Structure, Dynamics, and Function of Materials and Processes for Transport Technologies

Imaging for materials sciences at IPS is concerned with 'real-world' materials and processes for transport technologies. Using ultrafast X-ray cinetomography combined with in situ & operando environments we develop hierarchical, multiscale characterization methods for applications in automotive and aerospace fields. Topics of current materials imaging research at IPS include:

Synchrotron radiation-computed laminography (SRCL) acquires projection data sets similar to synchrotron computed tomography (SRCT), but it uses an inclined rotation axis at an angle θ < 90° instead of being perpendicular to the incoming beam (see figure). This makes SRCL suitable for 3D imaging of laterally extended (i.e. in the sheet directions perpendicular to the rotation axis) specimens. 

 

The cooperation project LAMBDA applies SRCL to investigate the three-dimensional (3D) imaging of the microstructure inside flat sheet specimens evolving during material testing under such non-proportional loads.

 

Hypersonic re-entry of spacecraft into a planetary atmosphere introduces extreme loads on thermal insulation materials. Typically, there is a balance between the dimensioning of such thermal protection systems and the safety margins required for efficient flight design. Low density ablative TPS materials potentially provide signifcantly improvements to efficiency in insulation during high speed flights such as Moon return or Mars entry. 

 

In situ tomographic techniques provide time resolved information on the pyrolysis layer propagation, pore evolution, fibre shape etc. However, it is difficult, if not impossible, to combine a large scale high enthalpy facility with X-ray tomography. In the present study, a portable high enthalpy facility has been designed in DLR Stuttgart and used for proof-of-principle tomography experiments at the KIT synchrotron.

 

In modern gasoline direct injection engines, the fuel is (partially) superheated for a significant proportion of the time during operation. This means that the vapour pressure of the fuel, or at least of many of its components, is higher than the ambient pressure inside the engine during injection. If the excess fuel enthalpy cannot be removed by evaporation at the free surface of the spray, the liquid phase boiling creates new surfaces. This phenomenon is known as flash boiling. Flash-boiling atomization produces smaller droplets and can therefore be beneficial as an additional atomization mechanism. 

 

Within the project PN-Reduktion we employ high-speed X-ray radiography and shadowgraphy to characterize the physical development of fuel spray during its development and to correlate these data with flow-simulation models. For this a purpose-built mobile spray-injector chamber with an integrated high-speed camera setup will be realised.