Since gas turbines (other than radial turbines with swiveling nozzles) are by nature irreversible engines, reversal of motion has to be accomplished with the aid of special devices such as adjustable-pitch propellers. The operating reliability and efficiency of a gas turbine ship with an adjustable-pitch propeller (APP) largely depends on the nature of the transient processes occurring in the gas turbine installation; this is due to, on the one hand, the comparatively narrow operating-range flexibility of the gas turbine installation, restricted by the surging limits of the compressors, the limiting RPM, the temperature of gas ahead of turbine and the operating stability of the combustion chamber and, on the other, the intensity of perturbations experienced by the engine during the reverse motion. From the standpoint of the engine, reversal is the most difficult maneuver (rapid 100 percent load drop followed by rapid rise in load). By way of an example the transient processes in a GTU-20 gas turbine installation with APP during reversal from medium-speed forward to low-speed reverse in the course of shipyard trials of the gas turbine ship Parizhskaya Kommuna is examined. During that reversal the APP vanes are reset at a roughly constant rate (about 30 sec). To prevent an increase in the rotative speed of the propeller, as well as to prevent surging of the compressors, at the initial instant of vane resetting the engine load is thrown off 100 percent and a gas bypass valve (GBV) ahead of the low-pressure turbine is opened to assure a proper redistribution of power between the low- and high-pressure turbines. This is followed by a slow (about 35 sec) rise in fuel consumption (load) and closing of the GBV, thus easing the load on the propeller. To widen the surging margin of the high-pressure compressor and hence also to enhance the reliability of reversal, a slower resetting of the APP vanes in the neighborhood of the reverse-speed pitch may be recommended; this will prevent overloads on the propeller toward the end of resetting.

  • Corporate Authors:


    Leningrad,   USSR 
  • Authors:
    • Gitelman, A I
    • Pevzner, A M
  • Publication Date: 1967

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Filing Info

  • Accession Number: 00014998
  • Record Type: Publication
  • Source Agency: Joint Publications Research Service
  • Files: TRIS
  • Created Date: May 7 1973 12:00AM