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Viewing 1 to 30 of 5927
2010-04-12
Journal Article
2010-01-0451
Christoph Roth, Oliver Sander, Michael Hübner, Juergen Becker
A future car-to-x communication system has to fulfil a lot of different requirements concerning high performance and functionality that are given by the field of application. To be able to optimize the system architecture regarding these constraints an intensive architecture evaluation and investigation is necessary. Within this paper a simulative approach for comprehensive design space exploration, verification, and test of a car-to-x communication unit is presented. The proposed simulation environment allows for a flexible adaption to the test case by being able to interconnect an arbitrary number of simulators of different type and different granularity. As a novelty complete embedded car-to-x systems can be investigated by integrating several SystemC based architecture models into an environmental simulation and observing their behavior and interaction.
2011-04-12
Technical Paper
2011-01-0272
David C. Viano, Chantal Parenteau, Roger Burnett
Objective: This study analyzed available rear impact sled tests with Starcraft-type seats that use a diagonal belt behind the seatback. The study focused on neck responses for out-of-position (OOP) and in-position seated dummies. Methods: Thirteen rear sled tests were identified with out-of-position and in-position 5 th , 50 th and 95 th Hybrid III dummies in up to 47.6 mph rear delta Vs involving Starcraft-type seats. The tests were conducted at Ford, Exponent and CSE. Seven KARCO rear sled tests were found with in-position 5 th and 50 th Hybrid III dummies in 21.1-29.5 mph rear delta Vs involving Starcraft-type seats. In all of the in-position and one of the out-of-position series, comparable tests were run with production seats. Biomechanical responses of the dummies and test videos were analyzed.
2011-04-12
Technical Paper
2011-01-0274
David C. Viano
Purpose: This study presents cases of fracture-dislocation of the thoracic spine in extension during severe rear impacts. The mechanism of injury was investigated. Methods: Four crashes were investigated where a lap-shoulder-belted, front-seat occupant experienced fracture-dislocation of the thoracic spine and paraplegia in a severe rear impact. Police, investigator and medical records were reviewed, the vehicle was inspected and the seat detrimmed. Vehicle dynamics, occupant kinematics and injury mechanisms were determined in this case study. Results: Each case involved a lap-shoulder-belted occupant in a high retention seat with ≻1,700 Nm moment or ≻5.5 kN strength for rearward loading. The crashes were offset rear impacts with 40-56 km/h delta V involving under-ride or override by the impacting vehicle and yaw of the struck vehicle. In each case, the occupant's pelvis was restrained on the seat by the open perimeter frame of the seatback and lap belt.
2004-11-02
Technical Paper
2004-01-3089
Lionel D. Alford, Aaron Altman
The typical aeronautical engineering approach to low Reynolds number flight studies has been to start with known high Reynolds number aerodynamic paradigms and attempt to match them by scaling to observations of birds and insects. On the other hand, the typical biological approach to natural flight aerodynamics has been to try to fit the observations of birds and insects into the typical known aerodynamic paradigms. Neither of these approaches has met with much success, and although we know more about the potential processes of natural flight, we have not been able to describe them using the framework of conventional aerodynamics. The investigation of low Reynolds number aerodynamic flows at the University of Dayton has led to a proposed new method of characterizing and describing the aerodynamics of natural flight. Lift in natural flight is theorized to be based in the spanwise flow along the curvature of a flapping wing.
2004-07-19
Technical Paper
2004-01-2279
Eric P. Rubenstein, Marek A. Wójtowicz, Elizabeth Florczak, Erik Kroo, Robert C. Singleterry
AFR, Inc. is developing a multifunctional Carbon material that, in addition to excellent radiation shielding characteristics, is appropriate for certain energy storage applications. As an excellent Hydrogen gas sorbent, it increases the usable storage capacity of a gas cylinder by ~25% at 3500 PSI and by ~150% at 500 PSI. Our recent NASA-Langley SBIR study shows that when a sorbent-filled tank is charged with hydrogen, it provides shielding superior to polyethylene against most types of ionizing particles. Even as hydrogen is consumed, the carbon and tank ensure that significant radiation shielding capability is maintained. Vastly improved radiation shielding is a clear requirement for a potential manned mission to Mars or a long-duration base on the surface of the Moon. However, current shielding technologies are predicated upon systems dedicated solely to the task of shielding.
