A process for an efficient heat release prediction at the concepts screening stage of gasoline engine development

• Published in: International journal of engine research 2021-08, Vol.22 (8), p.2502-2520
• Main Authors: Rota, C, Morgan, RE, Mustafa, K, Osborne, R, Matrisciano, A
• Format: Article
• Language: English
• Subjects: Boundary conditions; Calibration; Combustion chambers; Computational fluid dynamics; Design optimization; Dimensional tolerances; Exploration; Fluid dynamics; Fluid flow; Fuel economy; Gasoline engines; Hardware; Knock; Nuclear fuels; Prototyping; Regulations; Scaling factors; Screening; Systems design; Three dimensional models; Turbulence models
• ISSN: 1468-0874; 2041-3149
• DOI: 10.1177/1468087420947317

In recent years, the exploration of new combustion technologies has accelerated in response to increasingly stringent emissions regulations and fuel economy demands. Virtual engineering tools, that enable the screening of novel hardware and engine calibrations at the early stage of engine development, have become imperative to meet new emission regulations. One-dimensional engine simulations are used at the start of the design of a new engine to define the overall combustion system geometries. Later, more complex three-dimensional computational fluid dynamics calculations are coupled to one-dimensional engine system codes to optimise initial concept geometries and define a system design ready for prototyping. To provide meaningful results, one-dimensional engine system codes often use empirical-based combustion models to calculate the engine burn rate. Moreover, realistic engine burn rates responses, for the entire engine map and for different calibrations, are required to provide three-dimensional computational fluid dynamics codes with correct boundary conditions during the design optimisation phase. Thus, the burn characteristic of new non-traditional combustion solution, for which little experimental data are available, needs to be initially assumed. To improve virtual development and reduce this uncertainty, the industry’s attention shifted towards quasi-dimensional combustion models capable of providing engine burn rate predictions. Within the quasi-dimensional modelling framework, turbulence models, adding extra user-input variables, are required to capture the effect of different combustion chamber geometries on the engine combustion rate. Rigorous validation of zero-dimensional turbulence models for different engine concepts and calibrations is therefore needed to enable quasi-dimensional combustion models to predict the engine burn rate. An alternative methodology, with limited dependency on previous test data, is required to enhance the exploration of novel combustion strategies and geometric architectures. An available process, based on a quasi-dimensional combustion stochastic reactor model, a one-dimensional engine system model and non-combusting three-dimensional computational fluid dynamics calculations, was used for this work. The approach uses limited non-combusting computational fluid dynamics calculations and a previously developed scaling factor response for the stochastic reactor model turbulence input (τSRM) to quickly predict the en