Effect of Sauter Mean Diameter on the Combustion Related Parameters in a Large-Bore Marine Diesel Engine

Author(s):  
Stanislav N. Danov ◽  
Ashwani K. Gupta
2016 ◽  
Vol 9 (3) ◽  
pp. 186-198 ◽  
Author(s):  
Fei Yan ◽  
Yuchen Du ◽  
Lihui Wang ◽  
Wenxian Tang ◽  
Jian Zhang ◽  
...  

Numerical simulation of the cavitation and spray in a marine diesel engine is performed to investigate the effects of injection pressure on the cavitation flow and spray characteristics in the marine diesel engine, which in turn influence atomization and combustion in the cylinder. A two-phase flow model combined with single bubble dynamics and a droplet break-up model are used to simulate cavitation and spray, respectively, and the results are compared to the experimental data. With increasing injection pressure, the pressure fluctuations inside the nozzle become more intense. The spray penetration is proportional to time at the beginning of injection. Higher injection pressure increases the spray angle. In addition, massive structures on spray edge can return to the spray body, whereas the massive structures on the spray head remain unchanged throughout its lifetime. Each additional 20 MPa of injection pressure reduces the Sauter mean diameter by approximately 9%.


Author(s):  
Salman Abdu ◽  
Song Zhou ◽  
Malachy Orji

Highly increased fuel prices and the need for greenhouse emissions reduction from diesel engines used in marine engines in compliance with International Maritime Organization (IMO) on the strict regulations and guidelines for the Energy Efficiency Design Index (EEDI) make diesel engine exhaust gas heat recovery technologies attractive. The recovery and utilization of waste heat not only conserves fuel, but also reduces the amount of waste heat and greenhouse gases dumped to the environment .The present paper deals with the use of exergy as an efficient tool to measure the quantity and quality of energy extracted from waste heat exhaust gases in a marine diesel engine. This analysis is utilized to identify the sources of losses in useful energy within the components of the system for three different configurations of waste heat recovery system considered. The second law efficiency and the exergy destroyed of the components are investigated to show the performance of the system in order to select the most efficient waste heat recovery system. The effects of ambient temperature are also investigated in order to see how the system performance changes with the change of ambient temperature. The results of the analysis show that in all of the three different cases the boiler is the main source of exergy destruction and the site of dominant irreversibility in the whole system it accounts alone for (31-52%) of losses in the system followed by steam turbine and gas turbine each accounting for 13.5-27.5% and 5.5-15% respectively. Case 1 waste heat recovery system has the highest exergetic efficiency and case 3 has the least exergetic efficiency.


2013 ◽  
Vol 331 ◽  
pp. 148-152
Author(s):  
Xiu Xu Zhao ◽  
Zhi Xiang Hu ◽  
An Jian Huang

According to the characteristics of large size, small clearance ratio, high oil film pressure and thin oil film thickness in the actual conditions of high power marine diesel engine bearing, this Paper analyzes oil film pressure distribution on inner surface of bearing bush based on the finite difference method, uses finite element method to establish the hierarchical model, and analyzes stress and strain distribution on bearing alloy. In addition, this Paper researches the changes of stress and strain distribution on bearing alloy layer when alloy layer thickness changes for the optimization design of high power marine diesel engine bearing bush.


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