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Book Flexible Aircraft Modelling for Flight Loads Analysis of Wake Vortex Encounters

Download or read book Flexible Aircraft Modelling for Flight Loads Analysis of Wake Vortex Encounters written by Tobias Mauermann and published by . This book was released on 2010 with total page 190 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Book Flexible Aricraft Modelling for Flight Loads Analysis of Wake Vortex Encounters

Download or read book Flexible Aricraft Modelling for Flight Loads Analysis of Wake Vortex Encounters written by Tobias Mauermann and published by . This book was released on 2012 with total page 190 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Book Aircraft Dynamic Loads Generated in Wake Vortex Encounters

Download or read book Aircraft Dynamic Loads Generated in Wake Vortex Encounters written by Carles Suñer Perucho and published by . This book was released on 2014 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: The study illustrated in these pages was developed in the Structural Dynamics and Aeroelasticity Department of the Military Aircraft division of Airbus Defence and Space in Getafe, Madrid (Spain). That department is a multidisciplinary one involving several categories. Some of its competences are the analysis of impacts, acoustics and vibrations for the aircraft and all their systems. Also, the dynamic response of the aircraft to different events is part of the tasks for that department. It is in that field where this project is located. Wake vortex encounters are a dynamic phenomenon similar to other excitations faced by aircraft in its usual operation. That excitation will induce dynamic loads in the aircraft structures as it passes through the wake. Obtaining and analyzing those loads are the main aims of this study. First, it is important to introduce the concept of aircraft wake. In order to achieve the goals of the study, it is necessary to start with the basics of the problem. This is the acknowledgement of the physics of aircraft wakes and how they are generated. Then, how those wakes act as an excitation for other aircraft as they perturb the velocity field of the air. Once the aircraft wakes are introduced, the next step consists of explaining the corresponding aircraft that will face those encounters. In this case, the particular aircraft is an Airbus A400M because that was the one used by Airbus Defence and Space in the campaign of the wake vortex encounters. The following considerations involve the procedures of the Structural Dynamics department in the computation of the numerical simulation for that kind of event. Therefore, it is necessary to know what the tools available for the resolution of this problem are and which aspects face each one. Furthermore, the software and models used in this study have been validated with flight tests and they are an excellent representation of the aircraft and problem considered. After the presentation of the problem, the aircraft considered and tools used, the wake model is the next aspect of study. This is one of the widest fields of aircraft wakes. Having a good wake model is necessary for the accuracy of the results and the main tasks are focused on the wake aging model. That is how the wake evolves and changes as times goes by. With all that, the last aspect of this study is the computation of the dynamic loads induced in wake vortex encounters. As it is an event that is not considered in aircraft regulations, it was difficult to define a particular scenario that is representative of the problem. For that reason, a stochastic analysis of the problem has been chosen to obtain the aircraft loads generated in this kind of event. This analysis consists of scattering the input variables affecting the problem and executing a high number of simulations. In that way, it is possible to derive a statistical behavior of the load response and establish a probability of occurrence for the results obtained. Finally, comparing those results with the reference loads of the aircraft, it is feasible to predict whether wake vortex encounters could be a significant event for the aircraft structure during its operational life.

Book Response of Aircraft Encountering Aircraft Wake Turbulence

Download or read book Response of Aircraft Encountering Aircraft Wake Turbulence written by Robert C. Nelson and published by . This book was released on 1974 with total page 144 pages. Available in PDF, EPUB and Kindle. Book excerpt: The investigation deals with the dynamic behavior of an airplane encountering aircraft wake turbulence. A digital computer simulation was developed to study the response of an aircraft flying into a trailing vortex wake. The simulation includes the complete six degree of freedom equations of motion, a description of the vortex velocity field, unsteady aerodynamics, and pilot control input. The parameters included the penetration angle, separation distance, aircraft size, and pilot control input. Predicted vortex induced motions are presented for general aviation, business, and light jet transport type aircraft.

