The relation of exhaust smoke and the improvement of specific fuel consumption are the most important requirement in a diesel engine. To realize these two items, the characteristics of fuel spray were investigated using a model chamber which had the same shape of piston crown as that of real engine. Spray tip penetration and spray cone angle were measured from 16mm high-speed photography. With reference to these results, relation between exhaust smoke and combination of shape of piston crown and injection angle of spray were investigated in an operated engine. The combination has a greater effects on the smoke at low load than that at high load. From the examinations, the smoke reduction, especially at low load, could be reached by decreasing mean equivalence ratio in fuel spray at the moment of impinging on the piston wall and by designing the piston bowl considering the spray does not hit the cylinder liner wall.
In this paper, the separation performance of water droplets from air including water droplets by eliminators is investigated theoretically and experimentally. The plates of eliminators used here are made of polyvinyl chloride, and are approximately represented by the sine-wave form. These eliminators have three different half wavelengths 65, 38, 16 mm, wave amplitudes 18, 9, 4.5 mm, and gaps between plates 30, 15, 12 mm, respectively. The number of wave cycles in their corrugated plates is three, therefore the bending number is six. For comparison, the other eliminators are prepared which are made of 1.0 mm thick acrylic sheet bended sharply to make zig-zag flow passages. For all of the eliminators mentioned above, the mass flow rate of water droplets is varied over the range of 16.14×10-3 to 234.96×10-3 mg/mm2 min., with the size of water droplets being varied over the range of 5 to 125μm. The separation efficiencies of these eliminators are sufficiently in good agreement with those predicted by theoretical analysis for water droplets to be assumed to have a Stokes law resistance to relative motion with the air. And, as the results of this theoretical analysis show, the separation efficiencies of the eliminators with the sine-wave form are nearly consistent with those of the eliminators with sharply bended form through experiments, but the resistance coefficients of the sine-wave eliminators are about 40 percent in the maximum value less than those of the another eliminators in this experimental range. Furthermore, characteristics of water droplet size distributions at the inlet and the outlet to the eliminators are also investigated.
Experiments were carried out to obtain useful knowledge how to attach a panel resiliently to vibrating ship structures in order to isolate vibration effectively and to confirm the noise reduction effect by good resilient mount lining system in a cabin model. The results obtained are as follows. Vibration isolation mats, such as Rockwool boards, have much greater vibration isolation performance than isolation rubber for elastic mount of panels. The isolation effects predicted by the presented method, replacing the static mass of panel by effective dynamic one acts on the mounting rubber, are compared with experimental data obtained for rubber mount. Agreement with experimental results is better than those of the static mass method. Light weight panels used for inner walls and ceilings, such as plywood thinner than 9mm thick, can not be isolated vibration effectively compared with heavy floor panels, and this causes the poor noise reduction effect (≤10dB (A) ) for floating accommodation system. Average radiation ratio of resiliently mounted lining shows several dB higher than that of rigidly attached lining.
We, manufacturer of medium-sized, medium-speed diesel engines since 1954, has made a debut of the newest model T240 type marine diesel engine designed for burning 700cSt/50°C heavy fuel. The T240 diesel engines are based on the experiences gained with NEW ENERGY SAVING SERIES ENGINES since the energy crisis in the mid 1970's. It was developed and designed to the philosophy of meeting the customer's needs, i.e. betterment of fuel consumption, use of lower grade fuel, higher reliability and easy maintenance. The design concepts used in developing the T240 type engine, its main features and the shop test results of the first engine for burning M.D.O. and 700cSt/50°C heavy fuel are described. And also, the results of service operation using 180cSt/50°C heavy fuel are reported. The T240 type engine features the good energy-saving performance to a decisive degree and high reliability, as proved in the various measurements of shop tests and service operation.
For the design of the engine room ventilating system, designers have to refer to many informations and synopses. This paper is convenient as manual to plan or design it from the initial stage to the final stage. Principal contents are as follows. (1) General; kinds of ventilating fans, arrangement of ventilating system etc. (2) Planning of design; procedure, distribution of flow, arrangement, calculation of friction loss etc. Detail design will be described in the 2nd report.