Matching Items (16)
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- All Subjects: Aerodynamics
- Creators: Mechanical and Aerospace Engineering Program
- Resource Type: Text
Description
This experiment used hotwire anemometry to examine the von Kármán vortex street and how different surface conditions affect the wake profile of circular airfoils, or bluff bodies. Specifically, this experiment investigated how the various surface conditions affected the shedding frequency and Strouhal Number of the vortex street as Reynolds Number is increased. The cylinders tested varied diameter, surface finish, and wire wrapping. Larger diameters corresponded with lower shedding frequencies, rougher surfaces decreased Strouhal Number, and the addition of thick wires to the surface of the cylinder completely disrupted the vortex shedding to the point where there was almost no dominant shedding frequency. For the smallest diameter cylinder tested, secondary dominant frequencies were observed, suggesting harmonics.
ContributorsCoote, Peter John (Author) / Takahashi, Timothy (Thesis director) / White, Daniel (Committee member) / Mechanical and Aerospace Engineering Program (Contributor) / Barrett, The Honors College (Contributor)
Created2017-05
Description
Active flow control for airfoil designs has been researched for the past few decades. This has been achieved through steady blowing, pulsed blowing, synthetic jets, and plasma jets. These techniques have been applied to both single and dual jet configurations. This technology was examined for a wind turbine blade application so that lift and drag can be altered without needing a mechanical flap. Research was completed to also allow for thicker airfoils with more blunt trailing edges that result in the higher structural strength needed for large, heavy wind turbine blades without the negative aerodynamic effects such as boundary layer separation. This research tested steady blowing in a dual jet configuration for the S830 airfoil from the National Renewable Energy Laboratory (NREL) database of airfoils. Computational Fluid Dynamics was used in the software Ansys Fluent. Calculations were completed for a modified S830 airfoil with a rounded trailing edge surface at momentum coefficients of 0.01 for the lower jet and 0.1, 0.12, and 0.14 for the upper jet. These results were then compared to the original S830 results for the lift over drag efficiency. The design with momentum coefficients of 0.12 for the upper surface resulted in the highest increase in efficiency of 53% at an angle of attack of 12 degrees. At this momentum coefficient, the angle of attack where zero lift occurred was at -8.62 degrees, compared to the case with no blowing at -1.90 degrees. From previous research and research completed in this thesis it was concluded that active flow control is an effective technique to improve wind turbine energy collection.
ContributorsStapleton, Paige (Author) / Mertz, Benjamin (Thesis director) / Herrmann, Marcus (Committee member) / Mechanical and Aerospace Engineering Program (Contributor) / Barrett, The Honors College (Contributor)
Created2018-05
Description
The focus of education in the classroom traditionally is one of fact memorization and recall. The teaching process of linear knowledge progression is not always in tune with the way that the human brain actually processes, conceptualizes, and comprehends concepts and information. In an introductory engineering class, focused on materials engineering and its related concepts, a system of lecture interventions has been put in place to increase concept comprehension by supplementing lecture units with various activities, from additional worksheets, explicit concept discussions, and most recently, YouTube videos showcasing specific concepts and situations. In an attempt to correct the lack of actual concept comprehension, these interventions seek to interact with the human mind in a way that capitalizes on its ability to process and interpret non-linear knowledge and information.
Using a concept test given prior to the lecture unit, and after, the difference in scores is used to recognize if the concepts presented have actually been comprehended. Used specifically in a lecture unit on solubility and solutions, the concept test tested student’s knowledge of supersaturated, saturated, and unsaturated solutions. With a visual identification and a written explanation, the student’s ability to identify and explain the three solutions was tested.
In order to determine the cause of the change in score from pre- to post-test, an analysis of the change in scores and the effects of question type and solution type was conducted. The significant results are as follows:
The change in score from pre- to post-test was found to be significant, with the only difference between the two tests being the lecture unit and intervention
From pre- to post-test, solution type had a significant effect on the score, with the unsaturated solution being the most easily recognized and explained solution type
Students that felt that the YouTube videos greatly increased their concept comprehension, on average, performed better than their counterparts and also saw a greater increase their score from pre- to post-test
Using a concept test given prior to the lecture unit, and after, the difference in scores is used to recognize if the concepts presented have actually been comprehended. Used specifically in a lecture unit on solubility and solutions, the concept test tested student’s knowledge of supersaturated, saturated, and unsaturated solutions. With a visual identification and a written explanation, the student’s ability to identify and explain the three solutions was tested.
