Aerodynamics and Fluid Mechanics Commons^™

Exploration Of A Computational Fluid Dynamics Integrated Design Methodology For Potential Application To A Wind Turbine Blade, Gaurav Kapoor

Doctoral Dissertations and Master's Theses

The main purpose of this thesis is to conduct a parametric sensitivity study on the blade design of AOC 15/50 wind turbine based on a CFD approach and optimize the blade design for maximizing the power output. The ANSYS® Fluent® flow solver using the k-ω SST turbulence model was validated by simulating the flow over two dimensional airfoils comprising the AOC 15/50 wind turbine blade. The CFD results have shown a considerable agreement with the experimental data for the airfoils. Parametric correlation study and sensitivity analysis were conducted by performing actual flow simulations over the turbine blade using ANSYS® Fluent®. …

Unsteady Viscous Cavity Flow Using Computational Fluid Dynamics, Chandramouli Vadlamudi

Doctoral Dissertations and Master's Theses

The problem of unsteady viscous incompressible flow in a two-dimensional cavity is treated using the unsteady incompressible Navier-Stokes equations with various initial and boundary conditions. First the case of a square cavity with one inlet and one outlet is treated in steady and unsteady flows. The software package ANSYS FLUENT was used in the CFD simulations. This approach captures the appearance of separation bubbles and vortex formation inside the cavity. Steady state flows are also obtained from the unsteady simulations after convergence of the time dependent solutions. Then the case of a cavity with a synthetic jet and two outlets …

Freedrop Testing And Cfd Simulation Of Ice Models From A Cavity Into Supersonic Flow, Thomas J. Flora

Theses and Dissertations

Weapon release at supersonic speeds from an internal bay is highly advantageous. For this reason, both experimental and numerical methods were used to investigate store separation from a cavity (L=D=4.5) into Mach 2.94 flow. The experiment used a piezoresistive pressure transducer, Schlieren and high-speed photography for data acquisition. The computational solution used the OVERFLOW solver. A sphere and a Mk-82, scaled to 1:20, were formed using frozen tap water. The sphere model was freedrop tested experimentally and computationally, while the sub-scale store shaped model was freedrop tested experimentally. The total pressure was varied to alter the dynamic response of the …

Cfd Study On Aerodynamic Effects Of A Rear Wing/Spoiler On A Passenger Vehicle, Mustafa Cakir

Mechanical Engineering Master's Theses

Aerodynamic characteristics of a racing car are of significant interest in reducing car-racing accidents due to wind loading and in reducing the fuel consumption. At the present, modified car racing becomes more popular around the world. Sports cars are most commonly seen with spoilers, such as Ford Mustang, Subaru Impreza, and Chevrolet Corvette. Even though these vehicles typically have a more rigid chassis and a stiffer suspension to aid in high-speed maneuverability, a spoiler can still be beneficial. One of the design goals of a spoiler is to reduce drag and increase fuel efficiency. Many vehicles have a fairly steep …

A Filter-Forcing Turbulence Model For Large Eddy Simulation Incorporating The Compressible "Poor Man's" Navier--Stokes Equations, Joshua Strodtbeck

Theses and Dissertations--Mechanical and Aerospace Engineering

A new approach to large-eddy simulation (LES) based on the use of explicit spatial filtering combined with backscatter forcing is presented. The forcing uses a discrete dynamical system (DDS) called the compressible ``poor man's'' Navier--Stokes (CPMNS) equations. This DDS is derived from the governing equations and is shown to exhibit good spectral and dynamical properties for use in a turbulence model. An overview and critique of existing turbulence theory and turbulence models is given. A comprehensive theoretical case is presented arguing that traditional LES equations contain unresolved scales in terms generally thought to be resolved, and that this can only …

Numerical Modeling Of The Cn Spectral Emission Of The Stardust Re-Entry Vehicle, Alexandre Martin, Erin D. Farbar, Iain D. Boyd

Mechanical Engineering Faculty Publications

Re-entry vehicles designed for space exploration are usually equipped with thermal protection systems made of ablative material. In order to properly model and predict the aerothermal environment of the vehicle, it is imperative to account for the gases produced by ablation processes. In the case of charring ablators, where an inner resin is pyrolyzed at a relatively low temperature, the composition of the gas expelled into the boundary layer is complex and may lead to thermal chemical reactions that cannot be captured with simple ow chemistry models. In order to obtain better predictions, an appropriate gas ow chemistry model needs …

Cfd Analysis Of A Uni-Directional Impulse Turbine For Wave Energy Conversion, Carlos Alberto Velez

