Experimental and numerical analysis of hovering multicopter performance in low-Reynolds number conditions

Unmanned Aircraft Systems (UAS) are state of the art in the aerospace industry and are involved in many operations. Although initially developed for military purposes, commercial applications of small- scale UAS, such as multicopters, are abundant today. Accurate engineering tools are required to assess the performance of these vehicles and optimize power consumption. The thrust and power curves of the rotors used by small-scale UAS are essential elements in designing efficient aircraft. The scarcity of experimental data and sufficiently accurate prediction models to evaluate rotor aerodynamic performance in the flight envelope are primary limitations in UAS science. In addition, for small-scale rotors at usual rotation rates, chord-based Reynolds numbers are typically smaller than 100,000, a flow regime in which performance tends to degrade. In this paper, experimental data on small-scale multicopter propulsion systems are presented and combined with a Computational Fluid Dynamics (CFD) model to describe the aerodynamics of these vehicles in low Reynolds numbers conditions. We use the STAR-CCM+ software to perform CFD simulations adopting both a dynamic-grid, time-accurate analysis and a static-grid, steady- state technique that solves the Navier-Stokes equations in a suitable framework. Comparing numerical simulation results on a conventional UAS propeller with related experimental data suggests that the proposed approach can correctly describe the thrust and torque coefficients in the range of Reynolds numbers characterizing the UAS flight envelope

Measurements of radioactivity in the environment for radiation protection purposes

Measurements of radioactivity in the environment, according to Article 35 of the Euratom Treaty, are routinely carried out by regulatory bodies and operators in charge. These activities are performed both locally and nationally, in order to assess effective doses to the population. In this context, therefore, it is necessary not only to determine the component due to external irradiation, but also to evaluate the deposit and accumulation of radioactivity in the environment that can reach the public via inhalation or ingestion. The contribution presents a brief description of the aspects regarding programs of monitoring and evaluation of the radioactivity in the environment, in particular the environmental matrices to be monitored, the analyses to be carried out, the related reporting levels as well as the features concerning the influence of the climate on the variations of dose rate values. Finally, a focus on some radiometric measurements performed over the last forty years in the environmental monitoring activities carried out in the ENEA Casaccia Research Center (Rome), in which two nuclear research facilities are currently operating, is presented