Aerotecnica Missili & Spazio最新文献

The Aerospace Program at the Malta College of Arts, Science and Technology (MCAST) is a research and development program that focuses on addressing challenges in the aerospace industry, in particular, but not exclusively, in the field of protection of aerospace structures and systems from space debris impacts. This paper provides a comprehensive overview of the program, including five main projects currently under development. The first project presents a collaboration between MCAST and the University of Padova to develop a single-stage Light-Gas Gun impact facility in Malta, with operational ranges which could be complementary to other impact laboratories in Europe. The second project focuses on the study of 3D-printed Kevlar shields for aerospace applications; the outcome of this project will be the development of repair strategies for aviation structures and efficient novel small satellite shields. The third project addresses the issue of fragmentation of brittle materials for aerospace following a hypervelocity impact. The fourth project presents MCAST's participation in Malta's third space bioscience experiment, led by the University of Malta, the experiment investigated how microgravity affects the behavior of foot ulcer microbiomes in Type 2 Diabetes Mellitus patients. Finally, the paper discusses the ASTROBEAT project, that will be on board of the International Space Station, marking a significant milestone for the MCAST aerospace program; the project results from a collaboration with the South East Technological University (SETU), Ireland, and aims to explore the application of the cold-welding phenomenon for spacecraft repair. It will lead to the development of an experimental test rig to apply custom repair patches of different materials to pre-damaged metallic structures and monitor its performance. The projects presented in this paper reflect MCAST's commitment to contribute to the advancement of the aerospace industry and offer new opportunities for research, development, and commercialization. Furthermore, the importance of the MCAST Aerospace Program is relevant since Malta in 2024 will upgrade its status in the framework of the ESA Plan for European Cooperating States (PECS).

We present FLEW, an in-house high-fidelity solver for direct numerical simulation (DNS) of turbulent compressible flows over arbitrary shaped geometries. FLEW solves the Navier–Stokes equations written in a generalized curvilinear coordinate system, in which the surface coordinates are non-orthogonal, whereas the third axis is normal to the surface. Spatial discretization relies on high-order finite-difference schemes. The convective terms are discretized using an hybrid approach, combining the near-zero numerical dissipation provided by central approximations with the robustness of weighted essentially non-oscillatory (WENO) schemes, required to capture shock waves. Central schemes are stabilized using a skew-symmetric-like splitting of convective derivatives, endowing the solver with the energy-preserving property in the inviscid limit. The maximum order of accuracy is eighth for central schemes (also used for viscous terms discretization) and seventh for WENO. The code is oriented to modern high-performance computing (HPC) platforms thanks to message passing interface (MPI) parallelization and the ability to run on graphics processing unit (GPU) architectures. Reliability, accuracy and robustness of the code are assessed in the low-subsonic, transonic and supersonic regimes. We present the results of several benchmarks, namely the inviscid Taylor–Green vortex, turbulent curved channel flow, transonic laminar flow over a NACA 0012 airfoil and turbulent supersonic ramp flow. The results for all configurations proved to be in excellent agreement with previous studies.

This work presents the development of an OpenFOAM solver aimed at correctly predicting dynamics of concentrated suspensions when subjected to non-uniform shear flows. The newly implemented solver is able to predict the behavior of a heterogeneous mixture whose characteristics depend on the solid particle local concentration. To simulate such behavior, the conservation equation expressing the time variation of the particle volume fraction has been implemented in OpenFOAM; this was achieved by modifying a pre-existing solver, pimpleFoam, which discretizes the Navier–Stokes system of equation through the PIMPLE algorithm. As a first step, the formulation of the momentum equation has been adapted to correctly solve cases with non-Newtonian fluids. Successively, the Krieger’s correlation has been used to model the viscosity variation in the domain to take in account heterogeneous particle distributions. Finally, the iterative cycle for the solution of the migration equation has been included within the time loop. The above-mentioned code has been successfully validated by comparing the numerical results with the measured data provided by experiments reported in literature.

