Transient Analysis of Four-Layer Natural Materials in Thermal Cloaking Performance

Abstract

This thesis investigates the thermal cloaking and shielding performance in a thermal cloak from transient to steady state The thermal cloak design is relatively simple and the materials are common natural materials To better match the analytical requirement for anisotropic heat conductivity and inhomogeneous product of density and specific heat capacity the proposed thermal cloak uses four layers In order to study the transient thermal cloaking performance the temperature distribution differences among the designed cloak bilayer cloak and the background were first compared by defining specific parameters and conducting computer simulation to allow a quantitative comparison In addition to numerical analysis experiment was carried out using an infrared camera to measure the temperature distribution and the results were verified with the simulation The simulation results show that during most of the transient evolution the four-layer cloak has a lower temperature difference between the maximum and minimum value on the measuring lines than that for the bilayer cloak Also the average temperature on the measuring lines is closer to the background temperature without cloak for the four-layer cloak compared to the bilayer cloak Hence the transient performance of the four-layer cloak is better than the bilayer cloak Finally the performance of the designed four-layer cloak were assessed using a transient figure of merit based on the difference between the transient average temperature in the cloaked region and the initial temperature Both numerical and experimental result demonstrate the effectiveness of cloaking area a relatively long period compared to the case without cloak

Date of Award	2019
Original language	English
Supervisor	Ruey-Jen Yang (Supervisor)