Photophoretic lift for carbon-nanotube-coated polyester film: A combined numerical and experimental approach

The photophoretic effect is considered a potential mechanism for generating lift and enabling long-duration flight in the mesosphere. The most prominent photophoretic effect occurs during the transition regime. However, developing a reliable model and accurately quantifying the photophoretic lift remains a significant challenge. In this study, we directly measure the photophoretic lift through conducting takeoff acceleration tests on polyester films coated with carbon nanotubes. By integrating experimental data with direct simulation Monte Carlo (DSMC) simulations to obtain the thermal accommodation coefficient, we develop an accurate semi-analytical model for predicting the photophoretic lift. The result shows an error of less than 10% compared with experimental measurements. Additionally, we use the model to analyze the effects of ambient pressure, surface thermal accommodation coefficient, and sample characteristic dimensions on the photophoretic lift. This study provides valuable insights into the photophoretic mechanism and has profound implications for the design of future photophoretic-based flight vehicles.