Book Vortex wakes of Aircrafts

Download or read book Vortex wakes of Aircrafts written by A.S. Ginevsky and published by Springer Science & Business Media. This book was released on 2009-07-07 with total page 166 pages. Available in PDF, EPUB and Kindle. Book excerpt: Investigation of vortex wakes behind various aircraft, especially behind wide bodied and heavy cargo ones, is of both scientific and practical in terest. The vortex wakes shed from the wing’s trailing edge are long lived and attenuate only atdistances of10–12kmbehindthe wake generating aircraft. The encounter of other aircraft with the vortex wake of a heavy aircraft is open to catastrophic hazards. For example, air refueling is adangerous operationpartly due to thepossibility of the receiver aircraft’s encountering the trailing wake of the tanker aircraft. It is very important to know the behavior of vortex wakes of aircraft during theirtakeoff andlanding operations whenthe wakes canpropagate over the airport’s ground surface and be a serious hazard to other depart ing or arriving aircraft. This knowledge can help in enhancing safety of aircraft’s movements in the terminal areas of congested airports where the threat of vortex encounters limits passenger throughput. Theoreticalinvestigations of aircraft vortex wakes arebeingintensively performedinthe major aviationnations.Usedforthispurpose are various methods for mathematical modeling of turbulent flows: direct numerical simulation based on the Navier–Stokes equations, large eddy simulation using the Navier–Stokes equations in combination with subrigid scale modeling, simulation based on the Reynolds equations closed with a differential turbulence model. These approaches are widely used in works of Russian and other countries’ scientists. It should be emphasized that the experiments in wind tunnels and studies of natural vortex wakes behind heavy and light aircraft in flight experiments are equally important.

Book Wake Turbulence

    Wake Turbulence

    Book Details:
  • Author : National Research Council
  • Publisher : National Academies Press
  • Release : 2008-04-27
  • ISBN : 0309113792
  • Pages : 102 pages

Download or read book Wake Turbulence written by National Research Council and published by National Academies Press. This book was released on 2008-04-27 with total page 102 pages. Available in PDF, EPUB and Kindle. Book excerpt: Without major changes, the current air transportation system will be unable to accommodate the expected increase in demand by 2025. One proposal to address this problem is to use the Global Positioning System to enable aircraft to fly more closely spaced. This approach, however, might be limited by the wake turbulence problem, which can be a safety hazard when smaller aircraft follow relatively larger aircraft too closely. To examine how this potential hazard might be reduced, Congress in 2005 directed NASA to request a study from the NRC to assess the federal wake turbulence R&D program. This book provides a description of the problem, an assessment of the organizational challenges to addressing wake turbulence, an analysis of the technical challenges in wake turbulence, and a proposal for a wake turbulence program plan. A series of recommendations for addressing the wake turbulence challenge are also given.

Book Wake Vortex Separation Standards

Download or read book Wake Vortex Separation Standards written by David Burnham and published by . This book was released on 1997 with total page 92 pages. Available in PDF, EPUB and Kindle. Book excerpt: Wake vortex separation standards are used to prevent hazardous wake vortex encounters. A 'safe' separation model can be used to assess the safety of proposed changes in the standards. A safe separation model can be derived from an encounter hazard model and a vortex decay model. This report presents subsequent developments and applications of such a model which was first developed in the early 1980s. A static encounter hazard model is coupled with a decay model based on sodar measurements of vortex decay. The separation standards and procedures used from 1976 to 1994 are assumed to be safe based on the absence of IFR accidents. Various versions of the model are used to assess how aircraft should be classified and to evaluate the safety of a possible four-class aircraft separation system. Recommendations are made for ways of improving the safe separation models.

Book Dynamics of Flexible Aircraft

Download or read book Dynamics of Flexible Aircraft written by Rafael Palacios and published by Cambridge University Press. This book was released on 2023-06-30 with total page 527 pages. Available in PDF, EPUB and Kindle. Book excerpt: Explore the interface between aeroelasticity, flight dynamics and control in this fresh, multidisciplinary approach. New insights into the interaction between these fields, rarely separately considered in most modern aircraft, are fully illustrated in this one-of-a-kind book. The comprehensive, systematic coverage will enable the reader to analyse and design next-generation aircraft. Presenting basic concepts in a rigorous yet accessible way, the book builds up to state-of-the-art models through an intuitive step-by-step approach. Both linear and non-linear attributes are covered, and by revisiting classical solutions using modern analysis methods this book provides a unique, modern perspective to bridge the gap between disciplines. Numerous original numerical examples, including online source codes, help to build intuition through hands-on activities. This book will empower the reader to design better and more environmentally friendly aircraft, and is an ideal resource for graduate students, researchers and aerospace engineers.

Book A Parametric Study of Accelerations of an Airplane Due to a Wake Vortex System