In order to determine the cause of the change in score from pre- to post-test, an analysis of the change in scores and the effects of question type and solution type was conducted. The significant results are as follows:
The change in score from pre- to post-test was found to be significant, with the only difference between the two tests being the lecture unit and intervention
From pre- to post-test, solution type had a significant effect on the score, with the unsaturated solution being the most easily recognized and explained solution type
Students that felt that the YouTube videos greatly increased their concept comprehension, on average, performed better than their counterparts and also saw a greater increase their score from pre- to post-test
ContributorsLinich, Christopher Graham (Author) / Krause, Stephen (Thesis director) / Middleton, James (Committee member) / Barrett, The Honors College (Contributor) / Mechanical and Aerospace Engineering Program (Contributor)
Created2014-05
Description
The emerging market for unmanned aerial vehicles, or UAV's, demands the development of effective design tools for small-scale aircraft. This research seeks to validate a previously developed drag build-up method for small air vehicles. Using the method, a drag prediction was made for an off-the-shelf, remotely controlled aircraft. The Oswald efficiency was predicted to be 0.852. Flight tests were then conducted using the RC plane, and the aircraft performance data was compared with the predicted performance data. Although there were variations in the data due to flight conditions and equipment, the drag build up method was capable of predicting the aircraft's drag. The experimental Oswald efficiency was found to be 0.863 with an error of 1.27%. As for the CDp the prediction of 0.0477 was comparable to the experimental value of 0.0424. Moving forward this method can be used to create conceptual designs of UAV's to explore the most efficient designs, without the need to build a model.
ContributorsGavin, Tyler Joseph (Author) / Wells, Valana (Thesis director) / Garrett, Fred (Committee member) / Barrett, The Honors College (Contributor) / Mechanical and Aerospace Engineering Program (Contributor)
Created2014-05
Description
Each year, the CanSat Competition organizers release aerospace based engineering mission objectives for collegiate teams to compete in. This year, the design is an aerodynamically stable probe that will descend from an altitude of 725 meters at a rate between 10-30 meters/sec until it reaches an altitude of 300 meters, where it will then release a parachute as its aerobraking mechanism as it descends at 5 meters/sec until it reaches the ground. The focus of this paper is to investigate the design of the probe itself and how slender body theory and cross flow drag affect the lift and aerodynamic stability of this bluff body. A tool is developed inside of MATLAB which calculates the slender body lift as well as the lift from the cross flow drag. It then uses that information to calculate the total moment about the center of gravity for a range of angles of attack and free stream velocities. This tool is then used to optimize the geometry of the probe. These geometries are used to construct a prototype and that prototype is tested by a drop test from a 6-story building. The initial tests confirm the calculations that the probe, bluff body, is stable and self-correcting in its descent. Future work involves more high-altitude and ground-level tests that will further verify and improve on the current design.
