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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 30 for “"wave drag"”.
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Orographic Gravity Wave Drag and the Large Scale Atmospheric Circulation
… which is affected by orographic gravity waves and the drag force that they exert on the mean flow. The effects of Orographic Gravity Wave Drag (OGWD) are what is explored in this thesis. By experimenting on the OGWD forcing in an idealized General Circulation Model. Firstly, the impact of …
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Development of an Interactive Wave Drag Capability for the OpenVSP Parametric Geometry Tool
<p>Minimizing wave drag is critical to successful and efficient transonic and supersonic flight. Area-ruling is the process of managing the cross-sectional area of an aircraft to lessen the wave drag experienced in flight. Effectively calculating the necessary areas for a given aircraft can be …
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Efficient inverse methods for supersonic and hypersonic body design, with low wave drag analysis
… pressure distributions, a study of minimum drag body shapes was conducted over a Mach number range from 3 to 12. Numerical results show that the power law bodies result in low drag shapes, where the n=.69 (l/d = 3) or n=.70 (l/d = 5) shapes have lower drag than the previous theoretical …
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Calculation of the wave drag due to lift for an arbitrary rectilinear-planform wing-body combination
no abstract provided by author
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Efficient and robust design optimization of transonic airfoils
… the design problem of lift maximization with wave drag and area constraints. A simple linear approximation was utilized for the approximation of the lift. Accurate approximations for sensitivity derivatives of the wave drag were obtained through the utilization of Nixon's coordinate straining …
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Hydrofoil shape optimization by gradient methods
… line theory was used to account for induced drag and downwash at the leading edge of the foil. Strip theory was used to extend the two-dimensional wave drag solutions to three dimensions for high aspect ratio foils. A semi-empirical correction was added to account for viscous drag. The …
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THE EFFECTS OF CURRENT BLOCKAGE ON OFFSHORE STRUCTURES
… on fixed space-frame structures in combined waves and an in-line steady current. Because of current blockage, the actual drag force experienced by such structures is over-predicted by the standard Morison equation and the present industry standard practice. A set of analytical models of …
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Propulsion considerations for supersonic oblique flying wings
… quasi D thermodynamic cycle analysis. Lift-to-drag ratio, thrust specific fuel consumption, and nacelle wave drag were examined as intermediate figures of merit that would ultimately impact the final performance metric-namely, range parameter and specific excess power. It was found that higher …
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Resistance and wake prediction for early stage ship design
… the viscous resistance and propeller wake. The wave drag is calculated using a modified linear theory, thus eliminating the need to run fully three-dimensional free surface CFD codes. The tool developed is validated against published Series 60 test data.
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Multidisciplinary optimization of high-speed civil transport configurations using variable-complexity modeling
… are used to estimate aircraft weight, supersonic wave drag and drag due to lift, and landing angle of attack. The methodology is applied to the minimization of the gross weight of an HSCT that flies at Mach 2.4 with a range of 5500 n.mi. Results are presented for wing plan form shape optimization …
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Saturn’s Upper Atmosphere in the Ultraviolet: Temperature and Compositional Trends from Cassini UVIS with Implications for Energy Balance and Dynamics
… predicted. Meridional winds generated by ion drag showed peak equatorward speeds of 20–40 m/s. Gravity wave signatures in the thermosphere were analyzed to derive 2D fields of gravity wave drag. The addition of gravity wave drag reduced the speed of zonal jets and increased the meridional …
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Surrogate Models for Transonic Aerodynamics for Multidisciplinary Design Optimization
… of pressure location, the lift curve slope, the wave drag, and the maximum allowable lift coefficient before buffet. These models have good agreement with the original CFD results for the airfoil. The models are integrated into the aerodynamic and aeroelastic sections of the MDO code.
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Conceptual Assessment of an Oblique Flying Wing Aircraft Including Control and Trim Characteristics
… aircraft could be trimmed at given conditions. Wave drag was investigated to determine benefits for an oblique flying wing. This form of drag was reduced by the distribution of volume afforded by the slewing of the aircraft's wing. Once a reasonable concept was developed, aerodynamic conditions …
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Aerodynamic Performance Enhancement of a NACA 66–206 Airfoil Using Supersonic Channel Airfoil Design
… have been shown to significantly reduce drag in high-speed flows over diamond shaped airfoils by Ruffin and colleagues. The effect of applying these techniques to a NACA 66-206 airfoil is presented. The design domain entails channel heights of 8-16.6% thickness-to-chord and speeds from …
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Navier-Stokes simulations of steep breaking water waves with a coupled air-water interface
Wave breaking on the ocean surface significantly facilitates the transfer of mass, momentum, heat and energy across the air-sea interface. In the context of the near field flow about a surface ship, the breaking bow wave is a key element to the bubbly signature and an appreciable portion of the …
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Response to stratospheric forcing and its dependence on the state of the troposphere
… winds sufficiently weaken, there is an increased wave drag in the lower stratosphere which then projects onto the annular modes.
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Integrated aerodynamic-structural wing design optimization
… with the complex models provided by volumetric wave drag analysis and panel methods. In addition, simple algebraic models for wave and drag due to lift provide inexpensive approximations during most of the optimization cycles. With the minimization of the costly complex sensitivity calculations, …
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Multidisciplinary Design Optimization and Industry Review of a 2010 Strut-Braced Wing Transonic Transport
… reduced wing thickness to increase the lift to drag ratio. The thinner wing has less transonic wave drag, permitting the wing to unsweep for increased areas of natural laminar flow and further structural weight savings. High aerodynamic efficiency translates into reduced fuel consumption and …
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Experimental investigation into the reduction of supersonic skin-friction drag on a flat plate using transpiration and a cavity with mass addition
… evaluation of an operational facility for wall drag measurement and evaluation of the total drag of various wall configurations. The drag of three possible supersonic combustor wall configurations was measured to determine if reduction in skin friction and/or wave drag could be achieved through …
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Mult-Scale Jet/Front Interactions that Organize Typical Cloud Seeding Environments in the Sierra Nevada
… the meso-β/γ scale caused by orographic form and wave drag embedded within the first front. There were four typical quasi-marginal cloud seeding case studies that were investigated in this research study and they all occurred in the 2014 water year. Observations, including GFS and NARR analyses, …
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