Aerodynamics and Fluid Mechanics Commons^™

Improving The Reliability And Performance Of A Supersonic Indraft Tube Wind Tunnel, Christian J. Kaml

Master's Theses

Access to supersonic testing is increasing in demand, and wind tunnels remain one of the safest and most cost-effective methods for gathering high-speed flow data. Despite being more economical than alternative options, supersonic wind tunnel facilities often require substantial investment to construct, operate, and maintain.

The novel indraft tube tunnel architecture was conceived as a high-speed flow testbed that incorporates features of both Ludwieg tubes and indraft wind tunnels to maintain costs low enough to be accessible even to small universities. This design was first developed and tested in 2018 at California Polytechnic State University, featuring a cost per test …

Design And Analysis Of A Customizable 6-Dof Force/Torque Sensor, Pyeongkang Kim

Master's Theses

This thesis presents the design, development, calibration, and testing of a novel customizable six-degree-of-freedom force/torque sensor, called the Kustom Force/Torque Sensor (KFTS), for use in the Cal Poly Low Speed Wind Tunnel (LSWT). The KFTS was developed as an alternative to commercial multi-axis force/torque sensors that feature fixed specifications. The swappable components and configurable structure of the KFTS enables changes to the sensor sensitivity, sensing range, and frequency response. Experimental testing verified that the sensor behaved as a linear time-invariant system, enabling calibration through the method of least squares and allowing the applied forces and moments to be reconstructed as …

A Higher Order Panel Method With Vortex Particle Wake, Luca Flick-Kaiser

Master's Theses

Panel codes were some of the earliest methods for computing the flow around aircraft. Despite the availability of higher fidelity CFD methods, panel methods remain an essential tool for the development of modern aircraft, allowing engineers to quickly iterate during the conceptual design phase.

This work develops and implements a high order panel method using Python. The wake is modeled using vortex particles, resulting in an accurate wake representation with minimal user input. The integration of the higher order singularity distributions has been extended to include the calculation of the velocity gradients necessary for the vortex particle implementation. The use …

Design And Development Of A Resonance Ignition System Using Gaseous Propellants, Benjamin J. Hoefer

Master's Theses

This work presents the development and experimental evaluation of a resonance igniter (RI) operating with premixed gaseous propellants. Resonance ignition is a non-electrical ignition concept in which an underexpanded jet impinges on a closed-end Hartmann–Sprenger tube (HST), generating cyclic compression and expansion waves that rapidly heat gas near the tube endwall. A modular experimental system was designed and built to investigate resonance ignition using methane–air and methane–oxygen mixtures. The system includes a supplemental configuration that may probe for mixture conditions favorable to ignition, informing RI testing. Pressure and temperature measurements were used to characterize pressure control, mixture pressure ratio (MPR), …

Thermally Perfect Augmentation Of A Supersonic Inlet Design Tool That Uses Method Of Characteristics, Mario V. Guardado

Master's Theses

This work is the first in a series to augment a supersonic air inlet design tool based in Python 3 to incorporate new models that increase the range of applicability of the tool. This effort focuses on improving the thermodynamics model by incorporating a thermally perfect gas model. This tool utilizes method of characteristics to solve the governing equations for an inviscid, irrotational, isentropic, steady, supersonic flow field. Multiple test cases are used to assess the accuracy of all new models. A comparison is made between the original code’s test case for a supersonic inlet at low temperatures to verify …

Data Driven Analysis Of Samara Seed Kinematics And Dynamics, Shashwat Sparsh

Master's Theses

Samara Seeds are a class of fruit most famously belonging to the Acer species and are characterized by their single-bladed geometry and their auto-rotation response during descent. This steady-state auto-rotation response is the subject of aerodynamic analysis which aim to quantify the performance. The period prior to the beginning of steady-state auto-rotation is classified as the transition regime and has not been the subject of intense scrutiny.

