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Full-Text Articles in Engineering
The Effect Of Systematic Error In Forced Oscillation Wind Tunnel Test Apparatuses On Determining Nonlinear Unsteady Aerodynamic Stability Derivatives, Brianne Y. Williams
The Effect Of Systematic Error In Forced Oscillation Wind Tunnel Test Apparatuses On Determining Nonlinear Unsteady Aerodynamic Stability Derivatives, Brianne Y. Williams
Mechanical & Aerospace Engineering Theses & Dissertations
One of the basic problems of flight dynamics is the formulation of aerodynamic forces and moments acting on an aircraft in arbitrary motion. Classically conventional stability derivatives are used for the representation of aerodynamic loads in the aircraft equations of motion. However, for modern aircraft with highly nonlinear and unsteady aerodynamic characteristics undergoing maneuvers at high angle of attack and/or angular rates the conventional stability derivative model is no longer valid. Attempts to formulate aerodynamic model equations with unsteady terms are based on several different wind tunnel techniques: for example, captive, wind tunnel single degree-of-freedom, and wind tunnel free-flying techniques. …
Boundary Interference Assessment And Correction For Open Jet Wind Tunnels Using Panel Methods, Wael Ahmed Mokhtar
Boundary Interference Assessment And Correction For Open Jet Wind Tunnels Using Panel Methods, Wael Ahmed Mokhtar
Mechanical & Aerospace Engineering Theses & Dissertations
The presence of nearby boundaries in a wind tunnel can lead to aerodynamic measurements on a model in the wind tunnel that differ from those that would be made when the boundaries of the moving fluid were infinitely far away. The differences, referred to as boundary interference or wall interference, can be quite large, such as when testing aircraft models developing high lift forces, or whose wingspan is a large fraction of the wind tunnel width, or high drag models whose frontal area is a large fraction of the tunnel cross section. Correction techniques for closed test section (solid walled) …
Studies Related To The Design Of A Magnetic Suspension And Balance System For An Ultra-High Reynolds Number Flow Facility, Oscar Magno Michael Gomeiz
Studies Related To The Design Of A Magnetic Suspension And Balance System For An Ultra-High Reynolds Number Flow Facility, Oscar Magno Michael Gomeiz
Mechanical & Aerospace Engineering Theses & Dissertations
The basic design principles for a magnetic suspension and balance system applied to the test section of an ultra-high Reynolds number facility are defined. The design of the cross-sectional area to be used in the test section is analyzed. The parameters of the permanent magnet to be used in the model inside the test section are investigated. The testing of magnetic fields at the center of a test pipe and validation of data by computer finite element analysis is described with the purpose of finding common results. The performance of the magnet configuration is evaluated with relation to the magnetic …
An Experimental Investigation Of Wall Cooling Effects On Hypersonic Boundary Layer Stability In A Quiet Wind Tunnel, Alan E. Blanchard
An Experimental Investigation Of Wall Cooling Effects On Hypersonic Boundary Layer Stability In A Quiet Wind Tunnel, Alan E. Blanchard
Mechanical & Aerospace Engineering Theses & Dissertations
One of the primary reasons for developing quiet tunnels is for the investigation of high-speed boundary-layer stability and transition phenomena without the transition-promoting effects of acoustic radiation from tunnel walls. In this experiment, a flared-cone model under adiabatic- and cooled-wall conditions was placed in a calibrated, 'quiet' Mach 6 flow and the stability of the boundary layer was investigated using a prototype constant-voltage anemometer. The results were compared with linear-stability theory predictions and good agreement was found in the prediction of second-mode frequencies and growth. In addition, the same 'N=10' criterion used to predict boundary-layer transition in subsonic, transonic, and …
Control Of Low-Speed Turbulent Separated Flow Over A Backward-Facing Ramp, John C. Lin
Control Of Low-Speed Turbulent Separated Flow Over A Backward-Facing Ramp, John C. Lin
Mechanical & Aerospace Engineering Theses & Dissertations
The relative performance and flow phenomena associated with several devices for controlling turbulent separated flow were investigated at low speeds. Relative performance of the devices was examined for flow over a curved, backward-facing ramp in a wind tunnel, and the flow phenomena were examined in a water tunnel using dye-flow visualization. Surface static pressure measurements and oil-flow visualization results from the wind tunnel tests indicated that transverse grooves, longitudinal grooves, submerged vortex generators, vortex generator jets (VGJ’s), Viets’ fluidic flappers, elongated arches +a + a (positive angle of attack), and large-eddy breakup devices (LEBU’s) +a + a placed near the …
Evaluation Of Hydrogen As A Cryogenic Wind Tunnel Test Gas, Richard Carl Haut Ii
Evaluation Of Hydrogen As A Cryogenic Wind Tunnel Test Gas, Richard Carl Haut Ii
Mechanical & Aerospace Engineering Theses & Dissertations
A theoretical analysis of the properties of hydrogen has been made to determine the suitability of hydrogen as a cryogenic wind tunnel test gas. By using Cryogenic hydrogen, instead of air or cryogenic nitrogen, as the wind tunnel test gas, a significant increase in the test Reynolds number may be achieved without increasing the aerodynamic loads. Under sonic conditions, for example, compared to air at ambient temperature, cryogenic hydrogen at a pressure of one atmosphere produces an increase in Reynolds number of a factor of approximately fourteen while cryogenic nitrogen, at the same pressure, produces an increase of only a …