Reacting Flow
Research » Reacting Flow
The next generation of turbulence modelling in computational fluid dynamics (CFD) will be LES. For the appropriate applications, such as reacting flows, LES can offer significant advantages over traditional Reynolds Averaged Navier Stokes (RANS) modelling approaches. The main advantage of LES over computationally cheaper RANS is the increased level of detail that LES can deliver. While RANS provides “averaged” results, LES can predict instantaneous flow characteristics and resolve turbulent flow structures. In engine research, this is particularly valuable in simulations involving chemical reactions. While the “averaged” concentration of chemical species may be too low to trigger a reaction, there can be localized areas of high concentration in which reactions will occur. LES is also significantly more accurate than RANS for flows involving flow separation or acoustic prediction. Thus, LES can be used to study cycle-to-cycle variability, provide more design sensitivity for investigating both geometrical and operational changes, and produce more detailed and accurate results. As inexpensive computing power increases, the ability to use LES in applications is increasing.
Liquid Fuel Spray
Various engineering devices of diverse industries use liquid fuel sprays, especially in internal combustion engines, industrial furnaces, rocket propulsion and gas turbines. Numerical simulation of sprays is challenging owning to the complex and multi-scale physics and chemical processes involved. In practical high-speed fuel sprays, DNS, which is capable of resolving the shear layer near the injector region, is usually not desirable due to the computational cost. Although, RANS method is commonly used for simulating sprays, LES modeling can offer a number of more temporal and spatial details than RANS, and is becoming more prevalent in simulating sprays.
Sandia Flame Series
Computational fluid dynamics (CFD) is an effective tool for the study of turbulent combustion. Large-eddy simulations (LES) can consume fewer computing resources than direct numerical simulation (DNS), and provides a much more detailed assessment of turbulent flows than the Reynolds averaged Navier-Stokes (RANS) approach. With the rapid development of computer technology, LES has become a mainstream CFD technique for understanding turbulence and combustion interactions.
Cambridge-Sandia Stratified Swirl Burner (SwB)
The Cambridge Stratified Swirl Burner provides a flame series that allows for the numerical investigation of flames operating at laboratory conditions closer to those of an industrial configuration, while providing detailed experimental data against which to validate models.
MILD Combustion
Moderate or intense low-oxygen dilution (MILD) combustion is a feasible solution to high thermal efficiency and low emission of pollutants MILD combustion conditions correspond primarily to the low-Damkohler number combustion regime. Thus the interactions between flows and reactions in MILD conditions are much stronger than those in traditional combustion. The well-known lean combustion concept, homogeneous charge compression ignition (HCCI) engine, can fall under the category of MILD combustion.
