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Technical Paper

Numerical Analysis of a Cycloidal Rotor Under Diverse Operating Conditions and Altitudes

2019-09-16
2019-01-1872
The current paper deals with the numerical study of the downwash flowfield characteristics in a cycloidal rotor. In an aircraft equipped with this kind of thruster, the downwash flow plays significant role in different flight modes. The interaction of this downwash jet with ground in effective height levels is studied using CFD simulations. Several operating conditions like pitching oscillation angles, rotation speeds and height levels are all considered in this work. The results declare that close-ground operating states augments the efficiency of cyclorotor. The vertical and horizontal forces of a single blade is also analyzed in a complete cycloid in different operating conditions. A lead and lag in maximum and minimum extremes of force curves of a single blade cycloid is obtained while being subjected to different functional conditions.
Technical Paper

Hypersonic Flow Simulation Towards Space Propulsion Geometries

2019-09-16
2019-01-1873
This work aims to expand the applicability of an open-source numerical tool to solve hypersonic gas dynamic flows for space propulsion geometries. This is done by validating the code using two well-known hypersonic test cases, the double cone and the hollow cylinder flare, used by the NATO Research and Technology Organization for the validation of hypersonic flight for laminar viscous-inviscid interactions (D. Knight, "RTO WG 10 - Test cases for CFD validation of hypersonic flight," in 40th AIAA Aerospace Sciences Meeting & Exhibit, 2002). The Computational Fluid Dynamic (CFD) simulation is conducted using the two-temperature solver hy2Foam that is capable to study external aerodynamics in re-entry flows. In the present work the assessment of hy2Foam to solve hypersonic complex flow features with strong interactions including non-equilibrium effects was demonstrated.
Technical Paper

Energetic, Environmental and Range Estimation of Hybrid and All-Electric Transformation of an Existing Light Utility Commuter Aircraft

2018-10-30
2018-01-1933
Today it is necessary to face the energetic, environmental, and safety-related issues of a significant industrial sector such as aeronautic one. It is a marginal contributor to today global GHG emissions (less than 3%), In any case, the associated impacts grows with the increase of air traffic with annual rate 5%. Consequently, aviation will need to face four fundamental problems for the future: 1 the overall impact of aviation is expected to grow up to 10÷15% of global GHG emissions by 2050; 2 the emissions of pollutants by commercial aviation affects the fragile atmospheric layers in the low stratosphere; 3 the increasing age of the flying fleet deals with increasing maintenance and safety issues; 4 the dependence on fossil fuels relates to problems of geopolitical instability and consequence volatility of prices. Substantial innovations are expected for both reducing energy consumption and environmental impacts of aviation and reducing the age of the fleets.
Technical Paper

Safety Analysis of an Airship Which Loses Lifting Gas from the Hull

2018-10-30
2018-01-1954
This study investigates the physical phenomena that affect a high-altitude airship in the presence of lifting gas losses from the hull. General atmospheric thermodynamics and basic physical principles are adopted to describe the behavior of an airship with envelope failures that generate buoyant gas dispersion or depressurisation phenomena. Overpressure that could grant to maintain some controllability during a large part of the descent is assessed by mean of the thermodynamic model of the envelope in the presence of gas losses. Optimisation of the inflation parameters is provided and the conditions for avoiding dangerous crashes on the ground and the potential recovery of a damaged vehicle, people and its payload. In particular, the requirements for a slow depressurisation is computed by the equilibrium with the atmosphere and then how can it be possible to sustain controlled navigation are determined.
Technical Paper

A New VTOL Propelled Wing for Flying Cars: Critical Bibliographic Analysis

2017-09-19
2017-01-2144
This paper is a preliminary step in the direction of the definition of a radically new wing concept that has been conceived to maximize the lift even at low speeds. It is expected to equip new aerial vehicle concepts that aim to compete against helicopters and tilt rotors. They aim achieving very good performance at very low speed (5 to 30 m/s) by mean of an innovative concept of morphing ducted-fan propelled wing that has been designed to maximize the lift force. This paper presents an effective bibliographic analysis of the problem that is a preliminary necessary step in the direction of the preliminary design of the wing. A preliminary CFD evaluation allows demonstrating that the claimed results are in line with the initial expectations. According to the CFD, results it has been produced a preliminary energetic evaluation of the vehicle in a flying car configuration by EMIPS method.
Technical Paper

Control, Propulsion and Energy Assessment of a Spherical UAS for Low Speed Operations

2017-09-19
2017-01-2065
This paper presents a comparison between different hypotheses of propulsion of a spherical UAS. Different architectures have been analyzed assessing their specific aerodynamic, energetic, and flight mechanics features. The comparison has been performed assuming the robustness of flight control in different wind conditions, defining for each the specific operative ranges, mission profiles, and energy assessment. An effective energy assessment and comparison against a commercial UAS has been produced. Even if the paper considers a preliminary simplified configuration, it demonstrates clearly to be competitive against traditional quadcopters in a predefined reference mission.
Technical Paper

