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Viewing 1 to 30 of 800
2011-04-12
Technical Paper
2011-01-0176
Sinisa Krajnovic
The paper discusses an appropriate usage of large eddy simulation (LES) in external vehicle aerodynamics. Three different applications, wheelhouse flow, gusty flow and active flow control, are used to demonstrate how LES can be used to obtain new knowledge about vehicle flows. The three examples illustrate the information that can be extracted using LES in vehicle aerodynamics and show the potential of LES in explorations of this complex flow.
2004-11-16
Technical Paper
2004-01-3415
Marcelo Lopes de Oliveira e Souza, Gilberto da Cunha Trivelato
In this work we discuss some types of simulation environments and laboratories, their characteristics and applications to the simulation and control of aerospace vehicles. This includes: the basic definitions, types and characteristics of simulators and simulations (physical, computational, hybrid, etc.; discrete events, discrete time, continuous time, etc; deterministic, stochastic, etc.) their basic compromise (simplicity × fidelity), their man-machine interfaces and interactions (virtual, constructive, live, etc.), their evolution law (time, events, mixed, etc.), their architectures (“stand-alone”, PIL, HIL, MIL, DIS, HLA, etc.), and especially, their environments (discrete, continuous, hybrid, etc.) and laboratories (physical, computational, hybrid, etc.), and their applications to the simulation and control of aerospace vehicles. This is illustrated by some examples driven from the aerospace industry.
2004-07-19
Technical Paper
2004-01-2317
Valter Perotto, Vincenzo Mareschi
ALTAN (ALenia Thermal ANalyser) is a tool developed in Alenia Spazio, for the thermal simulation of satellites. Distinctive features of ALTAN are the description of the system in terms of thermal objects that can be considered as high level primitives, the accurate modelling of the energy sources (planets and sun) and of the optical properties, the integration in a single tool of the steps of radiative, conductive and thermal calculations and of the post-process of the results. An example of ALTAN application is given for Bepi-Colombo mission to Mercury, in particular the modelling of the highly variable planet temperature and the directional optical properties of the planet surface.
2004-07-19
Technical Paper
2004-01-2274
Vincenzo Mareschi, Valter Perotto, Matteo Gorlani, Danilo Lazzeri, Olivier Pin
Stochastic method is being used in several domains for design optimisation, but its application to spacecraft thermal control design is not yet consolidated. The paper presents an assessment of this technique applied to spacecraft thermal control design, made by Blue Engineering and Alenia Spazio under ESA contract, with the objective to assess the applicability of the method, the requirements for its implementation, the effects on the design process.
2004-07-19
Technical Paper
2004-01-2275
B. Cullimore, S. G. Ring, J. Baumann
Thankfully, the age of stand-alone fixed-input simulation tools is fading away in favor of more flexible and integrated solutions. “Concurrent engineering” once meant automating data translations between monolithic codes, but sophisticated users have demanded more native integration and more automated tools for designing, and not just evaluating point designs. Improvements in both interprocess communications technology and numerical solutions have gone a long way towards meeting those demands. This paper describes a small slice of a larger on-going effort to satisfy current and future demands for integrated multidisciplinary tools that can be highly customized by end-users or by third parties. Specifically, the ability to integrate fully featured thermal/fluid simulations into Microsoft’s Excel™ and other software is detailed. Users are now able not only to prepare custom user interfaces, they can use these codes as portals that allow integration activities at a larger scale.
2010-10-17
Technical Paper
2010-36-0546
Giuliano Quiqueto, Luiz Chamon, Sylvio Bistafa
In order to generate in-flight acoustic and vibration fields inside an aircraft cabin mock-up, an N&V simulator was developed. The preliminary work on the development, setup and characterization of the N&V simulator will be presented. Firstly, an overview of the system will be given, including the desired input signals, followed by the presentation of the control software, which was developed to simplify the operation of the system by end users during routine testing. Secondly, the set-up strategy to adjust the reproduction of levels and spectrum of both acoustic and vibration fields will be presented, along with comparative vibroacoustics results between the mock-up and original in-flight recordings. Finally, a discussion on different methods for adjusting the simulator reproduction by means of optimal filtering is made, and further developments are presented.
