Rules like IMO Tier II/III for marine applications and EPA Tier 4 for land based off-highway applications have led to intensive development activities in order to fulfill the current requirements regarding exhaust gas conditions.
The drastically reduction of nitrogen oxides (NOx) and soot is typically achieved by not only optimizing a single engine parameter or component, but by a combination of different technical enhancements and modifications. Internal measures target the combustion process itself by modifications of ignition timing, increased peak pressure and optimized gas exchange. These are often combined with after-treatments like exhaust gas recirculation (EGR) or selective catalytic reduction (SCR).
Besides these challenges the trend towards lighter engines with better fuel-efficiency and higher power density remains unbroken. However, issues like rising cylinder pressure lead to increased load on the mechanical components of an engine. In direct driven 2-stroke propulsion plants de-rating and slow-steaming have become keywords for state of the art fuel saving technologies. Very often this has a direct influence on the torsional situation in these applications.
This paper gives an overview about the influence of different design strategies for emission regulation and fuel efficiency on the torsional vibration situation in large diesel and gas engines. It describes the effort that has to be made on the mechanical side in order to successfully combine reduced emissions with higher fuel efficiency and power density.
Torsional Vibrations Development