A Three-Dimensional, Analytical Wind Turbine Wake Model: Flow Acceleration, Empirical Correlations, And Continuity,
2022
Portland State University
A Three-Dimensional, Analytical Wind Turbine Wake Model: Flow Acceleration, Empirical Correlations, And Continuity, Zein Ahmad Sadek
Dissertations and Theses
A new, three-dimensional, analytical, steady state wake model is presented which includes local flow acceleration near the rotor improving wake description compared to existing models. Wake structures such as the momentum deficit and regions of accelerated flow are concisely described with compound and normal Gaussian functions. Large-eddy simulations (LES) are used as training data to develop the model using two, inline turbines under various inflow conditions parameterized by hub height wind speed and turbulence intensity. Mass conservation is considered by fixing two components of the wake velocity model and optimizing the third to best satisfy continuity; after which, the model …
Structural Loads And Preliminary Structural Design For A World Speed Record-Breaking Turbo-Prop Racing Airplane,
2022
California Polytechnic State University, San Luis Obispo
Structural Loads And Preliminary Structural Design For A World Speed Record-Breaking Turbo-Prop Racing Airplane, Matthew G. Slymen
Master's Theses
The Cal Poly SLO Turbo-Prop Racer project aims to design a world speed record-breaking aircraft, capable of flying more than 550 miles per hour on a 3-kilometer closed course. To further this endeavor, this thesis presents the calculations of load distributions across the aircraft’s wing and tail and preliminary structural estimates of primary structural components for verification of the loads calculations and for use in a future finite element model. The aircraft’s fundamental design characteristics effect on the structure of the aircraft, namely the unique Y-tail design, are first examined. Then, loads are calculated in accordance with the regulation dictated …
Channeling Influence On Noise And Aerodynamic Performance Of Naca 0012 Airfoil As A Possible Solution Of Wind Turbines Noise,
2022
Western Michigan University
Channeling Influence On Noise And Aerodynamic Performance Of Naca 0012 Airfoil As A Possible Solution Of Wind Turbines Noise, Hussein Khudhayer Mohammad
Dissertations
This work numerically and experimentally investigates the effect of using channels inside airfoils on the noise level as a possible resolution for aerodynamic noise generated by wind turbines. The work also investigates aerodynamic performance and turbulence around the employed airfoils. The results reveal that some of the samples show some improvement in reducing the aerodynamic noise. The reduction of the aerodynamic noise is explained as the trailing edge blowing injection that reduces the wake momentum deficit of the blade and reduces the pressure fluctuation which is responsible for noise production. Particularly, the angles of channel inclination with respect to the …
Flow And Heat Transfer In Swirl Tubes — A Review,
2022
Institute of Aerospace Thermodynamics, University of Stuttgart
Flow And Heat Transfer In Swirl Tubes — A Review, Florian Seibold, Phillip M. Ligrani, Bernhard Weigand
PRC-Affiliated Research
The development of modern gas turbines for aircraft propulsion and power generation demands ever-increasing efficiency, which can be achieved by rising the turbine inlet temperature. Therefore, turbine components and especially the leading edge of turbine blades are exposed to particular high thermal loads with temperatures that are well above the melting point of the material. As a result, efficient cooling techniques are essential. Swirling flows in cyclone cooling systems are a promising technique for internal turbine blade leading edge cooling since they promise high heat transfer rates in combination with relatively uniform heat transfer distributions. The current paper presents a …
Aerodynamics And Turbulent Wake-Flow Characteristics Of Owls During Flapping Flight,
2022
Coastal Carolina University
Aerodynamics And Turbulent Wake-Flow Characteristics Of Owls During Flapping Flight, Krishnamoorthy Krishnan
Electronic Theses and Dissertations
