The SPH code turboSPH is a weakly compressible smoothed particle hydrodynamics code developed at ITS.

With turboSPH, the Lagrangian Navier-Stokes equations are solved without having to mesh the computational domain. At ITS, the SPH particle method is mainly used for the numerical investigation of complex two-phase flows in turbomachinery or related applications. The code is implemented in C++ and MPI and contains tools for pre- and post-processing of simulation data.

Gallery

Here you can find some of our simulations with turboSPH. Further explanations can be found in the related research topics.

Primary decay of a planar, film-legendary airblast atomizer

The video shows the simulation of a primary decay process of a generic, film-legendary airblast atomizer. Several decay events could be captured, which are also known from experimental work. To date, this simulation with a total of 1.2 billion particles and a spatial resolution of 5 µm is one of the largest calculations within the atomization community. Since the turboSPH code is massively parallelized, a physical time window in the order of ~100 dwell times could be simulated with comparably low computational effort.

The work demonstrates that reliable simulations of air-assisted atomizers are now possible.

The video is part of the work published in High Performance Computing in Science and Engineering by Braun et al. (2016). DOI: 10.1007/978-3-319-47066-5_22

Primary decay of an industrial airblast atomizer

The video shows a reconstructed phase boundary of a simulation of a fuel nozzle carried out with turboSPH. This is the world's first 3D-SPH simulation of the fuel spray of a realistic nozzle geometry of a turbofan engine.

The simulation was carried out with 1200 CPUs over a period of several months. With a resolution of 8 µm, the spatial discretization results in a total number of half a billion particles.

The video is part of Dr. Koch's keynote presentation at the MCS.

Oil jet-gear interaction

In order to exploit the potential advantages of new types of aircraft engines with high bypass ratios and thus realize more efficient and environmentally friendly aircraft engines, the use of a high-performance gearbox is required. Knowledge of how the oil spreads after the oil jets hit the gear flanks is important to ensure reliable cooling and lubrication of the gearbox.

The video shows a 3D simulation of the oil jet-gear interaction achieved with turboSPH. Due to the Lagrangian nature of the SPH method, the strong deformation of the oil phase is accurately captured and the gear rotation is computationally efficiently simulated (compared to conventional grid-based methods). Due to the high level of detail of the simulation result, new quantitative insights into this complex flow process could be gained.

The video is part of the work published in the Journal of Tribology by Keller et al. (2019) DOI: 10.1115/1.4043640

Lagrangian coherent structures

One of the advantages of the SPH method is the much more cost-effective identification of "Lagrangian coherent structures" (LCS) in flows using the "Finite-Time Lyapunov Exponent" (FTLE). This scalar value describes the deposition rate with respect to neighboring particles over a finite time interval, which can be used as a diagnostic tool to analyze vortex and interface dynamics.

At ITS, we have developed our own post-processing tool, postAtom, to analyze the data generated by turboSPH simulations on a large scale. Such analysis allows us to identify vortex structures at different length scales along with their temporal evolution, providing a unique insight into the local atomization phenomena and the possibility to trace the influence of geometric variations.

The video is part of the work published in Energies by Dauch et al. (2019). DOI: 10.3390/en12132552

Research focus

Atomization

• Fuel atomization in engine combustion chambers
• Urea injection for NOx emission control
• Non-Newtonian viscous slurry atomization

Turbomachinery flows

• Oil jet-gear interaction in high performance gears of geared turbofan aircraft engines
• Oil flow in engine bearing chambers of aircraft engines
• Oil supply to engine bearing chambers of aircraft engines

Method development

• Multiphase contact angle and surface tension effects in SPH
• Spatial adaptivity in SPH
• Vortex dynamics in SPH
• High performance computing with SPH

Other topics

• High pressure homogenization
• Manufacturing process of discontinuously reinforced fiber composites
• Charge change of a piston engine
• Cooling, lubrication and transportation in machining processes