Simulation of cavitation and erosion in fuel injection systems of medium/heavy duty Diesel engines at injection pressures reaching 3000bar

The medium/heavy duty Diesel engine industry is facing new challenges for meeting the forthcoming emission regulations. Injection pressure above 2500bar and possibly reaching 3000bar and multiple injection strategy can drastically reduce the NOx/PM trade-off and allow use of cheap after treatment systems for meeting the set legislations. However, such injection strategies inevitably result to formation of cavitation which may have an adverse effect of the durability of the fuel injection system against surface erosion. This proposal will launch a knowledge-transfer programme between industries and Universities for designing durable fuel injection systems through use of existing as well as newly developed CFD models that will build upon those currently used by the industrial partners. These models will include effects not captured so far but believed to be of imperative importance: the prediction of cavitation surface erosion occurring upon collapse of cavitation bubbles. The new models will account for the effect of extreme pressure and temperature developing instantaneously at the time of bubble collapse.
In addition, the heat produced during the fast acceleration of the fuel as it flows through the injection holes can result to flow boiling and thus, significantly alter the heat transfer characteristics between the flowing fluid and the metal of the injector. Models for boiling heat transfer will be included to the CFD models predicting the cavitating flow development and surface erosion. By exchanging personnel between the industrial and academic partners, a dedicated group of researchers will be formed that can make connections between engine legislations and operating conditions, availability of experimental data for cavitation erosion and advanced computational approaches that are required to fulfil the objective of this project. The result of this project is the development of innovative new model and a sustained collaboration beyond the end of this project.