2010-10-17
Technical Paper
2010-36-0545
Fred Mendonca, Alex Read, Fabiano Imada, Vinicius Girardi
The transport industries face a continuing demand from customers and regulators to improve the acoustic performance of their products: reduce noise heard by passengers and passersby; avoid exciting structural modes. In both the aerospace and automotive areas, flow-induced noise makes a significant contribution, leading to the desire to understand and optimize it through the use of simulation. Historically, the need for time-consuming, computationally expensive transient simulations has limited the application of CFD in the field of acoustics. In this paper are described efficient simulation processes that, in some instances, remove the requirement for transient analyses, or significantly reduce the total process time through intelligent pre-processing. We will outline this process and provide both automotive and aerospace industrial examples, including analyses of highly complex geometries found in real life.
2010-10-17
Technical Paper
2010-36-0517
P. B. Salazar, T. A. Heleno, J. G. Slama
The objective of this paper is to present a method of determination of airport noise levels and environment noise using computer simulation, thus reducing the need for physical measurements in the areas affected by airport noise. Through the simulations, the hourly airport noise was characterized for a wide range of critical receivers. Levels for airport and environment noise had been calculated, considering that environment noise is generated mostly by the flow of motor vehicles on the nearby roads. From the results of these simulations it was possible to choose points where continuous noise measurements are made. Using the simulated values, we hope to determine a safe and precise way of predicting the noise generated from airports throughout the country minimizing the needs of conducting physical measurements to obtain the noise curves.
2010-10-17
Technical Paper
2010-36-0506
Micael G. V. do Carmo, Julio R. Meneghini
The Brazilian Silent Aircraft Program (Programa "Aeronave Silenciosa) is an initiative of six Brazilian Universities and Institutes (USP-Poli "University of Sao Paulo - Polytechnic School, USP/EESC - University of Sao Paulo - Sao Carlos Engineering School, UFSC - Federal University of Santa Catarina, UFU - Federal University of Uberlandia, UnB - University of Brasilia and IAE - Brazilian Institute of Aeronautics and Space) together with Embraer to develop methodologies and solutions for the aircraft external noise problem. The main goal of this initiative is to study and develop methodologies that will allow estimation of aircraft noise generation and propagation through three main approaches: numerical simulation (CAA), analytical and semi-empirical models, and wind tunnel and flight tests.
2011-06-13
Technical Paper
2011-38-0001
Jie Xiao, Katherine E. Mackie, Joseph H. Osborne, Jill Seebergh, Santanu Chaudhuri
In-flight icing occurs when supercooled water droplets suspended in the atmosphere impinge on cold aircraft surfaces. Thin layers of accreted ice significantly increase aerodynamic drag while thick layers of ice severely alter the aerodynamics of control surfaces and lift. Chunks of ice can break away from the airframe and cowlings and be ingested into engines causing considerable damage. Developing durable surfaces that prevent the nucleation of supercooled water or reduce ice adhesion to a point where airstream shear forces can remove it would allow the design of a more robust, energy efficient deicing/anti-icing system for aircraft and other applications. In this work, a simulations based framework is developed to predict anti-icing performance of various nanocomposite coatings under the in-flight environment.
