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Full-Text Articles in Engineering
Boundary Layer Measurements In The Trisonic Gas-Dynamics Facility Using Particle Image Velocimetry With Co₂ Seeding, Daniel B. Wolfe
Boundary Layer Measurements In The Trisonic Gas-Dynamics Facility Using Particle Image Velocimetry With Co₂ Seeding, Daniel B. Wolfe
Theses and Dissertations
Particle image velocimetry (PIV) is utilized with solid carbon dioxide (CO2) seeding material to conduct boundary layer measurements in the test section of the Air Force Research Laboratory's Trisonic Gas-dynamics Facility (TGF), which has a 24 inch by 24 inch cross-section. Freestream velocity was set at Mach 0.3, Mach 0.5, or Mach 0.8 while stagnation pressure ranged from 500 to 2400 pounds per square foot (psf). High pressure liquid CO2 was directed through expansion nozzles into shroud tubes which led to solidified particles in the wind tunnel stagnation chamber. Two different sets of shroud tubes were used …
Particle Size Control For Piv Seeding Using Dry Ice, Brian T. Love
Particle Size Control For Piv Seeding Using Dry Ice, Brian T. Love
Theses and Dissertations
Particle image velocimetry (PIV) has been carried out using solid carbon dioxide (CO2) particles as the seed material to continue the development of clean seeding for use in large-scale, closed-circuit tunnels. Testing occurred in two wind tunnels at subsonic and supersonic speeds using dry ice particles generated by allowing liquefied CO2 to expand from a small diameter injector tube through a larger diameter shroud tube. The particles were injected into the plenum and discrete solid particles, suitable for PIV measurements, were present in the test section. Data on particle size were first collected using a Malvern particle …
Flow Measurements Using Particle Image Velocimetry In The Ultra Compact Combustor, Levi M. Thomas
Flow Measurements Using Particle Image Velocimetry In The Ultra Compact Combustor, Levi M. Thomas
Theses and Dissertations
Velocity measurements were performed using the Particle Image Velocimetry (PIV) technique on the Ultra Compact Combustor (UCC) test rig at the Air Force Institute of Technology (AFIT). Velocity patterns and time-averaged turbulence statistics were calculated for data taken with the UCC burning hydrogen fuel in the straight cavity vane and curved cavity vane configurations. The equivalence ratio was varied from 0.7 to 1.5, while the ratio of cavity air to main air was varied from 5% to 20% in testing performed on the straight vane configuration. Spanwise velocity was observed to decrease linearly with distance from the cavity vane over …
Characterization And Control Of Carbon Dioxide Seed Particle Image Velocimetry, Bartt G. Greene
Characterization And Control Of Carbon Dioxide Seed Particle Image Velocimetry, Bartt G. Greene
Theses and Dissertations
Particle Image Velocimetry (PIV) data was acquired in two separate supersonic wind tunnels with carbon dioxide (CO2) particles utilized as the seed material. Previous work in clean seeding showed CO2 could be used as seed material to produce velocity maps. This research provides the first quantitative assessment of particle response, particle size control via purge gas, and scalability using CO2 particles. A variety of feed tube and shroud configurations, in combination with varying volumetric flow rates of purge air were measured using a laser diffraction device. The CO2 particles were injected into the stilling chamber …
Piv-Based Examination Of Deep Stall On An Oscillating Air Foil, Daniel E. Fredberg
Piv-Based Examination Of Deep Stall On An Oscillating Air Foil, Daniel E. Fredberg
Theses and Dissertations
A number of studies suggest that the deep stall flow fields produced by a pure-pitch and a pure-plunge oscillating airfoil are equivalent, when effective angles of attack are matched. This assumption is examined using particle image velocimetry (PIV). Sinusoidal oscillations of a pure-plunge and pure-pitch airfoil with matched reduced frequency k = 3.93 and with kinematically equivalent amplitudes of effective angle of attack are comparatively examined using results of PIV in a free surface water tunnel at AFRL/RB, Wright Patterson AFB. Experiments were conducted at Re = 10,000 and Re = 40,000, based on free stream velocity and airfoil chord, …
