COMPUTATIONAL AND SCIENTIFIC ENGINEERING

Computational and Scientific Engineering

Principal Investigator: Stefan Platzer , Institute of Helicopter Technology, Technical University of Munich

HPC Platform used: SuperMUC-NG of LRZ

Local Project ID: pn56lu

Rotorcraft are regularly operating in ground effect over moving ship decks or on hillsides. However, only a very limited amount of research has been done to investigate the complex three-dimensional flow fields in these flight conditions and the resulting changes in rotor performance. Therefore, a hovering rotor in non-parallel ground effect was simulated in this project. URANS CFD simulations were made using various turbulence models to gain insight into the three-dimensional flow field, the rotor tip vortex evolution and the velocity distribution in the rotor plane. Best agreement with available experimental data was seen with a Reynolds stress model. Overall, the flow field was most affected close to the rotor hub and on the uphill side.

Computational and Scientific Engineering

Principal Investigator: Philip Ströer, Anthony D. Gardner, Kurt Kaufmann , Institute of Aerodynamics and Flow Technology, German Aerospace Center (DLR), Göttingen

HPC Platform used: SuperMUC and SuperMUC-NG of LRZ

Local Project ID: pr83su

Investigations of different approaches to transition modelling on rotors were undertaken, including comparison to experimental data and results of other European CFD codes. For flows at Reynolds numbers below 500,000 the transition transport models predict unphysically large areas of laminar flow compared to the experimental data. A new boundary layer transition model was developed to improve the transition prediction for a wide range of parameters crucial to external aerodynamics. The new model was implemented into the DLR TAU code and works on either structured or unstructured grids. The agreement of the new model with the experimental data is significantly improved compared to the results of the basic transition transport model.

Computational and Scientific Engineering

Principal Investigator: Klaus Hannemann , Institute of Aerodynamics and Flow Technology, Spacecraft Department. German Aerospace Center (DLR), Göttingen

HPC Platform used: SuperMUC and SuperMUC-NG of LRZ

Local Project ID: pr27ji

Combustion instabilities in rocket thrust chambers pose a serious risk for the development of future launch vehicles as they can’t be predicted reliably by numerical simulations. To better understand the interaction between the flames and acoustic waves inside a combustion chamber, this project numerically investigates the flame response to forced transversal excitation by using Detached-Eddy simulations. In a first step, the eigenmodes of a model combustion chamber are determined from an impulse-response and they are compared to experimental results. We then investigate a specific mode coupling scenario in which the oxygen injector longitudinal eigenmode is adjusted to match the dominant transversal combustion chamber eigenmode.

Computational and Scientific Engineering

Principal Investigator: Klaus Hannemann , Spacecraft Department, Institute of Aerodynamics and Flow Technology, German Aerospace Center (DLR)

HPC Platform used: SuperMUC and SuperMUC-NG of LRZ

Local Project ID: pr62po

The aerodynamics of generic space launch vehicles, in particular the flow field at the bottom of the vehicle, at transonic conditions are investigated  numerically using hybrid RANS-LES methods. The focus of the project is the investigation of the impact of hot plumes and hot walls on the flow field. It is found that both higher plume velocities and higher wall temperatures shift the reattachment location downstream, leading to a stronger interaction of shear layer and plume. An additional contribution in the pressure spectral content is observed that exhibits a symmetric pressure footprint. The increased wall temperature leads to reduced radial forces on the nozzle structure due to a slower development of turbulent structures.

Computational and Scientific Engineering

Principal Investigator: Christian Bauer , Institute of Aerodynamics and Flow Technology, German Aerospace Center (DLR)

HPC Platform used: SuperMUC and SuperMUC-NG of LRZ

Local Project ID: pr62zu

A large amount of the energy needed to push fluids through pipes worldwide is dissipated by viscous turbulence in the vicinity of solid walls. Therefore the study of wall-bounded turbulent flows is not only of theoretical interest but also of practical importance for many engineering applications. In wall-bounded turbulence the energy of the turbulent fluctuations is distributed among different scales. The largest energetic scales are denoted as superstructures or very-large-scale motions (VLSMs). In our project we carry out direct numerical simulations (DNSs) of turbulent pipe flow aiming at the understanding of the energy exchange between VLSMs and the small-scale coherent.

Computational and Scientific Engineering

Principal Investigator: Andreas Goerttler, Anthony Gardner , Institute for Aerodynamics and Flow Technology, German Aerospace Center (DLR), Göttingen

HPC Platform used: SuperMUC and SuperMUC-NG of LRZ

Local Project ID: pr53fi

Using DLR’s finite-volume solver TAU, researchers of the Institute for Aerodynamics and Flow Technology at DLR Göttingen numerically investigated the vortex system of four rotating and pitching DSA-9A blades. The computations were validated against experimental data gathered using particle image velocimetry (PIV) carried out at the rotor test facility in Göttingen. Algorithms deriving the vortex position, swirl velocity, circulation and core radius were implemented. Hover-like conditions with a fixed blade pitch were analyzed giving a good picture of the static vortex system. These results are used to understand the vortex development for the unsteady pitching conditions, which can be described as a superposition of static vortex states.

Computational and Scientific Engineering

Principal Investigator: Frank Holzäpfel , German Aerospace Center (DLR), Institute of Atmospheric Physics

HPC Platform used: SuperMUC of LRZ

Local Project ID: pr63zi

Aircraft wake vortices pose a potential threat to following aircraft. Highly resolving numerical simulations provide valuable in-sights in the physics of wake vortex behaviour during different flight phases and under various environmental conditions. Hybrid simulation techniques introduce the flowfield around detailed aircraft geometries into an atmospheric environment that controls the vortical aircraft wake until its decay. The vision of virtual flight in a realistic environment is addressed by the two-way coupling of two separate flow solvers. To mitigate the risk of wake encounters and thereby to improve runway capacity, so-called plate lines have been developed and tested at Vienna airport.

Computational and Scientific Engineering

Principal Investigator: Apl.-Prof. Dr. P. Gerlinger , Institute of Combustion Technology, German Aerospace Center (DLR), Stuttgart (Germany)

HPC Platform used: SuperMUC of LRZ

Local Project ID: pr87zi

Researchers at the Institute of Combustion Technology at the German Aerospace Center (DLR) use petascale HPC system SuperMUC at LRZ in Munich for the simulation of soot evolution in lifted, turbulent, ethylene-air jet flames. The scope of their work is to develop and analyze simulation techniques for turbulent combustion with focus on soot predictions. The long-term objective is to develop validated high fidelity simulation techniques for soot predictions in turbulent combustion systems such as aeroengines.

Computational and Scientific Engineering

Principal Investigator: Olga Shishkina , German Aerospace Center (DLR)

HPC Platform used: SuperMUC of LRZ

Local Project ID: pr63ro

Turbulent thermal convection is of fundamental interest in many fields of physics and engineering. Examples to mention here are the convective flows in the Earth’s atmosphere and oceans, in its core and mantle, but also in the outer layer of stars, in chemical engineering or in aircraft cabins. Frequently, these systems are also strongly influenced by rotation.

Computational and Scientific Engineering

Principal Investigator: Frank Holzäpfel , German Aerospace Center (DLR)

HPC Platform used: SuperMUC of LRZ

Local Project ID: pr63zi

As an unavoidable consequence of lift, aircraft generate a pair of counter-rotating and persistent wake vortices that may pose a potential risk to following aircraft. The highest risk to encounter wake vortices prevails in ground proximity, where the vortices cannot descend below the glide path but tend to rebound due to the interaction with the ground surface.