bluuebunny/crossref_metadata_2025_split huggingface dataset:
Statistical analysis of sloshing-induced dissipative energy across a range of Froude numbers
Authors: Constantin L , Courcy J J De , Titurus B , Rendall T C S , Cooper J E 
Published: February 2022

AbstractFuel sloshing-induced damping is currently being studied extensively within the EU-funded SLOWD project as a means of passively reducing dynamic loads in aircraft wings. It is of interest to be able to determine which parameters have the greatest influence on the added damping from the sloshing motion. An uncertainty in the measured sloshing force has been observed when multiple consecutive and identical oscillation cycles are considered in sinusoidal excitation experiments, leading to variations in the measured energy dissipation. This current work considers liquid undergoing vertical sloshing motions for different fill level and excitation conditions (frequency and amplitude) leading to energy dissipation via several possible physical mechanisms. The sloshing dissipation is measured experimentally across a large number of excitation cycles and for each excitation amplitude, expressed in the form of Froude (Fr) numbers. Depending on the Fr number, distinct sloshing mechanisms dominate the dissipative effects and induce a particular variance across the identical cycles analysed. The sloshing-induced energy dissipation variation is quantified and correlated with different mechanisms depending on Fr number, helping to explain various non-stationary effects that are observed even in well-controlled experimental conditions. As well as improving the insights into the inherent dispersion nature of the studied phenomena, this research also establishes experimental characteristics suitable for future model validation and calibration.
The preliminary design of a scaled Composite UHBR Fan for a wind tunnel test campaign
Authors: Paletta N. , Flüh J. , Lindemann J. , Seume J. , Goessling J. , Friedrichs J. , Eggers T. , Russo S. , Natale N. , Vlachos D. , Mazarakos D. , Baltopoulos A. , Vavouliotis A. 
Published: February 2022

Abstract
The ambition of the CA3ViAR project is to design an open test case fan that experiences instability mechanisms, which are representative for ultra-high bypass ratio (UHBR) fans of civil aircrafts, and to perform a comprehensive experimental investigation to measure aerodynamic, aeroelastic and aeroacoustic performance in a wide range of operational conditions. Experimental tests will be performed in the Propulsion-Test-Facility (PTF) of the Institute of Jet Propulsion and Turbomachinery (IFAS) of Technische Universität Braunschweig, Germany. The final objective of the project is to provide an open test case for the entire research community, with geometries, numerical and experimental results to establish a new reference for composite UHBR fan design. This will support the development of new methods and tools for the development of safer, lighter and more efficient composite fans for greener UHBR engines. In this work the preliminary design of the low transonic fan (LTF) to be used as test article, whose main requirement is to be operated in a safe and controlled way in conditions of aerodynamic and/or aeroelastic instability during wind tunnel operations, is presented. More in particular, consolidated aerodynamic design, strategy adopted to drive the structural design, flutter analysis taking into account acoustic reflection at the intake, dynamic and stress analyses, as well as aeroacoustic measurement optimization are presented and discussed. The preliminary mechanical design of composite blades and the rotor hub, together with the rotor instrumentation and related studies to embed sensors in the composite blades, are also part of this article, and complemented by manufacturing trials and demonstration tests give the full picture of all the project activities up to the preliminary design review.
Algorithm for calculation design loading cases of perspective civil aircraft
Authors: Vedernikov D. V. , Dubovikov E. A. , Guseva N. V. 
Published: February 2022

Abstract
This paper presents a description of the algorithm that accelerates the search for design cases of loading the perspective airframe for civil aircraft, which differ from traditional layouts. The results of validation of the algorithm for a regional aircraft with a high aspect ratio wing are presented. It was shown that the use of the proposed algorithm makes it possible to reduce the calculation time for finding the critical loading factors by at least 10 times compared to the traditional algorithm.
A hybrid approach of machine learning and expert knowledge for projection of aircraft operability
Authors: Manikar Sagar Shenoy , Jézégou Joël , Saqui-Sannes Pierre de , Asseman Philippe , Benard Emmanuel 
Published: February 2022

