• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2012.10a
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• pp.89-92
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• 2012

Marine diesel generator(D/G) set which is supported with resilient mounts for vibration isolation has been experienced the resonance problem by the main engine or propeller excitations and rigid body modes. Then the avoidance of resonance is difficult because the several excitations and 6 rigid body modes have to be considered simultaneously. In this paper, stiffness adjustable mounts was developed and proposed to control the natural frequencies of installed D/G set. Operating concept of the mount is that the total stiffness of mount can be changed according to the engagement of secondary rubber element in addition to primary one. The performance of mount was verified with the test rig and actual experiment in D/G set.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2012.04a
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• pp.157-162
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• 2012

A structural modification of baseframe is an effective method to avoid resonance in marine diesel generator (D/G) set which consists of diesel engine, generator and baseframe. However the reinforcement with thick plates or additional parts to increase the natural frequency can be less effective because of increased weight. Especially fine control of target mode based on the experience is difficult because the weight and interference of system have to be considered. In this paper, the design optimization of baseframe was performed to reduce the resonant vibration using a gradient descent method. The design parameters such as thickness, shape and location of baseframe parts are optimized to increase the torsional natural frequency of D/G set. From the actual test, the new designed baseframe reduced the vibration level in resonance by 55% without any increase of weight and interference. interference.

• Proceedings of the Korean Society of Marine Engineers Conference
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• 2006.06a
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• pp.39-40
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• 2006

Diesel power plant(DPP) with the medium speed diesel engine is operated under the very severe condition in aspect of load and operating time as compared with the marine diesel generator set. So, minimized vibration level have to be insured for the more stable operation of engine and generator. The vibration of generator set mainly comes from the resonance between the rigid modes by resilient mount or distortion modes by structural stiffness and the excitation forces of engine. Then, avoidance of resonance with structural modification is generally well known. In this paper, the first order vibration in non-resonance range and local vibration modes were investigated by impact test, response/ODS(operational deflection shape) measurement and 3D finite element analysis for the additional reduction of vibration. The proposed countermeasures were actually applied and their final effects were verified through the in-situ measurement.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2014.04a
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• pp.381-385
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• 2014

This paper investigates the magneto-rheological(MR) mount for the marine diesel-generator(D/G) sets. Sometimes, significant vibrations over the allowable limit are observed on the D/G sets due to their huge excitation forces. Because the severe vibration can lead to structural damages to the D/G sets, it should be reduced below the limit. Although passive mounts with rubber isolators are usually used, the vibration reduction performance is not always sufficient. In addition, expecting that the vibration levels required by customers will get more severe, vibration reduction devices need to be developed. To the aim, the flow mode type of MR mount has been designed. Especially, the annular-radial configuration was adopted to enhance the damping force within the restricted space. The geometry of the mount has been optimized to obtain the required damping force and the magnetic field analysis has been carried out using ANSYS APDL. To verify the performance of the developed MR mount, an excitation test was conducted. In addition, they were applied to a medium-speed diesel generator and it was verified that about 40% of vibration reduction was yielded.

• Journal of the Korean Society of Marine Environment & Safety
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• v.25 no.1
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• pp.117-121
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• 2019

In this study, research and a demonstration for applying DC distribution systems to ships as an environmental and energy conservation solution in domestic and foreign countries were actively carried out. In order to apply a generator to a DC distribution system, a variable speed engine was used. Both engine speed and fuel consumption were reduced. In this paper, a DC generator for DC distribution was constructed using a diesel generator, a generator controller, a governor, and an AVR. A system configuration method for a generator, power quality test, and the power characteristics of a variable speed generator were analyzed. The voltage (250 - 440 VAC) and frequency (34 - 60 Hz) of the variable speed generator were set to 60 - 100 % of the rated value, and the engine was set to operate from 1100 - 1800 rpm. It was confirmed that the voltage, current, and frequency of the generator output fluctuated in a stable manner according to the power amount when changing the engine speed of the generator according to the load variation.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2005.05a
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• pp.648-655
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• 2005

The resilient mounts of a diesel engine installed onboard a ship should be designed for both static and dynamic loads. If possible, the resonance frequencies of the six rigid body modes of the installation and the flexible modes of the engine support structure should not lie within the engine operation range. In this paper a design criterion is proposed to evaluate an isolation system which involves the summation of dynamic forces transmitted through the resilient mounts and elastic potential energy index stored in the mounts. A case study is also presented in which a diesel engine generator, which had an elastic foundation and was mounted in a 5500 TEU container vessel, was studied both theoretically and experimentally. The theoretical analysis of the test model was performed by using a single mass 6 degree of freedom system. Actual measurements of mechanical vibration of the Engine and its foundation onboard were carried out, which showed the importance of including the flexibility of the engine support structure in the mode

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.16 no.4 s.109
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• pp.329-338
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• 2006

The resilient mounts of a diesel engine installed onboard a ship should be designed for both static and dynamic loads. If possible, the resonance frequencies of the six rigid body modes of the installation and the flexible modes of the engine support structure should not lie within the engine operation range. In this paper a design criterion is proposed to evaluate an isolation system which involves the summation of dynamic forces transmitted through the resilient mounts and elastic potential energy index stored in the mounts. A case study is also presented in which a diesel engine generator, which had an elastic foundation and was mounted in a 5500 TEU container vessel, was studied both theoretically and experimentally. The theoretical analysis of the test model was performed by using a single mass 6 degree of freedom system. Actual measurements of mechanical vibration of the engine and its foundation onboard were carried out, which showed the importance of including the flexibility of the engine support structure in the mode.

• Journal of Advanced Marine Engineering and Technology
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• v.38 no.7
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• pp.877-882
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• 2014

The reduction of CO2 emission has been discussed in the Marine Environment Protection committee in the International Maritime Organization as the biggest causes of GHG for the purpose of indexing CO2 amounts released into the atmosphere from ships. Accordingly, various methods including the change in the hull design to improve energy efficiency, the coating development to reduce friction resistances, the additives development for improving thermal efficiency in an engine, the low-speed operation to reduce fuel consumptions, and etc. have been applied. The main engine of a ship is an electronic engine for improving the efficiency of the whole load area. However, marine generator engines still use mechanical drive engines in intake, exhaust, and fuel injection valve drive cams. In addition, most of marine generator engines in ships apply a part-load operation of less then 80% due to an overload protection system. Therefore, marine auxiliary diesel engine set at 100% load is necessary to readjust in order to efficient operation because of part-load operation. The objective of this study is to report the results of the part-load fuel consumption improvement by injection timing readjust to identifying the operational characteristics of a marine generator engine currently operated in a ship.