Aerodynamics and Fluid Mechanics Commons^™

Scale Modeling Of Cessna 172, Chee-Woon Kim

Aerospace Engineering

This report describes how the scale-model aircraft can be built when the Reynolds number is out of range for using dynamic similitude method. Due to lack of time and budget for designing an actual model for testing, Cessna 172 was used to calculate the size of the temporary scale-model aircraft. The method that was used for this project was matching aerodynamic coefficients such as drag coefficient or lift coefficient of the prototype and the model. Based on this method, the takeoff distance, landing distance and the rate of climb of the model came out to be 218 ft, 91 ft …

An Investigation Of Cavity Resonance And Its Relationship To Store Force And Moment Loading, Christopher J. Coley

Theses and Dissertations

A store which is released from an internal bay is subjected to a highly unsteady flowfield which influences the release characteristics for the store. Pressure transducer information is often used to estimate store loading, although no direct correlation between the observed frequencies from the pressure transducers and the store loading has been developed. The relationship between the acoustic modes present in the cavity and the force and moment loading on a store released from a bay are investigated through a CFD study using the OVERFLOW 2.1 solver. The acoustic modes of the cavity are calculated from the pressure fluctuation histories …

Biological Investigation Of The Stimulated Flapping Motions Of The Moth, Manduca Sexta, Travis B. Tubbs

Theses and Dissertations

No abstract provided.

An Investigative Study Of Gurney Flaps On A Naca 0036 Airfoil, Gregory F. Altmann

Master's Theses

This project examined the effect of Gurney flaps on a 2D, 2-ft chord NACA 0036 airfoil in the Cal Poly 3’x4’ low speed wind tunnel at 25 m/s.  It also covered the numerical simulation of the experiment in computational fluid dynamics (CFD).  During the study, problems with the wind tunnel data were seen.  After a careful diagnosis, the problem was traced to dirty flow conditioners which were subsequently replaced.

Five Gurney flaps at 1, 2, 3, 4, and 5% of the chord were tested.  The Gurney flaps had the effect of eliminating the lift reversal effect and lowering the profile …

Two Element Linear Strength Vortex Panel Method, Clifton A. Cox

Aerospace Engineering

A linear strength vortex panel method was developed to predict the C_p and C_l for a lifting two element airfoil. The linear strength vortex panel method was first validated against thin airfoil theory and experimental data for a single NACA 2412 airfoil. At 2 degrees angle of attack, the linear strength vortex panel method predicted a C_l of about 0.49. Experimental data and thin airfoil theory gave C_l estimations of 0.45 and 0.22 respectively. The Matlab code was then modified to accept a two element airfoil. The two key modifications were the separation of the two …

Effect Of Thermally Induced Deformation In A Supersonic Combustion Facility, Aditya Ajit Gupte

Master's Theses - Daytona Beach

Nastran and ANSYS finite element analysis (FEA) and Wind-US computational fluid dynamics (CFD) solvers are used to simulate the effect of thermal deformation on the reacting flow developing within the University of Virginia (UVa) Supersonic Combustion Facility (SCF). A detailed thermal-structural model is developed to resolve the temperature distribution and the resulting structural deformation taking place within the scramjet engine flowpath. The predicted thermal deformation is used to refine the CFD model and produce a new set of results for direct comparison with experiment during both ramjet and scramjet modes of operation. Improved agreement between CFD and experiment is afforded …

Influence Of Initial Mean Helicity On Homogeneous Turbulent Shear Flow, Frank G. Jacobitz, Kai Schneider, Wouter J. T. Bos, Marie Farge

School of Engineering: Faculty Scholarship

Helicity statistics are studied in homogeneous turbulent shear flow. Initial mean helicity is imposed on an isotropic turbulence field using a decomposition of the flow into complex-valued helical waves. The initial decay of the turbulent kinetic energy is weakened in the presence of strong mean helicity, consistent with an analytic analysis of the spectral tensor of velocity correlations. While exponential growth of the mean turbulent kinetic energy is obtained, the mean helicity decays. Probability distribution functions (PDFs) of helicity are skewed and show that the imposed mean helicity prevails throughout the simulations. A wavelet-based scale-dependent analysis shows a trend to …