2004-04-20
Technical Paper
2004-01-1817
Scott Gilchrist, Daniel Ewing, Chan Ching, Joseph Brand, Michael Dowhan
A new aero-engine nose cone anti-icing system using a rotating heat pipe has been proposed to replace the current method of blowing hot compressor bleed air over the nose cone surface. Here, the heat is transferred from a hot source within the engine to the nose cone through a rotating heat pipe along the central fan shaft. A compact evaporator is used at the evaporator end due to space constraints in the engine. The system is modeled as a thermal resistance network where the thermo-fluid dynamics of each component determine the resistors. This paper reviews each of the component models and results, which show that the evaporator thermal resistance is one of the limiting factors for adequate transfer of heat for anti-icing.
2011-05-17
Technical Paper
2011-01-1704
Nickolas Vlahopoulos, Geng Zhang, Ricardo Sbragio
Vehicle design is a complex process requiring interactions and exchange of information among multiple disciplines such as fatigue, strength, noise, safety, etc. Simulation models are employed for assessing and potentially improving a vehicle's performance in individual technical areas. Challenges arise when designing a vehicle for improving mutually competing objectives, satisfying constraints from multiple engineering disciplines, and determining a single set of values for the vehicle's characteristics. It is of interest to engage simulation models from the various engineering disciplines in an organized and coordinated manner for determining a design configuration that provides the best possible performance in all disciplines. The multi-discipline design process becomes streamlined when the simulation methods integrate well with finite element or computer aided design models.
1999-10-19
Technical Paper
1999-01-5659
R. Kruk, N. Link, L. Reid, S. Jennings
The Enhanced/Synthetic Vision System (E/SVS) is a Technology Demonstrator (TD) project supported by the Chief, Research and Development of the Canadian Department of National Defence. E/SVS displays an augmented visual scene to the pilot that includes three separate image sources: a synthetic computer - generated terrain image; an enhanced visual image from an electro-optical sensor (fused as an inset); and aircraft instrument symbology, all displayed to the pilot on a Helmet Mounted Display (HMD). The synthetic component of the system provides a 40 degree vertical by 80 degree horizontal image of terrain and local features. The enhanced component digitizes imagery from electro-optic sensors and fuses the sensor image as an inset (20 degrees by 25 degrees) within the synthetic image. Symbology can be overlaid in any location within the synthetic field-of-view and may be head, aircraft, target or terrain referenced.
1999-10-19
Technical Paper
1999-01-5605
Jean H. Slane, Robert C. Winn
If an airplane crashes, the recorded radar data can be used to reconstruct a time history of the airplane’s calibrated airspeed, load factor, excess thrust, bank angle, etc. Previous work on this problem has used a rectilinear approach to the calculations involved in the flight parameter reconstruction. The rectilinear approach gives excellent results for relatively straight flight; however, it routinely underestimates the airspeed and the bank angle when the airplane is maneuvering. In the present study, the authors present a curvilinear approach to flight parameter reconstruction that addresses this shortcoming. The analysis presented shows that the curvilinear approach is a far superior tool than the rectilinear approach for the reconstruction of maneuvering flight including steep turns and high-speed spirals.