Owls exhibit unique flight capabilities in the low Reynolds number flow regime which is prone to complex viscous flow phenomena. They possess unique feather features and flexible wing structures which are postulated to help them fly nearly silently and stably at low speeds in a complex flow setting. Understanding the aerodynamics of owls could pave the way to enhance the future designs of small flying vehicles. Though it has been a focus of research over multiple decades, no conclusive agreement has been attained on the aerodynamic mechanisms associated with owl flight. Particularly, the aerodynamics of flapping owl flight is severely …
Optical Microresonator-Based Flow-Speed Sensor,
2022
Southern Methodist University
Optical Microresonator-Based Flow-Speed Sensor, Elie Ramon Salameh
Mechanical Engineering Research Theses and Dissertations
Optical sensors have become more prominent in atmospheric measurement systems, with LiDAR instruments deployed on a variety of earth-bound, air-borne, and space-based platforms. In recent years, the interest in the human exploration of Mars has created a substantial push towards reliable and compact sensing elements for Mars exploration missions, particularly during a spacecraft’s entry, descent, and landing stages. Real-time sensors able to reliably measure the craft’s speed relative to the surrounding atmosphere during these stages are thus of great interest. In this dissertation, a proof-of-concept for an optical microfabricated sensor, which leverages the whispering-gallery-mode (WGM) and Doppler shift principles, is …
Direct Simulation And Reduced-Order Modeling Of Premixed Flame Response To Acoustic Modulation,
2022
Mississippi State University
Direct Simulation And Reduced-Order Modeling Of Premixed Flame Response To Acoustic Modulation, Zheng Qiao
Theses and Dissertations
This dissertation introduces a general, predictive and cost-efficient reduced-order modeling (ROM) technique for characterization of flame response under acoustic modulation. The model is built upon the kinematic flame model–G-equation to describe the flame topology and dynamics, and the novelties of the ROM lie in i) a procedure to create the compatible base flow that can reproduce the correct flame geometry and ii) the use of a physically-consistent acoustic modulation field for the characterization of flame response. This ROM addresses the significant limitations of the classical kinematic model, which is only applicable to simple flame configurations and relies on ad-hoc models …
Application Of The Formal Design Of Experiments To Deformed Airfoil Testing,
2022
University of Mississippi
Application Of The Formal Design Of Experiments To Deformed Airfoil Testing, Alex Ligman
Honors Theses
Traditionally, one factor at a time (OFAT) testing is used to accomplish wind tunnel
experimentation. OFAT testing is a process whereby one of the defined factors in the experiment is changed while all of the other factors are held constant. Afterwards, a new factor is chosen as the one to be manipulated, and the process is then repeated until all factors have been run through. Due to the possible cost-intensive and time-consuming nature of wind tunnel testing, formal design of experiments (DOE) has begun to be applied to wind tunnel experiments. In doing so, unique analyses can be made that …
A Study Of Asymmetric Supersonic Wind Tunnel Nozzle Design,
2022
Old Dominion University
A Study Of Asymmetric Supersonic Wind Tunnel Nozzle Design, Brittany A. Davis
Mechanical & Aerospace Engineering Theses & Dissertations
Achieving higher Mach numbers for private and commercial flight is a growing interest in the aerospace community. To qualify vehicles prior to flight, tests must be run in wind tunnels. Asymmetric wind tunnel nozzles are of continuing interest to the aerospace community due to their ability to change throat geometry, allowing for a range of Mach numbers to be achieved that encompasses all of the supersonic regime. The sliding block wind tunnel at Old Dominion University (ODU) is designed for a range of Mach numbers from about 1.8 to 3.5 but is limited to an upper limit of 2.8 by …
Development Of A Bio-Inspired Artificial Butterfly Vehicle,
2022
University of Alabama in Huntsville
Development Of A Bio-Inspired Artificial Butterfly Vehicle, Thomas Payne Clark
Honors Capstone Projects and Theses
No abstract provided.