Abstract
Aircraft operational performance is a key driving factor to flight punctuality and airline profitability. The ability of a system to meet its operational requirements in terms of reliability, availability and costs is termed as ’Operability’. It is of high importance for aircraft manufacturers to project operability during the early stages of development of an aircraft in order to make trade-off studies. This paper proposes a hybrid approach of using machine learning and expert knowledge to aid the projection of aircraft operational performance during the early design stages. This approach aims to benefit from the huge amount of in-service data available from the current and past fleet of aircraft. Hence, machine learning techniques are used to learn how different technical issues and their associated maintenance activities impact aircraft operations. Expert knowledge is used to establish the default rules of the simulation model used for the operability projection. Results from machine learning are used to improve these rules allowing one to make holistic projections of the operational performance of future aircraft. This approach allows one to estimate the elapsed time in different operational states of an aircraft like flying, turn-around, etc. which can then be used to calculate different operability Key Performance Indicators (KPIs) like aircraft reliability and maintenance unavailability.
Instrumentation and Ground Testing of a Composite Elastic Wing Wind Tunnel Model
Authors: Keimer Ralf , Giannaros Efthimis , Kilimtzidis Spyridon , Kotzakolios Athanasios , Kostopoulos Vassilis 
Published: February 2022

Abstract
The Goal of the Project GRETEL is to build a composite elastic wing wind tunnel model. This model incorporates morphing aerodynamical structures and is to be delivered for testing in the Large Low speed Facility (LLF) wind tunnel of DNW. In order to be allowed to be tested in a wind tunnel, a ground test is required to assure the integrity of the design of the wing. In this paper a short introduction to the overall setup of the model is given including an overview of integrated sensors. A short introduction into the different configurations of the wing to be tested is given as well as the rationale for the derived test-matrix of the ground tests. The mechanical setup for the ground tests is described. There are two main tests done, on the one hand the static tests of the wingbox, on the other hand the dynamic tests for determination of modal parameters of the model in its different configurations. The static tests are done to identify mechanical responses of the model as built and compare them to the predictions of the Finite Element simulations. The method to derive the boundary conditions, i.e. loads and deformations, for the static tests from the simulation is documented and discussed. The static tests are also used to calibrate the integrated strain gauges to enable load monitoring in the wind tunnel tests. First experimental results from the ground tests are shown and discussed, comparing them to predictions from the simulation.
Manufacturing, Assembly and Integration of a Large Scale Composite Wing Wind Tunnel Model and the Design and Implementation of an associated Measurement System
Authors: Baucke Jan , Steeger Stefan , Keimer Ralf 
Published: February 2022

Abstract
Building a wind tunnel model with an innovative aerodynamic design including a laminar airfoil concept and morphing parts requires a suitable manufacturing and assembly plan to transfer the virtual model to concrete reality.
The contribution of the INVENT GmbH within the GRETEL consortium is the manufacturing of the main structural components of the Wing and the integration of the Wind Tunnel Model. To realize such a precise projection, the main approach is to implement a high overall accuracy of the later model by realizing a low percentage of geometry deviation already on piece part level. Beginning with a material dedicated tool design concerning cure cycle parameters and induced strain effects, for aspects of geometrical manufacturing accuracy, also suitable inspection techniques, regarding the verification of structural requirements and material conditions are implemented in the integration process at specified steps.
A further part of the integration process of the GRETEL Wind Tunnel Model is the installation of application-related measurement equipment. The Institute of Composite Structures and Adaptive Systems of the German Aerospace Center (DLR) is responsible for the design and realization of such a project customized measurement concept. For the measurement of the pressure distribution along the profile contour with various angles of attack and wing configurations during the testing, the wing is equipped with several pressure taps. Further, the measurement equipment spectrum covers also the registration of acceleration forces and mechanical loads of the inner wing structure components. This concept creates a holistic picture of the coherences between aerodynamical and mechanical dimensions for each tested configuration.
The implementation of all aforementioned aspects into the large-scale model is elucidated and discussed in the light of morphing parts of the model being delivered by another project. The integrated equipment is described and the impact of the integration into the design and assembly of the overall model is illustrated.
Development of an innovative noise generation system for turboprop aircraft fuselage testing
Authors: Dal Borgo M , Alvarez M , Blanco S , Ophem van , Denayer H , dell’Aversana P , Polito T , Staibano L , Bianco R , Peeters B , Pluymers B , Desmet W 
Published: February 2022

