ENGINEERING AND CFD
HELISIM
Principal Investigator:
Dr. Manuel Keßler
Affiliation:
Institute of Aerodynamics and Gas Dynamics, University of Stuttgart
Local Project ID:
GCSHELISIM
HPC Platform used:
Hazel Hen and Hawk of HLRS
Date published:
The simulation of rotorcraft, with their complex aerodynamics, aeromechanics and aeroacoustics, is the primary research focus of the helicopter and aeroacoustics group at the Institute of Aerodynamics and Gas Dynamics (IAG). Over the last two decades, many PhD students have continuously enhanced the framework, adding new functionalities and considering increasingly more physics in order to represent real engineering problems and to answer difficult research questions accurately and reliably at the same time.
The complexity of the aircraft necessitates a multi-physics approach, including fluid-structure coupling, flight mechanics, a plethora of flow phenomena, and, above all, access to high performance computing capability. Advanced numerics implemented in massively parallel algorithms are routinely run on the Hawk System at HLRS in Stuttgart.
Fig. 01: Simulation snapshots of a helicopter start transitioning from hover to forward climb flight. © IAG, University of Stuttgart
Recent investigations have focused on the fundamental phenomenon of dynamic stall as well as the application to multicopters, a promising configuration for the upcoming urban air mobility sector. Moving forward, the team plans to enhance its models to concentrate on the vibration prediction for helicopters, building upon the technology developed to study tail shake simulations within the last funding period. Another effort is dedicated to manoeuvre flight situations. Previously, only stationary flight cases were simulated, usually in combination with a flight mechanical trim, which means an adaptation of control parameters (like the pilot’s stick position and the helicopter’s attitude) to reach and keep a specified flight condition. In the future, transient manoeuvres will be simulated, such as a take-off procedure with transition to forward flight and climb, as shown in the Figure, or the flare during a landing manoeuvre.
Computational performance is obviously of paramount importance, especially for the very demanding manoeuvre simulations. The Hawk supercomputer newly installed at HLRS nominally provides a huge computational capacity, but requires substantial code adaptations and customizations to be utilized optimally. By default, this is an ongoing effort in the course of the lifetime of any HPC platform.
HELISIM – in the meantime promoted to a GCS large-scale project – is the computational vehicle sustainably embraces IAG’s efforts on high fidelity numerical simulation of rotorcraft. The framework thus provides the capability to continuously improve helicopters and similar configurations in terms of safety, efficiency, noise and performance.
mp4 video: Quickstop manoeuvre decelerating quickly from forward flight to hover. © IAG, University of Stuttgart
References
- Manuel Keßler. Rotorcraft aeromechanics simulation - when applied mathematics hits real engineering. PAMM, 17(1), 2017.
- Johannes Letzgus, Anthony D Gardner, Till Schwermer, Manuel Keßler, and Ewald Krämer. Numerical investigations of dynamic stall on a rotor with cyclic pitch control. In 43rd European Rotorcraft Forum, Milan, Italy, 2017.
- Johannes Letzgus, Lukas Dürrwächter, Ulrich Schäferlein, Manuel Keßler, and Ewald Krämer. Optimization and HPC-applications of the flow solver FLOWer. In Wolfgang E Nagel, Dietmar H Kröner, and Michael M Resch, editors, High Performance Computing in Science and Engineering’17, pages 305–322. Springer, Cham, 2018.
- Ulrich Schäferlein (né Kowarsch), Manuel Keßler, and Ewald Krämer. Aeroelastic simulation of the tail shake phenomenon. Journal of the American Helicopter Society, 63(3):1–17, 2018.
- Felix Frey, Johannes Herb, Johannes Letzgus, Pascal Weihing, Manuel Keßler, and Ewald Krämer. Enhancement and application of the flow solver FLOWer. In Wolfgang E Nagel, Dietmar H Kröner, and Michael M Resch, editors, High Performance Computing in Science and Engineering ’18. 2018.
- Constantin Öhrle, Felix Frey, Jakob Thiemeier, Manuel Keßler, and Ewald Krämer. Coupled and trimmed aerodynamic and aeroacoustic simulations for Airbus helicopters’ compound helicopter RACER. In AHS Specialists’ Conference on Aeromechanics Design for Transformative Vertical Flight, San Francisco, CA. American Helicopter Society, 2018.
- Constantin Öhrle, Ulrich Schäferlein, Manuel Keßler, and Ewald Krämer. Higherorder simulations of a compound helicopter using adaptive mesh refinement. In 74th AHS Annual Forum, Phoenix, AZ, 2018.
- Johannes Letzgus, Pascal Weihing, Manuel Keßler, and Ewald Krämer. Assessment of delayed detached-eddy simulation of dynamic stall on a rotor. In 7th Symposium on Hybrid RANS-LES Methods, 2018.
- Felix Frey, Jakob Thiemeier, Constantin Öhrle, Manuel Keßler, and Ewald Krämer. Aerodynamic interactions on Airbus Helicopters’ compound helicopter RACER in cruise flight. In 75th VFS Annual Forum, Philadelphia, PA, 2019.
- Jakob Thiemeier, Constantin Öhrle, Felix Frey, Manuel Keßler, and Ewald Krämer. Aerodynamics and flight mechanics analysis of Airbus Helicopters’ compound helicopter RACER in hover under crosswind conditions. CEAS Aeronautical Journal, 11(1):49–66, Jan 2020.
- Johannes Letzgus, Manuel Keßler, and Ewald Krämer. Simulation of dynamic stall on an elastic rotor in high-speed turn flight. Journal of the American Helicopter Society, (65), 2020.
- Sebastian Miesner, Manuel Keßler, Ewald Krämer, and Ulrich Schäferlein. Investigation of Near Ground Effects in Hover Flight for the Multi-Rotor aircraft Volocopter 2X. In 76th VFS Annual Forum, Virtual online event, 2020.
- Felix Frey, Jakob Thiemeier, Constantin Öhrle, Manuel Keßler, and Ewald Krämer. Aerodynamic Interactions on Airbus Helicopters' Compound Helicopter RACER in Cruise Flight. Journal of the American Helicopter Society (65), 2021.
- Constantin Öhrle, Felix Frey, Jakob Thiemeier, Manuel Keßler, Ewald Krämer, Martin Embacher, Paul Cranga, and Paul Eglin. Compound helicopter X3 in highspeed flight: Correlation of simulation and flight test. Journal of the American Helicopter Society (66), 2021.
Scientific Contact:
Dr. Manuel Keßler, Dipl.-Phys.
Institut für Aerodynamik und Gasdynamik
Universität Stuttgart
Pfaffenwaldring 21, D-70550 Stuttgart (Germany)
e-mail: kessler [@] iag.uni-stuttgart.de
Website: Helicopter and Aero Acoustics Group, IAG, University of Stuttgart
Local project ID: GCSHELISIM
November 2020