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Improving and Evaluating Aircraft Maintenance On-Time Performance for Wide-Body A-Checks Delays

SORT Engineering GmbH-Adel A. Ghobbar
  • Technical Paper
  • 2019-01-1909
To be published on 2019-09-16 by SAE International in United States
Martinair is based on Schiphol Oost and is part of the KLM Group since 2008. The KLM Group on its turn is part of the Air France – KLM Group. Martinair started as a charter company and was founded by Martin Schröder. Martinair is now a cargo operator with its own maintenance base at Hangar 32 on Schiphol Oost. It operates 7 McDonnell Douglas MD-11’s and 6 Boeing B747-400’s. The focus will be on the MD-11 tri-jet in this thesis. Due to the entry in the KLM Group in 2008, changes have been made for synergy reasons to the Martinair organisation. Martinair Maintenance and Engineering is now focussing on becoming a Regional Jet Center. The maintenance on the Embraer E-190 of KLM Cityhopper will be the main part of the work. Due to the new focus of the Martinair maintenance and engineering department, the maintenance capacity for a MD-11 A-check will no longer be available. It is therefore chosen to outsource the MD-11 A-check from Martinair maintenance and engineering to KLM engineering and maintenance. The…
 

A simple approach for the estimation of the exhaust noise source at the valves

CMT-Universitat Politecnica de Valencia-Antonio J. Torregrosa
CMT-Universitat Politècnica de València-Pablo Olmeda
  • Technical Paper
  • 2019-24-0174
To be published on 2019-08-15 by SAE International in United States
Exhaust noise emission is the result of the propagation of pressure perturbations along the exhaust line. Such perturbations are primarily originated by the discharge of hot, high-speed gases through the exhaust valves. These gases do not simply displace the gases present in the exhaust port but compress them, giving rise to the perturbation mentioned above. Therefore, any attempt at the prediction of exhaust noise is based on the knowledge of the instantaneous mass flow rate across the exhaust valves. However, this magnitude is not readily accessible to measurements, and it is thus imperative to use predictive models. It is apparent that, while information on the instantaneous mass flow through the exhaust valves may be obtained from well-validated commercial gas-dynamic codes, the data required is not always available or fully defined at the time of starting the design of an exhaust line. It is therefore desirable to be able to estimate the instantaneous mass flow passing through the valve starting from a reduced set of geometrical and operation data, which can be either representative for a…
 

Large Eddy Simulations and Tracer-LIF Diagnostics of wall film dynamics in an optically accessible GDI research engine

ETH Zurich-Nicolò Frapolli, Konstantinos Boulouchos
ETH Zurich/Combustion+FlowSolutions GmbH-Yuri M. Wright
  • Technical Paper
  • 2019-24-0131
To be published on 2019-08-15 by SAE International in United States
Large Eddy Simulations (LES) and tracer-based Laser Induced Fluorescence (LIF) measurements have been performed to study the dynamics of fuel wall-films on the piston top of an optically accessible, four-valve pent-roof GDI research engine for a total of eight operating conditions. Starting from a reference point, the systematic variations include changes in engine speed (600; 1,200 and 2,000 RPM) and load (WOT and 500 mbar intake pressure); concerning the fuel path the Start Of Injection (SOI=360°, 390° and 420° CA after gas exchange TDC) as well as the injection pressure (10, 20 and 35 MPa) have been varied. For each condition, 40 experimental images were acquired phase-locked at 10° CA intervals after SOI, providing valuable insights with respect to the wall film dynamics in terms of spatial extent, thickness and temperature. The simulation framework was developed as follows: first, the spray model was calibrated using spray morphology evolution data of the same injector, characterized in a constant volume spray chamber by means of high-speed shadow imaging. In a second step, the wall impingement and film…
 
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Simulations of Thin Film Dynamics on a Flat Plate and an Airfoil

Baylor University-Jordan Sakakeeny, Stephen T. McClain, Yue Ling
Published 2019-06-10 by SAE International in United States
The goal of the present study is to investigate the dynamics of a thin water film on a flat plate and an airfoil using direct numerical simulation (DNS). The first case for a wetted flat plate is used to model former experiments and investigate the dynamics of a wind-driven water film. The second case for a thin film on a NACA 0012 airfoil of chord length 0.5 m is used to investigate the dynamics of a wind-driven water film on a curved surface. Particular attention is paid to the interaction between the liquid film and the air shear-layer above the film. As the incoming airflow moves over the thin water film, instability is triggered at the gas-liquid interface. Interfacial waves develop and are advected downstream. The interaction between the air flow and the interfacial waves induces shedding vortices near the interface, which in turn perturb the liquid film farther downstream. Simulations are performed using the open source multiphase flow solvers, Gerris and Basilisk. Both solvers employ a finite-volume approach and the interface is captured using…
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Separating-Reattaching Flows Over an Iced Airfoil

Diakon Solutions LLC-Ezgi Oztekin
Federal Aviation Administration (FAA)-James Riley
Published 2019-06-10 by SAE International in United States
Delayed Detached Eddy Simulations (DDES) of separating-reattaching flows on the suction side of an ice-contaminated airfoil were conducted. A single-section straight-wing NACA23012 airfoil with leading-edge ice was studied. The geometry represents a realistic glaze horn-ice contamination obtained during the icing test campaigns described in [1], which has aerodynamic data for comparison. The three-dimensional transient flow behavior was simulated using the open-source flow solver OVERFLOW, version 2.2l [2] developed by NASA Langley Research Center. Configurations at three angles of attack that exhibit unsteady flow behavior starting with the bursting angle were examined at Mach number of 0.18 and Reynolds number of 1.8x106. As the stall angle was approached the aerodynamic performance parameters displayed large-scale unsteadiness where periods of attached and separated flows were observed. The time-averaged results show good agreement with the aerodynamic test data. The calculated Strouhal number for the self-sustained low-frequency oscillations is consistent with the previous experimental research.
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Extension of a 2D Algorithm for Catch Efficiency Calculation to Three Dimensions