Abstract
This paper presents the development of a cabin noise testing equipment that will be used to evaluate the interior noise of regional aircraft as well as to aid the development of noise reduction techniques. The innovative noise generation system consists of three loudspeaker arrays positioned around the fuselage circumference to synthesize a pressure field that is similar to the pressure field seen by the fuselage during a flight. The acoustic pressure field generated by the loudspeakers is measured by a number of microphones scattered on the fuselage surface. These microphone signals are then fed back to the controller with the purpose of minimising the error between the target pressure field and the measured one by means of an iterative learning approach. The number and location of the microphones used in the control loop are selected through a pre-test optimisation analysis, which aims to reduce the time and cost of the set-up. A small-scale electroacoustic demonstrator has been built to develop the feedback control approach. A frequency domain multi-input multi-output feedback controller is used to replicate the random pressure field generated by the turbulent boundary layer excitation. The multi-harmonics of the propeller induced excitation are then added to the time histories of the broadband noise using a time waveform replication technique. Different arrangements of the driving signal distribution are investigated, and the results are then presented in terms of accuracy of the pressure field reproduction.
Virtual Test Approach of Titanium/Composite in Service Repair, Installed on Certified Composite Flap
Authors: Giacalone V. , Avigliano V. , Pascali L. , Orlando S. , Starace F. 
Published: February 2022

Abstract

Virtual test methods can contribute to reducing the great effort for physical tests in the development of composite structure and in particular on the In-service Repair. The present work describes an approach for virtual testing of titanium/composite repair based on the Building Block Approach and the Finite Elements Method. Building on a multitude of physical tests on composite panels and joints, adequate sub-models are developed, validated and the results show that the method used for the substantiation of the generic repairs (GREOs) compared with test results is conservative. This thesis intends to provide a hierarchical virtual testing approach, which enables the prediction of the failure behavior and the strength of composite In-service repairs by means of validated FEM simulation.

In particular the objective of this work will be to investigate the damage mechanisms in composite bonded skin/stringer constructions with metallic (titanium) bolted repair under uniaxial (in-plane/out-of-plane) loading conditions as typically experienced by aircraft flap skin panels.
Modelling studies of the hazards posed by liquid hydrogen use in civil aviation
Authors: Holborn P G , Ingram J M , Benson CB 
Published: February 2022

Abstract
As part of the ENABLEH2 project, modelling studies have been carried out to examine liquid hydrogen release and dispersion behaviour for different LH2 aircraft and airport infrastructure leak/spill accident scenarios. The FLACS CFD model has been used to simulate the potential hazard effects following an accidental LH2 leak, including the extent of the flammable LH2 clouds formed, magnitude of explosion overpressures and pool fire radiation hazards. A comparison has also been made between the relative hazard consequences of using LH2 with conventional Jet A/A-1 fuel. The results indicate that in the event of accidental fuel leak/spill LH2 has some safety advantages over Jet A/A-1 but will also introduce additional hazards not found with Jet A/A-1 that will need to be carefully managed and mitigated against.
Addressing Safety concerns in Hybrid Electric Aircrafts: In-Flight Icing Detection, Moisture Detection in Fuselage and Electrical Wiring and Interconnect System (EWIS)
Authors: Sohail Mehak , Pfeiffer Helge , Wevers Martine 
Published: February 2022

