Effect of Small Variations of Parameters in the Turboprop Cycle

Citation

Holmquist, Carl Oreal (1951) Effect of Small Variations of Parameters in the Turboprop Cycle. Engineer's thesis, California Institute of Technology. doi:10.7907/B34Z-JX85. https://resolver.caltech.edu/CaltechETD:etd-12282005-104251

Abstract

A cycle analysis of the turbine-propeller engine is given in terms of the parameters of the cycle and the component efficiencies of the engine with and without regeneration. By means of a Taylor expansion about the point of ideal efficiencies, total power output, specific fuel consumption, and optimum jet pressure ratio are given in terms of the ideal values plus corrections for small variations in the component efficiencies from 100%. In this way, the relative importance of component efficiencies in affecting the performance of the ideal turboprop cycle is demonstrated by means of simple analytical expressions involving the basic cycle parameters and the component efficiencies. The analysis of the ideal turboprop cycles is given in terms of three basic parameters which are functions of the forward flight speed, the compressor pressure ratio, and the limiting combustion chamber temperature. For the ideal cycle, the jet pressure ratio for optimum division of power between propeller and jet results in the total work of the cycle being done by the propeller. Of the component efficiencies, the turbine efficiency was found to be the most important in affecting the performance criteria of the ideal turboprop cycle. Since all work is done by the propeller in the ideal cycle, the propeller efficiency was also found to be important in affecting performance. Regeneration, as considered in this analysis, decreased the total power output and decreased the specific fuel consumption of the ideal turbine-propeller engine.

Thesis Files