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Full-Text Articles in Engineering
Analysis Of Hypersonic Vehicle Wakes, Matthew A. Kania
Analysis Of Hypersonic Vehicle Wakes, Matthew A. Kania
Theses and Dissertations
As advancements are made with ballistic missiles, particularly in the area of hypersonic bodies, there is a growing need to advance the methods of detecting these new ballistic weapons. As a result, the National Air and Space Intelligence Center has asked the Air Force Institute of Technology to examine the wake region behind hypersonic bodies. A thorough understanding of the aerothermal phenomena and the chemical reactions occurring in the wake region will enable an advancement of tracking hypersonic bodies. This research examined the wake region behind a hypersonic body using computational fluid dynamics.
This study used Pointwise® to develop a …
Dynamic Supersonic Base Store Ejection Simulation Using Beggar, Michael D. Johnson
Dynamic Supersonic Base Store Ejection Simulation Using Beggar, Michael D. Johnson
Theses and Dissertations
Static and dynamic conditions throughout various aft supersonic store separation events are examined using the Beggar Computational Fluid Dynamics (CFD) code from Air Force SEEK Eagle Office at Eglin Air Force Base, FL. An 8.9 deg half angle sphere cone is used for the carrier vehicle with an identically shaped store stowed within a hollow compartment in the aft section of the carrier body. Dynamic store separation simulations are implemented at a free-stream Mach of 2.9 with a Reynolds number of Re = 6.9 x 106/m referenced against carrier base diameter. Analysis covers multiple dynamic separation events along …
Handling Qualities Evaluation Of A Supersonic Tailless Air Vehicle, Steven W. Speares
Handling Qualities Evaluation Of A Supersonic Tailless Air Vehicle, Steven W. Speares
Theses and Dissertations
This thesis presents the results of a handling qualities evaluation of a supersonic tailless air vehicle. The 2006 Quadrennial Defense Review mandated the need for the next generation of long-range strike aircraft by 2018. Due to speed and stealth requirements, this resulted in a tailless aircraft with an instantaneous center of rotation located well forward of that of a conventional aircraft. This thesis examines how this center of rotation affected pilot handling qualities ratings. This effect should have been the most pronounced during approach and landing, and was where the testing focused. The goal of this research was to develop …
Spatially-Resolved Temperature Diagnostic For Supersonic Flow Using Cross-Beam Doppler-Limited Laser Saturation Spectroscopy, Grady T. Phillips
Spatially-Resolved Temperature Diagnostic For Supersonic Flow Using Cross-Beam Doppler-Limited Laser Saturation Spectroscopy, Grady T. Phillips
Theses and Dissertations
Optical techniques for measuring the temperature in three-dimensional supersonic reactive flows have typically depended on lineshape measurements using single-beam laser absorption spectroscopy. However, absorption over extended path lengths in flows with symmetric, turbulent eddies can lead to systematically high extracted temperatures due to Doppler shifts resulting from flow along the absorption path. To eliminate these problems, Cross-Beam Saturation Absorption Spectroscopy (CBSAS) and Cross-Beam Inter-Modulated Fluorescence (CBIMF) have been developed which utilize two crossed and nearly copropogating laser beams.to record the spectral signal of an I2 ro-vibrational line in a small three-dimensional volume using a tunable CW dye laser. Temperature …
Wind Tunnel Study Of Interference Effects Relating To Aft Supersonic Ejection Of A Store, Timothy P. Jung
Wind Tunnel Study Of Interference Effects Relating To Aft Supersonic Ejection Of A Store, Timothy P. Jung
Theses and Dissertations
An investigation into the issues surrounding the release of a store into a supersonic wake was conducted. A 10-degree half-angle cone was used to model the carrier vehicle as well as the store. The store was 42% than the vehicle. The experiments were conducted at a freestream Mach number of 2.93 and at zero degrees angle of attack. This study analyzed the effects of a support or strut mounted under the wind tunnel model. Research was conducted on the effects of a store at various positions in the wake, as well as the effects of a rear cavity in the …
An Investigation Of Starting Techniques For Inward Turning Inlets At Flight Speeds Below The On-Design Mach Number, John D. Mack
