Tribochemical Transformation of Nano iO₂ to Ilmenite on the Surface of Wearing Steel Parts: Antiwear Action of Nano TiO₂ as an Additive in Engine Oil

<div><p></p><p>TiO₂ nanoparticles of average size about 20-30 nm were hydrothermally synthesized from TiCl₄ under mild acidic conditions. The nanoparticles were mixed with dispersant and base oil to give partially transparent concentrate having 1.5Wt% of Ti content. The concentrate was dispersed in hexane and base oil to characterize, respectively by electron microscopy (TEM) and DLS (Dynamic light scattering). The concentrate was diluted with base oil to have ppm level of Ti containing dispersion blends which were evaluated for wear and friction control performance. Nano TiO₂ containing fully formulated oil blend has shown excellent load bearing capability in SRV test. Four ball test result shows WSD (wear scar diameter) considerably reduced to 0.30 mm for TiO₂ added blend compared to neat base oil (0.60mm). The performance of TiO₂ added blend was comparable to secondary ZDDP (zinc dialkyl dithiophospate) added blend under identical condition. Raman spectrum of the worn surface on the tested ball revealed the presence of ilmenite (FeTiO₃) and no deposits of pure TiO₂.</p></div

Synthesis of Aero-Propulsive Interaction Studies Applied to Conceptual Hybrid-Electric Aircraft Design

This paper presents a synthesis of aero-propulsive interaction studies performed at Delft University of Technology, applied to conceptual aircraft designs with distributed hybrid-electric propulsion (DHEP). The studied aero-propulsive interactions include tip-mounted propulsion, wing leading-edge distributed propulsion and boundary-layer ingestion, combined with different primary propulsion-system arrangements. This paper starts with a description of the applied design framework and an overview of the aero-propulsive interactions. Subsequently, the different aircraft configurations are sized for a set of top-level requirements covering the range between regional turboprop to typical narrow-body turbofan aircraft. Results indicate that lower shaft power ratios show better performance, with the unoptimized DHEP concepts showing values of maximum take-off mass (MTOM) and payload-range energy efficiency (PREE) comparable to their reference aircraft. It was shown that beyond 20% shaft power ratio, the PREE decreases and MTOM increases much more than between 10% and 20%, indicating a possible local optimum between these values since even lower values did not yield any significant improvements. The benefits of tip-mounted propulsion are found to be constrained by the propeller blade tip Mach number in this particular analysis for the selected reference blade loading distribution. At the high range case for Mach 0.5, it can be seen that the distributed propulsion systems show the largest improvement.Flight Performance and Propulsio