Abstract
Moisture - in the form of water or ice – has adverse consequences on the performance of an aircraft including wing stall, tail stall, loss of thrust, engine flameout, and material damage arising from corrosion and electrical shortcuts. During flight, a large flux of supercooled water droplets on the surface of a hybrid electric aircraft per unit time could result into icing. A prototype to detect ice accretion on supercooled aircraft surface using acoustic emissions is developed. Moreover, during descend, a large portion of frost/ice melts rapidly due to rise in temperature. If not controlled, water may seep inside a hybrid electric aircraft body through gaps in joints. Furthermore, for the problem of water ingression in the wiring of hybrid aircrafts, titanium carbonitride-polyvinyl alcohol (TiCN-PVA) composite material is placed in direct water contact to work as grid health monitoring sensor. For the problem of water ingression inside structural parts (floor, bilge, etc.), an electrically conductive epoxy – carbon black composite is fabricated, characterized using SEM, and tested for DC conductivity under dry and wet conditions. Effect of different mixing intensities on morphology of carbon black in epoxy has also been explored. Through literature survey and trial and error, an optimized method at laboratory scale for preparation of carbon black-epoxy composite material has been presented.
Opportunities of cryogenic system for hybrid electric propulsion aircraft/solar airship with LH2 and high temperature superconductor
Authors: Ravikovich Yury , Ponyaev Leonid , Holoptsev Dmitry , Domjan Rafael 
Published: February 2022

Abstract
A comprehensive analysis for research and development (R&D) of the technical appearance and calculation of the technical characteristics of a new hybrid electric propulsion aircraft/solar airship (HEPA) with LH2 and cryocooling system with high temperature superconductivity (HTS) can be used at any stage of the design process of a hybrid electric passenger aircraft in the implementation of the EU FUTPRINT50 international program. A new conceptual synthesis for the creation of an optimal cryogenic cooling system based on the Brayton reverse cycle using turbomachines with basic design schemes for the use of significant cryogenic power with low temperature values has been created for computational mat. models using test thermodynamic models of individual circuit elements, taking into account the efficiency of each element, their hydraulic losses in the lines of all elements of the system: calculation of hydraulic losses in the channel element, thermal control in regenerative heat exchangers with a turbocharger and calculation of a turbo expander. The real-time use of a low-capacity wireless sensor-detector or additional charging components from solar energy based on the Seebeck-Peltier effect will be more effective due to the introduction of graphene structures in the design. Experimental development of a two-stage electric compressor and a turbo expander for demonstration tests of a cryogenic cooling system in the MAI laboratory has been carried out.
Energy consumption and environmental impact of Urban Air mobility
Authors: Donateo T. , Ficarella A. , Surdo L. 
Published: February 2022

Abstract
Urban Air Mobility (UAM) is a recent concept proposed for solving urban mobility problems, such as urban traffic pollution, congestion, and noises. The goal of this investigation is to develop a backward model for an electric aerial taxi in order to estimate the electric consumption and the indirect emissions of carbon dioxide in a specified mission. The model takes as input the time histories of speed and altitude and estimates the power at the rotor shaft during the mission with a quasi-static approach. The shaft power is used as input for the electric drive where the motor is modelled with an efficiency map and a transfer function while an equivalent circuit model which includes aging effects is used for the battery. The emissions of CO2 are calculated as a function of the Greenhouse emission intensity and compared with that of a hybrid electric taxi performing the same mission with the same payload. A plug-in Toyota Prius modelled through the software ADVISOR is considered for the comparison. The results show that the air taxi behaves better than the road taxi not only in terms of trip time but also from the environmental point of view if the charging of the battery is performed with the emission intensity factory expected to be reached in Europe in 2025.
Layout and testing of a serial hybrid electric powertrain for a light twin demonstrator platform
Authors: Lay J , Bender A , Strohmayer A 
Published: February 2022

