Elucidating the True Role of Surface Microtexturing in Friction Reduction and Enhanced Convective Heat Transfer

点击翻译按钮获取中文摘要

The goal of this project is to elucidate the role that surface microtexturing (roughness) has on friction reduction and convective (flow-based) heat transfer. Understanding flow behavior and heat transfer interactions with microtexturing will have significant impact on the general area of superhydrophobic (water repelling) surfaces, particularly for friction reduction and thermal management purposes. The results of this research should have major implications for microscopic flow systems used in electronics cooling and portable biochemical diagnostics applications, as well as larger scale flow systems used in climate control and power generation applications. This project also provides new classroom materials for courses that the researchers teach as well as outreach activities geared towards elementary school audiences. An undergraduate summer internship program aimed Northeastern University freshmen and sophomores from groups that are underrepresented in STEM fields is being established to prepare them for future careers in engineering. The governing physics behind the flow within surface microgeometry for different wetting degrees, gas-liquid interface immobilization, and Re conditions is being studied and analyzed. A multi-task research program is in place that includes thermo-hydraulic and optical diagnostics characterization of microtextured samples, numerical simulations of single and two-phase flow with different boundary conditions, and microgeometry optimization of the microtexturing. The project is comprised of the following specific thrusts: (1) Development of an experimental infrastructure to characterize pressure-flow rate behavior, slip velocity, fluid/wall temperature, and wall heat flux for different wetting and thermal conditions. These results are being validated against numerical simulations and analysis; (2) Assessment of the friction reduction characteristics of the microtextured samples under varying degrees of wetting due to pressure and temperature effects, and under different degrees of gas-liquid interface immobilization; and (3) Characterization of friction reduction on the convective heat transfer of the microtextured microchannels, addressing the tradeoffs between reduced thermal diffusion in the gap space and enhanced thermal advection due to the friction reduction brought about by said gap spaces.