1999-08-17
Technical Paper
1999-01-2893
Yuri A. Krassin
A new application is proposed for a light aircraft in personal transportation - that is of a long range grand tourism vehicle; the role it can perform much better than an automobile. Light aircraft more conventional usage for short ranges is more suitable for business goals. A convertible road to air vehicle (aircar) having a high CL/CD ratio is considered to be the most suitable means of personal transportation in the future. A rather low CL/CD of previously built aircars is considered to be one of the reasons of their failure in the past. A narrow road module having a controlled body tilt and a high aspect ratio wing are proposed as remedies. Simple original equations comparing light aircraft expenses against that of an automobile or an airliner ticket cost are proposed. They show that the light aircraft costing up to $35K per passenger at CL/CD =12 can be competitive with an airliner on a range of up to 2,500 miles and an aircar at CL/CD =20 or more of up to 12,000 miles.
1999-10-19
Technical Paper
1999-01-5564
R.C.J. Ruigrok, R.N.H.W. van Gent, J.M. Hoekstra
This paper describes the initial results of a simulation experiment in which the human factors implications of three Mixed Equipage, Integrated Air-Ground, Free Flight Air Traffic Management (ATM) scenarios were investigated. The experiment primarily addressed how to accommodate a fleet of mixed equipped aircraft, with and without Airborne Separation Assurance System (ASAS), in a transitional free flight era in which both air and ground players have defined responsibilities. All three transitional ATM operational concepts evaluated, were designed with the idea that equipping aircraft should be immediately beneficial to the airlines.
1999-10-19
Technical Paper
1999-01-5563
Brian Hilburn, Wouter D. Pekela
This paper presents selected results of four experiments into air traffic control (ATC) aspects of free flight (FF). The first two examined basic human performance implications of FF, in terms of workload and ability to monitor traffic. The third explored the potential for improved ATC displays to benefit controllers under FF traffic patterns. The fourth experiment examined methods for accommodating mixed equipage, such as during a transitional FF era in which both FF capable and FF incapable aircraft would be expected to share the same airspace. The first three experiments involved controllers operating in “open-loop” simulations, with computer-generated traffic and simulated pilot responses. In the final experiment, pilots and controllers were linked in real-time sessions.
1999-10-19
Technical Paper
1999-01-5566
Eric Hoffman, Karim Zeghal, Gildas Courtet
The Evolutionary Air-ground Co-operative ATM Concepts (EACAC) study of the Freer-Flight project investigates the delegation by the controller to the pilot, of some tasks related to separation assurance. Starting from the analogy of visual clearances, EACAC investigates the possibility of giving electronic clearances. One of the issues of the study deals with the appropriate assistance scheme to be provided to the pilot, considering the proposed concept of limited delegation. The “scales of separations” is one of the levels of assistance envisaged. Two models of turns and their appropriateness for lateral scales of effects are investigated. The scales of separations implementing these models will be evaluated by pilots, first through a cockpit environment in a stand-alone mode (end 1999), and then using a cockpit simulator in a real-time simulation with controllers (mid 2000).
1999-10-19
Technical Paper
1999-01-5565
Karim Zeghal, Eric Hoffman, Jean-Pierre Nicolaon, Anne Cloerec, Isabelle Grimaud
This paper presents the initial evaluation of the EACAC study, which is investigating delegation by the controller to the pilot of some tasks related to separation assurance. The concept is applied in managed airspace for two classes of application: crossing and passing in enroute, and sequencing in Terminal Manoeuvring Area. The concept relies on two key points discussed in the paper: “limited delegation” and “flexible use of delegation”. The initial evaluation using a simplified ATC environment has been set up to get “feedback” from both controllers and pilots, and to assess the operational feasibility and potential interest of the concept. The overall feeling about the method is “promising” with a “great potential”, and could reduce workload. The notion of “flexible use of delegation” would enable the gradual growth of confidence and would also provide flexibility to use the method under different conditions (traffic, airspace, practice level).
