MAAT system design – weight model of very large lighter-than-air vehicle

Paper presented to the 10th International Conference on Heat Transfer, Fluid Mechanics and Thermodynamics, Florida, 14-16 July 2014.The main objective of this paper is to provide a realistic weight model, based on the physical-mathematical foundations, for the design of the new very large lighter-than-air vehicle, called Multibody Advanced Airship for Transport (MAAT), the ongoing European FP7 project, which is currently under intensive research and development activities. The Modeling and Simulation (M&S) principles, aided with simulations and visualization tools, have been extensively used, as the key enablers to combine, manage and structure such highly complex engineering process, which emerged as a natural integration mechanism and evidence provider of the encountered complexity, successfully encompassing the MAAT multidisciplinary design requirements. The authors experience, in solving the M&S problems, gained within the European R&D projects, was efficiently reused, where the use of such software technologies have been successfully demonstrated, and today, further applied for the new generation transportations solutions, as envisaged by MAAT, especially addressing the best practices in taking advantage of the variety of multi-physics software and their related analysis tools. The MAAT system is envisaged to be composed of two airships: the Cruiser, which stays at a constant altitude of 16 km, travelling horizontally; and the Feeder, which acts like an elevator system connecting the Cruiser to the ground. In this paper, the proposed weight model is similar to the typical one applied in the aircraft design process. The main difference is primarily the airship teardrop shape, which is commonly applied for the currently produced airships. The main challenge is that MAAT has a very large shape, which has required the introduction of new elements and references, as being presented in this work. The achieved results show that MAAT can be realized, by taking into account the significant weight estimated for such aircrafts, to be for the Cruiser about 533 tons, while the Feeder weight is about 12 tons. As highlighted before, the MAAT design is still under intensive developments, and thus, it is expected that in the coming years, by taking into account the new emerging technological solutions, the lightening of such aircrafts structure is inevitable. In addition, the authors plans are to further investigate new materials and their related applications, in order to improve the structural part of the MAAT system, as one of the essential parts in such new transportation system, expected to become the reality in the forthcoming future.cf201

Heat generation mechanisms of DBD plasma actuators

During the last twenty years DBD plasma actuators have been known by their ability for boundary layer flow control applications. However, their usefulness is not limited to this application field, they also present great utility for applications within the field of heat transfer, such as a way to improve the aerodynamic efficiency of film cooling of gas turbine blades, or de-icing and ice formation prevention. Nevertheless, there is a relative lack of information about DBD’s thermal characteristics and its heat generation mechanisms. This happens due to the extremely high electric fields in the plasma region and consequent impossibility of applying intrusive measurement techniques. Against this background, this work describes the physical mechanisms behind the generation of heat associated to the DBD plasma actuators operation. An experimental technique, based on calorimetric principles, was devised in order to quantify the heat energy generated during the plasma actuators operation. The influence of the dielectric thickness, as well as the dielectric material, were also evaluated during this work. The results were exposed and discussed with the purpose of a better understanding of the heat generation mechanisms behind the operation of DBD plasma actuators

A new aircraft architecture based on the ACHEON Coanda effect nozzle: flight model and energy evaluation

Purpose Aeronautic transport has an effective necessity of reducing fuel consumption and emissions to deliver efficiency and competitiveness driven by today commercial and legislative requirements. Actual aircraft configurations scenario allows envisaging the signs of a diffused technological maturity and they seem very near their limits. This scenario clearly shows the necessity of radical innovations with particular reference to propulsion systems and to aircraft architecture consequently. Methods This paper presents analyses and discusses a promising propulsive architecture based on an innovative nozzle, which allows realizing the selective adhesion of two impinging streams to two facing jets to two facing Coanda surfaces. This propulsion system is known with the acronym ACHEON (Aerial Coanda High Efficiency Orienting Nozzle). This paper investigates how the application of an all-electric ACHEONs propulsion system to a very traditional commuter aircraft can improve its relevant performances. This paper considers the constraints imposed by current state-of-the-art electric motors, drives, storage and conversion systems in terms of both power/energy density and performance and considers two different aircraft configurations: one using battery only and one adopting a more sophisticated hybrid cogeneration. The necessity of producing a very solid analysis has forced to limit the deflection of the jet in a very conservative range (±15°) with respect to the horizontal. This range can be surely produced also by not optimal configurations and allow minimizing the use of DBD. From the study of general flight dynamics equations of the aircraft in two-dimensional form it has been possible to determine with a high level of accuracy the advantages that ACHEON brings in terms of reduced stall speed and of reduced take-off and landing distances. Additionally, it includes an effective energy analysis focusing on the efficiency and environmental advantages of the electric ACHEON based propulsion by assuming the today industrial grade high capacity batteries with a power density of 207 Wh/kg. Results It has been clearly demonstrated that a short flight could be possible adopting battery energy storage, and longer duration could be possible by adopting a more sophisticated cogeneration system, which is based on cogeneration from a well-known turboprop, which is mostly used in helicopter propulsion. This electric generation system can be empowered by recovering the heat and using it to increase the temperature of the jet. It is possible to transfer this considerable amount of heat to the jet by convection and direct fluid mixing. In this way, it is possible to increase the energy of the jets of an amount that allows more than recover the pressure losses in the straitening section. In this case, it is then possible to demonstrate an adequate autonomy of flight and operative range of the aircraft. The proposed architecture, which is within the limits of the most conservative results obtained, demonstrates significant additional benefits for aircraft manoeuvrability. In conclusion, this paper has presented the implantation of ACHEON on well-known traditional aircraft, verifying the suitability and effectiveness of the proposed system both in terms of endurance with a cogeneration architecture and in terms of manoeuvrability. It has demonstrated the potential of the system in terms of both takeoff and landing space requirements. Conclusions This innovation opens interesting perspectives for the future implementation of this new vector and thrust propulsion system, especially in the area of greening the aeronautic sector. It has also demonstrated that ACHEON has the potential of renovating completely a classic old aircraft configuration such as the one of Cessna 402

SAE 2013 AeroTech Congress & Exhibition Unmanned Aerial Systems - Propulsion (Session Code: ATC1402)

This session discusses UAV propulsion systems development and performance. All propulsion systems will be considered, from solar to fuel cell, to turbine. Propulsion alternatives for small airborne vehicles will be also discussed. Reliability, performance, and integration of existent UAV propulsions technologies will be addressed. New engine technology, new designs, or even new fundamental research and propulsion concepts are also of interest

Mathematical model of a constructional coanda effect nozzle.

This paper analyses the ACHEON Coanda effect nozzle for aircraft propulsion, based on the dynamic equilibrium of two jet streams. The ACHEON concept, and, in particular, the HOMER nozzle, which is its main component, are presented, together with the literature milestones from which the idea originally stems. A subsystem analysis inspired by the principles of Constructal Theory is presented for the current architecture. A mathematical model of a 2D case of the system is developed, focusing on the combined effect of the mixing of the two streams and the Coanda adhesion over a convex surface. A validation of the model is also reported, based on 2D CFD analyses, under the hypothesis of incompressible flow. Results highlight that, in spite of its relative simplicity, the model produces accurate results.ACHEON Project | Acheon Project - Aerial Coanda High Efficiency Orienting-jet Nozzle project, with ref. 309041 supported by the European Union through the 7th Framework Programm

Numerical modeling of coanda effect in a novel propulsive system

Coanda effect (adhesion of jet flow over curved surface) is fundamental characteristics of jet flow. In the present paper, we carried out numerical simulations to investigate Coanda flow over a curved surface and its application in a newly proposed Propulsive system "A.C.H.E.O.N" (Aerial Coanda High Efficiency Orienting jet Nozzle) which supports thrust vectoring. The ACHEON system is presently being proposed for propelling a new V/STOL airplane in European Union. This system is based on cumulative effects of three physical effects such as (1) High speed jet mixing speeds (2) Coanda effect control by electrostatic fields (3) Coanda effect adhesion of an high speed jet to a convex surface. The performance of this nozzle can be enhanced by increasing the jet deflection angle of synthetic jet over the Coanda surface. This newly proposed nozzle has wide range of applications. It can be used in industrial sector such as plasma spray gun and for direct injection in combustion chamber to enhance the efficiency of the combustion chamber. Also, we studied the effect of Dielectric barrier discharge (DBD) plasma actuators on A.C.H.E.O.N system. Dielectric barrier discharge (DBD) plasma actuators are active control devices for controlling boundary layer and to delay the flow separation over any convex surfaces. Computations were performed under subsonic condition. Two dimensional CFD calculations were carried out using Reynolds averaged Navier stokes equations (RANS). A numerical method based on finite volume formulation (FVM) was used. SST k-ω model was considered to model turbulent flow inside nozzle. DBD model was used to model the plasma. Moreover, a body force treatment was devised to model the effect of plasma and its coupling with the fluid. This preliminary result shows that, the presence of plasma near Coanda surface accelerates the flow and delays the separation and enhances the efficiency of the nozzle

Experimental analysis of dielectric barrier discharge plasma actuators thermal characteristics under external flow influence

Dielectric barrier discharge (DBD) plasma actuators have several applications within the field of active flow control. Separation control, wake control, aircraft noise reduction, modification of velocity fluctuations, or boundary layer control are just some examples of their applications. They present several attractive features such as their simple construction, very low mass, fast response, low power consumption, and robustness. Besides their aerodynamic applications, these devices have also possible applications within the field of heat transfer, for example film cooling applications or ice formation prevention. However, due to the extremely high electric fields in the plasma region and consequent impossibility of applying classic intrusive techniques, there is a relative lack of information about DBDs thermal characteristics. In an attempt to overcome this scenario, this work describes the thermal behavior of DBD plasma actuators under different flow conditions. Infra-red thermography measurements were performed in order to obtain the temperature distribution of the dielectric layer and also of the exposed electrode. During this work, we analyzed DBD plasma actuators with different dielectric thicknesses and also with different dielectric materials, whose thermal behavior is reported for the first time. The results allowed to conclude that the temperature distribution is not influenced by the dielectric thickness, but it changes when the actuator operates under an external flow. We also verified that, although in quiescent conditions the exposed electrode temperature is higher than the plasma region temperature, the main heat energy dissipation occurs in the dielectric, more specifically in the plasma formation region

An insight into the coanda flow through mathematical modeling

The mechanism of the Coanda flow is investigated. One should not neglect the viscous effect as it also affects the boundary layer. The effect of viscous is discussed in detail at the vicinity of the curved surface. Incorporation of set of boundary conditions gave the set of solutions which can be the case of dual jet and or turbulent jet flow. A nature of turbulent length scales was discussed and can be the source of the subgrid scale modeling, which will be performed in the next level of this research