Augmentor fuel system

An optical sensor (40) located in the manifold area (20) of an augmentor senses the presence of liquid. The engine control provides a high fuel flow rate from remotely located augmentor fuel control (58) until liquid is sensed. Flow is then reduced to the desired metered rate.

We claim:

1. A fuel supply system for the augmentor of a gas turbine engine comprising:

fuel supply means for supplying fuel under pressure;

a plurality of augmentor spray bars located in the engine gas stream;

at least one manifold supplying said spray bars;

conduit means for conveying fuel from said fuel supply means to said manifold;

valve means for modulating the fuel flow quantity;

means for determining the desired fuel flow to the augmentor;

sensing means for sensing the presence of liquid, located in said supply manifold area; and

control means for providing a high fuel flow in response to the absense of liquid at said sensing means, and for providing the desired flow in response to the presence of liquid at said sensing means.

2. A fuel supply system as in claim 2:

said sensing means comprising;

an optical liquid level sensor including a glass prism immersed in the fluid within said manifold, a light emitting source focusing light to the prism-fluid interface, and means for detecting the presence of refracted light which occurs when said fluid is liquid.

3. A fuel supply system as in claim 1:

delay means for delaying the signal of said sensing means until liquid is detected for a finite time interval.

4. A fuel supply system as in claim 2:

said prism having at least one face transverse to the flow and facing downstream.

5. A fuel supply system as in claim 2:

said conduit means having a large flow area; and

said manifold having a small flow area.