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Author :
Publisher :
ISBN 13 :
Total Pages : 78 pages
Book Rating : 4.:/5 (317 download)
Download or read book Application of a Panel Method to Wake-vortex/wing Interaction and Comparison with Experimental Data written by and published by . This book was released on 1987 with total page 78 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Author : Brian E. Smith
Publisher :
ISBN 13 :
Total Pages : 230 pages
Book Rating : 4.:/5 (116 download)
Download or read book Application of Panel Method to Wake-vortex/wing Interaction and Comparison with Experimental Data written by Brian E. Smith and published by . This book was released on 1984 with total page 230 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Author : Aaron D. Kuenn
Publisher :
ISBN 13 :
Total Pages : 0 pages
Book Rating : 4.:/5 (136 download)
Download or read book Trailing Wake Vortices written by Aaron D. Kuenn and published by . This book was released on 2022 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Available literature has demonstrated a scarcity of data collected behind simple, academic wings that were not NACA profiles. Additionally, comparison of the simplified vortex models is typically performed piecewise without a broad comparison between models. In the present investigation, the structure of an isolated wake vortex is studied and a more thorough comparison of wake vortex models is performed. Experimental data is presented that primarily focuses on the vortex generated by a flat-plate wing. Additional data for a NACA 0015 wing of similar aspect ratio is investigated to validate the experimental method. The experimental method presented utilizes a linear two-axis traverse to position a conventional seven-hole probe in the wake of the generating wing. A semi-span model is used to generate the vortex. Twenty-two vortex surveys are presented between four and sixteen chord lengths downstream of the trailing edge of the generating wing. Vortex core circulation ranges from 8 × 104 to 66 × 104. Vortices presented exhibit a faster decay in peak tangential velocity than reported in some experimental data, but circulation within the core region is shown to remain constant. Comparisons of the current experimental data and simplified models suggests that both the flat plate and NACA 0015 models produce a turbulent vortex. Evidence is presented that suggests that vortex circulation is not the only governing factor on whether a vortex exhibits a laminar or turbulent profile. Fourteen axisymmetric vortex models are considered and their circulation, tangential velocity, and vorticity distributions compared. Both laminar and turbulent models are considered. Discussion is presented on the relationship of vortex circulation and the transition from a laminar to turbulent character. Comparisons highlight a common trend of increased tangential velocity in turbulent vortices at larger radii for the same vortex strengths. Some models estimate unbounded circulation, particularly among turbulent formulations.
Author : Glenn H. Robinson
Publisher :
ISBN 13 :
Total Pages : 68 pages
Book Rating : 4.:/5 (31 download)
Download or read book A Flight Evaluation of Methods for Predicting Vortex Wake Effects on Trailing Aircraft written by Glenn H. Robinson and published by . This book was released on 1972 with total page 68 pages. Available in PDF, EPUB and Kindle. Book excerpt: The results of four current analytical methods for predicting wing vortex strength and decay rate are compared with the results of a flight investigation of the wake characteristics of several large jet transport aircraft. An empirical expression defining the strength and decay rate of wake vortices is developed that best represents most of the flight-test data. However, the expression is not applicable to small aircraft that would be immersed in the vortex wake of large aircraft.