Electronic Theses and Dissertations

Ocean energy research has grown in popularity in the past decade and has produced various designs for wave energy extraction. This thesis focuses on the performance analysis of a uni-directional impulse turbine for wave energy conversion. Uni-directional impulse turbines can produce uni-directional rotation in bi-directional flow, which makes it ideal for wave energy extraction as the motion of ocean waves are inherently bi-directional. This impulse turbine is currently in use in four of the world’s Oscillating Wave Columns (OWC). Current research to date has documented the performance of the turbine but little research has been completed to understand the flow …

Novel Inverse Airfoil Design Utilizing Parametric Equations, Kevin A. Lane

Master's Theses

The engineering problem of airfoil design has been of great theoretical interest for almost a century and has led to hundreds of papers written and dozens of methods developed over the years. This interest stems from the practical implications of airfoil design. Airfoil selection significantly influences the application's aerodynamic performance. Tailoring an airfoil profile to its specific application can have great performance advantages. This includes considerations of the lift and drag characteristics, pitching moment, volume for fuel and structure, maximum lift coefficient, stall characteristics, as well as off-design performance.

A common way to think about airfoil design is optimization, the …

Multi-Element Airfoil Optimization Using Computational Fluid Dynamics, Mustafa Kubilay Ictuzer

Mechanical & Aerospace Engineering Theses & Dissertations

High-lift systems are frequently used on commercial transport aircrafts to obtain low speed performance, in terms of take-off and landing field lengths and approach speed. To maximize the take-off and landing performance within the critical restrictions required by the new generation transport wing designs, enhanced high-lift technologies are needed. Moreover, the economic realities faced by the airlines require a design that is mechanically simple and effective. These facts lead us to the optimization of the high lift systems.

Optimizing a high-lift system improves an aircraft's take-off and landing performance. The weight of the system, the advantages and the disadvantages all …

Cfd Analysis Of Experimental Wing And Winglet For Falconlaunch 8 And The Exfit Program, Benjamin P. Switzer

Theses and Dissertations

Reusable launch vehicles have many benefits over their expendable counterparts. These benefits range from cost reductions to increased functionality of the vehicles. Further research is required in the development of the technology necessary for reusable launch vehicles to come to fruition. The Air Force Institute of Technology’s future involvement in the ExFIT program will entail designing and testing of a new wing tip mounted vertical stabilizer in the hypersonic regime. One proposed venue for experimentation is to utilize the United States Air Force Academy’s FalconLAUNCH Program which annually designs, builds, and launches a sounding rocket capable of reaching hypersonic speeds. …

Thermal Modeling Of Lithium-Ion Energy Storage Systems For Hybrid Electric Vehicles Using Computational Fluid Dynamics With Conjugate Heat Transfer, Craig R. Czlapinski

Master's Theses - Daytona Beach

The success and performance of a Hybrid Electric Vehicle (HEV) relies largely on its Energy Storage System (ESS). High temperatures and thermal variations can significantly affect a battery's performance and lifecycle. An effective thermal management system is vital to the health and safe operation of the ESS's batteries. A well designed thermal management system begins with the accurate prediction of the battery's thermal conditions. In hot climates, HEVs may be required to operate within ten degrees Celsius of the maximum safe operating temperature of their batteries. This study aims to evaluate the thermal management system of a lithium-ion based energy …

Efficient Simulation Of Fluid Flow, David Hannasch, Monika Neda

Undergraduate Research Opportunities Program (UROP)

We are computationally investigating fluid flow models for physically correct predictions of flow structures. Models based on the idea of filtering the small scales/structures and also the Navier-Stokes equations which are the fundamental equations of fluid flow, are numerically solved via the continuous finite element method. Crank-Nicolson and fractional-step theta scheme are used for the discretization of the time derivative, while the Taylor-Hood and Mini elements are used for the discretization is space. The effectiveness of these numerical discretizations in time and space are examined by studying the accuracy of fluid characteristics, such as drag, lift and pressure drop.

A Cfd Investigation Of Axisymmetric Microthruster Nozzles For Use On Nano-Satellites, Michael R. O'Gara

Master's Theses - Daytona Beach

The performance of microthruster nozzles (^ 0.1 N thrust) depending on nozzle contour, propellant and surroundings, destined for use in nanosatellite missions, is investigated via a numerical approach using the Wind-US flow solver. An experimental apparatus designed to measure microthruster performance in atmospheric or vacuum conditions used to aid numerical simulations is also presented. Comparing the numerical and experimental results show an approximate 25% drop in efficiency for unknown reasons. An evaluation of favorable nozzle contours suggested by previous researchers is conducted, and the results demonstrate the need for a more rigorous treatment of the nozzle flow at the exit …

A Computational Method For Flow Separation Detection And Control For Axial Compressor Airfoils, Chang Jun Meang

