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Volume 59, Issue 568
Displaying 51-55 of 55 articles from this issue
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Mamoru Suzuki, Keiya Nishida, Hiroyuki Hiroyasu1993 Volume 59 Issue 568 Pages 4038-4045
Published: December 25, 1993
Released on J-STAGE: March 28, 2008
JOURNAL FREE ACCESSWe propose a newly developed measuring technique for the simultaneous concentration measurement of fuel vapor and liquid in an evaporating diesel spray. This measurement technique is based on the principle of the laser light attenuation caused by the ultraviolet light absorption by fuel vapor and caused by the visible light scattering by fuel droplets in the α-methylnaphthalene diesel spray. Applications have been made of this new measuring technique to an evaporating diesel spray impinging upon a flat wall with high injection pressure. With an increase in the injection pressure, the vaporization of fuel droplets near the impingement point and the entrainment of ambient gas into the spray are enhanced, so the distribution of the fuel vapor along the impingement wall becomes more homogeneous. In the case of an impinging spray, an optimum impinging distance exists for facilitating the evaporation of liquid droplets and the entrainment of the ambient gas.View full abstractDownload PDF (873K) -
Makoto Ikegami, Koji Yamane1993 Volume 59 Issue 568 Pages 4046-4051
Published: December 25, 1993
Released on J-STAGE: March 28, 2008
JOURNAL FREE ACCESSHigh-pressure injection is effective in reducing diesel smoke. However, much is not known about selecting the best combination of the spray number and the nozzle-orifice diameter at high injection pressure. To make this clear, effects of the orifice diameter on the spray characteristics at elevated injection pressures are assessed in detail based on current spray theories. The results suggest that at a smaller orifice diameter, a rise in the injection pressure increases much faster than otherwise, not only the flow rate of air in entrained in terms of the fuel flow rate but also the microscopic mixing rate within the spray, thereby preparing a leaner and less heterogeneous mixture and ensuring a less smoky combustion. Theoretical background is given for the finding that a nozzle having more orifices of smaller diameter should be combined with a lower swirl intensity for high-pressure injection.View full abstractDownload PDF (694K) -
Masataka Arai, Yuichi Ida, Kenji Amagai1993 Volume 59 Issue 568 Pages 4052-4058
Published: December 25, 1993
Released on J-STAGE: March 28, 2008
JOURNAL FREE ACCESSThe performance of a 6-stroke diesel engine was numerically analyzed by means of a simple thermodynamical model. Since the 6-stroke diesel engine proposed in this report has two combustion processes in one cycle, it will offer new methods of the Combustion Control which could not be attained in an ordinary 4-stroke diesel engine. For example, the second combustion stroke provides the oxidation process of the soot that formed in the first combustion stroke. With this method, the in-cylinder gas temperature related to the NOx and soot formation in the combustion processes was predicted. It was confirmed that under various conditions, the maximum gas temperature of the 6-stroke diesel engine was lower than that of the 4-stroke engine. Furthermore, a 6-stroke low-heat-rejection diesel engine was analyzed. It was predicted that in comparison with the temperature in an ordinary 4-stroke engine, a higher thermal efficiency would be attained with a lower in-cylinder gas temperature.View full abstractDownload PDF (688K) -
Hideo Kawamura, Hiroshi Matsuoka, Shinji Hara1993 Volume 59 Issue 568 Pages 4059-4063
Published: December 25, 1993
Released on J-STAGE: March 28, 2008
JOURNAL FREE ACCESSIn order to eliminate the cooling system from all internal combustion engine, we studied heat-insulated construction of an engine. It is very difficult to increase the heat-insulation rate to above 50% in a heat-insulated engine having a combustion chamber wall coated with a zirconia layer. Heat flux and temperatures have been calculated by means of the finite-element method. Calculated results are compared with the measured temperatures in an engine which has a combustion chamber wall made of silicon nitride and a compound heat-insulated construction composed of an air gap and a gasket with very low thermal conductivity. We obtained the results that the compound heat-insulated construction is very effective in reducing heat flow from the combustion chamber wall to the outer cylinder made of cast iron. The calculated results show good correspondence with the measured data when large heat-transfer coefficients are used for the piston when fuel is burning briskly, and when low heat-transfer coefficients are employed on the cylinder liner in contact with the combustion gas.View full abstractDownload PDF (646K) -
Naozo Hattori, Tadashi Takahashi1993 Volume 59 Issue 568 Pages 4064-4068
Published: December 25, 1993
Released on J-STAGE: March 28, 2008
JOURNAL FREE ACCESSExperiments were carried out on forced convection heat transfer from a single row of circular cylinders in cross flow, in a water tunnel. Average and local Nusselt numbers for a cylinder, placed at a lateral cylinder spacing from 1.3d to 3.3d, were measured precisely in the Reynolds number range from 80 to 6x103. A correlation equation for average Nusselt number is given in a relatively high Reynolds number range, regardless of the interaction between wake flows behind the cylinders.View full abstractDownload PDF (462K)