Author : Omer Ali El-Sayed
Publisher :
ISBN 13 :
Total Pages : 360 pages
Book Rating : 4.:/5 (957 download)
Download or read book Aircraft Wake Vortices Characterization and Alleviation written by Omer Ali El-Sayed and published by . This book was released on 2010 with total page 360 pages. Available in PDF, EPUB and Kindle. Book excerpt: The serious impact of the trailing vortices from large aircraft is well known. Many examples exist of the damage caused to following aircraft caught up in the swirling wake shed from an upstream aircraft. Motivation behind the present investigation is the alleviation of the rolling moment induced on the following aircraft by means of a differential spoiler setting DSS's. An experimental investigation on a wing tip vortex generated by generic aircraft model, Subsonic Wall Interference Model (SWIM) in plain and flapped wing configurations was conducted in a low speed wind tunnel at Korean Aerospace Research Institute (KARI). Particle image velocimetry was used to characterize wing tip vortex structures as well as to distinguish and quantify vortex meandering and further remove its effects. In subsequent experiments investigation on wake vortices has been carried out in the international Islamic University Malaysia (IIUM) low speed wind tunnel for the evaluation of differential spoiler settings (DSS) capabilities in modifying the span-wise wing load and further reduces the wake vortex hazard. Advanced PIV technique was used to measure the wake velocities at four cross-section planes down-stream of the aircraft half model in the near and extended near wake field. Model was investigated at high lift configuration as well as at four DSS configurations believed to modify the span-wise wing loading (two inboard and two outboard loading cases). Results reveal a noticeable inboard shift of wing loading along with the direct interaction of the spoiler's wake and flap tip vortex for the inboard loading cases. Implementation of DSS results in a substantial redistribution of the flap tip vortex circulation with a diameter of the merged vortex increased by a factor of up to 2.72 times, relative to the undisturbed flap tip vortex. Inspection of the cross-stream distribution of axial vorticity shows up to 2.33 times reduction in the peak vorticity value. A 44% decrease of the maximum cross-flow velocity was recorded for the case of deployed spoilers relative to undisturbed flap tip vortex maximum cross-flow velocity. The wing tip vortex experiences the effect of wing load modification but doesn't show appreciable difference, both in terms of cross-flow velocity and local circulation distribution. Evaluations of the outboard loading results indicate a limited diffusion experienced by the vortex due to the increased level of turbulence. Influence of DSS's on the wake vortex structure emphasizes that separation distance (spoiler wake/wing-flap tips vortices) plays an important role in the favorable interaction expected. Finally assessment of the DSS's capabilities as a wake vortex attenuation device reveals, while position of the maximum induced rolling moments in the flap tip area is little influenced by the DSS's, the maximum induced rolling moment coefficient was reduced to a nearly one third relative to the undisturbed flap tip vortex value.
Author : M. R. Brashears
Publisher :
ISBN 13 :
Total Pages : 249 pages
Book Rating : 4.:/5 (227 download)
Download or read book Analysis of Predicted Aircraft Wake Vortex Transport and Comparison with Experiment. Volume I. Wake Vortex Predictive System Study written by M. R. Brashears and published by . This book was released on 1974 with total page 249 pages. Available in PDF, EPUB and Kindle. Book excerpt: A unifying wake vortex transport model is developed and applied to a wake vortex predictive system concept. The fundamentals of vortex motion underlying the predictive model are discussed including vortex decay, bursting and instability phenomena. A parametric and sensitivity analysis is presented to establish baseline uncertainties in the algorithm to allow meaningful comparison of predicted and measured vortex tracks. A detailed comparison of predicted vortex tracks with photographic and groundwind vortex data is presented. Excellent agreement between prediction and measurement is shown to exist when sufficient wind data are available. Application of the Pasquill class criteria is shown to be an effective technique to describe the wind profile in the absence of detailed wind data. The effects of wind shear and the Ekman spiral on vortex transport are discussed. It is shown that the combination of wind shear and ground plane may be possible mechanisms underlying vortex tilting and a theoretical explanation is advanced that is somewhat supported by comparison with the experimental data. Finally, recommendations for further vortex data collection in the vicinity of an airport are presented. (Author).
