Spring 2020 Physics Colloquium

Thursday, April 30th

"Using 3D Printing Techniques for Prototyping Absorbers for Solar Air Heaters"
presented by Olivia Young '20 and Rachel Krewson '20

This paper examines how 3D-printing techniques can be used to prototype new solar air heater absorber designs.  We consider four factors when designing the new absorbers: how well they absorb light, how well they transfer heat to the air, the cost to create them, and if it is feasible to 3D-print them.  We focus on the light absorption properties of the new absorbers and test these properties in stagnation temperature experiments.  In this study we derive how the temperature of the absorbers increase.  We provide detailed explanations of the heat losses for each absorber as well as the view factor calculations to determine the IR radiative losses.  We found that absorbers with fewer flat surfaces and a large surface area have the best view factors, as they only lose between 10% and 15% of the IR radiation they emit to the glazing.  While 3D-printing is a good technique for prototyping the new absorbers, it is not a viable option for creating large scale absorbers as the time required to 3D-print them would be much too long.  Additive manufacturing is an excellent tool to optimize existing absorber designs and to explore absorber designs that have heretofore not been considered.

“Using Schlieren Optics To Visualize Ultrasonic Standing Waves In Acoustic Levitation”
presented by Ming Hua Chang '20

Schlieren optics refers to an imaging system that allows for the visualization of density changes in air; this is most striking due to the ability to image both temperature and sound. Acoustic levitation is the phenomenon wherein a standing sound wave can be used to levitate small objects. Theory on acoustic levitation has been subject to recent debate due to the subtleties involved in the process. The objective thus, is to verify the properties of standing waves experimentally. Since schlieren imaging and acoustic levitation both involve density changes, they naturally complement each other in this endeavor. Using a tripartite approach, involving a visual analysis, pressure measurements of the wave and schlieren imaging, we conclusively establish the properties of standing sound waves.

Noon
Presented via Zoom https://zoom.us/j/94706797828
Meeting ID: 947 0679 7828

Wednesday, May 6th
Departmental Meeting with Majors

12:30pm EDT
Via zoom (email hamiltoc@dickinson.edu for zoom link)