ISSN Online: 2688-7231
ISBN Online: 978-1-56700-524-0
Proceedings of the 26thNational and 4th International ISHMT-ASTFE Heat and Mass Transfer Conference December 17-20, 2021, IIT Madras, Chennai-600036, Tamil Nadu, India
Investigation of Thermal Contact Conductance Across Pressed Bi-Metallic Aerospace Joints at Low Temperature
Many low temperature applications require bimetallic joints and heat transfer through such joints are critical for the system design. The mechanical properties of the joining materials vary at low temperature which in turn influences the thermal contact conductance (TCC). The experimental evaluation of TCC across bi-metallic joints formed with aerospace alloys namely AA 2219, AISI 321 and Ti6Al4V are taken up in vacuum, which are subjected to sub MPa contact pressure. The influence of temperature and contact pressure is investigated in all three bimetallic joints in 150 K to 300 K range with contact pressure between 140 kPa to 700 kPa. The study reveals that the thermal contact conductance of the bimetallic joints is mainly controlled by the softer material. It is also controlled by factors like differential contraction as well as mechanical properties of specimens and change in geometry of the mating surfaces. The loading is found to be effective in joints with soft materials like aluminium. Improvement up to 90 % in thermal contact conductance is observed for aluminium joints at low temperature with contact pressure changes from 140 kPa to 700 kPa. Change in temperature from 150 K to 300 K enhances thermal contact conductance by 35 %.