ContributorsMcCourt, Anthony Michael (Author) / Takahashi, Timothy (Thesis director) / Herrmann, Marcus (Committee member) / Mechanical and Aerospace Engineering Program (Contributor) / Barrett, The Honors College (Contributor)
Created2018-05
Description
This study consisted of two fundamental experiments that examined the effects of surface parameters on baseball aerodynamics. The first experiment measured drag and lift coefficients in response to varied surface treatments of a non-spinning baseball. This experiment found that rougher surfaces (rubbing mud, increased ball usage, and scuffing) decrease drag coefficient by up to 0.05 for Reynolds numbers of up to 1.5x105 (wind speeds of 30 m/s or 67 mph). The maximum observed increase in lift coefficient was 0.20, caused by heavily scuffing the top of the ball. These results can be explained by boundary layer transition phenomena and asymmetry in the surface roughness of the ball. A decrease in drag coefficient of 0.05 can translate to an increase in the flight distance of a batted ball by as much as 50 ft (14%), and an increase of 0.20 in lift coefficient can increase flight distance by 70 ft (19%) \u2014 numbers that can easily mean the difference between a routine fly out and a monster home run. The second experiment measured drag and lift coefficients in response to varied stitch geometries of a non-spinning, 3D-printed baseball. Increasing stitch height, width, and spacing was found to increase drag coefficient, while increasing stitch length had little effect on lift coefficient. Increasing any parameter of the stitch geometry was found to increase lift coefficient. These results can be explained by boundary layer transition phenomena, blockage effects, and asymmetry in the stitch geometry of the ball. Future work would do well to repeat these experiments with a larger wind tunnel and a more sensitive force balance. These results should also be validated at higher wind speeds, and for spinning, rather than stationary baseballs. In addition, future work should explore the degree to which surface roughness and stitch geometry affect drag and lift coefficients at different ball orientations.
ContributorsDwight, Jeremiah Robert (Author) / Squires, Kyle (Thesis director) / Steele, Bruce (Committee member) / Mechanical and Aerospace Engineering Program (Contributor) / Barrett, The Honors College (Contributor)
Created2016-05
Description
The premise of the embodied cognition hypothesis is that cognitive processes require emotion, sensory, and motor systems in the brain, rather than using arbitrary symbols divorced from sensorimotor systems. The hypothesis explains many of the mechanisms of mental simulation or imagination and how they facilitate comprehension of concepts. Some forms of embodied processing can be measured using electroencephalography (EEG), in a particular waveform known as the mu rhythm (8-13 Hz) in the sensorimotor cortex of the brain. Power in the mu band is suppressed (or de-synchronized) when an individual performs an action, as well as when the individual imagines performing the action, thus mu suppression measures embodied imagination. An important question however is whether the sensorimotor cortex involvement while reading, as measured by mu suppression, is part of the comprehension of what is read or if it is arises after comprehension has taken place. To answer this question, participants first took the Gates-MacGinitie reading comprehension test. Then, mu-suppression was measured while participants read experimental materials. The degree of mu-suppression while reading verbs correlated .45 with their score on the Gates-MacGinitie test. This correlation strongly suggests that the sensorimotor system involvement while reading action sentences is part of the comprehension process rather than being an aftereffect.
ContributorsMarino, Annette Webb (Author) / Glenberg, Arthur (Thesis director) / Presson, Clark (Committee member) / Blais, Chris (Committee member) / Department of Psychology (Contributor) / Barrett, The Honors College (Contributor)
Created2016-05
Description
The aerodynamics of golf club heads effect the forces on the club head throughout the swing. The bluff body geometry and passive flow control elements make the aerodynamics of golf club heads far more complex. The theory behind the geometry of the bluff body aerodynamics relies on the state of the boundary layer and its interaction with the golf club head. Laminar and turbulent boundary layer flow result in drag, but in varying degrees. Separation, or attachment, of the boundary layer in these laminar and turbulent boundary layer flows is part of the cause of the induced drag. Skin friction and pressure drag are the two forms of surface forces which vary according to the state of the boundary layer. To review the state of the boundary layer flow and provide validation data for the corresponding, the golf club head was tested in a wind tunnel. Drag readings from the experiment showed the lowest drag occurred while the club face was perpendicular to the flow from the range of 50 miles per hour to 90 miles per hour. Additionally, the decrease in drag varied greatly depending on the orientation of golf club head. The decrease in the coefficient for the club perpendicular to the flow was approximately 3.99*〖10〗^(-6) C_d/Re while the decrease for the club at 110° was 1.07*〖10〗^(-6) C_d/Re. The general trend of the slopes indicated the pressure drag resulted in major variations while the drag due to skin friction remained relatively constant.
For the testing of the golf club head, two probes were developed to measure the turbulent intensity in the flow. The probes, based on Rossow’s (1993) three probe system, compared the dynamic pressure of the flow with the stream-wise dynamic pressure in the flow. The resultant measurements could then produce the ratio of the cross-stream fluctuations in velocity to the time-averaged velocity. The turbulence intensity calculations would provide insight on the turbulence in the boundary layer flow and wake.
