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Articles 1 - 13 of 13
Full-Text Articles in Aerodynamics and Fluid Mechanics
Winddensity-Mbir: Model-Based Iterative Reconstruction For Wind Tunnel 3d Density Estimation, Karl J. Weisenburger, Gregery T. Buzzard, Charles A. Bouman, Matthew R. Kemnetz
Winddensity-Mbir: Model-Based Iterative Reconstruction For Wind Tunnel 3d Density Estimation, Karl J. Weisenburger, Gregery T. Buzzard, Charles A. Bouman, Matthew R. Kemnetz
Faculty Publications
Experimentalists often use wind tunnels to study aerodynamic turbulence, but most wind tunnel imaging techniques are limited in their ability to take non-invasive three-dimensional (3D) density measurements of turbulence. Wavefront tomography is a technique that uses multiple wavefront measurements from various viewing angles to non-invasively measure the 3D density field of a turbulent medium. Existing methods make strong assumptions, such as a spline basis representation, to address the ill-conditioned nature of this problem. We formulate this problem as a Bayesian, sparse-view tomographic reconstruction problem and develop a model-based iterative reconstruction algorithm for measuring the volumetric 3D density field inside a …
Forced Displacement Technique For Measuring Blunt Body Aerodynamics In A Magnetic Suspension Wind Tunnel, Mark Schoenenberger, David Cox, Colin Britcher, Caleb Hull
Forced Displacement Technique For Measuring Blunt Body Aerodynamics In A Magnetic Suspension Wind Tunnel, Mark Schoenenberger, David Cox, Colin Britcher, Caleb Hull
Mechanical & Aerospace Engineering Faculty Publications
The Old Dominion University/NASA Langley 6-Inch Magnetic Suspension Wind Tunnel has developed the ability to levitate blunt bodies which can oscillate freely about the yaw axis. This allows for the measurement of static and dynamic stability coefficients without sting interference. The magnetic suspension controller introduces other translational forces which affect the vehicle dynamics complicating data reduction. Exciting model oscillations in a reliable way has also been a challenge. A new test method has been developed that produces capsule oscillations from forced oscillatory translational motion at the resonant yaw oscillatory frequency of the capsule. After oscillations are excited, the translational forcing …
Time Domain Boundary Element Method Prediction Of Noise Shielding By A Naca 0012 Airfoil, Douglas M. Nark, Fang Q. Hu
Time Domain Boundary Element Method Prediction Of Noise Shielding By A Naca 0012 Airfoil, Douglas M. Nark, Fang Q. Hu
Mathematics & Statistics Faculty Publications
As aircraft noise constraints become more stringent and the number/mixture of aircraft configurations grows, it becomes more important to understand the interaction of individual aircraft noise sources with nearby aircraft structures. Understanding these interactions and exploring possible approaches to mitigate or exploit their acoustic impact is essential for overcoming key noise barriers. This paper describes the further validation of a time domain boundary element approach for the prediction of the interactions between incident noise sources and nearby aircraft structures. Predictions were completed for multiple source locations and comparisons of these results with measured data are presented. Overall, very good agreement …
Characterization Of A Robotic Manipulator For Dynamic Wind Tunnel Applications, James C. Lancaster
Characterization Of A Robotic Manipulator For Dynamic Wind Tunnel Applications, James C. Lancaster
Theses and Dissertations
The newly acquired 6-DOF Motion Test Apparatus (MTA) was installed to perform dynamic wind tunnel testing in the AFIT Low Speed Wind Tunnel. Several complex motions revealed that the overall performance of the test rig needed improvement especially during small motions. The motions exposed that further enhancements would need to be performed individually for each joint. This research effort focused on the improvement of the MTA wrist roll motor and controller using a pitch oscillation. The controller software was improved using position feedback because the MTA wrist roll motor and controller exhibited reduced signal bias and amplitude attenuation. The enhanced …
Experimental Study On Influence Of Pitch Motion On The Wake Of A Floating Wind Turbine Model, Stanislav Rockel, Elizabeth Camp, Jonas Schmidt, Joachim Peinke, Raúl Bayoán Cal, Michael Höllimg
Experimental Study On Influence Of Pitch Motion On The Wake Of A Floating Wind Turbine Model, Stanislav Rockel, Elizabeth Camp, Jonas Schmidt, Joachim Peinke, Raúl Bayoán Cal, Michael Höllimg
Mechanical and Materials Engineering Faculty Publications and Presentations
Wind tunnel experiments were performed, where the development of the wake of a model wind turbine was measured using stereo Particle Image Velocimetry to observe the influence of platform pitch motion. The wakes of a classical bottom fixed turbine and a streamwise oscillating turbine are compared. Results indicate that platform pitch creates an upward shift in all components of the flow and their fluctuations. The vertical flow created by the pitch motion as well as the reduced entrainment of kinetic energy from undisturbed flows above the turbine result in potentially higher loads and less available kinetic energy for a downwind …
Experimental Characterization Of Turbulent Flow Around Cylinder Arrays, Adam D. Harder
Experimental Characterization Of Turbulent Flow Around Cylinder Arrays, Adam D. Harder
Theses and Dissertations
