Aerodynamics and Fluid Mechanics Commons^™

Simulations Of Phugoid Motion Of Jal 123, Dereth J J. Drake Scheuermann

Georgia Journal of Science

Airplanes rely on a balance between the four forces of flight: lift, weight, thrust, and drag. If these forces are balanced, the airplane will remain stable. However, if structurally or systematically compromised, the motion can rapidly become unstable. In the aviation industry, mistakes in repairs and aircraft design can lead to accidents causing the loss of life in some cases. In this article, we will be analyzing what happened 70 Japan Airlines flight 123 and how the flight’s motion deteriorated due to a defective repair. More specifically, we will discuss the aerodynamic effects of phugoid motion and how it developed …

Mastering Uncoordinated Flight: Slips And Skids, Nihad E. Daidzic

Aviation Department Publications

FAA Safety Webinar (GL15103784) held online at 9:00 CST on Saturday, April 10, 2021.

Flight Dynamics Nonlinearity Assessment Across A New Aerodynamic Attitude Flight Envelope, Ayman Muhammad Abdallah

Mechanical & Aerospace Engineering Theses & Dissertations

A new asymmetric level aerodynamic attitude flight envelope is introduced in this dissertation. The aerodynamic attitude envelope is an angle of attack vs. sideslip angle region which describes the extent of where an aircraft can sustain a steady slipping horizontal flight condition. The new envelope is thus an extension of the more common speed-altitude symmetric level flight envelope. This new envelope can be used for design requirements, dynamic analysis, control synthesis, or performance comparison. Moreover, this envelope provides enhanced insight into trimability-controllability limitations within the aircraft design model. The aerodynamic attitude flight envelope is constructed for a six degree of …

Design Advantages Of Skin Friction Drag Reduction Using Riblets, John Michael Gregory

Mechanical & Aerospace Engineering Theses & Dissertations

The research reported here has examined the potential improvements in overall aircraft performance that can result from integrating skin friction reduction technology, such as riblets, early in the aircraft design cycle. This study has shown that riblets can improve the payload capacity, increase the range, and improve performance of transport aircraft. If recent advances in fabrication techniques make it possible to create aluminum wing surfaces with integral riblet geometries, the applications could be widespread and the gains significant.

Boundary Layer Measurements Related To Wind Tunnel Testing Of Riblets, Emrah Cinar

Mechanical & Aerospace Engineering Theses & Dissertations

With fuel economy being a significant factor in today's world of aviation, aircraft manufacturers have been looking into ways to decrease drag to save fuel. Drag reduction using riblets on wing and fuselage surfaces is . an area that has been studied extensively for the last two decades. In preparation for a larger project which will use several methods to simulate this phenomena, small scale research had to be done to find ways to generate similar conditions on scaled models in a low speed wind tunnel and examine boundary layer behavior.

In this project, boundary layer measurement techniques, such as …

Airplane Landing Flare-The Last 5 Seconds, Nihad E. Daidzic

Aviation Department Publications

No abstract provided.

Multi-Element Airfoil Optimization Using Computational Fluid Dynamics, Mustafa Kubilay Ictuzer

Mechanical & Aerospace Engineering Theses & Dissertations

High-lift systems are frequently used on commercial transport aircrafts to obtain low speed performance, in terms of take-off and landing field lengths and approach speed. To maximize the take-off and landing performance within the critical restrictions required by the new generation transport wing designs, enhanced high-lift technologies are needed. Moreover, the economic realities faced by the airlines require a design that is mechanically simple and effective. These facts lead us to the optimization of the high lift systems.

Optimizing a high-lift system improves an aircraft's take-off and landing performance. The weight of the system, the advantages and the disadvantages all …

Computational Solution Of Tail Buffet Response And Active Flow Control, Kaushik Laxmikant Joshi

Mechanical & Aerospace Engineering Theses & Dissertations

In this thesis, numerical simulation of the multidisciplinary method for prediction and control of vortex induced tail buffeting is studied using delta wing-single tail configuration. Flow conditions are chosen such that wing vortex cores experience vortex breakdown and the resulting wake flow impinges on the vertical tail. The aero/structure problem is solved sequentially using three sets of equations on a multi-block grid structure. To obtain aerodynamic loading on the tail, the fluid flow around the wing-tail assembly is computed by time-accurately solving unsteady, laminar, compressible Navier-Stokes equations using an implicit, upwind, flux-difference splitting finite volume scheme. Then the aeroelastic equations …

