The fuel consumption of a gas-turbine engine alternately equipped with variable-area fuel nozzles and with fixed-area fuel nozzles was investigated at altitudes up to 40,000 feet. At 40,000 feet, the engine when equipped with variable-area fuel nozzles operated with reduced fuel consumption at all engine speeds. At lower altitudes this reduction in fuel consumption occurred at progressively lower engine-speed ranges. This reduction was attributed to the increase in combustion efficiency that resulted from improved fuel atomization. A correlation between the percentage reduction in fuel consumption and the fuel consumption of the engine equipped with the fixed-area fuel nozzles is presented. On the basis of this correlation, the reduction in fuel consumption was approximately 16 percent under operating conditions at which the fuel consumption of the engine equipped with fixed-area fuel nozzles was 600 pounds per hour. The percentage reduction continually decreased until a fuel con¬sumption of 1300 pounds per hour was reached. Above 1300 pounds per hour, the fuel consumptions of the engine equipped with the variable and fixed-area fuel nozzles were equal.
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