As the material defect might be included in the present FCD (spheroidal graphite cast iron) mono-block piston, material defect should be taken into account for designing the piston. If this defect could be removed by the HIP (Hot Isostatic Pressing) processing, the optimal design could be performed on condition of non-defect. Namely, it enables to design a lower weight and higher power engine. In this research, we have at first confirmed whether the defect is able to be eliminated by performing HIP processing to the specimen in which defects existed. Then, we have confirmed the influence of HIP processing on the strength by comparing with the specimen of healthy part. Consequently, it turned out that the defect can be eliminated when the defect locates at the inside of material. Although the cavity is eliminated in the crushed part of shrinkage cavity, the flake of the graphite remained there. Though the tensile strength can be improved considerably by eliminating the defect, it can not be improved up to the strength of a non-defect part due to the influence of the flake of graphite.
The combustion characteristics of marine heavy fuel seem to be managed by many factors, e.g. Density, Carbon Residue, Aromatisity, and Carbon/Hydrogen Ratio, Molecular Weight etc. When the causes of diesel engines' combustion troubles are searched, what properties should we primarily check to identify the main cause of the trouble? The authors studied the relationships between some properties and ignition delay (milli-second), combustion period (ms) of marine fuel oils submitted from ship owners, shipyards and surveyors by using a combustion test apparatus, so-called FIA 100. The authors found that; 1. The aromatisity index, CCAI, and Carbon/Hydrogen (Weight) Ratio has good correlation to the combustion characteristic of fuel oil, which cannot be ignored for a trouble shooting. 2. Carbon Residue, Asphaltene in fuel oil has no relationship to Ignition Delay, but some portion for Combustion Period. 3. Average Molecular Weight of fuel oil has less relationship to both Ignition Delay and Combustion Period. 4. Ignition Delay over 8 ms and Combustion Period over 28 ms might have some relationships to engine's operational problems.
The purpose of this paper is to estimate the combustion process in two-stroke slow-speed diesel engines with side fuel injection type for marine use. The rate of heat release data is generally utilized as an indication of diesel combustion process. In the first report, the characteristics of the rate of heat release obtained from the cylinder pressure data in the test engine were discussed. In this paper, the combustion process which can be induced directly from the analyzed data of the rate of heat release curve, were estimated. As a result, it is found that the combustion rate decreases when the fuel spray arrives at a certain circumferential angle, which almost corresponds to the position of the next nozzle. Also, the rate of heat release curve shows double peaks in such case that combustion suspended period due to interference of the combustion gas from the nozzle at upstream side is short and the fuel that should be injected still remains a lot.
We propose a new reasoning method of crankshaft and propulsion shaft static alignment under any vessel condition. There are two measurement methods for alignment. One is called crankshaft deflection method. The other is bearing load method. Those methods do not lead directly to shaft alignment. It is necessary to solve the heights of each bearing by an inverse solution. Firstly, Crankshaft of n-cylinder engine and propulsion shaft is modeled simply in order to calculate the crankshaft deflections and the bearing loads. The model is solved by using transfer matrix method. Secondly, to solve the inverse problem, the bargaining game theory is applied. In the game, each bearing height is defined as player. The utility function is defined as the error function as compared with the measured results. The solution of the game is the maximum of the multiplication of utility values based on Nash bargaining solution. Genetic algorithm is used to calculate the solution. As the results, to apply on some actual vessel data, newly developed method is effective to reason the bearing height.