Recovery of release cloud from laser shock-loaded graphite and hydrocarbon targets: in search of diamonds

This work presents first insights into the dynamics of free-surface release clouds from dynamically compressed polystyrene and pyrolytic graphite at pressures up to 200 GPa, where they transform into diamond or lonsdaleite, respectively. These ejecta clouds are released into either vacuum or various types of catcher systems, and are monitored with high-speed recordings (frame rates up to 10 MHz). Molecular dynamics simulations are used to give insights to the rate of diamond preservation throughout the free expansion and the catcher impact process, highlighting the challenges of diamond retrieval. Raman spectroscopy data show graphitic signatures on a catcher plate confirming that the shock-compressed PS is transformed. First electron microscopy analyses of solid catcher plates yield an outstanding number of different spherical-like objects in the size range between ten(s) up to hundreds of nanometres, which are one type of two potential diamond candidates identified. The origin of some objects can unambiguously be assigned, while the history of others remains speculative

Recovery of release cloud from laser shock-loaded graphite and hydrocarbon targets: in search of diamonds

This work presents first insights into the dynamics of free-surface release clouds from dynamically compressed polystyrene and pyrolytic graphite at pressures up to 200 GPa, where they transform into diamond or lonsdaleite, respectively. These ejecta clouds are released into either vacuum or various types of catcher systems, and are monitored with high-speed recordings (frame rates up to 10 MHz). Molecular dynamics simulations are used to give insights to the rate of diamond preservation throughout the free expansion and the catcher impact process, highlighting the challenges of diamond retrieval. Raman spectroscopy data show graphitic signatures on a catcher plate confirming that the shock-compressed PS is transformed. First electron microscopy analyses of solid catcher plates yield an outstanding number of different spherical-like objects in the size range between ten(s) up to hundreds of nanometres, which are one type of two potential diamond candidates identified. The origin of some objects can unambiguously be assigned, while the history of others remains speculative

The Effect of Engine Location on the Aerodynamic Efficiency of a Flying-V Aircraft

The Flying-V is a novel flying wing concept where the main lifting surface has been fully integrated with the passenger cabin. This study focuses on the effect of engine positioning on aerodynamic interference under regulatory and structural constraints. An initial benchmark for the lift-to-drag ratio is obtained from a baseline Flying-V configuration, and the influence of the x, y and z position, as well as engine orientation are subsequently analysed. An Euler solver on a three-dimensional, unstructured grid is used to model the flow at cruise condition: M = 0.85, h = 13, 000 m, α = 2.9 ◦, and a thrust per engine of 50 kN. The viscous drag contribution is computed using an empirical method. A total of forty different engine locations are tested under these conditions to build a surrogate model that predicts the aircraft’s lift-to-drag ratio based on the position of the engine. The results obtained show that misplacing the engine can lead to significant lift-to-drag ratio losses going as high as 55% when compared against the ideal integration configuration. A region behind the airframe’s trailing edge is identified where the interference losses due to the installation are minimized. At this location, engine installation causes a 10% penalty in aerodynamic efficiency, a minimum one-engine-inoperative yawing moment and a small thrust-induced pitching moment. Flight Performance and Propulsio