Author : Hani bin Ludin @ Jamaluddin
Publisher :
ISBN 13 :
Total Pages : 238 pages
Book Rating : 4.:/5 (957 download)
Download or read book Numerical Study of Wake Vortex Alleviation written by Hani bin Ludin @ Jamaluddin and published by . This book was released on 2012 with total page 238 pages. Available in PDF, EPUB and Kindle. Book excerpt: A numerical investigation was undertaken to study the aerodynamic characteristics of wake vortices generated from an aircraft during taking-off or landing, and thus exploring the possible techniques of reducing hazard imposed to the following aircraft by means of passive wake vortex alleviation. An initial study has been carried out on passive wake vortex alleviation by using delta wing (DW) and reverse delta wing (RDW) as an add-on device. Simulations were performed using RANS turbulence model. The results were obtained and quantified at measurement section locations downstream, of x/c=1.359 and x/c=3.418 measured from leading edge point of the model. Comparison between numerical and experimental results has shown good agreement in term of aerodynamic forces for RDW, whereas the comparison is not so good for DW as far as the prediction of drag coefficient is concerned. Although the simulations capture vortex roll-up trends, the size of the vortex is not predicted correctly by RANS turbulence model. Overall, it can be concluded from the results that the wake vortex generated from DW exhibit higher tangential velocity magnitude and circulation than the one generated from RDW at a particular angle of attack (AOA) between 20o to 30o. Subsequently, a broader investigation of another passive wake vortex alleviation technique was performed to study the potential of differential spoiler setting (DSS) of a scaled, half-model aircraft in alleviating the rolling moment induced on the following aircraft. The model was simulated under high lift configuration (HLC) condition, using inherently unsteady technique adopted in LES turbulence model, for two outboard loading cases and two inboard loading cases, in addition to the baseline configuration case. The study has covered near-wake field and extended near-wake field by taking seven measurement section planes at x/b=0.345, x/b=0.444, x/b=0.658, x/b=1.076, x/b=1.794, x/b=2.691 and x/b=4.484. Comparison between numerical simulations and experimental results has shown good agreement in term of lift coefficient for all cases, and fairly acceptable agreement in term of maximum cross-flow velocity, maximum normalized total circulation and maximum induced rolling moment. However, there were some occasions where the comparison is not so good. For instance, the difference error has risen up to 40.3% in term of maximum normalized cross-flow velocity for baseline configuration. Evaluation of the results has showed promising outcomes for the inboard loading cases compared to the outboard loading cases. The interaction between spoilers' wake and outboard flap tip vortex of the inboard loading cases has reduced the tangential velocity magnitude and circulation of the wing tip vortex, and delayed vortex merging to farther distance downstream. This conclusion justifies the DSS's capabilities in wake vortex alleviation. Therefore, DSS can be considered as one of the promising techniques that can be used commercially in the future.
Author : Sarah Elizabeth Morris
Publisher :
ISBN 13 :
Total Pages : 176 pages
Book Rating : 4.:/5 (124 download)
Download or read book Vortex-wall Interactions and Sports-inspired Airfoil Motions written by Sarah Elizabeth Morris and published by . This book was released on 2020 with total page 176 pages. Available in PDF, EPUB and Kindle. Book excerpt: Understanding vortex-wall interactions has applications in the context of airplane trailing vortices, as wake vortices are an unavoidable by-product of aerodynamic lift. These vortices pose an increased hazard for aircraft at airport takeoffs and landings, as following aircraft flying through a vortex wake can experience dangerous rolling moments. In this work, we use a vortex generator tank and a delta wing in an XY-Towing Tank to study the dynamics of counter-rotating vortex pairs both in and out of ground effect, via PIV and flow visualization. When a vortex pair approaches a ground plane, the boundary layer that forms on the surface between the vortices and the wall separates, generating secondary vorticity and causing the primary vortex pair to ``rebound'' from the wall. Using a vortex generator tank to produce a temporally evolving vortex pair, it is shown that the introduction of perturbations at the ground plane results in earlier localized secondary vorticity generation. This leads to the formation of coherent secondary vortex structures, and an accelerated decay of the primary vortex pair. This passive, ground-based method could be a means to diminish the wake vortex hazard behind aircraft close to the ground. We study also the spatially evolving trailing vortices in the far-wake of a 75 degree leading-edge sweep-angle delta wing, using a novel technique to measure the axial flow in the vortex core. This technique is unaffected by vortex wandering, allowing us to capture axial flow data as close as 0.03 chord-lengths apart. Using this technique, the streamwise velocity profile is captured over 20 chord-lengths downstream of the delta wing, even when the vortex pair is in ground effect. In this thesis, we also study new modes of NACA 0012 airfoil motions using a ``sports-mimetic'' approach, inspired by the bodyweight motions of Olympic sailors as they maneuver their sailboats when racing. Olympic sailors use various unsteady aerodynamic techniques when racing to increase propulsion for their boat. One such technique is for sailors to use bodyweight movements to roll the boat about its longitudinal axis. This motion is used especially when turning in light winds by either ``roll tacking'' (upwind sailing) or ``roll gybing'' (downwind sailing); it is also used in ``sail flicking'' whereby the sailor rolls the boat, flicking the sail periodically. These motions are characterized in on-the-water experiments using a Laser sailboat and a 420 sailboat, equipped with a GPS, IMU, wind sensor and GoPro camera array. We study the underlying vortex dynamics of these maneuvers using these characteristic motions, along with full-scale flow visualization and laboratory experiments. Flow visualization experiments are conducted on Cayuga Lake with an Olympic Laser Sailboat, using an Enola Gaye WP40 smoke grenade to visualize large-scale flow features around the sail.
