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Search theses and dissertations gathered from participating repositories worldwide. Every result links back to the library that holds it. No account is needed.
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Showing 1 to 20 of 40 for “"Pitching Moment"”.
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Distribution of aerofoil section lift from section pitching moment applied to a dynamic model for aircraft poststall departure
… simulation is investigated. Aerofoil section moment data is used to divide and distribute into two parts the wing lifting line of Prandtl finite wing circulation theory. The method of lift distribution is applied in the aerodynamic package of a six degree-of-freedom flight simulator. The …
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Response surface approximations for pitching moment including pitch-up in the multidisciplinary design optimization of a high-speed civil transport
A procedure for incorporating a key non-linear aerodynamic characteristic into the design optimization of a high-speed civil transport has been developed. Previously, the tendency of a high-speed aircraft to become uncontrollable (pitch-up) at high angles-of-attack during landing or takeoff for …
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Ducted Fan Aerodynamics and Modeling, with Applications of Steady and Synthetic Jet Flow Control
… In particular, they exhibit a large nose-up pitching moment during wind gusts and when transitioning from hover to forward flight. Understanding ducted fan aerodynamic behavior and how it can be altered through flow control techniques are the two prime objectives of this work. This …
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Numerical prediction of the maneuvering characteristics of submarines operating near the free surface
… Calculated and measured vertical force and pitching moment are in excellent agreement for conditions where free-surface effects are minimal. In addition calculated vertical plane maneuvering coefficients are presented. There is no known experimental force and moment data available for …
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Propeller-Driven Rotor Twirl Phenomenon: Hover Performance, Dynamics, and Controls
… the propeller speed can generate the control moments for the rotor, eliminating the need for a conventional swashplate. Third, an unmanned design can eliminate a conventional fixed frame fuselage and tail rotor -- significantly reducing vehicle complexity and weight. Fourth, given these first …
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Effects of Duct Lip Shaping and Various Control Devices on the Hover and Forward Flight Performance of Ducted Fan UAVs
… with these vehicles in crosswinds, namely momentum drag and asymmetric duct lift. Because the duct itself, and not the fan, is the root cause of these unfavorable aerodynamic attributes, various lip shapes were tested to determine the effects of leading edge radius of curvature and duct …
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Unsteady Aerodynamics of Deformable Thin Airfoils
… deformable thin airfoils. Frequency-domain lift, pitching moment and thrust expressions are derived for an airfoil undergoing harmonic oscillations and deformation in the form of Chebychev polynomials. The results are validated against the time-domain unsteady aerodynamic theory of Peters. A case …
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A numerical study of the effects of leading edge vortex flaps on the performance of a 75° delta wing
… at 30°. Results for lift, drag, axial force, and pitching moment coefficients are compared with experimental data and show very good agreement. Individual pressure difference coefficients along the wing and flap are also presented and compared with experimental data. Overall, the method shows the …
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Numerical Studies of the Jet Interaction Flowfield with a Main Jet and an Array of Smaller Jets
… mechanisms. The first mechanism comes from the momentum of the injectant itself, basically the thrust of the jet. The second and subtler contribution comes from the jet interaction flowfield, the interaction of the expanding injectant with the crossflow. This interaction produces areas of high …
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An Extended Calibration and Validation of a Slotted-Wall Transonic Wall-Interference Correction Method for the National Transonic Facility
… corrections. Free-air lift, drag, and pitching moment coefficient predictions were compared for a range of lift production and Mach conditions to determine the uncertainty in the corrections process and the expected domain of applicability. Exploiting a previously designed statistical …
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Heat transfer effects on a subsonic delta wing
… of the maximum lift angle. Beyond this, lift and pitching moment show a very small decrease and increase, respectively, up to maximum lift while drag increases 15 percent to 25 percent at maximum lift. Further increases in drag occur when the wing is yawed. No decrease in stalling angle of attack …
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An experimental analysis of the hydrodynamic characteristics of the monoform: a novel hull form
… to test both their ability to correct for pitching moment and to create yaw moments. The draft of the model was also varied during this study and included drafts of 1.90, 2.21, and 2.42 hull diameters. All three forces and all three moments were measured. The model was tested in a 31 meter …
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Optimum Spanloads Incorporating Wing Structural Considerations And Formation Flying
… includes constraints for lift coefficient, pitching moment coefficient and wing root bending moment. This wing structural constraint has been introduced such that wing geometry is not changed but the modified load distributions can be related to wing weight. Changes in wing induced drag and …
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Aerodynamics of a chined forebody oscillating in pitch
… study of the effects of an oscillatory pitching motion on the flowfield of a chined forebody has been performed. These tests were conducted in the University of Illinois low-speed (0-240 ft/sec), low-turbulence ($<$0.1%), 3 by 4 ft, open circuit wind tunnel. The high fidelity, NC …
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A Comparison of Two Methods Used to Deal with Saturation of Multiple, Redundant Aircraft Control Effectors
… deal with allocating controls for unattainable moments in an aircraft was performed using a testbed airframe that resembled an F/A-18 with a large control effector suite. The method of preserving the desired moment direction to deal with unattainable moments is currently used in a specific …
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Analysis and reconstruction of dynamic-stall data from nominally two-dimensional aerofoil tests in two different wind tunnels
… dynamic-stall including the critical angle, the pitching moment and stall onset. (b) A comparison of the overall aerodynamic coefficients and (c) the carry out of final analysis of the most important quantities such as Cp deviation, vortex development and convection speed and re-establishment of …
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Dynamic control of aerodynamic forces on a moving platform using active flow control
… servo motors. The global aerodynamic forces and moments are regulated by controlling vorticity generation and accumulation near the trailing edge of the airfoil using hybrid synthetic jet actuators. The dynamic coupling between the actuation and the time-dependent flow field is characterized …
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Effect of Slot Span on Wing Performance
… span with the changes in the lift, drag, and pitching moment coefficient.</p>
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Aerodynamic Modeling Using Computational Fluid Dynamics and Sensitivity Equations
… steady (time-invariant) aerodynamic forces and moments. Such aerodynamic forces can be determined using computer simulation by determining numerically the associated steady flows around the aircraft when it is moving along such generalized steady trajectories. The method required the extension …
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Computational Simulations of a Non-body of Revolution Ellipsoidal Model Utilizing RANS
… good agreement for ahead and pitched forces and moments. Straight ahead skin friction values also showed good agreement, providing even improved agreement over an LES model which utilized wall functions. Yaw turn conditions also showed good agreement for roll angles up to 10 degrees. Steady …
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