Scientists working for the Institute of Combustion Technology at the Stuttgart-based German Aerospace Center, also known as the DLR, are developing new laser-based methods to investigate combustion processes in gas turbines. Their progress may help reduce the dangers associated with hydrogen-rich blends, which could destroy a turbine’s combustion chamber. Research and development in this field will be crucial to the success of Germany’s energy transformation. The mixtures make it possible to store surplus energy from intermittent renewable sources in the national pipeline system, from where it can be reconverted into power through gas turbines. Perfecting the technology could mark a major milestone in cutting carbon dioxide emissions and stabilizing the electrical grid.
Isaac Boxx and his team stand behind a large window pane made of fused quartz, observing a flame burning on the other side of the room. Several instruments analyze the green laser beam passing through the test rig. New equipment, developed to allow for rapid measurements at high time resolution, helps to keep track of the entire process. The scientists intend to improve the laser-based method further. “The human eye wouldn’t be able to identify the fluctuations in the turbulent flame,” Boxx says. The rig, designed to closely resemble real-world operation, is thought to change all of that. The Stuttgart-based laboratory is one of only a few facilities in the world to have the equipment and the know-how to even attempt these kinds of experiments.
Ten years have passed since Boxx started his research into gas combustion at the DLR. He is the manager of the project Hyburn, a short acronym for a rather long title: Enabling Hydrogen-Enriched Burner Technology for Gas Turbines through Advanced Measurement and Simulation.
The combustion processes he and his team observe happen in the span of milliseconds. To make them visible at all and aid in understanding what goes on inside the chamber, the new system delivers 10,000 frames per second. Boxx points out that it provides a highly accurate picture of both the flame structure and the flow field.
Software to analyze combustion patterns
The data from these laser-based measurements serves as a basis for simulating combustion processes that can be analyzed in detail on a computer. “The software application we developed is perfect for studying the impact of a higher percentage of hydrogen on flame behavior,” Boxx says, cheeringly. His project is being supported with what the European Research Council calls a consolidator grant, to support researchers who excel in their fields. In this case, the grant total is about EUR 2 million over five years.
Hyburn’s role in Germany’s energy transformation cannot be overstated. In late 2017, the proportion of electricity produced from renewable sources across the country added up to more than 33.1 percent, according to preliminary estimates by the German Energy and Water Industries Association. Wind and solar systems had contributed 217 billion kilowatt-hours to the total, nearly enough eco-power to achieve the federal government’s 2020 target of 35 percent. Their numbers, however, need to rise significantly if renewable energies are to make up between 80 percent and 95 percent of Germany’s electricity production by 2050 at the latest.
Written by Niels Hendrik Petersen