The Reheat Factor in Turbines and Turbocompressors: New Formulae for Calculating the Factors for Units with Finite Stages Based on Known Methods Used on the Infinite Stage Assumption Available to Purchase

IN the preliminary calculation for the design of a gas turbine or turbocompressor it is necessary to assume a value of the reheat factor R. The contemporary development of gas turbines and rotary compressors has aroused renewed interest in this quantity, which was studied earlier in connexion with steam turbines (refs. 1, 2, 7, 8 and 9). The paper contains an analysis of this value for a gaseous working fluid under appropriate assumptions; it is first calculated for an infinite number of stages with constant and variable specific heats; secondly, exact and approximate formulae are derived for finite numbers of stages of expansion and compression respectively and a method of estimating the heat recovery in turbines for working fluids with variable specific heats is indicated. Similar problems were considered in ref. 10 and the subject matter of Part III was presented to the Aeronautical Research Council (ref. 6).