Reduction at source of V-type Diesel engines’ vibrations

The development of modern diesel engines is characterized by a constant trend towards increasing specific power and efficiency. To meet these demands, the peak combustion pressure increases with each new engine generation (250 bar is the current state of the art, compared with 150 bar in the early 90s). Consequently, the reliability and durability of basic components such as the crankshaft are constantly being improved to keep pace with this trend. These technical challenges are compounded by increasingly stringent requirements in terms of pollutant emissions, low fuel consumption and economic return on investment.

Faced with this demanding technical and economic context, the development of high-performance internal combustion engines requires good control of the vibration behavior and durability of the various components, while minimizing their oversizing. With the considerable progress made in numerical simulations, this requires a number of parameters and aspects to be taken into account right from the start of the project. One of the major aims of this development phase is, if possible, to reduce motor vibration at source, as it can potentially come from multiple sources, manifest itself in many forms and, above all, cause numerous problems during operation. The essential aim of this article is to present the key parameters of the architecture of V-type internal combustion engines with up to 24 cylinders. Unlike in-line engines and small V-engines, the state of the art for engines with more than 12 cylinders is much less mature. What's more, there are a number of little-known or little-analyzed phenomena, which can be overcome by reference to experience or, indeed, by means of relatively comfortable safety factors.

This work mainly concerns 4-stroke diesel-cycle internal combustion engines running at high rotational speeds up to 15 m.s- ¹ mean piston speed. These engines are equipped with turbochargers enabling them to achieve mechanical power ratings of up to 5 MW, making them suitable for a wide range of applications, including marine, mining and stationary applications such as generator sets. To avoid restricting ourselves to this range of engines, many of the phenomena explained in this work can also be generalized to gasoline engines, gas engines, 2-stroke engines and naturally aspirated engines.

At the end of the article, readers will find a glossary and a table of symbols used.