An Investigation Of Starting Techniques For Inward Turning Inlets At Flight Speeds Below The On-Design Mach Number, John D. Mack
Theses and Dissertations
The purpose of this study was to create and investigate starting techniques aimed at allowing complex, three-dimensional, inward-turning inlets to start by swallowing the shock wave associated with unstarted inlets. The techniques are rooted in supersonic diffuser theory and the Kantrowitz limit; they attempt to alleviate the over contraction that occurs in inward-turning inlets at flight speeds below the on-design Mach number. Five cases, three geometries at two flow conditions and the base non-modified inlet at the two flow conditions, were generated, and all were numerically simulated using a commercially produced numerical solver: CFD++. The simulations were computed using the …
Experimental Investigation Of Non-Adiabatic Supersonic Slot Injection Into A Supersonic Cross-Flow, Kelly C. Tucker
Experimental Investigation Of Non-Adiabatic Supersonic Slot Injection Into A Supersonic Cross-Flow, Kelly C. Tucker
Theses and Dissertations
Turbulence and mean flow measurements were acquired downstream of a normal, supersonic (M=1.6), two-dimensional, slot injection into Mach 3.0 flow (Re/m = 15x106). Two non-adiabatic cases Ti/T∞ = 1.11 and Ti/T∞ = 0.93) were studied. Multiple overheat anemometry and conventional mean flow analysis, as well as shadowgraph and schlieren photography, were utilized to study the turbulent mixing layer. The mean flow data included the Pitot, cone-static, and Mach number profiles. The measured turbulence data included shear stresses, mass flux, total temperature turbulence intensities, and turbulent heat fluxes. The temperature and density variation …
Numerical Simulation Of Supersonic Turbulent Boundary Layer Flow Under The Influence Of Mild Pressure Gradients, Eric T. Fick
Numerical Simulation Of Supersonic Turbulent Boundary Layer Flow Under The Influence Of Mild Pressure Gradients, Eric T. Fick
Theses and Dissertations
Mach 2.9 boundary layer flow (Re/m ≈ 1.75x107) under the influence of mild pressure gradients is studied numerically. Baldwin-Lomax and k - ω turbulence models are incorporated into a cell centered finite volume flow solver and the results are compared with hot wire anemometry and Laser Doppler Velocimetry (LDV) measurements obtained for the same geometries in the AFIT Mach 2.9 wind tunnel. Agreement between the present simulations obtained with the k - ω turbulence model and experimental velocity profiles is excellent in all test sections. Nondimensional turbulent shear stress predictions closely match experimental data in the …
Mach 2.9 Investigation Into The Flow Structure In The Vicinity Of A Wrap-Around Fin, Richard E. Huffman Jr.
Mach 2.9 Investigation Into The Flow Structure In The Vicinity Of A Wrap-Around Fin, Richard E. Huffman Jr.
Theses and Dissertations
A ceiling-mounted semi-cylindrical model containing a single wrap-around fin (WAF) was tested in the AFIT Mach 2.9 test facility. Flow visualization using oil- low streaklines, schlieren images and shadowgraph photography revealed a A-shock at the fin-body juncture and the development of an asymmetric bow-shock about the fin. Quantitative measurements were taken with a 100 cone-static pressure probe, a Pitot pressure probe and two cross-wire hot-film probes (u-v and u-w components, respectively). Measurements were made at cutting-planes from the inlet of the test section to aft of the model, with emphasis placed in the vicinity of the WAF. Results include cutting-plane …
Compressible Turbulence Measurement In The Mixing Layer Of An Adiabatic Normal Slot Injection Into Supersonic Flow, Christopher D. Whitcomb
Compressible Turbulence Measurement In The Mixing Layer Of An Adiabatic Normal Slot Injection Into Supersonic Flow, Christopher D. Whitcomb
Theses and Dissertations
In this study mean flow and compressible turbulence measurements were taken at a station x = 72W downstream of the injection, where W is the injector throat width, of an adiabatic 2-D Mach 1.6 normal slot injection into a Mach 2.9 flow. Data were collected using a conventional Pitot probe, a cone-static probe, and multiple overheat cross-wire anemometry. In addition, schlieren and shadowgraph flow visualization was used to investigate the flow structure at both the injection point and at the downstream data collection point. From these measurements, mass flux component turbulence intensities of 8% to 10% were seen. The total …
