2/20/2017 4 min read
SungWoo Nam and Nenad Miljkovic.MechSE assistant professors Nenad Miljkovic and SungWoo Nam were granted Young
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SungWoo Nam and Nenad Miljkovic.
The ONR Young Investigator Program identifies and supports young academic scientists and engineers in tenure-track appointments and who show exceptional promise for doing creative research.
Miljkovic’s proposal, “Durable Multi-Functional Surfaces for Low and High Surface Tension Fluid Phase Change Heat Transfer,” will be under ONR’s Ship Systems and Engineering Research division.
Miljkovic will study multifunctional nanoengineered surfaces to manipulate fluidic and heat transport processes for robust and long-lasting high-performance thermal management solutions that utilize both high (water) or low (refrigerant) surface tension fluids. Thermal management is a critical bottleneck for the advancement of a variety of important naval defense systems. Phase-change based microfluidic systems promise compact solutions with high-heat removal capability. However, challenges in implementation lead to poor heat transfer performance in both the evaporator and condenser. More recently, multifunctional nanoengineered surfaces have been developed that can significantly enhance the stability and performance of these systems using thin film evaporation, dropwise and jumping-droplet condensation. Although proven in lab scale environments, the wide spread utilization of these surfaces has not been successful due to their poor durability. To successfully implement these phase-change based approaches, the first critical step is obtaining the fundamental understanding of the complex degradation mechanisms on such surfaces with a range of working fluids having high and low surface tensions. Preliminary investigations by Miljkovic have identified that functional coating degradation as well as environmental interactions during vapor-to-liquid phase-change governs nucleation behavior and must be well understood in order to enhance long-term durability. The outcomes of his proposed work will make important contributions to basic science, and provide a necessary first step to advance the area of high-performance thermal management and enable new capabilities for defense and commercial systems.
Nam’s project, “Energy Harvesting, Structural Monitoring Sensor Based on Corrugated Atomically-thin Semiconductors,” is under the Naval Materials division, and part of its Non-Destructive Evaluation and Prognostics: Advanced Sensors and Technologies Program.
The development of distributed, self-powered, and maintenance-free integrated structural health monitoring systems is crucial to the next generation of defense technologies. Nam said he envisions miniaturized systems that will be able to provide real-time, stand-off diagnostics and prognostics information and better inform (sub)system states to enhance performance and extend system life cycles. Nam proposes to understand fundamental flexoelectric properties of emerging corrugated two-dimensional (2D) materials and further to explore their applications to high-performance sensing of strain, vibration, and force/acceleration, all in a distributed and wireless manner. He will investigate flexoelectricity of corrugated atomically-thin MoS2 to enhance the ultimate device strain limit and achieve higher levels of energy harvesting to allow for completely self-powered, active structural health monitoring, and stand-off wireless transmission of data. MoS2 is ideal because it can withstand orders of magnitude higher strain gradient via generation of out-of-plane three-dimensional (3D) buckling and wrinkling topographies. The combination of a powerful flexoelectric potential and ability to simultaneously sense small strains while withstanding large deformations as a feature of 3D corrugated structures will yield a material platform for compact, reliable, and efficient structural health monitoring devices.
Miljkovic and Nam were also two of the four faculty from MechSE to receive prestigious NSF CAREER awards in 2016.