Author : James K. Nathman
Publisher :
ISBN 13 :
Total Pages : 122 pages
Book Rating : 4.:/5 (22 download)
Download or read book A Study of Aerodynamic Control in Stalled Flight Leading-edge Vortex Formation Analysis written by James K. Nathman and published by . This book was released on 1984 with total page 122 pages. Available in PDF, EPUB and Kindle. Book excerpt: This report describes the theory and application of VORSEP, a wake preprocessor for panel methods that use an iterative procedure to determine the position of strongly interacting vortex sheets. The estimation of the wake geometry is based on slender body theory with separation. An unsteady, two-dimensional airfoil program was automated with the addition of routines to interpolate cross-sectional geometry from arbitrary three-dimensional bodies, generate multi-core wakes and synthesize a three-dimensional wake structure. Leading-edge wakes for a delta, straked wing and double delta are constructed and used in VSAERO, a three-dimensional panel method. The wake structures compare reasonably well to experimentally observed vortex core positions, while calculated pressures on the wings with the estimated wakes compare well near the nose but less well near the trailing edge. Keywords include: Panel methods; and Unsteady cross-flow analogy.
Author : Kelsey Shaler
Publisher :
ISBN 13 :
Total Pages : 162 pages
Book Rating : 4.:/5 (128 download)
Download or read book Wake Interaction Modeling Using a Parallelized Free Vortex Wake Model written by Kelsey Shaler and published by . This book was released on 2020 with total page 162 pages. Available in PDF, EPUB and Kindle. Book excerpt: Turbine-wake interactions pose significant challenges in the development of wind farms. These interactions can lead to an increase in wind energy cost through reduction in wind farm power efficiency as well as a reduction of functional turbine lifetime. The overall objective of this work is to extend and assess a moderatefidelity free vortex wake (FVW) model to capture turbine-wake interactions between multiple turbines. Specific focus areas include: (1) analyzing the effects of turbine-wake interaction; (2) benchmarking of the model against experimental wind farm measurements; and (3) comparing wake interaction effects between the FVW model and a dynamic wake meandering (DWM) model. Results show that FVW produces an increased dynamic response in wake-influenced turbines than FAST.Farm, which is an important factor in fatigue life of turbine blades. Parameter studies for various operating and layout conditions are performed. Analysis focuses on impact of wake interaction on wake structure, rotor power, and blade root bending moments. The parameter study shows expected power trends for all tested parameters. The effects of turbine-wake interactions are analyzed in terms of wake structure, rotor power, and structural response. The FVW model predicts increased unsteadiness in wake-influenced turbine rotor power and out-of-plane blade root bending moment. This could have implications for prediction of turbine life and suggests that the transient as well as average response of turbines should be considered to fully capture the effects of wake interaction. Comparisons between the FVW predictions and experimental measurements of relative rotor power are made over varying yaw angle and freestream velocity. Overall trends are predicted by the FVW approach, with less than 13% error on average when compared to wind farm measurements. These results indicate the FVW method is a useful tool for carrying out improved optimization of wind farms.
