LOAD-RANGE PERFORMANCE OF TURBINE-PROPELLER ENGINE IN TRANSONIC SPEED RANGE AND COMPARISON WITH LOAD-RANGE PERFORMANCE OF TURBOJET ENGINE

摘要

In order to investigate the effect on load-range performance of various combinations of compressor pressure ratio and turbine-inlet temperature for the turbine-propeller engine and to provide a means for comparing the load-range performance of the turbine-propeller and turbojet engines in the transonic speed range, an analysis was made of the turbine-propeller engine for flight speeds from 500 to 900 miles per hour, altitudes from 10,000 to 70,000 feet, compressor pressure ratios from 2 to 30, and turbine-inlet temperatures of 1700°, 2000°, and 2300° R. The assumptions used in this analysis are representative of the best values obtained in practice or in laboratory investi¬gations;for certain critical assumptions where rapid advance in the field may be anticipated, the effect of changes in these assumptions were shown. The variation, with flight conditions and engine opera¬ting variables, of the thrust per square foot of engine frontal area, thrust specific engine weight, thrust specific fuel consumption, ultimate range, range with pay load, and comparison of the load-range characteristics of the turbine-propeller and turbojet engines are discussed.nMaximum or near maximum ultimate range could be attained at any of the flight conditions investigated, except 70,000 feet, 700 and 800 miles per hour, with some compressor pressure ratio between 5 and 10 (not necessarily the same for all conditions). At 70,000 feet, 700 and 800 miles per hour, a compressor pressure ratio less than 5 was required. For altitudes up to 50,000 feet, a 2300° R turbine-inlet temperature gave about a 5 to 10 percent longer ultimate range than a 2000° R temperature, which in turn gave about a 7 to 17 percent longer ultimate range than a 1700° R temperature for the range of flight speeds studied. At 70,000 feet, these percentages were increased to about 11 to 16 and 20 to 36, respectively.