For the testing of the golf club head, two probes were developed to measure the turbulent intensity in the flow. The probes, based on Rossow’s (1993) three probe system, compared the dynamic pressure of the flow with the stream-wise dynamic pressure in the flow. The resultant measurements could then produce the ratio of the cross-stream fluctuations in velocity to the time-averaged velocity. The turbulence intensity calculations would provide insight on the turbulence in the boundary layer flow and wake.
ContributorsBrausch, Matthew James (Author) / Takahashi, Timothy (Thesis director) / Ghods, Sina (Committee member) / Mechanical and Aerospace Engineering Program (Contributor) / Barrett, The Honors College (Contributor)
Created2016-05
Description
The objectives of this project are to design a statically determinant load cell mechanism for a prototype tow tank ultimately culminating in the testing of the aerodynamic performance of a Formula One racing car model. This paper also serves as a proof of concept for force data collection for a full-sized tow tank being developed by Isabella All [8]. The project includes the design and construction of the load cell mechanism which utilizes a load cell to measure the force in a specific member of the mechanism which is then used to determine the semi-lift and drag forces for a given test model. For this specific project, a model of the front-end of an F1 racing car was used for data collection and analysis. It was found that for a short period of time within each test run, constant force data was able to be collected from the load cell which could then be transformed into semi-lift and drag force data. Ultimately, the drag coefficient acting on the model was found to be in the range of 0.9 to 1.3 which somewhat falls in line with the estimated values of 0.7 to 1.0 [1] for F1 racing vehicles. Although the final data collected may not be entirely accurate due to errors discussed in the paper, the ideas presented in this project can be fully realized with some minor changes and adjustments.
ContributorsAnderson, Spencer (Author) / Wells, Valana (Thesis director) / Pathikonda, Gokul (Committee member) / Barrett, The Honors College (Contributor) / Mechanical and Aerospace Engineering Program (Contributor)
Created2023-05
Description
An experimental investigation was conducted to calculate the aerodynamic drag on a cyclist wearing different types of clothing. The different outfits worn for this experiment were a professional skinsuit, a professional cycling kit, a t-shirt and shorts, and a long-sleeved flannel and jeans. The aerodynamic drag was ultimately found using the coast down method, a process in which a cyclist increases their speed to a chosen maximum threshold, and upon reaching this speed, ceases the pedal stroke and maintains the aero position until the bicycle comes to a stop. The data was gathered using an AeroPod, speed sensor, and GPS unit. The data gathered was imported into Excel for data analysis. The average CdA values at race speed (26-30 ft/s) for the skinsuit, cycling kit, t-shirt and shorts, and flannel were calculated to be 4.180 ft2, 3.668 ft2, 4.884 ft2, and 4.223 ft2, respectively. These race speed averages were found using data from three separate Ironman Triathlons. The cycling kit was found to be the most aerodynamic at the race speed. The results of this study reveal that cycling apparel can only be optimized for a small range of speeds and cycling outside of this optimal range delays the initiation of the reduction of boundary layer separation, thus resulting in more critical time spent in the flow transition region. The skinsuit’s performance was more aerodynamically efficient than the cycling kit at speeds greater than 36.8 mph. The cycling kit is more aerodynamic for speeds slower than 36.8 mph. The slickness of the skinsuit was found to be detrimental to the cyclist’s aerodynamic drag, as the lack of roughness on the skinsuit prevented the initiation of turbulent flow, which results in a decrease in drag. Overall, the experiment confirmed the hypothesis that a cyclist is more aerodynamic when wearing cycling apparel as opposed to casual, loose-fitting clothing.
ContributorsGlynn, Julia Daniel (Co-author) / Duffy, Kyle (Co-author) / Takahashi, Timothy (Thesis director) / Bergmann, Ande (Committee member) / Mechanical and Aerospace Engineering Program (Contributor) / Department of Information Systems (Contributor) / Barrett, The Honors College (Contributor)
Created2019-12