Pressure fluctuation in stern tube sealing for large ships was studied. An analysis was verified by using a test stand having seal rings of 1250 mm diameter.
The pressure fluctuation was caused by the following three factors; the inertia movement of oil accompanying with the shaft vibration in radial direction, the volume variation of a recess due to the vibration of sealing liner in axial direction and the propagation of pressure fluctuation generated in a recess.
Pressure fluctuation calculated by simulating a 170, 000 ton freight vessel was identical with a fluctuation observed in the vessel.
Air bag in a recess is effective for suppressing the pressure fluctuation caused by a resonance of oil in an oil groove with an axial shaft vibration.

View full abstract

The idea, conceived by the author, of ship propulsion system using electromagnetic gear which is a sturdy and reliable power transmitting device based on electromagnetic action instead of mechanical contact, such as that of reduction gears was already explained in a prior paper.
In order to turn the idea to practical use, a model having a capacity of 16, 000 ps has been jointly developed by Japan Ships' Machinery Development Association and Kawasaki Heavy Industries Co. Ltd.
Shore test of the new device were conducted, at first, in combination with two electric motors which are respectively connected with the input shaft and the output shaft, and secondarily in combination with a 14, 000 ps Kawasaki MAN V14V 52/55 type medium-speed four-cycle diesel engine. Sufficiently satisfied results which can make us believe that the device can be used practically on a ship have been obtained by these tests. Some noteworthy results of these tests are as follows:
(a) The conventional efficiency of the electromagnetic gear was 95% at the input power rating of 16, 000 ps and reached 95.5% at the input power rating of 20, 000 ps.
(b) The temperature rise of the armature winding of the stator was only 60°C by measuring with an embeded thermometer after loading the electromagnetic gear with the maximum continuous rating input power of the diesel engine.
(c) Temperature rise of damper winding was very low.
(d) The rotational direction of the outer rotor could be changed smoothly in the test.
Reference: MESJ technical paper, Dec. 1974, Fukuo Shibata: “Theory and Experiment for Ship Propulsion System Using Electromagnetic Gear”

View full abstract

The performance of planetary gearing system by means of floating intermediate rings have been found to be very good for practical usage. The reliable theory, which can quantitatively estimate the load sharing factors in the designing stage in order to apply this system for the reduction of rotation of the marine main engine, is required for understanding the performance.
This paper shows the calculating method of the static load sharing factors by introducing the coefficient‘ε’, where, ‘ε’is defined as the ratio of spring constant to load. This method can be applied for non-linear system such as oil film bearing. The influences of the factors (ratio of bearing width to diameter, centrifugal force, series connection with elastic spring and series connection with another oil film spring) on‘ε’of oil film spring are also shown. Furthermore, the theoretical results of the load sharing factors are compared with the experimental results in the cases of 175 Ps and 350 ps, and the theoretical results are found to agree very well with the experimental results in both cases.
It is established in this study that the use of floating intermediate ring in designing the planetary gear system has a very high reliability.

View full abstract

There are something impures contained in petroleum, metal compound make one of them. They are insoluble or melt as porphyrin complex in it, but they are small in quantity.
Compound of vanadium and nickel in petroleum has effect as catalyzer and cause of corrosion and wear of apparatus.
We measured vanadium and nickel contents of many crude oil and some kind of heavy fuel oil by absorptiometric analytical apparatus. Namely, analysis method of vanadium component take the JPI-5S-74T that use indicator of N-benzoyl-N-phenyl-hydroxylamine, and nickel component take the method of O.I. Milner's group that use indicator of di-methylglyoxime.
Beside those, as compared with the repetitional accuracy of each method and result of our method having different operation, these way produced results within acceptable JPI standard accuracy. And as an analysis of many crude oil, we could draw an interesting conclusion that vanadium/nickel ratio of crude oil was given by oil fields as the various numerical value.

View full abstract

In recent years rationalization of sea transport has brought about a change in the marine transportation pattern with increasing amounts of cargo being handled by specialized carriers. Meanwhile, requirements on the performance of marine propulsion plants-the range of output, the propeller revolution-have become diversified as the usage, size and speed of ships change in line with this trend.
Under such circumstances, the medium-speed geared diesel propulsion plant is attracting increasing attention to its big merit of being able to meet any requirements in output and propeller revolution performance using the least number of engine types.
However, in spite of many advantages, it is a fact that the medium-speed geared diesel engine is still in no position to replace other engine types. This is because of the complicated maintenance problems arising from the large number of cylinders in the plant. Without any solution to this problem, the above mentioned merits cannot be used to the best advantage.
Also, as the geared diesel engine is joined organically to other equipment such as the flexible coupling, reduction gear, as well as devices for the automatic supervision and remote control of the engine into one system, development of the plant without consideration for these is unthinkable.
Based on the above considerations, development of the geared diesel propulsion plant was carried out with close research and development of:
The main diesel engine.
Labor-saving maintenance devices.
A large capacity clutch with the flexible coupling.
Light, compact reduction gear.
Detecting devices for abnormality of the engine.

View full abstract