The Numerical Application working group is concerned with the application of numerical methods to solve highly complex flow processes in turbomachinery and turbomachinery components. For the investigation of phenomena such as transition, scale-resolving methods are used in order to be able to accurately represent the mechanisms involved. The development of post-processing methods in the time, frequency and modal range is a necessary component to make local and temporal structures visible in a targeted manner. Furthermore, the group develops methods for the design of turbomachinery for innovative energy storage concepts and innovative thermodynamic cycle designs in which special gases such as CO2 or ethanol are used. The working group uses both in-house and commercial tools.
The further development of one-dimensional and multi-dimensional numerical methods for the design and map calculation of compressors, turbines and aircraft engines consists on the one hand, of the development of new correlation models and, on the other hand of the thermophysical modelling of real gas properties already in the design process.
With the help of modern CFD methods, tranisient effects in multi-stage turbomachinery configurations are investigated at the chair. These include interaction mechanisms and secondary flow effects.
The correct capture of transient aerodynamics in highly complex geometries, such as vapour extraction geometries, requires extensive experience in the application of CFD methods, especially with regard to the complex generation of an adequate numerical grid. Both strutured and unstructured grid topologies are used.
Scale-resolution methods such as large-eddy simulation are used for the detailed phenomenological investigation of local flow effects such as boundary layer transition.
Fluid-structure interaction involves the investigation of the mutual influence of structure and flow. Numerical methods for flow (CFD) and structure calculation (FEM) are coupled with each other.
The in-house 3D flow solver SharC enables the predictive, numerical characterisation of the flow and operating behaviour in turbomachinery operating in cyclic processes such as the organic Rankine cycle (ORC) or the supercritically operated Brayton cycle. Both the direct integration of equations of state and transport property correlations of real gases or an integration by means of highly efficient tabulation techniques are possible.
The conceptual design and aerothermodynamic prediction of single-stage and multi-stage thermal turbomachinery of axial and radial design, as well as the determination of the associated operating behaviour, is fundamental as a functionally relevant key component in large-scale storage systems, such as compressed air storage systems or liquid air storage systems. For this purpose, both commercial and, above all, in-house design and calculation tools are used.
For the evaluation of transient data from CFD simulations, efficient post-processing methods are developed at the chair, which, depending on the requirements, work in the time, frequency or modal domain. These include methods based on "Proper Orthogonal Decomposition" (POD), "Dynamic Mode Decomposition" (DMD) or "Discrete Wavelet Transformation" (DWT).
The application of such methods allows a targeted analysis of the relevant flow phenomena, providing detailed insights into flow physical processes, such as boundary layer transition, condensation or combustion processes.