2010-10-06
Technical Paper
2010-36-0333
Jairo Cavalcanti Amaral, Marcelo Lopes de Oliveira e Souza
This work presents the analysis, design and simulation of the reconfigurable control architecture for the contingency mode of the MultiMission Platform (MMP). The MMP is a generic service module currently under design at INPE. Its control system can be switched among nine main Modes of Operation and other Sub-Modes, according to ground command or information coming from the control system, mainly alarms. The implementation followed the specifications when they were found, otherwise it was designed. They cover operations from detumbling after launcher separation and solar acquisition, to achieving payload nominal attitude and orbital corrections maneuvers. The manager block of the control system was implemented as a finite state machine. The tests are based in simulations with the MatriX/SystemBuild software. They focused mainly on the worst cases that the satellite is supposed to endure in its mission, be it during modes or transitions between modes and submodes.
2010-10-06
Technical Paper
2010-36-0278
Rafael F. Vieira, J A. A Lyrio, Juliano M. T. Cavalcanti
In a modern engineering design, the goal for high efficiency using optimization methods is fundamental to generate competitive and strategic advantages. It is even more evident on the development of aircrafts, in which Multi-Disciplinary Design Optimization (MDO) philosophies are each day more noticeable, due to a range of involved technologies on the project. The present work introduces a computational process, called HighLift2D, which is fitted on that context. This integrated tool is capable to simulate bidimensional flows in subsonic and transonic conditions over single element airfoils (cruise configuration wing) and multi element airfoils (take-off, maneuver or landing wings, with high lift devices - flap and/or slat) using high fidelity Computational Fluid Dynamics (CFD).
2010-10-06
Technical Paper
2010-36-0139
Mario Maia Neto, Luiz Carlos S. Goes, Rui Charles M. Furtado
The free-fall operation comprises a redundant, dissimilar and independent mechanically operated method of extending airplane landing gear due to a main hydraulic system failure or an electrical system malfunction. However, the emergency extension operation system design is not unique and spring-assisted, auxiliary hydraulics-assisted or even pneumatics-assisted landing gear free-fall design can be found in different airplanes. This paper aims at describing the model simulation and the optimization of certain parameters related to the associated hydraulic system, for emergency operation condition, in a non-assisted system configuration comprising simple extension by gravity.
2004-07-19
Technical Paper
2004-01-2576
Selen Aydogan, Seza Orcun, Gary Blau, Joseph F. Pekny, Gintaras Reklaitis
In this paper a SIMulation based OPTimization (SIMOPT) approach is used to study the dynamics of Advanced Life Support System (ALSS). The SIMOPT architecture uses a Deterministic Optimization (DO) algorithm to optimize the overall ALS behavior by minimizing the re-supplies which are difficult to procure or transport, in conjunction with a simulation model which introduces uncertainty, i.e. randomness, to the system. DO algorithm is a detailed deterministic optimization model of ALSS, which is used to determine the values of strategic decisions, such as the crop growth area. An aggregate time-dependent mass balance model of ALSS and an aggregate steady state mass balance model of ALSS are developed as the simulation and optimization modules in SIMOPT, respectively.
2011-06-13
Technical Paper
2011-38-0096
Shinan Chang
Electro-thermal deicing process was an unsteady heat transfer process including phase change. Based on the investigation of such a process, a code was developed to numerically simulate electro-thermal deicing process. Phase change was performed by an enthalpy method. A staircase approach was used to describe the variable ice thicknesses along the icing surface. The control volume method was adopted to discretize the governing equations. Tri-diagonal matrix method, alternating direction implicit method and block-correction technique were used to solve the discrete equations. Results of temperature distribution in this investigation were compared with experimental results of previous study. Their good agreements indicate the validity of our simulation. The effects of icing conditions, such as ambient temperature, liquid water content (LWC) and flight velocity, etc., were analyzed through a case. Some useful conclusions were achieved.
2016-01-05
Journal Article
2015-01-9086
Geethanjali Gadamchetty, Abhijeet Pandey, Majnoo Gawture
The three parameter Ramberg-Osgood (RO) method finds popular usage for extracting complete stress-strain curve from limited data which is usually available. The currently popular practice of assuming the plasticity to set in only at the Yield point provides computational advantage by separating the complete nonlinear curve, obtained from RO method, into elastic and plastic regions. It is shown, with an example problem, that serious errors are committed by using this method if one compares the obtained results with results of complete stress-strain curve. In the present work we propose a simple Taylor series based approach based on RO method to overcome the above deficiency. This method is found to be computationally efficient. The proposed method is applicable for stress-strain curves of materials for which RO method provides a good approximation.
