SNAME Philadelphia Section Discusses Torsional Vibrations In Diesel-Driven Equipment
The Philadelphia Section of The Society of Naval Architects and Marine Engineers recently met at the Engineer's Club in Philadelphia, Pa., to hear a paper, entitled: "Torsional Vibration Considerations of a Twin-Diesel, Single Controllable Pitch Propeller Vessel." The author of the paper, Roland Yang, from DeLaval Engine and Compressor Division, Oakland, Calif., described the torsional vibration considerations in a highly technical and comprehensible way, and drew broad interest from the audience.
The importance of torsional vibration considerations in any diesel-engine-driven equipment is well-known. In the case of two diesel engines driving a single controllable-pitch propeller through a combining speed reduction gear, considerations have to be made for operating modes like idle declutched, one engine engaged, both engines engaged, etc. The paper deals with the torsional considerations of the various modes of operation, and elaborates on the advantages from a torsional standpoint of a controllable-pitch propeller versus a fixed-pitch propeller. The paper also emphasizes the importance in the selection of a torsionally resilient coupling and the advantage of a nonlinear coupling over a linear coupling.
The author stated that the twin dieselpowered, single controllable-pitch propeller via single combining reduction gear arrangement proved to be a very efficient, torsionally clear system. Coupled with the sophisticated control enabling fully automated engine revolutions and propeller-pitch matching, it gives a very attractive package from technical and operational standpoints.
Discussers included Richard T. Woytowich of the American Bureau of Shipping and Bob McFadden of J.J. Henry Co., Inc. Fred W. Beltz Jr., DeLaval Turbine Inc., was acting as the coordinator of the meeting.