Aerodynamic And Acoustic Investigations Of An Advanced Over-The-Wing Nacelle Transport Aircraft Configuration, Geoffrey A. Hill

Mechanical & Aerospace Engineering Theses & Dissertations

The transonic aerodynamic and low-speed acoustic characteristics of an advanced, Over-the-Wing Nacelle (OWN), subsonic transport configuration are assessed. The cruise aerodynamics of the OWN were analyzed using both inviscid Euler and viscous Navier-Stokes CFD. Results of the assessments are compared to a similar configuration with a more traditional Under-the-Wing Nacelle (UWN) installation and a similar reference Wing-Body Qualitative observations and quantitative drag computations are made for the three configurations at a cruise Mach number of0.78, an approximate altitude of35,000-ft, and a C_L, of 0.44. It was found that the OWN's novel inboard wing channel design is effective in …

Global Modeling Of Pitch Damping From Flight Data, Noah M. Favaregh

Mechanical & Aerospace Engineering Theses & Dissertations

Flight testing using a designed experiment was used to model pitch damping in the longitudinal short-period mode of an aircraft. Multi-step elevator maneuvers were flown at different angles of attack and power levels on an electrically powered, propeller-driven UltraStick 120 remotely controlled model A Central Composite Response Surface Design was used to select angle of attack and power levels for each maneuver. During post flight analysis it was discovered that power was not measured correctly for this purpose so advance ratio was selected as a replacement factor. Parameter estimation results for each maneuver were modeled globally using a single response …

A Numerical Analysis Of A Non-Porous, Flexible Upper Airfoil Surface, Asao Omura

Mechanical & Aerospace Engineering Theses & Dissertations

The aerodynamic behavior of the early Wright brothers' airfoils is an important element of the history of aeronautics. Their fabric-covered wings were not constrained to maintain the airfoil shape of their wooden rib substructures and therefore differences in performance between rigid and flexible Wright airfoil shapes can be expected. The purpose of this thesis was to develop a systematic numerical approach that allows an assessment of the influence of the fabric on the overall aerodynamic behavior of the Wright Model B airfoil. The Model B airfoil was chosen because it is the earliest "production" airfoil and has sufficient documentation to …

Three-Dimensional Aerodynamic Design Optimization Using Discrete Sensitivity Analysis And Parallel Computing, Amidu Olawale Oloso

Mechanical & Aerospace Engineering Theses & Dissertations

A hybrid automatic differentiation/incremental iterative method was implemented in the general purpose advanced computational fluid dynamics code (CFL3D Version 4.1) to yield a new code (CFL3D.ADII) that is capable of computing consistently discrete first order sensitivity derivatives for complex geometries. With the exception of unsteady problems, the new code retains all the useful features and capabilities of the original CFL3D flow analysis code. The superiority of the new code over a carefully applied method of finite-differences is demonstrated.

A coarse grain, scalable, distributed-memory, parallel version of CFL3D.ADII was developed based on "derivative stripmining". In this data-parallel approach, an identical copy …

The Effectiveness Of Film Cooling In A Hypersonic Flowfield With Favorable Pressure Gradients, Julie A. Young

Mechanical & Aerospace Engineering Theses & Dissertations

The impetus of this technical document is to report results of aerothermodynamic cooling of a scramjet nozzle under favorable pressure gradients. The goals of film cooling are to protect the nozzle skin from the high enthalpy combustor flow, reduce regenerative cooling requirements, and decrease nozzle skin friction. A hypersonic nozzle configuration for which experimental data exists was selected as the basis of this numerical study. As a first step, the numerical results of film cooling along a flat plate are compared to previous literature to validate the numerical model. Subsequently, computations are performed to study the effects of varying the …

Sensitivity Analysis And Optimization Of Aerodynamic Configurations With Blend Surfaces, Almuttil Mathew Thomas

Mechanical & Aerospace Engineering Theses & Dissertations

A novel (geometrical) parametrization procedure using solutions to a suitably chosen fourth order partial differential equation is used to define a class of airplane configurations. Inclusive in this definition are surface grids, volume grids, and grid sensitivity. The general airplane configuration has wing, fuselage, vertical tail and horizontal tail. The design variables are incorporated into the boundary conditions, and the solution is expressed as a Fourier series. The fuselage has circular cross section, and the radius is an algebraic function of four design parameters and an independent computational variable. Volume grids are obtained through an application of the Control Point …

