Abstract
The ever-growing requirements relating to the efficiency, consumption reduction, emission characteristics, the acoustic behaviour and service life of modern engines confront development engineers with highly complex problems whereby precise information on the interplay of all individual components has a substantial effect on the final result. Although the validation of simulation results on the test bed is an indispensable part of the development process, nowadays purely experimental studies can no longer produce the required optimisation measures. Particularly the study, improvement and refinement of combustion and aftertreatment processes to meet not only current but also future requirements demand facilities that include physically precise simulation of the flow processes in the engine.
Efforts aimed at further shortening the time required for the development of engines must begin with the quality of the basic layout and concept. The necessary efficiency for this can only be achieved by intensive simulation, for which special software is required leading directly to the virtual engine, and thus an almost complete simulation of all engine components. In this context the CFD code FIRE has already been well established for three-dimensional flow and combustion calculation. Unlike earlier versions, which were based on the immediate predecessor, Version 8 represents a completely new development. With the achievable gain in speed and its wide-ranging applicability FIRE 8 sets new standards among currently available simulation platforms. During its development a major focus was put in particular on user-friendliness, enabling the design engineer to carry out extremely complex tasks with a few operations. The basis for this is the integrated CFD Workflow Manager, which can offer the user standardised applications, organise results automatically and, together with a significantly improved interface design makes it possible to considerably reduce training times. Although naturally also available in UNIX platforms, the Look and Feel of the graphical user interface resembles the quasi standard set up by Microsofts Office applications, so that users will find access easy.
Additionally, FIRE 8 is fully compatible with simulation tools from other fields, so to offer an integrated combustion and flow scenario for the engine. The combination of FIRE with the FAME three-dimensional mesh generator, the IMPRESS 3D visualisation and the BOOST one-dimensional gas-dynamic calculation tool creates a software package, which covers completely the simulation of all processes from the intake and the combustion through to the exhaust system. It is also possible to incorporate HYDSIM for the one-dimensional calculation of injection components. This integrative approach is not simply restricted to close links with other software tools, but also takes into account those users who have developed their own physical models: models which have been created outside the FIRE environment can be easily integrated via its open interface architecture.
Besides significantly improved functionality, the upgrade to Version 8 of the successful package of FIRE and the three-dimensional mesh generator FAME also offers considerable advantages in respect of possible project turnaround time. With FAME, the modelling time can be reduced by up to 75% as a result of the largely automated grid generation. The new solver excels with its unprecedented degree of robustness, flexibility, precision and especially low runtimes, with the achievable computing speeds of two to three times that of comparable products.
The handling of unstructured meshes and non-conform interfaces permits the efficient consideration of moving components in the simulation. Experimentally proven modules for the calculation of mixture formation and combustion processes support the use within a wide range of research and development tasks within the engine development process.