AO177 SIMULATION OF SHIP PROPULSION AND BOILER SYSTEMS

A computer model of the AO177 Navy Oiler propulsion system was utilized to predict the ship, propeller, and boiler performance during maneuvers. These studies determined (1) the turbine valve throttling rate for maximum maneuvering capability without violating boiler pressure and drum level constraints and (2) the ahead steam flow required to initiate a crash-back maneuver such that the boiler drum level would not exceed its specified limits. These values have been specified for the corresponding integrated turbine control (ITC) settings. To predict boiler drum level and pressure during rapid steam load transients, in particular crash-back, a detailed boiler model including the following was utilized: (1) boiler mass and volume parameters (2) boiler transient fluid transport and temperature characteristics, (3) feedwater and fuel flow parameters, (4) desuperheated steam requirements, and (5) header accumulator effects. The ship and propeller speeds were simulated by modelling the following: (1) ITC system including the Malfunction Proportional Control system and throttle valve control utilizing speed feedback, (2) turbine throttle valve flow characteristics, (3) turbine, gear, and shaft inertia and torque, (4) propeller torque, thrust, and efficiency, and (5) ship's weight, resistance, and hull efficiency. The stopping maneuver was most sensitive to turbine valve throttling rate. For example the ahead reach from full ahead (21.5 knots) was 8450, 6000, and 41000 feet for turbine valve throttling rates of 0.75, 1.67, and 50 (crash-back) % per second, respectively. The boiler drum level limits are not exceeded by a steam flow change consistent with a throttling rate of 1.67% per second or less for both upward and downward power maneuvers; however, the crash-back rate of 50% per second can only be used when the initial ahead flow is high to maintain the drum level below the specified normal limits.

  • Supplemental Notes:
    • Proceedings Fifth Ship Control Systems Symposium, David W. Taylor Naval Ship Research and Development Center, Annapolis, Maryland, October 30-November 3, 1978, Volume 4.
  • Corporate Authors:

    David Taylor Naval Ship R&D Center

    Bethesda, MD  USA  20084
  • Authors:
    • Labbe, D E
  • Publication Date: 1978

Media Info

  • Features: References;
  • Pagination: 23 p.

Subject/Index Terms

Filing Info

  • Accession Number: 00187961
  • Record Type: Publication
  • Source Agency: David Taylor Naval Ship R&D Center
  • Report/Paper Numbers: Proceeding
  • Files: TRIS
  • Created Date: Feb 3 1979 12:00AM