MODELLING SHIP PROPULSION PLANTS (LINEAR ANALYSIS)

This paper treats the derivation and significance of analytical expressions of the transfer functions of linearized ship propulsion models. The block diagram of a diesel engine powered ship is chosen as the standard model. It is shown how other types of propulsion plants can be reduced to the same standard form. A gas turbine powered ship with a C.P. propeller is taken as an example. Direct application of Mason's rule would yield a determinant with 50 terms. Therefore, the paper includes a step by step development of the transfer function. The resulting explicit analytical expressions have been studied by different techniques, including processing by the LISA 360 program. Numerical results are compared with the values yielded by implicit simulation techniques, including CSMP III. A closer study of the numerical values shows which factors are relevant and which are negligible. Accordingly, simplified expressions are obtained and the results yielded by them are compared with those calculated from the exact expressions. The transfer functions derived for the example have nine or ten poles. Significantly, one of the time constants is much larger than all the others. Based on this fact, a formula is derived for calculating this time constant directly from the ship and propulsion plant parameters.

Media Info

  • Features: References;
  • Pagination: p. 183-192
  • Serial:
    • Volume: 5

Subject/Index Terms

Filing Info

  • Accession Number: 00141336
  • Record Type: Publication
  • Source Agency: North-Holland Publishing Company
  • Report/Paper Numbers: Proceeding
  • Files: TRIS
  • Created Date: Oct 26 1976 12:00AM