Numerical Simulation Of Turbulent Flows Past Three-Dimensional Cavities, Shivakumar Srinivasan

Mechanical & Aerospace Engineering Theses & Dissertations

Computations have been performed to simulate turbulent supersonic, transonic, and subsonic flows past three-dimensional deep, transitional, and shallow cavities. Simulation of these self sustained oscillatory flows has been generated through time accurate solutions of Reynolds averaged full Navier-Stokes equations using the explicit MacCormack scheme. The Reynolds stresses have been modeled, using the Baldwin-Lomax algebraic turbulence model with certain modifications. The computational results include instantaneous and time averaged flow properties everywhere in the computational domain. Time series analyses have been performed for the instantaneous pressure values on the cavity floor. Comparison with experimental data is made in terms of the mean …

An Analytical Design Procedure For The Determination Of Effective Leading Edge Extensions On Thick Delta Wings, Farhad Ghaffari

Mechanical & Aerospace Engineering Theses & Dissertations

An analyt1cal des1gn procedure for Lead1ng-Edge Extensions (LEE) has been developed for thick delta wings. This LFE device is des1gned to be mounted to a w1ng along the pseudo-stagnation stream surface associated w1th the attached flow design lift coeff1cient of greater than zero. The intended purpose of the device is to improve the aerodynamic performance of high subsonic and low super son1c aircraft at incidences above that of attached flow design lift coefficient, by us1ng a vortex system emanating along the leading edges of the device. The low pressure assoc1ated with these vort1ces would act on the LEE upper surface …

Viscous Modeling And Computation Of Leading-And Trailing-Edge Vortex Cores Of Delta Wings, Balakrishnan Lakshmanan

Mechanical & Aerospace Engineering Theses & Dissertations

A Finite-Difference method is presented for calculating steady quasi-axisymmetric flow of an incompressible fluid at large Reynolds number. Approximations of the boundary-layer type are employed to reduce the Navier-Stokes equations to a pair of non-linear parabolic equations. Along with the governing equations, initial conditions are specified at some upstream cross section and boundary conditions are specified at the axis of symmetry and on the outer bounding surface.

The governing equations are replaced by a set of quasilinear finite-difference equations. The solution is obtained by a marching technique, which proceeds step-by-step in the axial direction. At each axial station, an iterative …

Interaction Of A Two-Dimensional Transverse Jet With A Supersonic Mainstream, Gilbert Otto Kraemer

Mechanical & Aerospace Engineering Theses & Dissertations

A experimental investigation of the interaction of a twodimensional sonic jet injected transversely into a confined main flow has been conducted. The main flow consisted of air at a Mach number of 2.9. The effects of varying the jet parameters on the flow field were examined using surface pressure and composition data. Also, the downstream flow field was examined using static pressure, pitot pressure, and composition profile data. The jet parameters varied were gapwidth, jet static pressure, and injectant species of either helium or nitrogen. The values of the jet parameters used were 0.039, 0.056,and 0.109 cm for the gapwidth …

Experimental Study Of Delta Wing Leading-Edge Devices For Drag Reduction At High Lift, Thomas Dwight Johnson Jr.

Mechanical & Aerospace Engineering Theses & Dissertations

Future fighter aircraft requirements specify efficient supersonic cruise and high-g maneuverability at high lift. The slender delta wing meets the first requirement but has large lift induced drag increments at high lift. One method to alleviate the drag is to control the flow at the wing leading edge (LE) by means of small LE devices, so as to maintain locally attached flow to higher angles of attack and thus increase the level of aerodynamic thrust.

The devices selected for evaluation were the fence, slot, pylon-type vortex generator (VG), and sharp leading-edge extension (SLEE). These devices were tested on a 60° …

Computer-Aided Design Of Light Aircraft To Meet Certain Aerodynamic And Structural Requirements, Joanne Lynn Walsh

Mechanical & Aerospace Engineering Theses & Dissertations

Nonlinear mathematical programming techniques are applied to a particular aircraft design problem, that of determining the maximum range design for light aircraft subject to certain aerodynamic and structural requirements. Search techniques available in an existing nonlinear optimization computer program, AESOP, are applied to the design problem. Seven design variables are used to define the wing dimensions, the wing skin thickness, the cruise velocity, the amount of fuel carried, and the engine horsepower. The influence of different design requirements on the range is observed and discussed.