TS-90
X-mode Vibration Controls of Low Speed Two Stroke Diesel Engines On the Diesel Power Plants
Donchool LEE* ・ Seungnam YOO** ・ Jungdae YU** ・ Uekan KIM***
ABSTRACT
Nowadays, diesel power plant using low speed two stroke diesel engine is much to be used with a benefit of high thermal efficiency and durability comparing to the others. Furthermore over 8 cylinder engine is relevant due to get large power and reduce torque fluctuation, which incite to increase axial length of diesel engine and so X-mode vibration is liable to be troublesome for diesel power plant.
Three different examples are introduced in this paper. The first case is modifying cylinder firing angle unevenly to reduce 5th and 6th order X-moment most likable to be resonance. At second case, X-mode vibration is controlled by dynamic vibration absorber fitted at engine cylinder frame. At third, by adapting top bracing and synchrophaser between two units, vibrations of main structure and adjacent buildings are controlled. These methods must be selected considering characteristics of diesel power plants and theoretical background and actual results are shown in this paper.
Key Words: Diesel Power Plant, X-mode Vibration Control, Resonance, Generator Synchronized Speed, Uneven Firing Angles, Dynamic Vibration Absorber, Top Bracing, Synchrophaser
1. INTRODUCTION
Diesel engine has high thermal efficiency and mobility comparing to the others and so two stroke low speed diesel engine is used for not only propulsion system but also power plant geometrically isolated place or island. However, rotating parts of diesel engine are main source of various vibration excitation.(1〜3) X-mode vibration shown as Fig. 1 is one of the common aspect of engine structural vibration for which pertinent countermeasure should be taken. For power plant use, it is an advantage only to control around generator synchronized speed is sufficient unlike propulsion shafting system. However, torsional vibration in low load condition is willing to be increased due to combination of gas combustion pressure of cylinder and inertia force, of rotating parts. So, X-mode vibration is to be controlled by practical method considering many factors such as manufacturing, installation and economy.
Fig. 1 X-mode vibration of engine column
* Mokpo National Maritime University
#571 Cukkyo-Dong, Mokpo, Chonnam, Korea
Fax.:+82-61-240-7282, E-mail:ldcvib@mail.mmu.ac.kr
** Hyundai Heavy Industries Engine & Machinery Div.
Fax.:+82-52-230-7425, E-mail:vibyjd@hhi.co.kr
*** Korea Maritime University
#1 Dongsam-Dong, Yeongdo-Ku, Pusan, Korea
Fax.:+82-51-404-3986, E-mail:nhv@hanara.kmaritime.ac.kr
