The vibration stresses of crankshafts in the reciprocating combustion engines have become severer with increase of their power and speed. It has become much more important to estimate all the vibration stresses accurately in the design stage of a crankshaft.
The first report described the three dimensional analysis of forced vibrations of the crankshaft by the transfer matrix method in detail. This analysis program can calculate axial, bending, and torsional vibrations of a crankshaft.
The second report referred to the numerical calculation by the analysis program, and it was found that the estimated torsional vibration stresses are in approximate agreement with the measured ones under forced torsional vibration.
In this report, it is described that the measured bending stresses of the crankshafts are compared with the calculated ones and that they are in good accordance. And it is found that the coupled bending stresses caused by torsional vibration can be estimated in a certain degree of approximation by this analysis program.

View full abstract

Heat transfer simulation method in boiler furnace was developed to obtain temperature distribution and heat absorbing rate distribution in the furnace. The results were compared with experimental data from a small boiler for heavy oil. The method analyzes simultaneously the three dimensional viscous flow by vector potential method, combustive heat generating rate by a flame model with Wiebe's function, three dimensional radiative heat transfer by Monte Carlo method, and convective heat transfer and enthalpy transport due to the flow by finite difference method. Following results were obtained by this simulation.
(1) The effects on in-furnace heat transfer of the flow pattern are rather small compared with the effects of the heat generating rate distribution.
(2) Heat generating rate in boiler furnaces were made possible to be estimated by determining the Wiebe's function's parameters in the flame model by comparing the analytical results with the experimental one's.
(3) Relationship among the heat generating rate and the fuel flow rate and the air fuel ratio was investigated, and by using this, analytical results of temperature and heat absorbing rate distributions were obtained with practically sufficient degree of accuracies compared with the experimental results.

View full abstract

So far many papers on the results of the failure and the maintenance of the Marine Engine Systems have been reported. Among them, the SR-85 report which was made a thorough investigation of the marine use mechanical devices by the Shipbuilding Research Association of Japan for a period of four years from 1966 to 1969, is one of the most important results in the viewpoint of the Reliability and Maintenability (R&M) of ships. After that, many authors including T. Hashimoto, et al., have investigated the statistical characteristics of the R & M of the marine engine systems.
In the present article, the important results obtained till now are summarized and on the basis of the results, the statistical trends are considered. Then, the statistical characteristics of the R & M of the main diesel engine in the latter half of 1970's are made newly clear by comparing the results in the latter half of 1960's.

View full abstract

The economic evaluation for the adaption of the new machineries and system is usually made from the view point of the pay-off time by the ordinary methods with a few parameters such as investiment cost, fuel cost, maintenance cost, etc.
In this paper, the Authors propose one of the more proper methods of the evaluation with new concept taking into account maintainability, reliability, noise, vibration, manoeuvability, maintenance time, etc.
By the introduction of the new method, the more minute analysis can be expected.

View full abstract

The recent competition in reduction of specific fuel oil consumption (FOC) among the marine engine manufacturers has realized engines whose FOC is as low as on the order of 120 g/ (PS⋅h) {163 g/ (kW⋅h) }, and a further improvement is still under way.
Under these circumstances it will be valuable to estimate the limit of FOC reduction, and in view of this, the diesel engine thermal efficiency is thermodynamically analyzed by computer simulation of the performance and thermal load.
The effects of the mean effective pressure, maximum combustion pressure, scavenging air pressure, degree of explosion (or compression ratio) as factors influencing the theoretical thermal efficiency, and those of turbocharger efficiency and longer stroke on FOC are examined.
The effects of the combustion period, opening speed of the exhaust valve, nonsymmetrical scavenging method, cooling and insulating conditions of combustion chamber as factors influencing the diagram factors on FOC are quantitatively clarified.
The possible limit of thermal efficiency improvement for mean effective pressure on the engine alone is analyzed by the above examination results.
In order to improve the overall thermal efficiency, the low air/fuel ratio cycle and such compound systems as power recovery from turbo-charger and that by Rankine cycle system are examined.

View full abstract