Typical load characteristics of a high-power ultrasonic homogenizer equipment for used with fuel improvement are described.
The load equivalent circuit as an electrical-acoustic conversion system is derived from practical consideration of power supply designing. On the basis of that equivalent circuit, the load variations such as depth, clearance, viscosity, and output frequency changes are analyzed as load admittance changes. The load characteristic is experimented by a constant current system.
Especially, in the case of mechanical resonance frequency tracking strategy, a result that the load admittance variation with load change is extremely small is proved.
Further, a tracking strategy method of mechanical resonance frequency is investigated.

View full abstract

The big end of a connecting rod is separated into two parts. On its separated surfaces, a serration is usually employed.
Fretting failures sometimes occur on the serration surfaces. The reliability of the connecting rod depends upon the behavior of the serrations. So we carried out the following studies concerning the serrations; F.E.M analysis, photoelasticities, and the loading test.
Through the investigations, the following were clarified.
(1) The separation angle of the connecting rod is hoped to be larger than 35° to reduce the stresses of the serrations.
(2) The most suitable shape of the connecting rod is introduced here by the optimum structural design of F.E.M.
(3) The suitable shape of the serration is the one with the teeth of 90° in angle and with relief on the tops of the teeth.
(4) The small size serration is good for the uniform contact, but is not so good for the initial loosening of the tightening bolts, although the large size serration has the contrary effects.
(5) For giving the uniform contact pressure between the serrations, four bolts tightening of the connecting rod is better than two bolts tightening.
(6) Getting the contact pressure between the serrations near to zero, there come out the possibility to give rise the fretting failure.
(7) When the serrations separate each other, the fretting failure occurs between the separate teeth and the contact teeth.

View full abstract

Recently, in Japan, the transportation by the car-ferry, especially by the long route car-ferry of which important cargos are trucks, is remarkably growing. This paper analyzes the characteristics and the present status of the car-ferry transport energy efficiency with regarding the role of the ferry as an alternative way of the land transportation by the truck. The hull resistance and propulsion efficiency of the ferry are better than the common cargo ship. This characteristic is due to the capability of differentiating the hull function into the buoyant support function and the shipment function. The payload-to-displacement ratio has a great influence on the transport energy efficiency of the ferry. This ratio is determined by the carriage deck area. Therefore the catamaran type hull is very favorable for the ferry.
The estimation based on the actual transport energy efficiency reveals that the ferry transportation consumed about 1.4 million tons of oil fuels at 1975 in Japan. The ferry transport energy efficiency is estimated by the comparison with the land truck transportation. The result shows that, at the present, the small and medium sized ferry are worse than the truck, but the large sized, that is, long route ferry can compare favorably with the truck. The improvement of the payload-to-displacement ratio would extend the region where the ferry could be used as an alternative way of the land truck.

View full abstract

In the marine Diesel engine, there still remains problems about the relation between thermal loads of engines and the indicated values of thermometer. Therefore, the exact measurement of exhaust gas temperature has expected up to the present. The indicated value is mainly affected by two factors which are the measurement factors of exhaust gas temperature and the gas flow in the exhaust pipe, and it is still not clear how these two factors affect the indicated value.
In this study the measurement factors affecting on the indicated value were examined, using two kinds of steady state exhaust gases in the duct and the thermometer well which was filled several thermocouples up the axial surface. Owing to the results, the temperature of the tip of well usually is different from gas temperature, even if the longitudinal length of well takes enough. Therefore, it seems that it is not suitable to make the reading gas temperature, the correcting of the reading is necessary to take account thermal characteristics of well in the duct.

View full abstract

The Lubricating Oil Purifying Systems of Diesel Engine Power Plants are usually consisting of several filters and centrifuges, and many varieties of combinations of such separating equipments are in practical use today.
Assuming total weight and particle size distribution of incomming sludges into the lubricating oil systems, and particle retention rate of each separating equipments, by a most reasonable way, amounts of dust flows passing through engines can be easily found by simple calculations. Author proposes, in this paper, to take this amount of sludges entering into the engine per unit time, as a numerical index showing overall efficiencies of an oil purifying system.
An example of calculations, as well as author's opinions for several physical phenomena inside the lubricating oil systems, are described herein.

View full abstract

It occurred to the shipping world that the oilshock pressed the derating of marine engine load in 1974 worldwidely.
This paper describes whether there is such a same derating effect upon the marine engine load as electronics power derating can make contribute to the higher reliability and maintainability evaluation or not.
From the total value 8250 occurrences of marine engine failure reports submitted by 33 diesel ships and 10 turbine ones during 80×10⁴ propelling hours of two surveyed periods which are both the separate two years of 1972, 1973 and 1977, 1978, there are obtained the linear regression equation X=a+bL between three kinds of evaluation indices X (λ; occurring rate, MI; manning index, mh; man-hour per occurrence) and marine engine load L.
According to the coefficient b (=∂X/∂L) of regression equation, the three following derating effect patterns are ascertained for three classifications of ships and the four types of main engine licensers;
(1) Derating Pattern A (b>0; positive correlation) ; Diesel container ship and C type of main engine license: the less load of their main engines make contribute to the less occurring rate, the less manning index and the larger man-hour per occurrence.
(2) Derating Pattern B (b<0; negative correlation) ; Diesel cargo ship and A type and B type of main engine: the less load of ones do the higher occurring rate, the more manning index and the larger man-hour per occurrence.
(3) Derating Pattern C (b>0/L>L_u, b<0/L<L_l<L_u; mixed relation) ; Turbine ships: the less occurring rate, the smaller man-hour per occurrence between about 50 [%] and 80 [%] of normal load.

View full abstract