1958-01-01
Technical Paper
580150
JACK ANDRESEN, E. H. SCHROEDER
1957-01-01
Technical Paper
570144
EDWARD L. BRAUN, GEOFFREY POST
1957-01-01
Technical Paper
570160
A. C. BUTTERWORTH, G. E. HULL
Increasing complexity of airplanes, and diversification of routes over which they operate, have rendered it imperative to “streamline” route analysis methods. Modern operational problems are of such variety that hand computing, and the use of simple performance charts, can provide only “outline” analyes in a limited period of time. Comprehensive route analyses, if they are to be performed in time to be of direct use to the operator, require the use of digital computers. This paper examines the basic operating problem: the reasons for its complication; and the methods by which solutions of the final complex problem are obtained.
1954-01-01
Technical Paper
540140
D. G. DILL, M. D. LAMOREE, F. W. MELCHING, R. H. STRINGHAM
2007-07-09
Technical Paper
2007-01-3168
John Fricker, Dominick Mancuso, Jud Hedgecock, Rich Patten, Lindsay Aitchison
This paper describes the effort performed by Oceaneering Space Systems, Air-Lock, Inc., Raven Aerospace Technology, Inc., and David Clark Company, Inc. to develop lightweight and low-profile spacesuit bearings. Current spacesuit bearings constitute a significant portion of the spacesuit mass and reducing this weight will improve extravehicular activity (EVA) capabilities and reduce launch mass. Reducing the profile of the bearings will increase crew comfort in the suit on long duration missions. The recommended concepts for the waist, scye (shoulder), arm, and wrist bearings share the same basic configuration to achieve weight reduction and a low profile with little technical risk. The bulk structural material is a lightweight carbon/epoxy composite. The bearing race material is 440C stainless steel for wear resistance and hardness. Many features of existing spacesuit bearings were retained to minimize technical risk.
2007-10-30
Technical Paper
2007-32-0098
Takafumi YAMADA, Yasuo MORIYOSHI
For a disaster relief and automatic inspections, an unmanned helicopter is strongly expected. To develop this, a very high power density source is required. A Wankel-type rotary engine can be the best candidate for the power source. In this study, the development of a very small rotary engine with a displacement of 30 cc is targeted. In order to improve the combustion efficiency, gas exchange and stable ignition, a multi dimensional simulation inside the combustion chamber was carried out. At first, the effect of volumetric efficiency on the maximum power is mentioned. Secondly, the effect of scavenging efficiency is discussed. Thirdly, a blow off through a plug hole is described. The position of plug hole was found important to reduce the blow off amount. Finally, the effect of combustion speed on the engine performance is predicted. As a result, the proposed design will be tested using a proto-type engine.
2007-09-17
Technical Paper
2007-01-3899
Nazli E. Kahveci, Petros A. Ioannou, Maj D. Mirmirani
We propose an approximate implementation scheme for an adaptive linear quadratic control structure by employing a balanced truncation procedure in the loop prior to solving the associated Algebraic Riccati Equation (ARE). The control design combined with an adaptive law to compensate for uncertainties and possible changes in the dynamics is applied to the longitudinal model of an Unmanned Aerial Vehicle (UAV) in atmospheric flight. The tracking controllers based on the full and reduced order UAV models are constructed, and the resultant effect of the described model reduction on the flight performance of the vehicle is investigated through comparative simulations.