Download or read book A Parametric Study of Accelerations of an Airplane Due to a Wake Vortex System written by National Aeronautics and Space Administration and published by . This book was released on 2018-08-27 with total page 40 pages. Available in PDF, EPUB and Kindle. Book excerpt: A study was conducted using strip theory to systematically investigate the effects of progressively more complete descriptions of the interaction of an airplane with a wake vortex system. The emphasis was in roll-dominant, parallel, vortex encounters. That is, the simulated airplane's longitudinal axis was nearly parallel to the rotation axis of the vortex system for most of the results presented. The study began with a drag-less rectangular wing in the flow field of a single vortex and progressed to a complete airplane with aerodynamic surfaces possessing taper, sweep, dihedral, and stalling and immersed in the flow field of a vortex pair in ground effect. The effects of the pitch, roll, and yaw attitudes of the airplane on the calculated accelerations were also investigated. The airplane had the nominal characteristics of a Boeing 757, and the vortex flow field had the nominal characteristics of the wake of a Boeing 767. The Bumham-Hallock model of a vortex flow field was used throughout the study. The data are presented mainly in terms of contours of equal acceleration in a two-dimensional area centered on the vortex pair and having dimensions of 300 feet by 300 feet.Stewart, Eric C.Langley Research CenterAERODYNAMICS; FLOW DISTRIBUTION; RECTANGULAR WINGS; ROLL; ROTATION; VORTICES; YAW; AIRCRAFT WAKES; MATHEMATICAL MODELS; BOEING 757 AIRCRAFT; BOEING 767 AIRCRAFT; GROUND EFFECT (AERODYNAMICS)...

Book Modelling and Simulation of Gust and Atmospheric Turbulence Effects on Flexible Aircraft Flight Dynamics

Download or read book Modelling and Simulation of Gust and Atmospheric Turbulence Effects on Flexible Aircraft Flight Dynamics written by Pau Castells Marin and published by . This book was released on 2020 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: The prediction of the aircraft response to gust and turbulence is of major importance for different purposes. Gust load analysis is an essential part of aircraft design and certification. The effect of gust and turbulence on aircraft flight dynamics is also of interest. Models able to capture relevant effects at these conditions in early design phases are essential in order to anticipate and assess the aircraft response and flight control laws in realistic atmospheric disturbances before flight test. This work proposes a modelling strategy to capture relevant physics when simulating the aircraft response to gust and turbulence for flight dynamics investigations. The model provides accuracy at a low computational cost as well as consistency with gust loads analysis enabling multidisciplinary design. The approach is based on the integration of a nonlinear quasi-steady flexible flight dynamics model with an unsteady aeroelastic model linearized around a nonlinear steady state. The gust-induced forces have a significant impact on aircraft flight dynamics. Low computing times are required to cover several flight conditions and aircraft parameters. A computationally efficient multipoint aerodynamic model, which captures both unsteady aerodynamic and gust propagation effects, is generated from linearized Computational Fluid Dynamics (CFD) simulations in the frequency domain. The model is identified through a rational function approximation allowing for time domain simulations. A reduced number of additional aerodynamic states is sufficient to capture the main effects at low frequencies for flight dynamics analysis. The impact of dynamic flexibility on the response is also evaluated. Only the most energetic flexible modes are retained to reduce the number of states and ensure a low computation time. The approach is applied to simulate the vertical and lateral response of a passenger aircraft to theoretical disturbance profiles as well as realistic atmospheric turbulence at different flight conditions. Aerodynamic nonlinear effects, such as local stalls due to shock motion, in transonic conditions may appear. The linearized model is able to capture the global aircraft response at these conditions with low amplitude shock motions. Results are compared and validated with a CFD simulation based approach, coupled with a structural dynamics and flight mechanics solver. Measures from flight test are also used to assess the modelling approach. The effect of uncertainties on the response is analysed, in terms of the turbulence variation along the wingspan. Simulation results show that relevant aerodynamic effects due to gust and turbulence are captured in the frequency range of interest for flight dynamics investigations.

Book Aircraft Wake Vortices

Download or read book Aircraft Wake Vortices written by James N. Hallock and published by . This book was released on 1991 with total page 396 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Book A Preliminary Study of a Wake Vortex Encounter Hazard Boundary for a B737 100 Airplane

Download or read book A Preliminary Study of a Wake Vortex Encounter Hazard Boundary for a B737 100 Airplane written by National Aeronautics and Space Administration (NASA) and published by Createspace Independent Publishing Platform. This book was released on 2018-08-09 with total page 34 pages. Available in PDF, EPUB and Kindle. Book excerpt: A preliminary batch simulation study was conducted to define the wake decay required for a Boeing 737-100 airplane to safely encounter a Boeing 727 wake and land. The baseline six-degree-of-freedom B737 simulation was modified to include a wake model and the strip-theory calculation of the vortex-induced forces and moments. The guidance and control inputs for the airplane were provided by an autoland system. The wake strength and encounter altitude were varied to establish a safe encounter boundary. The wake was positioned such that the desired flight path traversed the core of the port Vortex. Various safe landing criteria were evaluated for defining a safe encounter boundary. A sensitivity study was also conducted to assess the effects of encounter model inaccuracies. Reimer, Heidi M. and Vicroy, Dan D. Langley Research Center NASA-TM-110223, NAS 1.15:110223 RTOP 505-64-13-02...