Performing Particle Image Velocimetry In A Supersonic Wind Tunnel Using Carbon Dioxide As The Seed Material, Donald W. Peltier Iii
Performing Particle Image Velocimetry In A Supersonic Wind Tunnel Using Carbon Dioxide As The Seed Material, Donald W. Peltier Iii
Theses and Dissertations
Particle image velocimetry (PIV) was performed utilizing clean seed particles generated by injecting liquid carbon dioxide (CO2) directly into an open-circuit blowdown Mach 2.9 supersonic wind tunnel. Rapid atomization and cooling of the liquid CO2 created a preponderance of nearly uniform and well dispersed microscopic dry ice particles which were illuminated using a frequency double Nd:YAG laser. Ample light was scattered from the flow tracers, which provided a strong signal to noise ratio. The particles completely sublimed into an innocuous gas downstream of the test section causing no side effects or problems with wind tunnel operation. A …
Demonstration Of Clean Particle Seeding For Particle Image Velocimetry In A Closed Circuit Supersonic Wind Tunnel, Charles M. Mcniel
Demonstration Of Clean Particle Seeding For Particle Image Velocimetry In A Closed Circuit Supersonic Wind Tunnel, Charles M. Mcniel
Theses and Dissertations
The purpose of this research was to determine whether solid carbon dioxide (CO2) particles might provide a satisfactory, and cleaner, alternative to traditional seed material for Particle Image Velocimetry (PIV) for use in a closed circuit supersonic wind tunnel. The Air Force Institute of Technology (AFIT) closed circuit pressure-vacuum supersonic wind tunnel was utilized, which achieves a nominal Mach number of Mach 2.9 in a 2.5 inch by 2.5 inch square test section. CO2 was dispensed into the flow as a liquid from a standard compressed gas liquid tank through two different injector styles at two injection …
Particle Image Velocimetry Using A Novel, Non-Intrusive Particle Seeding, Charles J. Delapp Ii
Particle Image Velocimetry Using A Novel, Non-Intrusive Particle Seeding, Charles J. Delapp Ii
Theses and Dissertations
The purpose of this research effort was to study the use of non-intrusive particle seeding for Particle Image Velocimetry (PIV). Current seeding material and techniques involve the use of either solid particles or liquid mixtures which can contaminate or damage closed circuit wind tunnels, and in some cases can introduce a potential fire or explosive hazard. The proposed method is based on creating seed particles utilizing Carbon Dioxide (CO2). The CO2 would be dispensed into the flow as a liquid, immediately condensing to solid seed particles as they leave the spray nozzle. The advantage of using these particles is that …
An Experimental Study Of A Pulsed Dc Plasma Flow Control Actuator, Jennifer D. Wall
An Experimental Study Of A Pulsed Dc Plasma Flow Control Actuator, Jennifer D. Wall
Theses and Dissertations
An experiment on the effects of a pulsed DC plasma actuator on a separated flow in a low speed wind tunnel was conducted. The actuator consisted of two asymmetric copper electrodes oriented normal to the flow separated by a dielectric barrier and mounted on a flat plate in the center of the tunnel. A contoured insert was constructed and used to create an adverse pressure gradient in the test section comparable to a Pak-B low pressure turbine blade distribution. Suction was applied from the upper wall to induce separation along the flat plate over the electrodes. The DC power supply …
Boundary Layer Flow Control Using Plasma Induced Velocity, Brian E. Balcer
Boundary Layer Flow Control Using Plasma Induced Velocity, Brian E. Balcer
Theses and Dissertations
An examination of the effects of plasma induced velocity on boundary layer flow was conducted. A pair of thin copper film electrodes spanned the test section, oriented at thirty degrees from normal to the free stream flow. An adverse pressure gradient was imposed over the electrode configuration using a pressure coefficient profile similar to that associated with suction side of a Pac-B low pressure turbine blade. In addition, suction was applied to keep flow attached on the upper wall, inducing separation over the electrode. The electrode is supplied by an AC source at three different power levels with the free …