Abstract
The Project “RS hybrid 1.0” funded by the LuFo Program of the German BMWi is being executed in order to develop and investigate a serial hybrid electric powertrain to be used in a light twin aircraft, that could be exclusively operated on two electric motors. The powertrain includes a generator system, that provides energy to all power sinks like propulsors, batteries and also covers the low voltage demand of the aircraft. In the frame of this project, all necessary components are developed including the electric propulsion units, the hybrid generator system, battery modules, and DC-Link and associated subsystems.
Everything is assembled in an iron bird testbed to be able to run the powertrain in an isolated fashion, to screen for potential issues and to measure operational data. Furthermore, a comprehensive control logic for the overall system and safety management of the powertrain is being developed and tested.
Optimal sizing of hybrid electric propulsion system for eVTOL
Authors: Marzougui Taher , Neuhaus Kolja , Labracherie Laurent , Scalabrin Gianmarco 
Published: February 2022

Abstract
Electric propulsion unmanned aerial vehicles (UAVs) attract much attention in aviation industry, with electric vertical take-off and landing (eVTOL) aircraft tending to gain ground. The current development of hybrid eVTOL aircraft intended for urban air mobility is facing many technical challenges. Among these challenges rises the optimal sizing of its hybrid power system (HPS). The latter requires an energy management strategy (EMS). In this paper, the adopted management strategy is based on filtering techniques using frequency-separation. The EMS ensures the optimal distribution of the load power requirement between the different sources while considering their limits. In addition, the optimal sizing allows to strengthen the complementarity between sources and to indirectly reduce their mass. In this work, the studied HPS consists of a fuel cell associated with an energy storage system (ESS), composed of lithium polymer batteries (Li-Po) and supercapacitors. The onboard sources are connected in parallel on the power bus through three DC-DC converters. The results of this study are presented and discussed to highlight the relevance of the proposed approach.
Strategy for 19-seat hybrid-electric short haul air transportation
Authors: Marksel M , Kamnik R , Božičnik S , Prapotnik A B 
Published: February 2022

Abstract
This paper addresses a way to implement greener aviation technologies, such as hybrid-electric propulsion, into the air transportation network to respond to the increasing environmental challenges posed by growing air traffic. New routes could be established between small airports to ensure better air connectivity in Europe while also connecting disadvantaged areas and relieve congestion at hub airports. Such routes could, for example, be served by micro feeder or 19-seat hybrid-electric aircraft, which produce low or no emissions, have lower operating costs, and are more applicable to environmental constraints. To achieve this and overcome the various challenges posed by the new hybrid-electric technologies, a new strategic roadmap for short-haul air transport is needed to optimize network services with small hybrid-electric aircraft.
Reliability Considerations of the Common Unit in Hybrid Electric Propulsion
Authors: Can Sinem , Gül Cemre Gizem , Koruyucu Elif , Yildiz Melih 
Published: February 2022

Abstract
Since the beginning of aviation, reliability has been one of the most important elements in terms of flight safety and certification. Reliability starts from the smallest part of the aircraft and covers all components up to the entire system. The use of a hybrid-electric propulsion system has become one of the important study topics today. When hybrid-electric propulsion architectures are examined, it is seen that some elements are repeating which the authors named as common unit. This common unit is similar to the all-electric propulsion architecture and consists of a battery, battery management system, and power electronics which are used in conjunction with the hybrid-electric systems. In this study, the components and units used in the hybrid-electric propulsion system and the common unit has been examined for reliability. The common unit is proposed as a means of simplification of both the sizing and certification of the hybrid electric architecture. The reliability of the battery, battery management system, and power electronics within the system that makes up the common unit is discussed in detail for determining the reliability of the hybrid electric architecture.