This paper presents BEA (Buoy Eau Air), an innovative multi-unmanned vehicle system to address the issue of marine traffic endangering scuba diving and free diving. Scuba diving is a popular recreational activity with over 6 million active participants worldwide. Boat drivers may fail to recognize universal markers due to a variety of factors, such as inattention, unfamiliarity with dive zones, or poor visibility. In addition, some boat drivers may deliberately speed too close to dive zones, unaware of the dangers they pose to divers. This risk is particularly pronounced in popular dive destinations like Malta, where boat traffic can be heavy. Divers in these areas are often more vulnerable to collisions. To mitigate these risks, the proposed system consists of an Unmanned Aerial Vehicle (UAV), an Unmanned Surface Vehicle (USV), and an Unmanned Underwater Vehicle (UUV), which work in synergy to monitor and protect divers. The UAV monitors the surface of the sea near the dive zone for any traffic, while the USV tracks the UUV, communicates with the other unmanned vehicles, and provides a takeoff/landing surface for the UAV. The USV can also be used to tow divers and equipment to and from the shore. Finally, the UUV tracks the diver and warns them if it is unsafe to surface. The paper provides an overview of the system’s design and architecture, as well as algorithms for boat detection, precision landing, and UUV tracking. Preliminary tests on a prototype have shown that the system is suitable for the intended application. The BEA system is the first in the world to use a multi-drone system to create a geo-fence around the diver and monitor the area within it. This has the potential to significantly improve diver safety with real-time alerts, providing also assistance with navigation, towing of divers and emergency response.

This research describes a near-optimal feedback guidance, based on nonlinear orbit control, for low-thrust Earth orbit transfers. Lyapunov stability theory leads to proving that although several equilibria exist, only the desired operational conditions are associated with a stable equilibrium. This ensures quasi-global asymptotic convergence toward the desired final orbit. The dynamical model includes the effect of eclipsing on the available thrust, as well as all the relevant orbit perturbations, such as several harmonics of the geopotential, solar radiation pressure, aerodynamic drag, and gravitational attraction due to the Sun and the Moon. Near-optimality of the feedback guidance comes from careful selection of the control gains. They are identified in two steps. Step (a) is an extensive table search in which the gains are changed in a large interval. Step (b) uses a numerical optimization algorithm that refines the gains found in (a), while minimizing the time of flight. For the numerical simulations, two scenarios are defined: (i) nominal conditions and (ii) nonnominal conditions, which arise from orbit injection errors and stochastic failures of the propulsion system. For case (i), gain optimization leads to obtaining numerical results very close to those corresponding to a known optimal orbit transfer with eclipse arcs. Moreover, for case (ii), extensive Monte Carlo simulations demonstrate that the nonlinear feedback guidance at hand is effective in driving a spacecraft from a low Earth orbit to a geostationary orbit, also in the presence of nonnominal flight conditions.

EFESTO-2 is an EU-funded project under Horizon Europe that aims to enhance European expertise in Inflatable Heat Shields (IHS). Building on the achievements of the previous EFESTO project (H2020 funds No 821801), EFESTO-2 focuses on advancing key IHS technologies to increase their Technology Readiness Level (TRL). The project pillars include analysing the business case for IHS applications, exploring additional aspects of IHS, improving tools and models and establishing a development roadmap for IHS systems. This paper outlines the project objectives and plan, highlighting ongoing and future activities for the next 2 years, positioning it within the European re-entry technology roadmap. This project has received funding from the European Union's Horizon Europe program (grant agreement No 1010811041).

The recent success of the Ingenuity Mars helicopter developed by the jet propulsion laboratory (JPL) demonstrated the feasibility of the Martian flight. Low pressure (660 Pa) and temperature (210 K) characterize the ground-level Martian atmosphere. Since such conditions are difficult and expensive to mimic on Earth, it is necessary to have reliable simulation tools that can correctly reproduce Martian aerodynamics. In the case of unmanned aerial systems (UAS), the latter is characterized by a high subsonic Mach number at the tip of the blades and an Ultra-low Reynolds number regime ((1000< hbox {Re} < 10000)). To this purpose, the laminar solver embedded in the commercial CFD code STAR CCM+ was validated by reproducing experiments carried out in the Martian Wind Tunnel at Tohoku University using a triangular airfoil wing at Reynolds 3000 and a Mach number of 0.5. Simulations are performed at angles of attack ranging from 0 to 16 degrees showing a satisfactory agreement with experimental results for very different flow conditions.