Computational Analysis Of The Effects Of Scarfed Nozzle Variations On Jet Plumes,
2022
Ohio Northern University
Computational Analysis Of The Effects Of Scarfed Nozzle Variations On Jet Plumes, Andrew J. La Sorsa
ONU Student Research Colloquium
A computational fluid dynamics analysis investigating the variation of effects on nozzles with non-orthogonal exit planes, known as scarfing, was performed. The steady Reynolds-averaged Navier-Stokes model, coupled with the Spalart-Allmaras turbulence model, was used to simulate and compare plume development and characteristics using various scarfing geometries at variable inlet conditions. The jet plume cross-section is significantly affected for overexpanded conditions, while retaining the nozzle exit shape for underexpanded conditions, although slight peaks (bifurcation) do occur at the centerline. The same observations occur when slightly changing the angle of scarf. However, inverting the overall geometry of the diverging portion of the …
Effects Of Vortex Generator Placement On A Horizontal Axis Wind Turbine Blade,
2022
Ohio Northern University
Effects Of Vortex Generator Placement On A Horizontal Axis Wind Turbine Blade, Dagan Sorensen
ONU Student Research Colloquium
Vortex generators are commonly used devices to control the flow over an airfoil or other surface. In this paper the effect of differing placements of vortex generators on a wind turbine airfoil, compared to an airfoil without vortex generators, were simulated using computational fluid dynamics(CFD). It was shown that, in some instances, the application of vortex generators effectively controlled the flow over the airfoil to increase the power produced by the wind turbine. According to the CFD results, the application of vortex generators at an angle increased the lift produced, as well as delaying the separation of the boundary layer.
Computational Comparison Of Dual Bell, Expansion-Deflection, And Aerospike Nozzles,
2022
Georgia Southern University
Computational Comparison Of Dual Bell, Expansion-Deflection, And Aerospike Nozzles, Manuel R. Abadie Ardon
Honors College Theses
In the search for a Single-Stage-to-Orbit rocket, Altitude Compensating Nozzles concepts (ACNs) have been proposed since the 1950s, but research has stalled despite the modern analysis tools available. These nozzle concepts offer optimum performance at two or more altitude settings. This research chose three of these concepts, these being the Dual Bell, Expansion-Deflection, and Aerospike, which were designed and analyzed at various pressure ratios (NPR=10,15,30,36,30,45) using Computational Fluid Dynamics (CFD) software FLUENT. Simulations generated pressure distributions along the nozzle wall, which allowed to calculate data values such as thrust coefficients. Nozzle efficiency is calculated from this data and used to …
Time-Resolved Piv Measurements Of Ship Airwakes With Quartering Winds,
2022
Embry-Riddle Aeronautical University – Daytona Beach
Time-Resolved Piv Measurements Of Ship Airwakes With Quartering Winds, Kaijus H. Palm
Doctoral Dissertations and Master's Theses
The unsteady, three-dimensional, turbulent airwake over the Simple Frigate Ship No. 2 (SFS2) with quartering wind flow directions was studied in a low-speed wind tunnel facility. Surface oil flow visualization and time-resolved stereoscopic and planar particle image velocimetry (PIV) measurements were made for three crosswise planes and a single centerline streamwise plane. Measurements included various configurations with the bow of the ship model at two different quartering wind conditions of 10 and 20 degrees, as well as cases with and without the effects of a simulated atmospheric boundary layer (ABL). A comparative analysis of the time-averaged flow structures between the …
Influence Of Wing Planform Shape On The Effectiveness Of A Fixed-Slot,
2022
Embry-Riddle Aeronautical University
Influence Of Wing Planform Shape On The Effectiveness Of A Fixed-Slot, Yuan Zhao
Doctoral Dissertations and Master's Theses
This thesis report explores the effect of the Clark-Y wing geometry on lift and drag to use as a reference during aircraft design stage. The different characteristics investigated are fixed slot span, taper ratio, washout, and sweep angle. Plain wings, half slotted wings, and fully slotted wings were built in CATIA with an aspect ratio of 6 and different taper ratio, washout, and sweep angles. Using the CATIA models to generate the 3-D grids in Pointwise. All the simulations were tested in Ansys-Fluent under sea-level conditions with a Reynold number of 609000. The relationships between the aerodynamic characteristics and the …
Aeroelastic Analysis Of Small-Scale Aircraft,
2022
California Polytechnic State University, San Luis Obispo
Aeroelastic Analysis Of Small-Scale Aircraft, Kent Roberts
Master's Theses
