AM Heat Exchangers + Severe Vibration = Contamination?

Conference Abstract: This work examines AM liquid flow through Heat Exchangers’ (HEX) propensity to contaminate an aircraft’s cooling system. The Northrop Grumman team hypothesized that flight-like conditions cause AM HEX to shed contaminant indefinitely and consistently. To investigate our hypothesis, we studied nine unique HEX geometries and evaluated the impact of two precleaning regimes. Test units were subjected to six hours of severe vibrational load (23g RMS) while coolant exiting the AM HEX was sampled for contamination. Contaminant emission was observed to be continuous but follow a logarithmic trend. Additionally, the quantity of mass emitted from the AM HEX was far below our ‘magnitude of concern’. This presentation covers Northrop Grumman Mission Systems' approach to cleaning parts and the observed contaminant emission behavior of AM HEX under a severe vibrational load. Additionally, the presentation explores techniques to quantify emission behavior and determine maximum allowable contaminant emission. Finally, a perspective is offered on how the question of AM HEX cleanliness impacts further adoption of AM technology.