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Advanced assembly solutions for the RACER joined-wing configuration

University of Nottingham-David Bainbridge, Konstantinos Bacharoudis, Andrea Cini, Alison Turner, Atanas Popov, Svetan Ratchev
  • Technical Paper
  • 2019-01-1884
To be published on 2019-09-16 by SAE International in United States
The demonstrator project RACER is developed under the leadership of Airbus Helicopters Group within a large European partnership and concerns the development of new VTOL formula in order to fill the mobility gap between conventional helicopters and airplanes. Thus, RACER is a compound rotorcraft including wings and propellers. The new wing arrangement suggested by Airbus Helicopters Groups is defined as a staggered bi-plane configuration with an upper and a lower straight wing at each side of the helicopter, both being interconnected at their outermost tips, forming a triangular framework. Responsible for the design, manufacturing and assembly of the wings is ASTRAL consortium consisted of GE Aviation and University of Nottingham. The identification of the best strategy to assemble the joined wing configuration is quite challenging. In order to ensure that the final wing assembly will fit to the fuselage, a jig that simulates the fuselage was suggested by Airbus Helicopters Group. The main question raised during the assembly design and thus the objective of this work concerns whether the jig should be a one-piece structure…
 

Landing Gear Integration into Aircraft Structure in Early Design Stage

Bauhaus Luftfahrt EV-Ulrich Kling, Mirko Hornung
  • Technical Paper
  • 2019-01-1890
To be published on 2019-09-16 by SAE International in United States
The demanded development towards various emission reduction goals set up by several institutions forces the aerospace industry to think about new technologies and alternative aircraft configurations. With these alternative aircraft concepts, the landing gear layout is also affected. Turbofan engines with very high bypass ratios could increase the diameter of the nacelles extensively. In this case, mounting the engines above the wing could be a possible arrangement to avoid an exceedingly long landing gear. Thus, the landing gear could be shortened and eventually mounted at the fuselage instead of the wings. Other technologies such as high aspect ratio wings have an influence on the landing gear integration as well. To assess the difference, especially in weight, between the conventional landing gear configuration and alternative layouts a method is developed based on preliminary structural designs of the different aircraft components, namely landing gear, wing and fuselage. Simplified parametric finite element structural models for the different components are introduced. These models are used to investigate different aircraft configurations with special regard on the landing gear integration. The…
 
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Experimental and Computer Model Results for a Carbon Nanotubes Electrothermal De-Icing System

Embraer-Rodrigo Domingos, Gilberto Becker
Published 2019-06-10 by SAE International in United States
Results from a three-dimensional computer model of a Carbon Nanotubes (CNT) based de-icing system are compared to experimental data obtained at COLLINS-Ohio Icing Wind Tunnel (IWT). The experiments were performed using a prototype of a CNT based de-icing system installed in a section of a business jet horizontal tail. The 3D numerical analysis tools used in the comparisons are AIPAC [1] and CFD++. The former was derived from HASPAC, an anti-icing computer model developed at Wichita State University in 2010 [3, 9, 10]. AIPAC uses the finite volumes method for the solution of the icing problem on an airfoil leading edge (or other 3D surfaces) and relies on any CFD solver to obtain the external flow properties used as boundary conditions. AIPAC is capable of predicting 3D multi-step ice shapes under rime, glaze and mixed regimes, and can also deal with the complex dynamics of cyclic ice accretion, melting, and shedding present in the realm of aircraft electrothermal de-icing systems. The latter is the CFD solver selected to provide the external flow properties for the…
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Additional Comparison of Iced Aerodynamic Measurements on a Swept Wing from Two Wind Tunnels

Federal Aviation Administration Technical Center-Timothy Smith
NASA Glenn Research Center-Andy Broeren
Published 2019-06-10 by SAE International in United States
Artificial ice shapes of various geometric fidelity were tested on a wing model based on the Common Research Model. Low Reynolds number tests were conducted at Wichita State University’s Walter H. Beech Memorial Wind Tunnel utilizing an 8.9% scale model, and high Reynolds number tests were conducted at ONERA’s F1 wind tunnel utilizing a 13.3% scale model. Several identical geometrically-scaled ice shapes were tested at both facilities, and the results were compared at overlapping Reynolds and Mach numbers. This was to ensure that the results and trends observed at low Reynolds number could be applied and continued to high, near-flight Reynolds number. The data from Wichita State University and ONERA F1 agreed well at matched Reynolds and Mach numbers. The lift and pitching moment curves agreed very well for most configurations. This confirmed results from previous tests with other ice shapes that indicated the data from the low Reynolds number tests could be used to understand iced-swept-wing aerodynamics at high Reynolds number. This allows ice aerodynamics testing to be performed at low Reynolds number facilities…
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Multi-Step Ice Accretion Simulation Using the Level-Set Method

Strasbourg University-Yannick Hoarau
Published 2019-06-10 by SAE International in United States
Ice accumulation in aircraft is modelled using the Level-Set (LS) method. Current two-dimensional and three-dimensional icing models are limited regarding complex re-meshing due to ice accretion. The Level-Set method allows fully multi-step simulation of ice accretion. The solid boundary is treated implicitly or explicitly. The solid body can be defined via a characteristic level set function in the former case, and as a layer or list of points in the later. Consequently, the boundary conditions for the airflow are applied through a penalization term, or by direct forcing. Correspondingly, the droplet transport is computed using an Eulerian approach in an Immersed Boundary Method (IBM) coupled with Level-Set (IBM-LS) framework, in which the droplet fields impinge on an explicit layer of cells defined by the LS function using a discrete IBM formulation of the interface.
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Structural Vibration of an Elastically Supported Plate due to Excitation of a Turbulent Boundary Layer