Master's Theses - Daytona Beach

Conducting full annulus experiments on multistage compressors is costly and time consuming due to the complexity of the experimental processes. To reduce complexity, Computational Fluid Dynamics (CFD) methods are applied to turbomachinery and other applications in recent analysis of such cases. CFD methods are widely used within the aerospace industry and are increasingly demonstrating their reliability. For axial compressors, it is known that highly staggered compressor stators will increase the aerodynamic loading on the stator, which directly relates to the compressor stall and efficiency. In this work, compressor stators stagger angle is increased 4 ° to induce separation on the …

Assessment Of The Thermal Improvements Awarded By Horseshoe Vortex Elimination On A Turbine Stator Blade In Computational Fluid Dynamics And Conjugate Heat Transfer, Laurent Lachmann

Master's Theses - Daytona Beach

The present work looks at an advanced turbine stator blade design and evaluates its thermal performance relative to a standard design. A new turbine stator blade is designed to eliminate the horseshoe vortex appearing at the leading edge. The new design is characterized by an extension of the leading edge at the hub and at the tip of about 30% of chord. By comparing this new design to an ordinary one (featuring straight leading edge), the present thesis verifies the horseshoe vortex elimination, and compares the thermal attributes of the fluid. The fluid is three-dimensional, viscous and turbulent. The analysis …

Comparative Study Of Aerodynamic Interference During Aft Dispense Of Munitions, Matthew G. Burkinshaw

Theses and Dissertations

Based on forthcoming USAF needs, an investigation was launched to further the understanding of aft dispense of munitions in a high-speed environment. A computational fluid dynamics (CFD) study was performed followed by a wind tunnel experiment. The study consisted of a strut-mounted cone simulating a parent vehicle and a sting mounted cone-cylinder store situated directly behind the cone. The CFD modeled the test objects inside a supersonic wind tunnel in which the experiments took place. The CFD study consisted of evaluating a new strut designed to reduce asymmetry in the airflow aft of the cone. The CFD study also included …

An Investigation Of The Dynamic Effects Of Flap Deflection On The Aerodynamic Characteristics Of An Airplane Wing Using Computational Fluid Dynamics, Alexander Moerchel

Master's Theses - Daytona Beach

Flaps are used to increase an airplane's lift and to adjust its stability and maneuverability. This study shows an application of STAR-CD, a commercial computational fluid dynamics (CFD) software, to an investigation of the dynamic effects of flap deflection on the lift, drag and moment coefficients, as well as on the location of the center of pressure. For this study, a plain flap was modeled with a moving mesh and was attached to a NACA 0012 airfoil and a wing of a general aviation aircraft for a 2D and 3D investigation, respectively. In addition, the flap deflection rates were varied …

Dynamic Aeroelastic Analysis Of Wing/Store Configurations, Gregory H. Parker

Theses and Dissertations

Limit-cycle oscillation, or LCO, is an aeroelastic phenomenon characterized by limited amplitude, self-sustaining oscillations produced by fluid-structure interactions. In order to study this phenomenon, code was developed to interface a modal structural model with a commercial computational fluid dynamics program. LCO was simulated for a rectangular wing, referred to as the Goland⁺ wing. It was determined that the aerodynamic nonlinearity responsible for LCO in the Goland+ wing was the combination of strong trailing-edge and lambda shocks which periodically appear and disappear. This mechanism limited the flow of energy into the structure which quenched the growth of the flutter, resulting …

Implementation And Testing Of Unsteady Reynolds-Averaged Navier-Stokes And Detached Eddy Simulation Using An Implicit Unstructured Multigrid Scheme, Juan A. Palaez

Mechanical & Aerospace Engineering Theses & Dissertations

Investigation and development of the Detached Eddy Simulation (DES) technique for the computation of unsteady flows on unstructured grids are presented. The motivation of the research work is driven by the ultimate goal of predicting separated flows of aerodynamic importance, such as massive stall or flows over complex non-streamlined geometries. These cases, in which large regions of massively separated flow are present, represent a challenge for conventional Unsteady Reynolds-Averaged Navier-Stokes (URANS) models, that in many cases, cannot produce solutions accurate enough and/or fast enough for industrial design and applications. A Detached Eddy Simulation model is implemented and its performance compared …

Three-Dimensional Aerodynamic Design Optimization Using Discrete Sensitivity Analysis And Parallel Computing, Amidu Olawale Oloso

Mechanical & Aerospace Engineering Theses & Dissertations

A hybrid automatic differentiation/incremental iterative method was implemented in the general purpose advanced computational fluid dynamics code (CFL3D Version 4.1) to yield a new code (CFL3D.ADII) that is capable of computing consistently discrete first order sensitivity derivatives for complex geometries. With the exception of unsteady problems, the new code retains all the useful features and capabilities of the original CFL3D flow analysis code. The superiority of the new code over a carefully applied method of finite-differences is demonstrated.

A coarse grain, scalable, distributed-memory, parallel version of CFL3D.ADII was developed based on "derivative stripmining". In this data-parallel approach, an identical copy …