An Experimental Investigation On The Dynamics Of Bubbles Utilizing Refrigerant R134a Under Pressurized Flow Boiling Conditions, Keon Vereen

Electronic Theses and Dissertations

Flow boiling heat transfer allows for the dissipation of large amounts of heat. In this work, the effect of heat flux and pressure on flow boiling of liquid refrigerant R-134a is studied in a vertical thin channel. The experimental setup mimics a refrigeration cycle and specifically looks at the effect of pressure and wall heat flux on the departure size and bubble generation rate. The experimental setup consists of a closed loop which includes a vertical narrow rectangular channel and two synchronized high speed cameras for optical measurements at either sides of the channel. The setup is built to employ …

Drag Reduction Of A Modern Straight Truck, Drew Landman, Matthew Cragun, Mike Mccormick, Richard Wood

Mechanical & Aerospace Engineering Faculty Publications

A wind tunnel test program was conducted at the Langley Full Scale Tunnel (LFST) to evaluate the performance of five passive drag reduction configurations on a modern straight truck at full scale. Configurations were tested in a build-up fashion with results representing a cumulative effect. Tested configurations include a front valance, a front box fairing, a boat-tail, an ideal side-skirt, and a practical side-skirt. Configurations were evaluated over a nominal 9 degree yaw sweep to establish wind averaged drag coefficients using SAE J1252. Genuine replicate yaw sweeps were used in an uncertainty analysis. Results show up to 28% improvement in …

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 …

Super-Adiabatic Combustion In Porous Media With Catalytic Enhancement For Thermoelectric Power Conversion, Kyle Thomas Mueller

Electronic Theses and Dissertations

The combustion of ultra-lean fuel to air mixtures provides an efficient way to convert the chemical energy of hydrocarbons into useful power. Conventional burning techniques of a mixture have defined flammability limits beyond which a flame cannot self-propagate due to heat losses. Matrix stabilized porous medium combustion is an advanced technique in which a solid porous matrix within the combustion chamber accumulates heat from the hot gaseous products and preheats incoming reactants. This heat recirculation extends the standard flammability limits and allows the burning of ultra-lean fuel mixtures, conserving energy resources, or the burning of gases of low calorific value, …

Analysis Of Surface Augmentation Of Airfoil Sections Via Flow Visualization Techniques, John Louis Vento

Aerospace Engineering

This report details an experiment done to verify the effectiveness of two passive flow control systems on two-dimensional airfoil sections. The flow control was tested on two types of airfoils: a symmetric NACA 0011, intended to represent an airplane in cruise, and a NACA16611, intended to represent an aircraft with flaps extended.  Two types of passive systems were employed, a dimple surface augmentation, similar to a golf ball, and a grit system located at 20% chord. Airfoils without either augmentation were tested as a control case. Using a water tunnel and dye to perform flow visualization, the effects of each …

The Influence Of Pressure Relaxation On The Structure Of An Axial Vortex, Robert L. Ash, Irfan Zardadkhan, Allan J. Zuckerwar

Mechanical & Aerospace Engineering Faculty Publications

Governing equations including the effects of pressure relaxation have been utilized to study an incompressible, steady-state viscous axial vortex with specified far-field circulation. When sound generation is attributed to a velocity gradient tensor-pressure gradient product, the modified conservation of momentum equations that result yield an exact solution for a steady, incompressible axial vortex. The vortex velocity profile has been shown to closely approximate experimental vortex measurements in air and water over a wide range of circulation-based Reynolds numbers. The influence of temperature and humidity on the pressure relaxation coefficient in air has been examined using theoretical and empirical approaches, and …

Techno-Economic Analysis And Engineering Design Consideration Of Algal Biofuel In Southern Nevada, Jian Ma

