Combustion engineering

Formaldehyde-LIF images of the ignition of two n-Decane droplets of 0.8 mm diameter at 5 bar, 700 K, 4 mm distance. From left: t = 0; t = 340 ms cool flame burning; t = 342 ms hot ignition in the upper right position; t = 344 ms hot flame consumes the formaldehyde; t = 346 ms hot ignition of the upper droplet; t = 350 ms hot burning of both droplets

The research activities of the Combustion Engineering group deal with application oriented fundamental questions. Experiments under microgravity conditions are one, but not the only important tool to answer those questions. To support the development of future gas-turbines of the aero-propulsion type and for electric power generation of the lowest possible emissivity regarding environmentally harmful nitric oxides, we examine the self-ignition behavior of droplets and sprays at high temperature and high pressure. 

The underlaying gas-turbine concept is the lean-prevaporized-premixed (LPP) strategy. It turned out, that the same knowledge is applicable to future internal combustion engine concepts operated in a so called homogeneous-charge-compression-ignition mode (HCCI). Microgravity experiments on single droplet ignition as well as on droplet pair ignition support this aim. The overall goal is the development of a numerical code to simulate spray autoignition in an arbitrary environment of high pressure and temperature and realistic flow conditions. The experiments applying cutting edge laser diagnostics are to validate the simulation results.

This kind of research is directly related to the development of simplified model fuels for numerical simulation of the ignition of fossil- as well as of bio-synthetic fuels.

Our research on acoustic phenomena in ignition and combustion has led to the development of sound absorbing ceramic heat shields e.g. for gas-turbine application.

In the area of space related fire safety research, ZARM is aiming for new material qualification standards that can represent space fires far better than the actual ground based test methods can do.

Hybrid rocket propulsion is easier, cheaper and safer. The present deficit concerns lower regression rates compared to solid fuels. Our research tries to improve the regression rate of hybrid rockets, keeping the specific impulse high.