ENGINEERING AND CFD

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.

Researchers of the Institute of Aerodynamics at RWTH Aachen University used large-eddy simulation and computational aeroacoustics methods to analyze noise sources in turbulent flames and the interaction of the resulting acoustic waves with the flame and the turbulent flow field. To achieve accurate results of the flow and the acoustic field highly resolved large-scale simulations with several hundred million mesh points are necessary. The simulation results have given new insights into fundamental sound-generation mechanisms and their phase-relationship that are important for the prediction and control of thermoacoustic instabilities, and ultimately, the development of more efficient and gas turbines with lower pollutant emissions.

Researchers of the Institute of Aerodynamics (AIA) at RWTH Aachen University conducted large-scale benchmark simulations on supercomputer Hazel Hen of the High-Performance Computing Center Stuttgart to analyze the interaction of non-spherical particles with turbulent flows. These simulations provide a unique data base for the development of simple models which can be applied to study complex engineering problems. Such models are required in a larger research framework to improve the efficiency of pulverized coal and biomass combustion to significantly reduce the CO2 emissions.

In order to support sustainable powertrain concepts, synthetic fuels show significant potential to be a promising solution for future mobility. It was found that the formation of soot and CO2 emissions during the energy transformation process of synthetic fuels can be reduced compared to conventional fuels and that sustainable fuel production pathways exists. Simulations of these multiphase, reactive systems are needed to fully unlock the potential of new powertrain concepts. Due to the large separation of scales, these simulations are only possible with current supercomputers.

A research group from the Institute of Aerodynamics (AIA) of the RWTH Aachen University utilized the computing power of Hazel Hen for large-scale simulations to analyze the intricate wake flow phenomena of space launchers. The objective of the project is the fundamental understanding of the origin of so called buffet loads acting on the nozzle which can lead to critical structural damage and to develop flow control devices to increase the efficiency and reliability of orbital transportation systems necessary for the steadily increasing demand for communication and navigation satellites.

Noise reduction is a key goal in European aircraft policy. One of the major noise sources at aircraft take-off is the engine jet noise. Recently, chevron nozzles were introduced which have drawn a lot of attention in research and the aircraft industry. Since the flow structures in the jet depend on the details of the nozzle exit geometry and have a large impact on the noise sources in the jet, scientists of the RWTH Aachen University extensively investigate chevron nozzles by running large-scale simulations based on a highly resolved mesh with up to 1 billion mesh cells.

Within the framework of a research project which aims at reducing the emission of CO₂ by conventional coal-fired power plants through oxy-fuel combustion, scientists of the RWTH Aachen University simulated the heating processes of coal dust in order to gain a better understanding of the conditions causing carbon dust to ignite in an oxygen-carbon dioxide atmosphere. Since carbon particles are of irregular, non-spherical shape their motion is difficult to predict, thus simulations of large quantities of fully dissolved carbon particles moving freely in a turbulent flow require the availability of petascale HPC systems like Hazel Hen.

A research team of the Institute of Aerodynamics (AIA) of the RWTH Aachen University leveraged the petascale computing power of the HPC system Hornet for large-scale simulation runs which used the entirety of the system’s available 94,646 compute cores. The project “Large-Eddy Simulation of a Helicopter Engine Jet” aimed at analysing the impact of internal perturbations due to geometric variations on the flow field and the acoustic field of a helicopter engine jet. For this purpose, the researchers conducted highly resolved large-eddy simulations based on hierarchically refined Cartesian meshes up to 1 billion cells over a time span of 300 hours.

To increase the efficiency and reduce the pollutant emissions of combustion engines, researchers simulate the complex flow field in internal combustion engines which has significant influence on the formation of the fuel-air-mixture in the combustion chamber and on the combustion process itself.