1999-10-19
Technical Paper
1999-01-5540
Lynne Martin, Jeannie Davison, Judith Orasanu, Chesley Sullenberger
Despite efforts to design systems and procedures to support “correct” and safe operations in aviation, accidents still occur and errors in human judgment are found to be contributing factors. In this paper we examine how the wider aviation system may play a role in decision processes. Our strategy was to examine a collection of identified decision errors (National Transportation Safety Board [NTSB], 1994) through the lens of an aviation decision process model and to search for common patterns. The second and more difficult task was to determine what might account for those patterns. The decision process model suggests that decisions with undesirable outcomes can arise in two major ways: either through misassessment of the situation - a problem with situation awareness, or through judgment of the best course of action.
1999-10-19
Technical Paper
1999-01-5541
Jacqueline A. Duley, Scott M. Galster, Raja Parasuraman, Anthony J. Smoker
Increases in technological capability permit us to obtain more information with improved accuracy from the systems and actors in the NAS. Collaborative Decision Making is a philosophy of redistributing information such that airspace users and service providers can act cooperatively to solve problems in areas such as flow control, and ground or weather delays. Designers are creating new tools to access this information and provide it to the users and ATC. We are concerned with the controller interface to this information and its incorporation of these new tools. We recommend a human-centered approach to the development of an effective interface.
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.
2011-06-13
Technical Paper
2011-38-0013
Marco Fossati, Wagdi G. Habashi, Guido Baruzzi
The high computational cost of 3-D viscous turbulent aero-icing simulations is one of the main limitations to address in order to more extensively use computational fluid dynamics to explore the wide variety of icing conditions to be tested before achieving aircraft airworthiness. In an attempt to overcome the computational burden of these simulations, a Reduced Order Modeling (ROM) approach, based on Proper Orthogonal Decomposition (POD) and Kriging interpolation techniques, is applied to the computation of the impingement pattern of supercooled large droplets (SLD) on aircraft. Relying on a suitable database of high fidelity full-order simulations, the ROM approach provides a lower-order approximation of the system in terms of a linear combination of appropriate functions. The accuracy of the resulting surrogate solution is successfully compared to experimental and CFD results for sample 2-D problems and then extended to a typical 3-D case.
2011-06-13
Technical Paper
2011-38-0015
Robert Narducci, Tonja Reinert
The desire to operate rotorcraft in icing conditions has renewed the interest in developing high-fidelity analysis methods to predict ice accumulation and the ensuing rotor performance degradation. A subset of providing solutions for rotorcraft icing problems is predicting two-dimensional ice accumulation on rotor airfoils. While much has been done to predict ice for fixed-wing airfoil sections, the rotorcraft problem has two additional challenges: first, rotor airfoils tend to experience flows in higher Mach number regimes, often creating glaze ice which is harder to predict; second, rotor airfoils oscillate in pitch to produce balance across the rotor disk. A methodology and validation test cases are presented to solve the rotor airfoil problem as an important step to solving the larger rotorcraft icing problem. The process couples Navier-Stokes CFD analysis with the ice accretion analysis code, LEWICE3D.
2011-06-13
Technical Paper
2011-38-0014
Jason Wright, Roger J. Aubert
As part of icing certification flight test programs, artificial ice shapes are typically installed onto aircraft fixed leading edges in order to quantify changes to the handling qualities and performance characteristics of the aircraft in icing conditions. Artificial ice shapes allow a test team to evaluate what are generally the worst combinations of flight conditions for different ice protection system configurations. The goal of this paper is to discuss the details behind the design, development, construction, and installation of artificial ice shapes as they pertained to the evaluation of the need for horizontal stabilizer ice protection on the BA609 Tiltrotor with a focus on the extrapolation methods used to design the shapes.