Airbus-Christian Bartels
FH Joanneum GmbH-Thomas Neubauer, Wolfgang Hassler
Published 2019-06-10 by SAE International in United States
Accurate calculation of the catch efficiency β is of paramount importance for any ice accretion calculation since β is the most important factor in determining the mass of ice accretion. A new scheme has been proposed recently in [1] for accurately calculating β on a discretized two-dimensional geometry based on the results of a Lagrangian droplet trajectory integrator (start and impact conditions).This paper proposes an extension to the algorithm in Ref. [1], which is applicable to three-dimensional surfaces with arbitrary surface discretization. The 3D algorithm maintains the positive attributes of the original 2D algorithm, namely mass conservation of the impinging water, capability to deal with overlapping impingement regions and with crossing trajectories, computational efficiency of the algorithm, and low number of trajectories required to reach good accuracy in catch efficiency. At the same time, the new 3D algorithm avoids typical difficulties of other approaches to determine the catch efficiency β, like noisy β (results varying significantly between neighboring surface cells), catch efficiency of zero for surface cells surrounded by other cells with β > 0,…
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A Study of Droplet Breakup in the Vicinity of an Airfoil

INTA-Suthyvann Sor, Adelaida Garcia-Magariño
UPM-Angel Velazquez
Published 2019-06-10 by SAE International in United States
Supercooled large droplets can breakup before imping on aerodynamic surfaces and this should be taken into account in the icing codes. A study of droplets breakup in the vicinity of an airfoil has been conducted. Experiments for streams of droplets that were allowed to fall in the path of an incoming airfoil attached to a rotatory arm were conducted at the INTA facility. Droplets diameters ranged from 500 μm to 3 mm and two airfoils models of leading edge radius of 70 mm and 103 mm moving at velocities of 70 m/s, 80 m/s and 90 m/s were tested. Two subsets of experimental data for both bag and stamen breakup and shear breakup modes were used in this investigation. For these cases a numerical trajectory and deformation model was applied to obtain the evolution of the horizontal position, and the droplet maximum and minimum diameter. Breakup onset was determined from experimental data. Though previous works considered that breakup starts when there is a minimum in the minimum diameter, such minimum was not found in the…
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A Penalization Method for 2D Ice Accretion Simulations

Ecole Polytechnique Montreal-Pierre Lavoie, Eric Laurendeau
ONERA-Ghislain Blanchard, Emmanuel Radenac, Philippe Villedieu
Published 2019-06-10 by SAE International in United States
Numerical tools for 3D in-flight icing simulations are not straightforward to automate when seeking robustness and quality of the results. Difficulties arise from the geometry and mesh updates which need to be treated with care to avoid folding of the geometry, negative volumes or poor mesh quality. This paper aims at solving the mesh update issue by avoiding the re-meshing of the iced geometry. An immersed boundary method (here, penalization) is applied to a 2D ice accretion suite for multi-step icing simulations. The suggested approach starts from a standard body-fitted mesh, thus keeping the same solution for the first icing layer. Then, instead of updating the mesh, a penalization method is applied including: the detection of the immersed boundary, the penalization of the volume solvers to impose the boundary condition and the extraction of the surface data from the field solution. Although the current work is intended for 3D simulations, the content of this paper is limited to 2D applications to show the feasibility of the method. Tests are performed on multi-step rime and glaze…
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Machine Learning Based Technology for Reducing Engine Starting Vibration of Hybrid Vehicles

Toyota Motor Corp.-Kento Shimode, Keisuke Ishizaki, Masashi Komada
Published 2019-06-05 by SAE International in United States
Engine starting vibration of hybrid vehicle with Toyota hybrid system has variations even in the same vehicle, and a large vibration that occurs rarely may cause stress to the passengers. The contribution analysis based on the vibration theory and statistical analysis has been done, but the primary factor of the rare large vibration has not been clarified because the number of factors is enormous. From this background, we apply machine learning that can reproduce multivariate and complicated relationships to analysis of variation factors of engine starting vibration. Variations in magnitude of the exciting force such as motor torque for starting the engine and in-cylinder pressure of the engine and timing of these forces are considered as factors of the variations. In addition, there are also nonlinear factors such as backlash of gears as a factor of variations. For the variation factor analysis, it is difficult to measure the physical quantities mentioned above from experiments, because of the high time load of installing measuring sensors and lack of measurement technology for some factors. On the other…
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Technique Reverse-Engineers Complex 3D CAD Models

  • Magazine Article
  • TBMG-34403
Published 2019-05-01 by Tech Briefs Media Group in United States

Nearly all commercial products start as a CAD file — a 2D or 3D model with the product’s design specifications. One method that’s widely used to represent today’s 3D models is constructive solid geometry (CSG), a technique where numerous basic shapes (primitives) with a few adjustable parameters can be assembled in various ways to form a single object. When finalized, the compiled digital object is converted to a mesh of 3D triangles that defines the object’s shape. These meshes are used as input for many applications, including 3D printing and virtual simulation.