Turbulence - Spray Interactions

A primary research goal of the Emmy Noether project (GEPRIS) is to extend the fuel flexibility of auto-ignition-stabilised combustion processes (e.g., MILD, FLOX, distributed combustion) to liquid renewable chemical energy carriers. Such combustion concepts already offer excellent flexibility, scalability, and low pollutant emissions (especially NO_X and soot) when operated with gaseous fuels. When utilizing CO₂-neutral liquid fuels (e.g., Sustainable Aviation Fuels - SAF), these technologies can achieve nearly emission-free operation. The inherent high aerodynamic forces of the gas phase flow present an opportunity to optimize liquid fuel atomization and generate a fine droplet spray over a wide operational range. This enhances vaporisation rates, reduces mixture homogenisation timescales, and thereby maximises the potential of auto-ignition-stabilized combustion for minimal pollutant formation.

In this context, we investigate the influence of turbulence on primary breakup, transport, vaporisation, and mixture formation. For this purpose, we have developed canonical spray flow and combustion test rigs capable of simulating relevant conditions of auto-ignition-stabilized combustion processes. Our research test rigs can be equipped flexibly with academically simplified (e.g., jet-in-crossflow, planar wall films) and technically relevant (e.g., pressure-swirl and prefilming airblast) injection concepts. We employ various optical and laser-based measurement techniques for our experimental investigations.The research program addresses the following questions:

1. Influence of turbulence on primary breakup of different injection concepts. We deliberately modulate the turbulence of the gas phase flow, e.g., using fractal grids and swirlers, with the objective of suppressing or exciting disturbances on the liquid surface to favour atomization into the smallest possible droplets. This project is currently ongoing.
2. The chemical composition of renewable synthetic fuels affects their physical properties such as viscosity and surface tension, which significantly influences their atomization. To explore this relationship, we use various conventional and synthetic (SAF) fuels as well as reference fuels (e.g., n-dodecane) and systematically investigate the impact of physical fuel properties on spray quality for different injection concepts. This project is currently ongoing.
3. In addition to chemical composition, fuel temperature has a significant influence on viscosity and surface tension, favouring the vaporisation process and potentially accelerating mixture homogenisation. In this context, we vary the preheating temperature of fuels from room temperature to supercritical injection. This project is currently being initiated.
4. The influence of vaporisation, especially in high-turbulence (and convective) flows with multi-component (real) fuels, on mixture formation with focus on emissions formation.
5. The influence of ambient conditions, such as pressure and temperature, on atomization, mixture formation, auto-ignition-based flame stabilisation, and emissions formation in turbulent reacting multiphase flows with high Karlovitz number.

01.01.2022 – 31.12.2027

If you are interested in our project, have further questions, or would like to support us through student work, internships, or thesis projects, we would be delighted to hear from you via email or phone. Contact details can be found below.