Mechanical Engineering Faculty Research

As the biological and chemical technologies in algae biofuels production, engineering design, siting and resources are playing some dominant role in successfully developing and scaling locally. The southwest region in U.S. has been identified by DoE and the USDA as the most suitable area for developing algal biofuel production due to several merits like the high level of solar radiation, large arid land not good for food production. Among this region, Southern Nevada has unique advantage to grow microalgae biomass, which is the large amount of CO2 emission from about 16 power plants in Clark County to support the world …

Perch Landing Maneuvers And Control For A Rotating-Wing Mav, Jonathan Louis Lubbers

University of Kentucky Master's Theses

This thesis addresses flight control of the perch landing maneuver for micro-aerial vehicles. A longitudinal flight model is constructed for a pigeon-sized aircraft. In addition to a standard elevator control surface, wing-rotation also considered as a non-standard actuator for increasing low-speed aerodynamic braking. Optimal state and control trajectories for the perch landing maneuver are computed using commercial software. A neighboring optimal control law is then developed and implemented in a set of flight simulations. Simulations are run with both a quasisteady and an unsteady aerodynamic model. The effectiveness of wing rotation and of the neighboring optimal control law is discussed, …

A Shock Tube Technique For Blast Wave Simulation And Studies Of Flow Structure Interactions In Shock Tube Blast Experiments, Nicholas N. Kleinschmit

Department of Engineering Mechanics: Dissertations, Theses, and Student Research

Improvised explosive devices (IED’s) are widely used against US and allied forces fighting in Iraq and Afghanistan. Exposure to IED blast may cause blast-induced traumatic brain injury (bTBI). The injury mechanisms are however not well understood. A critical need in bTBI-related research is the ability to replicate the loading conditions of IED blast waves in a laboratory environment. In this work, experimental studies have been carried out to explore the use of the shock tube technique for generating air shock waves that mimic the temporal and spatial characteristics of free-field blast waves and to investigate the blast wave-test sample interactions …

Formula Sae Preliminary Aerodynamic Design, Robert Coates, Matt Wright

Von Braun Symposium Student Posters

No abstract provided.

Analytic Treatment Of Vortex States In Cylindrical Superconductors In Applied Axial Magnetic Field, Andrei Ludu, J. Van Deun, M. V, Milosevic, A. Cuyt, F. M. Peeters

Publications

We solve the linear Ginzburg–Landau GL equation in the presence of a uniform magnetic field with cylindrical symmetry and we find analytic expressions for the eigenfunctions in terms of the confluent hypergeometric functions. The discrete spectrum results from an implicit equation associated to the boundary conditions and it is resolved in analytic form using the continued fractions formalism. We study the dependence of the spectrum and the eigenfunctions on the sample size and the surface conditions for solid and hollow cylindrical superconductors. Finally, the solutions of the nonlinear GL formalism are constructed as expansions in the linear GL eigenfunction basis …

Development Of Measurement Methods For Application To A Wind Tunnel Test Of An Advanced Transport Model, Robert S. Ehrmann

Master's Theses

California Polytechnic State University, San Luis Obispo is currently working towards developing a Computational Fluid Dynamics (CFD) database for future code validation efforts. Cal Poly will complete a wind tunnel test on the Advanced Model for Extreme Lift and Improved Aeroacoustics (AMELIA) in the National Full-Scale Aerodynamics Complex (NFAC) 40 foot by 80 foot wind tunnel at NASA Ames Research Center in the summer of 2011. The development of two measurement techniques is discussed in this work, both with the objective of making measurements on AMELIA for CFD validation.

First, the work on the application of the Fringe-Imaging Skin Friction …

Implementation Of A Conrad Probe On A Boundary Layer Measurement System, Charles Rocky Ulk

Master's Theses

This thesis presents the design, calibration, and performance evaluation of a type of two-hole pressure probe anemometer known as a Conrad probe, as well as its subsequent implementation on an autonomous, compact boundary layer measurement device and its first application for subsonic in-flight measurements of a swept wing boundary layer. Calibration of the Conrad probe was accomplished using two calibration functions and a non-nulling method for resolving in-plane flow velocity direction and magnitude over a range of ±30 degrees. This approach to calibration and application offered the advantages of rapid data acquisition with lower energy consumption than alternative methods for …