3.2.2 Main frame
In Fig.15, main frame stress was evaluated with 3-dimensional FEM analysis. Load condition for calculation is tie rod tightening force, gas force, side thrust force and inertia force. By this analysis, the strength of each part was evaluated and optimized with sufficient fatigue safety factor.
3.2.3 Main bearing
The main bearing layer is white metal and its behavior is optimized by the method of EHD (elastohydrodynamic).
Fig.16 shows the results of calculated oil film pressure distribution of the main bearing (both upper and lower shells are shown as their development).
To get these results, the whole engine stiffness is analyzed by Three-Dimensional FEM method and whole inertia/gas forces are considered.
3.3 NOx emission control
The countermeasure against environmental problem has been researched and developed. Now, all UEC engines including UEC-LSE meet the first IMO-NOx regulation by engine fine tuning (fuel injection timing retard, low NOx fuel injection valve, etc). As you know, however, IMO NOx regulation is going to be revised every 5 years, and NOx limit is going to be lower than the present value. For the next step of the regulation mentioned above, we have already developed the stratified fuel water injection system as shown in Fig.17. It can reduce NOx up to approx. 50% without great increase of FOC as shown in Fig.18. The stratified fuel water injection can be applied as one optional item for UEC-LSE engines.
