Accession Number : ADA602610


Title :   Full-Scale Measurement and Prediction of the Dynamics of High-Speed Helicopter Tow Cables


Descriptive Note : Final rept. 1 Nov 2006-31 Dec 2013


Corporate Author : MASSACHUSETTS INST OF TECH CAMBRIDGE CENTER FOR OCEAN ENGINEERING


Personal Author(s) : Triantafyllou, Michael ; Geyer, Rockwell


Full Text : https://apps.dtic.mil/dtic/tr/fulltext/u2/a602610.pdf


Report Date : 14 Feb 2014


Pagination or Media Count : 16


Abstract : LONG-TERM GOALS: To provide the Navy with a non-invasive measurement technique and a numerical simulation tool for analyzing the vibration response of high-speed towed cables using a helicopter. The non-invasive measurement technique is based on fiber Bragg gratings, which measure the tensions and transverse vibrations of a high-speed tow cable at multiple sites along the cable. The numerical tool is based on combining two software applications, WHOI CABLE for calculating tow cable shape and an updated version of MIT's VIVA for calculating hydro-elastic multi-mode vibration response and variable drag coefficient of a cable in arbitrary current. OBJECTIVES: To construct and test in at sea trials a prototype electro-optical test cable with the same dimensions as that of the OAMCM tow cable. We are using the test cable to demonstrate, through full-scale measurements, that fiber Bragg gratings can measure the vibrational amplitudes and frequencies along the length of the cable under high speed towing conditions. The results from the full-scale measurements are used to verify the numerical simulation tool for predicting tow cable strumming and flutter. A numerical simulation that accurately models these processes will increase NSWC's ability to design tow cables with the proper distribution of ribbon and hard-nose fairing and to do mission planning. In addition, we are developing alternative designs to suppress strumming and at the same time avoid galoping and significant side curvatures.


Descriptors :   *TOWING CABLES , CABLE FAIRINGS , COMPUTERIZED SIMULATION , FIBER OPTICS , HELICOPTERS , VIBRATION


Subject Categories : Marine Engineering
      Fluid Mechanics
      Mechanics


Distribution Statement : APPROVED FOR PUBLIC RELEASE