2009-07-12
Technical Paper
2009-01-2403
Marinella Ferrino, Enrico Villata, Valter Basso, Mario Cardano
It is widely recognized that Virtual Reality (VR) environment fosters team performance and design quality in addition to provide time and cost savings in the frame of verification processes. The selected case studies described in this paper are based on the experience matured in the frame of the interaction between TAS-I HFE and other expert groups for MSP/PEI stage analysis performance in support of the COLUMBUS internal and external payloads overall operability. The selected case studies will be used for demonstrating and evaluating results, guiding the new emerging engineering system architecture, by integrating tools, methods and processes in the frame of the TAS-I Concurrent Design Facility (CDF) implementation for Aerospace applications.
2009-07-12
Technical Paper
2009-01-2568
R. Scott Miskovish, Michael Saeger
Successful implementation of temperature control is required in a variety of engineering applications. A method using the I-deas TMG finite volume thermal solver and MATLAB with the Control System Toolbox to characterize the control system performance of a thermal model was described by Saeger [1][2]; this paper describes an alternate approach to this method. The alternate method presented herein uses the TMG thermal solver to create linearized capacitance and conductance matrices of the thermal system. Then, MATLAB uses these matrices to create the frequency response curve using either matrix inversion or eigenvalue solution methods. Once the frequency response is generated, the MATLAB Control System Toolbox can be used to develop the control system.
2009-07-12
Technical Paper
2009-01-2453
Amauric Jarry, Dominique Fraioli
This paper is devoted to the methodology and techniques used by ASTRIUM-ST to analyze the aerothermodynamics of the A5 upper composite reentry. Direct Simulation Monte Carlo methods were applied to compute the composite's surrounding flows and thermal fluxes at walls for its different possible attitudes during deorbitation and along its various scenarios' flight paths. The results are then used as inputs for the determination of the composite's thermal behavior and especially of its main wall structures and equipments as well as propellant and helium tanks with the prediction of their rupture and the ejection velocity of their respective fragments.
2009-07-12
Technical Paper
2009-01-2463
Hiroyuki Miyajima
In recent years, with increased size of the manned space program and systems used in the programs, the role of computer simulations has increased. I have long used and developed independently several simulation tools for the design, operation, analysis, and optimization of the Life Support Systems (LSS). I recognized that the designer makes his/her own idea certain while building a simulation model on a computer. However, conventional simulation tools are not designed so that the interaction between the designer and a model building support environment is dynamically used to bring out a designer's idea. Therefore, in this paper, I consider the development of a conceptual design support tool in the design of the LSS, while focusing attention on the interaction between the simulation tool and the designer.
2009-11-10
Technical Paper
2009-01-3225
Scott A. Vander Weide, Jimmy Secretan
Aircraft maintenance is difficult and dangerous work, often involving cramped, extreme environments. Therefore, aircraft maintenance can result in damaged equipment and systems, or worse, injury to the maintainer. Furthermore, the safety of an aircraft and its passengers is largely dependent on the maintainers as well. This paper explores how Virtual Maintenance Trainers (VMTs), which are software-based simulated maintenance environments, have the potential to mitigate these risks, while reducing training time and costs. By providing a safe environment through which the maintainer can make otherwise dangerous or costly mistakes, VMTs improve the maintainer's ability to avoid these mistakes during actual maintenance. The ability to see consequences of a mistake, even in a virtual world, can be more effective than simply being informed of those consequences by an instructor.
2009-11-10
Technical Paper
2009-01-3221
George T. McWilliams, Kevin J. Alley
The objective of this research was to investigate the feasibility of using visual sensor technology to estimate the UAV's pitch, roll, and groundspeed for future use in advanced flight controls. In order to perform the investigation, a simulation environment was implemented for vision-based control of a UAV. The environment included a Simulink model of a generic UAV, including the flight dynamics, flight controller, and sensors. It also included an open-source graphical simulation, which is able to simulate vision sensors at any location and orientation on the aircraft. The images from the simulated vision sensors were fed back to the Simulink model through a frame grabber.
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