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- Aerodynamic measurements--Instruments (1)
- Aerofoils (1)
- Angle of attack (1)
- Boundary layer (1)
- Compressibility (1)
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- F-15 (Jet fighter plane) (1)
- Flutter (Aerodynamics) (1)
- Hypersonic wind tunnels (1)
- Jets--Fluid dynamics (1)
- Laser Doppler velocimeter (1)
- Lateral stability (1)
- Scramjet engines (1)
- Shock waves (1)
- Skin friction (Aerodynamics) (1)
- Stability of airplanes (1)
- Transonic aerodynamics (1)
- Turbulence--Measurement (1)
- Turbulent boundary layer (1)
- Turbulent boundary layer--Experiments (1)
- Vortex-motion (1)
Articles 1 - 7 of 7
Full-Text Articles in Engineering
Experimental Investigation Of Compressible Boundary Layers Under The Influence Of Pressure Gradients, Raymond C. Wier
Experimental Investigation Of Compressible Boundary Layers Under The Influence Of Pressure Gradients, Raymond C. Wier
Theses and Dissertations
This study examined the effect of mild pressure gradients on the mean and turbulent flow of high-speed boundary layers. Three Mach numbers (1.7, 3.0 and 5.0) were investigated. Three pressure gradients were examined; a zero pressure gradient (ZPG), a favorable pressure gradient (FPG), and a combined pressure gradient (CPG). The CPG consisted of an adverse pressure gradient followed by a favorable pressure gradient. Conventional pressure probes, hot-wire and particle image velocimetry (PIV) were used to examine the flow. Measurement included mean velocity, velocity turbulence intensity, mass flux turbulence intensity and energy spectra. Instantaneous (10 nsec) Mie scattering flow visualizations were …
Experimental Investigation Of Transverse Supersonic Gaseous Injection Enhancement Into Supersonic Flow, Mark P. Wilson
Experimental Investigation Of Transverse Supersonic Gaseous Injection Enhancement Into Supersonic Flow, Mark P. Wilson
Theses and Dissertations
In pursuit of more efficient and effective fuel-air mixing for a SCRAMJET combustor, this study was conducted to investigate relative near field enhancements of penetration and mixing of a discrete low-angled (25°) injected air jet into a supersonic (M=2.9) cross flow. The enhancements were achieved by injecting the transverse air jet parallel to the compression face of eight different ramp geometries. The jet-ramp interactions created collinear shock structures, baroclinic torque vorticity enhancement, ramp spillage enhanced vorticity, magnus effect penetration enhancement, and increased total pressure loss. Shadowgraph photography was used to identify the shock structures and interactions in the flow field. …
Direct Measurement Of Skin Friction In High Temperature And Impulsively Started Supersonic Flowfields, David M. Hazelton
Direct Measurement Of Skin Friction In High Temperature And Impulsively Started Supersonic Flowfields, David M. Hazelton
Theses and Dissertations
This study further developed and improved a miniature plastic cantilever floating element gauge for direct measurement of skin friction in shock tunnel tests. Gauge durability and usability were improved, and potential sources of error were quantified. A high frequency 30 kHz gauge (compared to the baseline 10 kHz gauge) was constructed by using an I-beam cantilever rather than a round beam. A directional gauge was developed and demonstrated by measuring the flowfield about a fin in the AFIT shock tunnel. The 10 kHz and 30 kHz gauges were used in two scramjet test sequences conducted at Mach 14 enthalpy (stagnation …
Nonlinear Analysis Of Airfoil Flutter At Transonic Speeds, Scott A. Morton
Nonlinear Analysis Of Airfoil Flutter At Transonic Speeds, Scott A. Morton
Theses and Dissertations
Hopf-bifurcation analysis is used to determine flutter boundaries of a pitch and plunge airfoil (PAPA) at transonic Mach number conditions. The PAPA model is a coupling of the Euler equations and a two-degree-of-freedom structural model composed of linear and torsional springs. The Euler equations are discretized using an upwind total variation diminishing scheme (TVD) of Harten and Yee. Equilibrium solutions of the PAPA model are computed using Newton's method and dynamic solutions are explicitly integrated in time with first-order accuracy. The Hopf-bifurcation point, which models the flutter condition, is computed directly by solving an extended system of equilibrium equations following …
An Investigation Into The Effects Of Lateral Aerodynamic Asymmetries, Lateral Weight Asymmetries, And Differential Stabilator Bias On The F-15 Directional Flight Characteristics At High Angles Of Attack, David R. Evans
Theses and Dissertations
The F-15 is a stable aircraft throughout most of its flight envelope. However, it still exhibits an uncommanded yawing and rolling tendency at high angles-of-attack. Identified influencing factors of this uncommanded motion are lateral aerodynamic asymmetries, lateral weight asymmetries, and differential stabilator bias. Previous research into the effects of these influencing factors has been qualitative. This thesis quantifies the effects and then identifies a symmetric F-15 configuration. The quantifying metric presented is net yaw acceleration. This thesis used both computer simulation and experimental flight test to quantify these effects. A discussion of each influencing factors effects on the F-15B high …
Compressible Turbulence Measurements In A Supersonic Boundary Layer With Impinging Shock Wave Interaction, Michael J. Meyer
Compressible Turbulence Measurements In A Supersonic Boundary Layer With Impinging Shock Wave Interaction, Michael J. Meyer
Theses and Dissertations
No abstract provided.
Riblet Effects On Gortler Vortex Development Over A Concave Surface, James A. Rothenflue
Riblet Effects On Gortler Vortex Development Over A Concave Surface, James A. Rothenflue
Theses and Dissertations
Riblet effects on Goertler vortex development in laminar and transitional flows were measured using three-dimensional laser-Doppler anemometry. Three freestream velocities were tested such that riblet spacing corresponded to Goertler vortex (GV) wavelengths which presumably would be either strongly amplified, weakly amplified, or attenuated by centrifugal forces on a curved surface. Experiments revealed the development of paired, counterrotating vortices within the riblet valleys over both flat and concave surfaces. For riblet spacings equivalent to weakly or non-amplified GV wavelengths, GV development on a curved surface was above the riblets and was delayed by the addition of riblets. The GV wavelength was …