The structural design of flight vehicles is a balancing act between maximizing loading capability while minimizing weight. An engineer must consider not only the classical static structural yielding failure of a vehicle, but a variety of ways in which structural deformations can in turn, affect the loading conditions driving those deformations. Lift redistribution, divergence, and flutter are exactly such dynamic aeroelastic phenomena that must be properly characterized during the design of a vehicle; to do otherwise is to risk catastrophe. Relevant within the university context is the design of small-scale aircraft for student projects and of particular consideration, the DBF …
Exploratory Measurement Of Recession Rates Of Low Temperature Ablators Subjected To Mach 6 Flow,
2022
Air Force Institute of Technology
Exploratory Measurement Of Recession Rates Of Low Temperature Ablators Subjected To Mach 6 Flow, Ross H. Kellet
Theses and Dissertations
The high speed/high-temperature effect of heat shield ablation was simulated in the low-enthalpy AFRL Mach 6 Ludwieg Tube using solid dry ice as a low-temperature sublimator. The experiments utilized both 21 half-angle cones and bi-conic models with a 7 ° half-angle leading edge followed by a 26° half-angle base contained within a cryogenic-cooled stainless steel holder. A method of fabricating dry ice test articles was developed using commercially procured dry ice and custom-made aluminum molds. Tests were performed at Mach 6.1 with a stagnation temperature of 490 K and stagnation pressures ranging from 40 - 500 psi. Unit Reynolds number …
Characterizing Wake Roll-Up And Vortex Structure For Delta Wing Configuations Featuring Flow Control Devices At Low Reynolds Number,
2022
Air Force Institute of Technology
Characterizing Wake Roll-Up And Vortex Structure For Delta Wing Configuations Featuring Flow Control Devices At Low Reynolds Number, Jeffrey M. Layng
Theses and Dissertations
Various configurations of a cropped delta wing featuring a NACA 0012 wing-section were evaluated experimentally at a Reynolds number of 5.0 x 105 in the Air Force Institute of Technology Low-Speed Wind Tunnel facility. The effects of active flow control (AFC) and passive boundary-layer fences (BLF) were shown to improve high angle of attack delta wing performance. The AFC BLFs were shown to replicate the performance enhancements found in passive BLFs without incurring a drag penalty. An experimental characterization of the wake region is presented to compare the wake roll-up and leading edge vortices for these baseline, passive BLF, …
Experimental Study Of Turbulent Flow Heat Transfer And Pressure Loss Over Surfaces With Dense Micro-Depth Dimples Under Viscous Sublayer,
2022
Institute of Turbomachinery, Shanghai Jiao Tong University
Experimental Study Of Turbulent Flow Heat Transfer And Pressure Loss Over Surfaces With Dense Micro-Depth Dimples Under Viscous Sublayer, Peng Zhang, Yu Rao, Phillip M. Ligrani
PRC-Affiliated Research
Presented are experimentally-measured heat transfer and pressure loss characteristics for dimpled surfaces, placed along one surface of a channel, with different ratios of dimple depth to channel height δ/H, and for Reynolds numbers ranging from 10,000 to 70,000. With the same relative dimple spacing to dimple print diameter, and the same ratio of dimple depth to dimple print diameter of δ/d = 0.20, experimental results for arrays of spherical indentation dimples with micro depths of δ = 0.6 and 1.0 mm (δ/H = 0.03 and 0.05) are compared with thermal characteristics for arrays of larger dimples with δ = 4.0 …
Flow Structure And Surface Heat Transfer From Numerical Predictions For A Double Wall Effusion Plate With Impingement Jet Array Cooling,
2022
Graduate school of Mechanical Engineering
Flow Structure And Surface Heat Transfer From Numerical Predictions For A Double Wall Effusion Plate With Impingement Jet Array Cooling, Hwabhin Kwon, Phillip M. Ligrani, Sneha Reddy Vanga, Heesung Park
PRC-Affiliated Research
To provide additional understanding of double wall cooling arrangements, especially local distributions of flow properties which are responsible for hot-side surface and cold-side surface heat transfer variations, investigated are numerically-simulated distributions of turbulent flow structural characteristics. Also considered are numerically-simulated surface heat transfer characteristics, including comparisons with experimentally-measured distributions. The numerical results are obtained using the ANSYS FLUENT Version 19.1 numerical code, with a k-ω SST turbulence model. The present arrangement includes a full-coverage effusion cooling plate, with coolant initially supplied by an impingement jet array. Considered are the effects of effusion blowing ratio, impingement jet Reynolds number, and streamwise …
