRV) is a new simple concept, patented and developed by Plessey Aerospace with support from the British Ministry of Defense, which contributes towards the realization of this objective. The SCRV is installed in the fuel system in place of the conventional bypass valve. It is a variable geometry ejector in which the energy in the spill flow (primary) is used to raise engine pump inlet pressure (secondary) whenever bypassing occurs. The maximum gain results during maximum bypass mode which is when it is most needed. Test data for certain conditions characteristic of a large civil bypass engine show: High pressure fuel pump pressure rise reduced, 27–31 percent; Fuel temperature rise reduced, 17–19 percent; Fuel heat sink capacity increased, 2.3–3 kw, NPSH increased, substantial. Relative figure has no significance. Results can be even more significant for engines in high performance combat aircraft.

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