2011-06-13
Technical Paper
2011-38-0005
Jason Mickey, Eric Loth, Colin Bidwell
A new technique is proposed for computing particle concentrations and fluxes with Lagrangian trajectories. This method calculates particle concentrations based on the volume of a parcel element, or cloud, at the flux plane compared against the initial volume and is referred to as the Lagrangian Parcel Volume (LPV) method. This method combines the steady-state accuracy of area-based methods with the unsteady capabilities of bin-based methods. The LPV method results for one-dimensional (1D) unsteady flows and linear two-dimensional (2D) steady flows show that a quadrilateral element shape composed of a single parcel (with four edge particles) is capable of accurately predicting particle concentrations. However, nonlinear 2D flows can lead to concave or crossed quadrilaterals which produce significant numerical errors.
2011-06-13
Technical Paper
2011-38-0004
Peng Ke, Xinxin Wang
Lagrangian approach has been widely adopted in the droplet impingement analysis for aircraft icing simulation. Some improvements were proposed, including: 1) The heat and mass transfer consideration in droplet dynamics; 2) More efficient droplet localization method, which could and facilitated to find the initial cell in Eulerian grid; 3) New computation method of impingement efficiency, which uses the cover ratio to transform the impingement efficiency of arbitrary impinged region to that of the cell element of body surface and avoids the iterative computation to find the trajectories reaching the corner of the panel or cell element. A numerical solver was built and integrated with the capabilities to deal with super-cooled large droplet (SLD) conditions by considering the splashing and bouncing of SLD. The computational results were validated with the experiment data, which shown good agreements in the impingement limitations and tendency.
2011-06-13
Technical Paper
2011-38-0006
Robert J. Flemming, Philip Alldridge
Sikorsky Aircraft certificated the Model S-92A™ helicopter for flight in icing conditions in 2005. Since that time, the aircraft has flown in icing conditions throughout the world and the approval to launch a flight when icing conditions are forecast or reported has been valuable to operators. However, when the rotor ice protection system was inoperative due to a system failure, use of the aircraft on days of forecast icing was prohibited. Sikorsky Aircraft, therefore, elected to obtain certification of the S-92A helicopter to an EASA limited icing Special Condition so that UK and Norwegian operators in the North Sea sector could complete a mission when icing conditions were forecast, should the RIPS be inoperative on that day. A review of previously available icing data indicated that the S-92A helicopter could meet the requirements of the EASA Special Condition, but that additional flights were required to demonstrate full compliance.
2011-06-13
Technical Paper
2011-38-0022
Marco Fossati, Rooh-ul-Amin Khurram, Wagdi G. Habashi
The irregular shapes that glaze ice may grow into while accreting over the surface of an aircraft represent a major difficulty in the numerical simulation of long periods of in-flight icing. In the framework of Arbitrary Lagrangian-Eulerian (ALE) formulations, a mesh movement scheme is presented, in which frame and elasticity analogies are loosely coupled. The resulting deformed mesh preserves the quality of elements, especially in the near-wall region, where accurate prediction of heat flux and shear stresses are required. The proposed scheme handles mesh movement in a computationally efficient manner by localizing the mesh deformation. Numerical results of ice shapes and the corresponding aerodynamic coefficients are compared with the experimental results.
2011-06-13
Technical Paper
2011-38-0021
Ben C. Bernstein, Frank Mcdonough, Cory Wolff
A large database is being created from icing flight programs completed by aircraft manufacturers for certification and by the NASA-Glenn Research Center for basic research. Although not yet complete, this database already provides an excellent opportunity to study aircraft icing conditions sampled in a wide variety of environments across eastern Canada and most of the United States, including Alaska. In this study, the focus is a comparison of conditions found within boundary-layer stratocumulus icing clouds over the Great Lakes, Pacific Northwest and Alaskan Interior. The clouds will be characterized in terms of temperature, liquid water content, median volumetric diameter, and drop concentration. Critical factors driving these parameters will be discussed.
