ENGINEERING AND CFD

Engineering and CFD

Principal Investigator: Karine Truffin , Institut Carnot IFPEN Transports Energie, Energies Nouvelles, Rueil-Malmaison (France)

HPC Platform used: JUWELS of JSC

Local Project ID: pra102/DNS4ICE

Today, car manufacturers rely on CFD tools to design and optimise spark-ignition engines. However, current models of turbulent combustion—which are built based on the assumptions of the flamelet regime—lose their predictivity when used to simulate a highly diluted or ultra-lean combustion involving high turbulent intensities. Yet the combustion in a diluted boosted spark-ignition engine shifts from the flamelet to the thin reaction zone (TRZ) regime. This research project performed direct numerical simulations of premixed C8H18/air statistically flat flame interacting with a turbulent flow field. Results were analysed to develop a combustion model suitable for combustion in the TRZ regime based on the formalism of the coherent flame model.

Engineering and CFD

Principal Investigator: Jian Fang , Scientific Computing Department, STFC Daresbury Laboratory, UK

HPC Platform used: Hawk of HLRS

Local Project ID: FlowCDR

Micro-scale directional grooves with spanwise heterogeneity can induce large-scale vortices across the boundary layer, which is of great importance to both theoretical research and industrial applications. The direct numerical simulation approach was adopted in this project to explore flow structure and control mechanism of convergent-divergent (C-D) riblets, as well as the impact of their spacing, wavelength and height. The results show that the C-D riblets produce a well-defined secondary flow motion characterised by a pair of weak large-scale counter-rotating vortices. This roll mode can play a key role in supressing separation when the flow undergoes adverse pressure gradients, but it may also lead to the increase of friction drag.

Engineering and CFD

Principal Investigator: Heinz Pitsch , Institute for Combustion Technology, RWTH Aachen University

HPC Platform used: JUWELS of JSC

Local Project ID: cjhpc09

A high fidelity, high Reynolds number direct numerical simulation (DNS) of a planar temporally evolving non-premixed jet flame was performed on the new supercomputer JUWELS of JSC. The DNS enabled the detailed investigation of combustion conditions with a high level of scale interaction between combustion chemistry and turbulence. Furthermore, the simulation was instrumental in understanding how the structure of scalar fields is affected by heat release in non-premixed flames. The insights gained from the DNS are instrumental in the development of new combustion models with the goal of improving the accuracy of simulations of real-world engineering applications.