The Marine Gas-turbine from the Viewpoint of an Aeronautical Engineer

Abstract

In view of the intensive development of gas turbines for aeronautical purposes, the author advocates the adoption of aero-design techniques for the production of gas turbines for marine and stationary purposes. A review is made of the more obvious features of various typical aircraft turbines, and the conclusions are drawn that multiple combustion systems and single- or two-stage turbines should be employed with a considerable reduction in the mass of metal in the assembly as compared with extant stationary designs, in order to reduce transient temperature stressing. A description is given of an experimental heat exchanger embodying the principles of light scantlings, symmetry of design, and purity of suspension. A brief excursion into the performance calculations for a marine turbine leads to a recommendation to use a compound cycle of 8/1 overall compression ratio, with centrifugal compressors for robustness, and with a high combustion-temperature involving the use of air-cooled blading. A life of 10,000 hours appears to be within reach, which figure is considered to be adequate for merchant ship service. A compact arrangement is suggested for a turbine of this type giving 4,000 s.h.p. at an overall thermal efficiency of 30 per cent. The manoeuvring and reversing problems are to be overcome by the fitting of a variable-pitch propeller, but development work on this device is required to reduce its alleged tendency to greater losses as compared with the fixed-pitch type.