2011-06-13
Technical Paper
2011-38-0024
Isik A. Ozcer, Guido S. Baruzzi, Thomas Reid, Wagdi G. Habashi, Marco Fossati, Giulio Croce
Numerically predicted roughness distributions obtained in in-flight icing simulations with a beading model are used in a quasi-steady manner to compute ice shapes. This approach, called "Multishot," uses a number of steady flow and droplet solutions for computing short intervals (shots) of the total ice accretion time. The iced geometry, the grid, and the surface roughness distribution are updated after each shot, producing a better match with the unsteady ice accretion phenomena. Comparisons to multishot results with uniform roughness show that the evolution of the surface roughness distribution has a strong influence on the final ice shape. The ice horns that form are longer and thinner compared to constant roughness results. The constant roughness approach usually fails to capture the formation of the pressure side horns and under-predicts the thickness of the ice in this region.
2011-06-13
Technical Paper
2011-38-0023
Guilherme Araujo Lima da Silva, Marcos Noboru Arima, Natashe Nicoli Branco, Marcos de Mattos Pimenta
This paper proposes wall function models to simulate the heat transfer around a cylinder in cross flow with an isothermal and rough surface. The selected case has similitudes with aircraft wing icing: the ice roughness shape, height and distribution. Moreover, the flow is somewhat similar to that found on iced airfoil; and the surface is isothermal like when icing. The Reynolds-Averaged Navier-Stokes, turbulence, energy and mass conservation 7-equation system is solved by two Computational Fluid Dynamics (CFD) codes. To represent accurately the effects of roughness on the heat transfer, the present authors had to modify both codes and to propose new thermal wall functions for them. In addition, it was implemented a momentum wall function that is not so common in CFD codes but it is a standard in aircraft icing simulation.
2011-06-13
Technical Paper
2011-38-0016
Tonja Reinert, Robert J. Flemming, Robert Narducci, Roger J. Aubert
A team from the USA rotorcraft industry, NASA, and academia was established to create a validated high-fidelity computational fluid dynamics (CFD) icing tool for rotorcraft. Previous work showed that an oscillating blade with a periodic variation in angle of attack causes changes in the accreted ice shape and this makes a significant change in the airfoil drag. Although there is extensive data for ice accumulation on a stationary airfoil section, high-quality icing-tunnel data on an oscillating airfoil is scarce for validating the rotorcraft icing problem. In response to this need, a two-dimensional (2D) oscillating airfoil icing test was recently performed in the Icing Research Tunnel at the NASA Glenn Research Center. Three leading-edge specimens for an existing 15-inch chord test apparatus were designed and instrumented to provide the necessary data for the CFD code validation.
2011-06-13
Technical Paper
2011-38-0020
Cory Wolff, Frank Mcdonough, Ben Bernstein
In the continental United States east of the Rocky Mountains cold fronts are quite common in wintertime due to the many cyclones moving through this region, and icing conditions in the vicinity of cold fronts are a major contributor to the overall occurrence of icing in the atmosphere. The conditions examined in this study will be those behind the cold front. Icing there is often found in stratocumulus clouds that form due to destabilization of the boundary layer through cold air advection and an inversion formed by subsidence aloft which caps their growth. Moist adiabatic lapse rates, small drop sizes, high drop concentrations, and moderate to high liquid water contents depending on the cloud depth often characterize these clouds.
2011-06-13
Technical Paper
2011-38-0067
Nathalie Alegre, David Hammond
This study reports aerodynamic properties of two runback ice shapes molded from a mid-span full scale B737 aerofoil leading edge together with a series of simplistic ice shapes of the type sometimes used by aircraft manufacturers to mimic performance loss due to runback ice. The runback ice shapes were taken from a study of runback ice growth which had produced flexible silicone rubber moulds. These moulds were used to produce ice shapes without curvature which, together with the “simplistic” shapes were mounted on flat plates and installed into the Cranfield University 8 by 6 foot wind tunnel. A boundary layer suction system was used to match the wall conditions more closely to what would be anticipated on a real aerofoil. The icing conditions approximate to a hold case with the two shapes representing a 4 and a 10 mm thick runback shape. The aerodynamic tests have been performed with a tunnel speed of 45 m/s.
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