The next speakers in our student seminar series will be Aslan Farjam and Guillaume Archambault . Aslan and Guillaume will be giving a talk entitled “Influence of Alumina Addition to Aluminum Fins for Compact Heat Exchangers Produced by Cold Spray Additive Manufacturing” and “Lay-up Moulding of a Carbon Fiber Reinforced Polymer Composite on a Cold Sprayed Metallic Layer”, respectively.
Where: CBY D207
Date: Wednesday June 11th, 2014
The abstracts of the talks are given below. Hope to see you all there!
****After the seminars, coffee and doughnuts will be served in CBY-A218 (courtesy of uOMEGA)****
Candidates: Aslan Farjam and Guillaume Archambault
Supervisor: Dr. Bertrand Jodoin
In this work, different percentages of pure aluminum and alumina (ceramic) powder mixtures were deposited through wire mesh masks on an aluminum substrate to produce pyramidal array of fins using cold spray technology. Using aluminum-alumina powder mixtures instead of pure aluminum powder to produce net-fin shapes could have many valuable properties, such as being cost-effective, and having useful nozzle clogging prevention properties during cold spray. Heat transfer and pressure drop tests were carried out using different ranges of applicable Reynolds numbers to compare each coating mixture and heat transfer capability. Numerical simulations were performed to model the fluid dynamics of the flow interaction, heat transfer, and pressure drop in each sample. Experimental measurements matched with the numerical calculations. The results indicate that by increasing the percentage of alumina in the aluminum-alumina powder mixture resulted in only a small variation in heat transfer of pyramidal fins. Furthermore, the numerical results open up new avenues in predicting other possible powder mixtures and fin shapes using numerical models.
The aerospace industry is continually investigating innovative techniques to increase flying efficiency. As a consequence of innovation, the cost of flying will be reduced; as the aircraft’s mechanical performance improves. To achieve an important weight reduction, the fuselage of aircrafts like The Boeing Company’s 787 ‘‘Dreamliner’’ is mainly made of carbon fiber based composites. By offering a low material specific strength-to-weight ratio, carbon fiber reinforced composites are state of the art materials for the aerospace industry.
The in-flight concern of having the aircraft subjected to lightning is an ongoing problem for the safety of the crew and passengers. In the event of lightning striking the fuselage, localized melting of the composite will commonly occur, as the medium is highly resistive. While melting the composite, the electrical current will dissipate through a specially designed embedded metallic mesh located below the carbon fiber composite. Consequently, after landing, the airplane will be out of service until the molten area is repaired. As of today, a solution to prevent localized melting of the composite is to rivet heavy metallic plates on the components prone to lightning.
To resolve weight issues arising from heavy riveted plates, it would be practical to deposit thin layers of conductive material on the surface of the carbon fiber based composite. Unfortunately, operating temperatures in conventional thermal spray processes would degrade the carbon fiber based composites. For instance, a new innovative technique, combining Cold Gas Dynamic Spray and lay-up moulding of composites, would enable production of metallic coated carbon fiber based composites.The present study presents a description of the experimental approach used to develop metallic coated composites while showing the manufacturability of such components. Technical barriers, such as obtaining a low resistivity metallized composite and producing an easily removable metallic layer from the mould during lay-up moulding, are essential for the production of such aerospace materials. The results produced in the University of Ottawa Cold Spray Laboratory showed that composites of various shapes, low porosity, high conductivity and easily removable from the metallic mould were possible to produce.