This research was done as part of an effort to develop alternative fire suppressant technologies for aircraft engine nacelles. A circular cylinder array was designed, built, and placed in the AFIT roll-around low speed wind tunnel to model generic clutter inside an engine nacelle. A turbulence grid was fabricated to enable measurements of the effects of turbulence level, independent of airspeed, on the flow over different model configurations. The wind tunnel test section was 12 inches wide x 12 inches high x 24 inches long. Pressure differential measurements were taken on various cylinder configurations. The configurations included one cylinder as …
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 …
The Design And Development Of A Low-Speed, Low-Force Wind Tunnel Data Acquisition System With An Application To Bicycle Front Fork Spacing, Alan W. Elledge
The Design And Development Of A Low-Speed, Low-Force Wind Tunnel Data Acquisition System With An Application To Bicycle Front Fork Spacing, Alan W. Elledge
Theses and Dissertations
This thesis encompassed the design, development, and application of a low-speed, low-force data acquisition system for the AFIT 5-ft Wind Tunnel. The new data acquisition system was designed and developed to measure approximately 0.045 N (about 0.01 lbf) at nearly 64.4 km/h (40 mph). Verification of the capability was obtained through testing of a cylindrical model. As part of a technology transition program with Wright Laboratory, this new system was used to investigate bicycle front fork blade spacing in order to determine the optimal spacing for minimum drag. As for the minimum drag of a bicycle with an …
A New Drag Measurement System For Wind Tunnel Testing Of The Racing Bicycle And Rider To Determine A Low Drag Configuration, Brian A. Parker
A New Drag Measurement System For Wind Tunnel Testing Of The Racing Bicycle And Rider To Determine A Low Drag Configuration, Brian A. Parker
Theses and Dissertations
This study investigated the application of splitter plate effects to reduce the aerodynamic drag of the racing bicycle and rider system. A sensitive, low-force, beam-type, single-component balance was developed to provide drag measurements accurate to within 0.053 N (0.012 lbf). The performance of the new system was verified by comparing the measured drag on a three-dimensioaal, right-circular cylinder model, 0.127 m (5.0 in) in diameter and 0.610 m (24 in) long, with the results from a commercial balance and a other similar data. The bicycle and rider model consisted of a full-scale mannequin comprising only the hips, legs …
A Wind Tunnel Study Of Magnus Effects On A Differentially Rotating Missile, Karen A. Naselius
A Wind Tunnel Study Of Magnus Effects On A Differentially Rotating Missile, Karen A. Naselius
Theses and Dissertations
This study investigates magnus effects on a non-firmed missile model which had three axially rotating sections that span at different rates. Five spin cases are examined; the mid section spinning only; the front and rear sections spinning only; all section spinning at the same speed; all sections spinning in the same direction with the mid section spinning at an additional ten revolutions per second; and all sections spinning with the mid sections spinning the opposite direction at an additional ten revolutions per second. These five cases are tested at three different spin rates for two different wind tunnel velocities. Since …
An Experimental Study Of A Sting-Mounted Circulation Control Wing, Steven J. Lacher
An Experimental Study Of A Sting-Mounted Circulation Control Wing, Steven J. Lacher
Theses and Dissertations
This wind tunnel study investigated the lift, drag, and pitching moment of a 20% thick, 8.5% camber, partial elliptical cross-section, single blowing slot, 2.325 aspect ratio, rectangular circulation control wing. The AFIT 5-foot wind tunnel was used. Lift and drag were referenced to the wind axis. The Reynolds number was 500,000 for all tests. Angle of attack was varied from -6 to 16 degrees and the effects of pulsed blowing were investigated. Effects of tripping the Coanda jet with a small flow barrier attached spanwise along the Coanda surface were also studied. Results indicate that there is a limit on …
An Experimental Study Of A Sting-Mounted Single-Slot Circulation Control Wing, Michael E. Pelletier
An Experimental Study Of A Sting-Mounted Single-Slot Circulation Control Wing, Michael E. Pelletier
Theses and Dissertations
This wind tunnel study investigated the feasibility of using a sting and force balance to measure the aerodynamic forces and moments on a circulation control wing. A 20% this, 8.5% camber, single blowing slot, rectangular wing was designed, built, and tested in the AFIT 5-ft wind tunnel. Lift and drag coefficients were referenced to the stability axis. The Reynolds number for all tests was 950,000; angle of attack was varied from -6 to +6 degrees. Trends in the data were similar to two dimensional data, with the exception of high drag coefficients with increased blowing. Results show it is feasible …
A Study Of A Wind Tunnel Measurement System For Unsteady Pressures Using Pneumatic Transmission Lines, Mohammed Javed Khan
A Study Of A Wind Tunnel Measurement System For Unsteady Pressures Using Pneumatic Transmission Lines, Mohammed Javed Khan
Theses and Dissertations
The application of pneumatic transmission lines theory to a tube-scanning valve system for unsteady pressure measurements in the AFIT 5-foot wind tunnel is investigated. Transfer gains of various tube-scanning valve configurations were experimentally measured and the validity of a theoretical model verified for a frequency range of 20 Hz to 140 Hz. The selected system having a 0.0625-in. ID flexible tube of 84 in. length connected to a scanning valve was installed in the wind tunnel. Unsteady pressures introduced over an 18 percent airfoil at zero angle of attack were measured with this system. Data were collected for 0, 40, …