Honors in Europe - getting to work:practical lessons for educators

This brochure is one of the results of the research project Honors in Europe at the Research Centre for Talent Development in Higher Education and Society at Hanze University of Applied Sciences Groningen in the Netherlands. It is based on the book Talent Development in European Higher Education – Honors programs in the Benelux, Nordic and German-speaking countries by Marca Wolfensberger, published in open access in 2015 at Springer Open. The book can be downloaded freely through www.honorsineurope.com. The brochure was prepared in cooperation with the European Honors Council (www.honorscouncil.eu)

In-situ particle sizing of agglomerates in aluminized solid composite propellants using digital inline holography (DIH)

Aluminized ammonium perchlorate composite propellants (APCP) form large molten agglomerated particles that can result in poor combustion performance and increased two-phase flow losses. Quantifying agglomerate size distributions is important for assessing these losses for different types of aluminum fuels that can help improve rocket performance. It is highly desirable to measure particle sizes in-situ using non-intrusive optical methods, rather than conventional particle collection, which can have large uncertainties. Regular high-speed microscopic imaging suffers from a limited depth of field. Digital inline holography (DIH) is an alternative approach that results in 3D information through numerical reconstruction. In this paper, DIH approach was used with two orthogonal viewing angles for simultaneous particle imaging and velocity measurements. Furthermore, two imaging speeds (4 Hz vs. 4,000 Hz) were compared to characterize biasing. DIH results were contrasted with high-speed visual imaging and conventional particle collection. All techniques were in agreement that ejected particles were larger than initial constituent particles. However, DIH allows for the acquisition of much less experimental data for statistically significant data sets when compared to videography and more accurately sizes agglomerates than particle collection. Low-speed DIH is found to be subject to biasing due to multiple counting of larger particles with slower velocities staying in the field of view. A model was employed to correct the velocity biasing was performed by adjusting the data based on size and velocity correlations. This was partially successful to reduce biasing of sizes for the low speed DIH data