Multifunctional Unmanned Reconnaissance Aircraft for Low-Speed and STOL Operations

2015-09-15
2015-01-2465
This paper presents a novel UAS (Unmanned Aerial System) designed for excellent low speed operations and VTOL performance. This aerial vehicle concept has been designed for maximizing the advantages by of the ACHEON (Aerial Coanda High Efficiency Orienting-jet Nozzle) propulsion system, which has been studied in a European commission under 7th framework programme. This UAS concept has been named MURALS (acronym of Multifunctional Unmanned Reconnaissance Aircraft for Low-speed and STOL operation). It has been studied as a joint activity of the members of the project as an evolution of a former concept, which has been developed during 80s and 90s by Aeritalia and Capuani. It has been adapted to host an ACHEON based propulsion system. In a first embodiment, the aircraft according to the invention has a not conventional shape with a single fuselage and its primary objective is to minimize the variation of the pitching moment allowing low speed operations.
Technical Paper

Energy Self Sufficient Aircrafts Can Become Reality through New Propulsion Design Approaches

2015-09-15
2015-01-2484
This paper focuses on the key problem of future aeronautics: which relates on energy efficiency and environmental footprint on a scientific point of view. Reducing emissions and increasing the energy efficiency would be both a key element to propel the market and increase the diffusion of personal aerial transport against ground transportation. Novel vehicle concepts and systems will be necessary to propel this innovation which could revolutionize our way of moving. This paper approaches an energetic preliminary design of a vehicle concept which could fulfill this social and cultural objective. Low cost energy efficient vehicles, which could be suitable for personal use with a high economic efficiency and without needs of airports, seem actually a real dream. Otherwise, is it a feasible goal or a scientific dream? Otherwise, a design method based on first and second law and thermodynamic and constructal law could allow reaching those goals.
Technical Paper

Preliminary Implementation Study of ACHEON Thrust and Vector Electrical Propulsion on a STOL Light Utility Aircraft

2015-09-15
2015-01-2422
One of the best airplanes ever realized by the European Aircraft industry was the Dornier Do 28D Skyservant, an extraordinary STOL light utility aircraft with the capability to carry up to 13 passengers. It has been a simple and rugged aircraft capable also of operating under arduous conditions and very easy and simple maintenance. The architecture of this airplane, which has operated actively for more than 20 years, is very interesting analyzing the implementation of a new propulsion system because of the unusual incorporation of two engines, as well as the two main landing gear shock struts of the faired main landing gear attached to short pylons on either side of the forward fuselage. This unconventional design allows an easy implementation of different propulsion units, such as the history of different experimental versions allowed.
Technical Paper

Roto-Cycloid Propelled Airship Dimensioning and Energetic Equilibrium

2014-09-16
2014-01-2107
Rotocycloid propulsion presents interesting performance as a possible long-term alternative to helicopters in a far future. It will lead to increase the energy efficiency of VTOL vehicles. This paper focuses on optimization of an airship with the possibility up to 2000 h/year of photovoltaic propelled flight at a cruise speed about 20 m/s. This paper demonstrates the feasibility of this airship concept and presents a full dimensioning according to the CDE (Constructal Design for Efficiency) developed at University of Modena and Reggio Emilia. The proposed solution has been deeply analyzed and the analysis of performances has been presented. The results allow thinking to a novel class of vehicles designed specifically to take the maximum advantage by this propulsion method.
Technical Paper

Thermojet: An Old Idea Can Define a Novel Family of Jets

2013-09-17
2013-01-2205
This paper investigates the ancient idea of augmenting the thrust produced by a rotating fan by producing a thermal gradient by heating the outflow. Some of the pioneers of aeronautics have originally conceived this idea: the indirect jet (Bleriot Coanda Monoplane, 1910) and the “thermojet” (Caproni-Ciampini CC2, 1942). They were abandoned because of the better performances by traditional jets such as the ones developed in Germany and USA during 2nd World War. Antony Colozza (NASA), one of the modern fathers of high altitude airships, has recently proposed it again to be used on fuel cells powered airplanes and airships. Most fuel cells have a large thermal dispersion at high temperature (about 40%), but it could be possible to use it for heating the propulsive stream of high-speed air produced into ducted fan propulsive units.
Journal Article

Fire-safe Airship System Design

2012-02-29
2012-01-1512
This paper presents the new Hydrogen Fire-safe Airship system that overcomes the limitations present in previous airships designs of that kind, when considering their functioning at advanced operative position. Hydrogen is considered to be more effective than helium because of its low-cost production by hydrolysis, which process is nicely driven only by the photovoltaic energy. This paper presents a novel architectural concept of the buoyant balloon designed to increase the fire related safety, when applying hydrogen as the buoyant gas. The proposed buoyant volume is designed as a multi-balloon structure with a naturally ventilated shape, to ensure that hydrogen cannot reach the dangerous concentration level in the central airship balloon. This concept is expected to be the start of a novel hydrogen airship type, to be much safer than preceding ones.
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