University of Michigan-Jonmarcos Diaz, Kevin Maki, Nickolas Vlahopoulos
Published 2019-06-05 by SAE International in United States
High-Reynolds number turbulent boundary layers are an important source for inducing structural vibration. Small geometric features of a structure can generate significant turbulence that result in structural vibration. In this work we develop a new method to couple a high-fidelity fluid solver with a dynamic hybrid analytical-numerical formulation for the structure. The fluid solver uses the Large-Eddy Simulation closure for the unresolved turbulence. Specifically, a local and dynamic one-equation eddy viscosity model is employed. The fluid pressure fluctuation on the structure is mapped to the dynamic structural model. The plate where the flow excitation is applied is considered as part of a larger structure. A hybrid approach based on the Component Mode Synthesis (CMS) is used for developing the new hybrid formulation. The dynamic behavior of the plate which is excited by the flow is modeled using finite elements. However, the rest of the surrounding structure is modeled using finite elements for the static modes and an analytical solution for the dynamic modes of the CMS decomposition. The two main elements of the new work,…
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Power Electronic Noise-Simulation Measurement Comparison

AVL LIST GmbH-Markus Resch, Thomas Resch, Stephan Brandl
AVL Software and Functions Gmbh-Peter Olbrich, Hartwig Reindl
Published 2019-06-05 by SAE International in United States
A growing development of hybrid or fully electrical drives increases the demand for an accurate prediction of noise and vibration characteristics of electric and electronic components. This paper describes the numerical and experimental investigation of noise emissions from power electronics, as one of the new important noise sources in electric vehicles.The noise emitted from the printed circuit board (PCB) equipped with multi-layer ceramic capacitors (MLCC) is measured and used for the calibration and validation of numerical model. Material properties are tuned using results from experimental modal analysis, with special attention to the orthotropic characteristic of the PCB glass-reinforced epoxy laminate sheet (FR-4). Electroacoustic excitation is pre-calculated using an extension of schematic-based EMC simulation and applied to the structural model. Structural vibrations are calculated with a commercial FEM solver with the modal frequency response analysis. Sound radiation is simulated using the wave-based approach (WBT). Simulation and experimental results are compared in a frequency range up to 10 kHz.The developed simulation methodology can successfully identify the main noise sources from the equipped PCB. Critical peak noise responses…
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Structural-Acoustic Modeling and Optimization of a Submarine Pressure Hull

Michigan Engineering Services, LLC-Geng Zhang
University of Michigan-James Spain, Nickolas Vlahopoulos
Published 2019-06-05 by SAE International in United States
The Energy Finite Element Analysis (EFEA) has been validated in the past through comparison with test data for computing the structural vibration and the radiated noise for Naval systems in the mid to high frequency range. A main benefit of the method is that it enables fast computations for full scale models. This capability is exploited by using the EFEA for a submarine pressure hull design optimization study. A generic but representative pressure hull is considered. Design variables associated with the dimensions of the king frames, the thickness of the pressure hull in the vicinity of the excitation (the latter is considered to be applied on the king frames of the machinery room), the dimensions of the frames, and the damping applied on the hull are adjusted during the optimization process in order to minimize the radiated noise in the frequency range from 1,000Hz to 16,000Hz. Constraints on the total amount of damping that can be used are considered (resource driven constraints) and structural collapse constraints are also taken into account in order to avoid…
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Multi-Physics and CFD Analysis of an Enclosed Coaxial Carbon Nanotube Speaker for Automotive Exhaust Noise Cancellation

Michigan Technological University-Suraj Madhav Prabhu, Andrew Barnard, Steven Senczyszyn
Published 2019-06-05 by SAE International in United States
Automotive exhaust noise is one of the major sources of noise pollution and it is controlled by passive control system (mufflers) and active control system (loudspeakers and active control algorithm). Mufflers are heavy, bulky and large in size while loudspeakers have a working temperature limitation. Carbon nanotube (CNT) speakers generate sound due to the thermoacoustic effect. CNT speakers are also lightweight, flexible, have acoustic and light transparency as well as high operating temperature. These properties make them ideal to overcome the limitations of the current exhaust noise control systems. An enclosed, coaxial CNT speaker is designed for exhaust noise cancellation application. The development of a 3D multi-physics (coupling of electrical, thermal and acoustical domains) model, for the coaxial speaker is discussed in this paper. The model is used to simulate the sound pressure level, input power versus ambient temperature and efficiency. The 3D model provides accurate results of the temperature profile and heat flow as compared to a 2D model. Also, the flow of exhaust gases can be efficiently modeled using a 3D model. The…
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Equivalent Material Properties of Multi-Layer, Lightweight, High-Performance Damping Material and Its Performance in Applications

3M Company-Taewook Yoo, Ronald Gerdes, Seungkyu Lee, Thomas Herdtle
3M Deutschland GmbH-Georg Eichhorn
Published 2019-06-05 by SAE International in United States
In this study, we investigated two aspects of a multi-layer, lightweight damping treatment. The first aspect studied was an equivalent material property estimate for a simplified finite element (FE) model. The simplified model is needed for computational efficiency, i.e. so that Tier 1 and OEM users can represent this complex, multi-layer treatment as a single, isotropic solid layer plus an aluminum constraining layer. Therefore, the use of this simplified FE model allows the multilayer treatment to be included in large body-in-white structural models. An equivalent material property was identified by first representing three unique layers (two adhesive layers plus a connecting standoff layer) by a single row of isotropic solid elements, then an optimization tool was used to determine the “best fit” for two properties including Young’s modulus and material loss factor. Equivalent properties were validated for various substrate thickness and coverage areas heights by comparison to center-driven long bar test results.Secondly, the effect of damping treatment size was studied using the previously identified equivalent material properties. This was a damper placement study to determine…
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