Author : Luigi Morino
Publisher : Springer Science & Business Media
ISBN 13 : 364285463X
Total Pages : 533 pages
Book Rating : 4.6/5 (428 download)
Download or read book Boundary Integral Methods written by Luigi Morino and published by Springer Science & Business Media. This book was released on 2012-12-06 with total page 533 pages. Available in PDF, EPUB and Kindle. Book excerpt: This volume contains edited papers from IABEM-90, the 1990 Symposium of the Interna tional Association for Boundary Element Methods (IABEM). As stated in the By-Laws of the Association, the purposes of IABEM are: 1. to promote the international exchange of technical information related to the devel opment and application of boundary-integral equation (BIE) formulations and their numerical implementation to problems in engineering and science, commonly referred to as the boundary element method (BEM); 2. to promote research and development activities for the advancement of boundary integral equation methods and boundary element solution algorithms; 3. to foster closer personal relationships within the BEM community of researchers. The objectives of the Symposium, in line with those of the Association, was to provide a forum where the two "souls" of the Association, i. e. , (i) mathematical foundations and numerical aspects, and (ii) engineering applications could be integrated. We believe that the first aspect has been neglected in too many of the BEM Symposia held in the past, which, with a few exceptions (notably, the IUTAM Symposia on the subject) have emphasized the practical aspects of the method. As a consequence, we have tried to give a stronger emphasis to the more theoretical issues: this is attested for instance, by the fact that the two general lectures were given by Prof. Gaetano Fichera, of the University of Rome "La Sapienza," and Prof.
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ISBN 13 :
Total Pages : 1460 pages
Book Rating : 4.:/5 (31 download)
Download or read book Scientific and Technical Aerospace Reports written by and published by . This book was released on 1991 with total page 1460 pages. Available in PDF, EPUB and Kindle. Book excerpt: Lists citations with abstracts for aerospace related reports obtained from world wide sources and announces documents that have recently been entered into the NASA Scientific and Technical Information Database.
Author : Gustavo Cesar Rachid Bodstein
Publisher :
ISBN 13 :
Total Pages : 370 pages
Book Rating : 4.E/5 ( download)
Download or read book A Theoretical and Experimental Study of the Interaction of a Streamwise Vortex with a Surface written by Gustavo Cesar Rachid Bodstein and published by . This book was released on 1993 with total page 370 pages. Available in PDF, EPUB and Kindle. Book excerpt:
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ISBN 13 :
Total Pages : 964 pages
Book Rating : 4.3/5 (126 download)
Download or read book Transonic Symposium: Theory, Application, and Experiment written by and published by . This book was released on 1989 with total page 964 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Author : Clinton E. Brown
Publisher :
ISBN 13 :
Total Pages : 41 pages
Book Rating : 4.:/5 (227 download)
Download or read book High Speed Computer Studies of Vortex Motions in Relation to Aircraft Wake Turbulence written by Clinton E. Brown and published by . This book was released on 1976 with total page 41 pages. Available in PDF, EPUB and Kindle. Book excerpt: Computations are presented and compared with experimental data from other sources for basic and advanced problems in aircraft - wake vortex interactions. Results are presented for coalescence of corotation and counterrotating vortex groups and finally a complete high speed computer method is developed for simulating the roll reaction of an aircraft to the wake produced by a large aircraft with flaps deployed. Suggestions for improved experimental approaches are also appended. (Author).
Author :
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ISBN 13 :
Total Pages : 1508 pages
Book Rating : 4.3/5 (243 download)
Download or read book Monthly Catalog of United States Government Publications written by and published by . This book was released on 1991 with total page 1508 pages. Available in PDF, EPUB and Kindle. Book excerpt:
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ISBN 13 :
Total Pages : 1508 pages
Book Rating : 4.:/5 (31 download)
Download or read book Monthly Catalogue, United States Public Documents written by and published by . This book was released on 1991-03 with total page 1508 pages. Available in PDF, EPUB and Kindle. Book excerpt:
