bluuebunny/crossref_metadata_2025_split huggingface dataset:
Design of a morphing leading edge as a high lift device for a regional aircraft
Authors: Contell Asins C , Landersheim V , Wacker J-D , Adachi S , Arnold-Keifer S , May M 
Published: January 2021

Abstract
Morphing technologies can provide a significant contribution to reduction of noise and fuel consumption for future aircraft. In the framework of the European Aviation research programme Clean Sky 2, a design of a morphing leading edge was developed, which allows the simultaneous increase of wing chord and camber to adapt the airfoil to different airspeed conditions. The final design has a sliding contact at the bottom, whereas the upper surface is continuous with variable camber. In contrast to classical high lift devices, the lift coefficient can be increased without adding sources for turbulences at the upper wing surface. CFD analyses have been performed in order to quantify the aerodynamic performance of the designed morphing leading edge. Furthermore, a design concept both for the skin and for the actuation system is presented. The skin is designed using carbon fiber reinforced plastics (CFRP). In order to achieve both the required stiffness and flexibility, a customized non-constant layup is developed. Its feasibility for the high deformations during morphing is demonstrated by means of both numerical analysis and experimental validation. The electro-mechanical actuation system is designed to completely fit inside the morphing leading edge while still considering space for other subsystems. Besides the space requirements also weight, mountability and bird strike aspects are taken into account. Altogether, for the overall design of a morphing system is presented in this paper, various design challenges are highlighted and appropriate solutions for these challenges are discussed.
Cooling system design for the internal combustion engine of a BWB UAV prototype
Authors: Alexiou E , Dimitriou S , Dimopoulos T , Paliaikos D , Panagiotou P , Yakinthos K 
Published: January 2021

Abstract
The current study presents an analytical design methodology for a compact thermal management system (cooling system) of a high-power density internal combustion rotary engine. The engine is installed on a fixed wing, tactical Blended-Wing-Body (BWB) Unmanned Aerial Vehicle (UAV) prototype that has been developed for the aerial delivery of cargo and lifesaving supplies. The design methodology is based mainly on a low-fidelity thermodynamic model and on high-fidelity Computational Fluid Dynamics (CFD) analyses. The results are validated against wind tunnel experiments for the cooling system of the engine. The overall methodology is divided into two distinct segments, the design of the heat exchanger (HEX) and the sizing of the cold-air inlet ducts. The low-fidelity thermodynamic model is based on 0D and 1D textbook methods and well-established formulae from the existing literature. The thermodynamic model is used for the calculation of the geometrical characteristics of the HEX. The high-fidelity CFD modeling is employed to yield a more detailed investigation of the flow field around the HEX and provide information about whether the airflow velocity requirements, for the 0D and 1D model, are met. Additionally, the detailed CFD computations assist the design of high-efficiency inlet ducts, in order to secure optimal airflow through the HEX and around the engine compartment. Using the proposed methodology, a functional HEX experimental prototype is designed and manufactured, as a proof of concept, in order to be thoroughly examined on a test rig in laboratory conditions. Multiple experiments are conducted in a variety of inlet temperatures and airflow velocities, for the validation and fine-tuning of the overall proposed design methodology. The study concludes with the final HEX design, as well as an analysis of its integration aspects on the tactical BWB UAV prototype.
Aerodynamic and stability analysis of a VTOL flying wing UAV
Authors: Bliamis C , Zacharakis I , Kaparos P , Yakinthos K 
Published: January 2021

Abstract
The stability analysis of an aerial vehicle is an of great importance integral part of its design procedure. It is of even greater importance in the case of tailless aircraft, which are prone to stability issues. In the present study, the aerodynamic and stability characteristics of a Vertical Take-off and Landing (VTOL) fixed wing Unmanned Aerial Vehicle (UAV), designated as MPU RX-4, are investigated. The MPU RX-4 has a flying wing layout and is capable of performing, both conventional flight, like a regular fixed wing aerial vehicle, as well as vertical hovering, like a multicopter, adapting on different operational demands and achieving rapid field deployment. In this study, the preliminary design phase of the MPU RX-4 is presented and the aerial vehicle’s aerodynamic performance, as well as, its stability and control behavior are assessed using both semi-empirical correlations, specifically modified for lightweight flying wing UAVs, and Computational Fluid Dynamics (CFD) analyses. These correlations are employed to estimate the non-dimensional aerodynamic coefficients for various flight conditions (e.g. cruise, loiter, maximum speed, etc.) of the MPU RX-4 flight envelope. Furthermore, the correlations are validated with dedicated CFD analyses in order to assure their level of accuracy. Finally, the MPU RX-4 stability and control derivatives, and the required control surfaces deflection for steady level flight are computed, in order to assess its overall aerodynamic performance and flight characteristics.
Multidisciplinary design of the wing for aircraft preliminary design purposes
Authors: Hospodár Pavel , Drábek Armand 
Published: January 2021

Abstract
In this paper, an aerodynamic and wing structure is investigated by low-fidelity methods. Bell-shaped lift distribution was rediscovered in the last decade as a perspective alternative to traditional wing design. This leads to lower aerodynamic drag than elliptical lift distribution for a given lift force and root bending moment. Root bending moment is used as a surrogate model of wing structure weight. It is relatively raw simplification introduced by Prandtl to estimate the weight of the spar as a main part of the wing structure. For a more accurate wing weight estimation, the main parts of the wing are dimensioned under CS-23 regulation in this work. The design procedure starts with defining the elementary parameters of the wing shape (chord/twist distribution, wingspan). After geometry generating a non-linear lifting line is used to calculate aerodynamic characteristics for all regime, determined from the flight envelope. The dimensions of a spar, ribs and skin are calculated in the next step of the procedure for given bending moment, load and torque moment distribution. The structure of the wing is assumed as a two-spar, manufactured by aluminum. A target of design is to find out the shape of the wing for given weight. The solution is verified by CFD calculation.
Analysis of fuselage skin reinforcements with beam element models in flexible aircraft panels for ditching simulations
Authors: Muñoz C Leon , Kohlgrüber D , Langrand B 
Published: January 2021

Abstract
This paper is dedicated to the use of beam element models for skin structural reinforcements in guided ditching simulations with a flexible aircraft panel. This approach was analysed by means of finite element simulations of the structure subjected to a constant pressure load and guided ditching loading conditions. To verify this approach, finite element models of different discretization types and different mesh sizes were considered in the computations. Moreover, guided ditching simulations were enhanced by comparisons with the coupled Finite Element-Smoothed Particle Hydrodynamics and the Arbitrary Lagrangian Eulerian methods.
Advanced materials and technologies for compressor blades of small turbofan engines
Authors: Pavlenko Dmytro , Dvirnyk Yaroslav , Przysowa Radoslaw 
Published: January 2021

Abstract
BACKGROUND: Manufacturing costs, along with operational performance, are among the major factors determining the selection of the propulsion system for unmanned aerial vehicles (UAVs), especially for aerial targets. OBJECTIVES: In this paper, the design requirements and operating parameters of small turbofan engines for single-use and reusable UAVs are analysed to introduce alternative materials and technologies for manufacturing their compressor blades, such as sintered titanium, a new generation of aluminium and an alloy based on titanium aluminides. METHODS: To assess the influence of severe plastic deformation (SPD) on the hardening efficiency of the proposed materials, the alloys in the coarse-grained and submicrocrystalline states were studied. Changes in physical and mechanical properties of materials were taken into account. The thermodynamic analysis of the compressor was performed in a finite element analysis system (ANSYS) to determine the impact of gas pressure and temperature on the aerodynamic surfaces of compressor blades of all stages. RESULTS: Based on thermal and structural analysis, the stress and temperature maps on compressor blades and vanes were obtained, taking into account the physical and mechanical properties of advanced materials and technologies of their processing. The safety factors of the components were established based on the assessment of their stress-strength reliability. Thanks to nomograms, the possibility of using the new materials and the technologies was confirmed in view of the permissible operating temperature and safety factors of aerofoils. CONCLUSIONS: The proposed alternative materials and production technologies for the compressor blades and vanes meet the design requirements of the turbofan at lower manufacturing costs.
The ACONIT project: an innovative design approach of active flow control for surge prevention in gas turbines
Authors: Dazin A , Joseph P , Romano F , Gallas Q , Marty J , Aigouy G , Stôβel M , Niehuis R 
Published: January 2021

Abstract
The objective of the ACONIT project is to design, manufacture and test actuators for flow control for an implantation in an aircraft engine. The actuators will fulfil aeronautics requirement in order to increase the Technology Readiness Level (TRL) in this domain. In particular, for the present proposal, one plans to focus on the extension of the stable operating range of axial compressor, allowing thus a reduction of the surge margin through postponing the stall onset. To do so, the first objective of the work is to improve the knowledge of the flow physics of an efficient flow control system by joint numerical and experimental analyses performed in a low speed, single stage axial compressor. The results of this analysis will be used to derive the fluidic specifications for high-TRL actuators and control systems. These specifications will be the base for the design and manufacturing of amplified piezo-electric actuator prototypes whose fluidic performance and operational performance in an environment with vibration and controlled level of temperature will be precisely evaluated before manufacturing final actuators that will be integrated in a full-scale engine test facility. Their performance will be evaluated in terms of Surge Margin Improvement (SMI) as well as in terms of energy balance between the induced consumption and the machine performance improvements. The consortium grouped for carrying out this project is composed of a SME (CTEC), two academic institutions (Bundeswehr University Munich and ENSAM) and a Research Centre (ONERA). It groups skills ranging from internal flow analysis in turbomachinery, to flow control or actuators design, manufacturing and characterisations.
Thermal Management challenges for HEA – FUTPRINT 50
Authors: Affonso Walter , Gandolfi Ricardo , dos Reis Ricardo Jose Nunes , da Silva Carlos Roberto Ilário , Rodio Nicolas , Kipouros Timoleon , Laskaridis Panagiotis , Chekin Andrei , Ravikovich Yury , Ivanov Nikolay , Ponyaev Leonid , Holobtsev Dmitry 
Published: January 2021

Abstract
Electric and Hybrid-Electric Aircraft (HEA) incorporate new systems, which demand an integration level higher than classical propulsion architectures systems do. High power electrical motors, converters, batteries or fuel cells, and distributed propulsion, all introduce new kinds of heat sources and dynamics that have to be accounted for and regulated. The latent opportunity to explore synergies among these systems requires the development of new models and their coupling with multi-disciplinary design optimization (MDO) toolchains. Also, an understanding of the implications into aircraft operations and trade-offs are critical to evaluate and validate gains at the aircraft level. This paper provides a definition of thermal management and functions of thermal management system (TMS) in aircraft, HEA thermal management challenges, main opportunities, conclusions and the way forward. A discussion of road ahead, regarding development of capabilities to support the design of TMS will be brought to the fore along the project, showcasing the open approach of FUTPRINT50 to be driven by open collaboration in order to accelerate the entry into service of this type of aircraft.
Safety and Certifiability Evaluation of Distributed Electric Propulsion Airplane in EASA CS-23 Category
Authors: Jézégou Joël , Sufyan Umair 
Published: January 2021

Abstract
Distributed Electric Propulsion (DEP) is one of the unconventional airplane architectures of interest in the quest for decreasing aviation environmental footprint. This configuration integrates strong and innovative couplings between systems and aircraft design disciplines. To address limitations of the traditional approach for certification and of the associated means of compliance when certifying innovative products, the European Union Aviation Safety Agency (EASA) issues in 2017 a novel certification philosophy that relies on high-level objective-based safety requirements. In this context, this paper presents a safety and certifiability evaluation of DEP airplane in EASA CS-23 category, with a methodology for aircraft-level safety assessment during preliminary design, a certification gap analysis with regards to existing means of compliance, and some proposals to clear the certification path for DEP configuration.
Economically driven requirements for a hybrid-electric 19-passenger commuter aircraft
Authors: Schuh G , Spangenberg M , Zhang Q 
Published: January 2021

Abstract
The appeal of reduced travel and transport times and electrification of aircraft drive the development of new aircraft for short distances. The goal of the CleanSky2 project ELICA (ELectric Innovative Commuter Aircraft) is to provide a preliminary design of a hybrid-electric 19-passenger commuter aircraft, whereby the passenger limit is defined by certification. This paper describes the initial set of Top Level Aircraft Requirements (TLARs) based on both a benchmark with existing 19-passenger commuter aircraft and the analysis of requirements derived from potential future markets Regional Air Mobility (RAM) and thin-haul air cargo services. Both of these are introduced briefly. A literature-based framework for TLARs and an analysis of existing airfield infrastructure in Europe and the US together with population data in the direct surroundings of such airfields are investigated. Additionally, insights on cabin design are discussed and important features such as noise emissions and operational cost of such aircraft are highlighted.
Validation of the simulation tool for environmentally friendly aircraft cargo fire protection system
Authors: Pathak A. , Norrefeldt V. 
Published: January 2021

Abstract
One of the objectives of CleanSky-2 project is to develop an Environmentally Friendly Fire Protection (EFFP) system (halon free fire suppression system) for the aircraft cargo hold. For this, an Aircraft Demonstrator including the cargo hold has been equipped with a nitrogen suppression system. The demonstrator is located in the Flight Test Facility low pressure vessel and can thus be subjected to realistic cruise pressure conditions and take-off and descent pressure variations. As a design tool, a zonally refined simulation model to predict the local oxygen and nitrogen concentration distribution in the cargo hold has been developed using the Indoor Environment Simulation Suite (IESS). The model allows for fast transient simulations of the suppression system operation. This paper presents a model validation case of a knockdown during cruise, followed by a holding phase and descent (repressurization of the cargo hold).
Effect of increased cabin recirculation airflow fraction on relative humidity, CO2 and TVOC
Authors: Norrefeldt Victor , Mayer Florian , Herbig Britta , StrÖhlein Ria , Ivandic Ivana , Wargocki Pawel , Lei Fang 
Published: January 2021

Abstract
In the CleanSky 2 ComAir study, subject tests were conducted in the Fraunhofer Flight Test Facility cabin mock-up. This mock-up consists of the front section of a former in-service A310 hosting up to 80 passengers. In 12 sessions the outdoor/recirculation airflow ratio was altered from today’s typically applied fractions to up to 88% recirculation fraction. This leads to increased relative humidity, carbon dioxide (CO2) and Total Volatile Organic Compounds (TVOC) levels in the cabin air, as the emissions by passengers become less diluted by outdoor, dry air. This paper describes the measured increase of relative humidity, CO2 and TVOC level in the cabin air for the different test conditions.
Diagnostics of Electro-Mechanical Actuators Based Upon the Back-EMF Reconstruction
Authors: Quattrocchi G , Berri P C , Vedova Dalla M D L , Maggiore P 
Published: January 2021

Abstract
Electrical systems are gradually replacing the more traditional hydraulic and pneumatic solutions for the transmission of secondary energy for onboard aircraft equipment. Therefore fault detection and health management strategies properly conceived for electrical devices are becoming a highly relevant topic for research and development in the aerospace disciplines. One possible practical implementation of these methodologies would be the identification of parameters for diagnostic and prognostic monitoring, which are highly sensitive to incipient faults but, at the same time, are less influenced by operating conditions (external loads, command input, temperatures, etc.). In this paper, the authors evaluated the effectiveness of counter-electromotive force (back-EMF) coefficient as a prognostic parameter, emphasizing a novel sampling approach that significantly lower the computational effort required while maintaining a good back-EMF coefficient curve reconstruction. The approach is virtual sensor-like, using only already available data for the correct operation of the BLDC motor. The proposed method was tested by evaluating the back-EMF coefficient reconstruction as a function of some progressive failures typical of EMA motors, such as inter-turn partial shorts and rotor static eccentricity. Its robustness to external disturbances has been tested by evaluating different actuation commands and operating conditions. As expected, the back-EMF signal shows a marked dependence on the considered failure modes and, at the same time, a suitable insensitivity to the other external factors.
A Team Allocation Decision for Aircraft Fleet Maintenance
Authors: Pereira D P , Melicio R , Mendes V M F 
Published: January 2021

Abstract
This paper is about a computer application for planning maintenance of aircraft fleet in what regards allocation of skilled technicians. The formalization for this planning is a mathematical programming problem written as a minimizing one. The decision variables are the allocation of the skilled technicians. The data are the number of available technicians, the working hours needed to accomplish maintenance, the costs due to the daily operation of facilities, and due to the fleet downtime. Although, the formalization is of a non-linear integer-programming problem, a transformation of variables from positive integer ones to Boolean ones is conceivable and allows a reformulation as a pure integer linear programming problem. Also, a relaxation of the integer variables to continuous ones allows for a relaxed formulation as a convex non-linear programming problem. A case study of two fleets illustrates both formulations: solved by the pyomo library calling the GLPK for the pure linear integer programming problem and calling solvers in Scipy library for the relaxed formulation. An inference presented about the results of the case study addresses the issue of using nonlinear programming to emulate the solution of linear integer programming.
Development of an autonomous power supply for oil and gas fields based on a gas turbine unit driven by an active-reactive turbine
Authors: Bazykin D A , Barakov A V 
Published: January 2021

Abstract
The relevance of the task lies in the development of an autonomous source of electrical power for oil and gas fields, significantly remote from power lines and the necessary infrastructure. An autonomous source is made on the basis of a gas turbine unit driven by an active-reactive turbine, which fuel is associated petroleum, low-pressure, untreated natural gas without preliminary preparation. The developed installation does not require frequent maintenance, the consumption of lubricants, preliminary preparation of fuel gas, and has relatively small overall dimensions. Atmospheric air is used as a working fluid while working surfaces are not subject to pollution. The work provides information on mining equipment, which must be continuously supplied with electric energy, on the currently available analogs of the developed device and their shortcomings. A diagram of the proposed gas turbine installation is given, its structure and principle of operation are described. Information about the developed equipment is given. Preliminary calculations of the main parameters are made, the results are shown.
Investigation of gas-sensitive properties of cobalt oxide films
Authors: Bespoludin V V , Polyakov V V , Petrov V V , Nesterenko A V , Vakulov Z E 
Published: January 2021

Abstract
This paper presents a study of the gas-sensitive properties of cobalt oxide films formed by rapid thermal annealing on a sitall substrate. Cobalt films were formed on a pre-cleaned sitall substrate by vacuum thermal evaporation. The thickness of the deposited films was 470 nm. Rapid thermal annealing (RTA) was used to form cobalt oxide films. RTA of cobalt films was carried out at temperatures of 500°C, 600°C and 700°C. The resistivity of the films after RTA at 500°C, 600°C and 700°C was 3.6 × 10–2 Ohm·cm, 1.2 × 103 Ohm·cm and 5.8 × 103 Ohm·cm, respectively. The surface morphology of the obtained films was investigated by the AFM method. The gas sensitivity of cobalt oxide films was studied for gases like CO, NO2, CH4, C3H6O (vapors of acetone), C3H8O (vapors of isopropyl) and NH3·H2O (vapors of ammonium hydroxide 25%). The gas sensitivity was measured at 300°C. The results of gas sensitivity measurements showed significantly lower sensitivity to gases such as CO, NO2 and CH4. It was found that cobalt oxide films have good sensitivity to gases such as C3H6O, NH3·H2O and C3H8O. Sensitive elements based on cobalt oxide films are interesting as gas sensor elements for the detection of C3H6O, NH3·H2O and C3H8O.