Experimental Investigation Of A Supersonic Turbulent Boundary Layer With Adverse Pressure Gradient, Chad S. Hale
Experimental Investigation Of A Supersonic Turbulent Boundary Layer With Adverse Pressure Gradient, Chad S. Hale
Theses and Dissertations
Laser Doppler Velocimetry (LDV) measurements were made to quantify the effect of adverse pressure gradient on the compressible turbulent flow structure in a Mach 2.9 boundary layer (Re/m= 1.75 x 107). Measurements included profiles of 2-D mean velocities, turbulence intensities, Reynolds shear stresses, intermittency, flatness and skewness. In addition, mean strain rates were also measured. The boundary layer measurements were acquired for both flat plate and compression ramp models. LDV measurements were made at two locations on the compression ramp model at 68 cm and 71 cm downstream of the nozzle throat. At these locations, Β …
Compressible Turbulence Measurement In Low-Angle Injection Into A Supersonic Flow, Gregory J. Mccann
Compressible Turbulence Measurement In Low-Angle Injection Into A Supersonic Flow, Gregory J. Mccann
Theses and Dissertations
Mean flow and compressible turbulence measurements have been obtained at two stations downstream of low-angle supersonic injection into a Mach 3.0 flow (Re/m = 15 x 106). Data were collected using conventional Pitot and cone-static probes, single and multiple overheat cross-wire anemometry, and flow visualization techniques (shadowgraphs and schlierens). A direct measure of total Reynolds shear stress was accomplished using a turbulence transformation of the Reynolds-averaged Navier-Stokes equations. Results show compressibility effects, indicated by density fluctuations, to be large relative to the velocity fluctuations and on the same order in all three components. Compressibility appears to account for …
Compressible Turbulence Measurements In A Supersonic Flow With Adverse Pressure Gradient, Jon W. Dotter
Compressible Turbulence Measurements In A Supersonic Flow With Adverse Pressure Gradient, Jon W. Dotter
Theses and Dissertations
Mean flow and compressible turbulence measurements have been obtained upstream and within a shock boundary interaction and a compression ramp in Mach 3 flow. Compressible turbulence models have met with little success in the accurate prediction of high-speed flows involving complicated shock boundary interactions and adverse pressure gradients because of a crucial lack of experimental data. Data were collected using conventional Pitot and cone static probes, single overheat cross-wire anemometry, multiple overheat cross-wire anemometry, and flow visualization techniques. Direct measurements of the total Reynolds shear stress were obtained using a turbulence transformation. Results indicate that compressibility effects, as evidenced by …
An Experimental Study Of Planar Heterogeneous Supersonic Confined Jets, Frederick J. Tanis Jr.
An Experimental Study Of Planar Heterogeneous Supersonic Confined Jets, Frederick J. Tanis Jr.
Theses and Dissertations
The effects of varying the exit pressure of a supersonic helium jet exhausting coaxially with two parallel supersonic air streams into a constant area duct were investigated. The method used to evaluate the mass entrainment rate was to measure helium molar concentration profiles and mass flux across the duct using a binary gas probe then calculate the mass entrainment into the helium jet. In order to conduct this study a novel binary gas probe was developed which allowed helium concentration and mass flux data to be obtained during continuous traverses across the supersonic flowfield. High exit pressure ratio (EPR) led …
An Experimental Investigation Of The Time-Dependent Separation Of Tangent Bodies In Supersonic Flow, Neal A. Mosbarger
An Experimental Investigation Of The Time-Dependent Separation Of Tangent Bodies In Supersonic Flow, Neal A. Mosbarger
Theses and Dissertations
An experimental, time-dependent separation of tangent bodies was performed in a supersonic wind tunnel (Mach 1.5 and 1.9) to investigate the significance of transient effects and the suitability of using steady-state assumptions to predict a dynamic even. The model configurations consisted of two bodies placed in a near tangent position. A stationary body, plate or ogive, was instrumented to obtain dynamic surface pressures, while a second body, a wedge attached to an air cylinder, was plunged in a constrained motion away from and towards the stationary model. Three-dimensional flow expansion around the edge of the wedge reduced the strength of …