This thesis employs a data-driven approach to analyzing the kinematic and dynamic response of these seeds during both the transition and auto-rotation stages of flight to quantify the performance with respect to the …

Enhancement Of A Python Integral Boundary Layer Method, Jeffrey T. Azuma

Master's Theses

This thesis presents a series of additions to a Python based integral boundary layer software library known as PyBL. This library provides the user the means to calculate boundary layer properties using different models for boundary layer behavior. The additions feature the integration of a set of new laminar and turbulent integral boundary layer models originally developed for and currently found in the program XFOIL. These models were modified to fit the ODE solver method at the foundation of PyBL. A new method for PyBL that stitches a laminar and turbulent solution together has been developed to improve the ability …

The Integration And Validation Of A Class 3b Laser For Stereo Particle Imaging Velocimetry, Jensen Lam

Master's Theses

Particle Imaging Velocimetry (PIV) is a laser flow diagnostic measurement technique used to measure spatial and temporal velocity fields. In an effort to promote experimental aerodynamic research, specifically an entry point for students to learn Particle Imaging Velocimetry, an in-house Class 3B laser PIV system was developed and its experimental results were verified with a Class 4 laser. Both systems were integrated on the Cal Poly Water Tunnel Laboratory. The work emphasizes the application of lasers controlled by a micro-controller to perform microsecond-based pulses and integrating a newly-developed device with an old system consisting of software, cameras, and synchronizers. The …

Sizing Wind Tunnel Heater For High Enthalpy Conditions, Justin M. Slavick

Master's Theses

This paper determines the feasibility of adding a heater to an existing blowdown supersonic wind tunnel to unlock new high-enthalpy test applications, considering cost and power requirements at a variety of different states. This process includes both modeling the current range of test section properties in Cal Poly's blowdown wind tunnel and determining the new range of properties that a heat exchanger could induce. These results are verified with a computational fluid dynamics study. Additionally, sublimation and ablation properties of materials are explored to create appropriate models to study atmospheric re-entry once the heat exchanger is implemented.

It is found …

The Pressure Distribution Of Rotating Cylinders Using An Onboard Wireless Data Acquisition System, Nathan Eller

Master's Theses

This thesis presents a novel, cost-effective method for mapping the pressure distribution on a rotating cylinder in cross flow, a phenomenon central to the Magnus effect. Utilizing commercial-off-the-shelf (COTS) micro-electromechanical system (MEMS) pressure sensors, a high-resolution data acquisition system was developed and integrated into a rotating cylinder model. Compared to traditional approaches, such as slip rings or one-off designs, this method proved significantly cheaper and faster while achieving comparable or superior resolution. The experimental setup, including a modified continuous rotation technique and adaptable model design, facilitated rapid testing across a broad range of Reynolds numbers and reduced frequencies, exceeding the …

Development Of Load Measurement Technique For Arbitrary Shapes, Quintin J. Cockrell

Master's Theses

Obtaining aerodynamic forces and moments about all three orthogonal axes for arbitrary shapes at arbitrary orientations in a fast manner via a measurement technique specific to Cal Poly’s low-speed wind tunnel to continually obtain the forces and moments under quasi-steady conditions is explored. A Continuous Rotation Technique (CR) uses a 6-DOF load cell and stepper motor to rotate an object about an axis for a complete rotation. The forces and moments acting upon the object pass through the stepper motor and interface plates and recorded by the load cell as the object is rotated continuously a finite number of rotations. …

Parametric Optimization Of A Wing-Fuselage System Using A Vorticity-Based Panel Solver, Chino Cruz

Master's Theses

Aerodynamic topology optimization is a useful tool in the aerodynamic design pro-
cess, especially when looking for marginal gains within a design. One example is
a turboprop racer concept aircraft that is designed with the goal of breaking world
speed records. An optimization framework was developed with the intention of later
being applied to this design. In the early design stages, the optimization framework
must focus on quicker methods of drag estimation, such as a panel codes. The large
number of design variables in topology optimization can exponentially increase func-
tion evaluations and thus computational cost. A vorticity-based panel solver …

Solving Supersonic Flows Using The Method Of Integral Relations In Python, Eddie Hsieh

Master's Theses

This thesis presents a modern approach to the Method of Integral Relations implemented in the Python programming language. This work is based on South's reports on solving supersonic conical flows and Belotserkovskii's publications on solving supersonic flows over blunt bodies. The Python SciPy library is extensively used in this thesis. A root finder module is used to perform South's solution process, and the Runge-Kutta ODE solver with dense output is implemented to replicate Belotserkovskii's solution process. The implementation of Python makes the development efficient and serves as an open-source framework for future work to build on. This work focuses on …

Coupled Boundary Conditions For Modeling Airbreathing Engines, Adam Louis Waldemarson

Master's Theses

Modeling the flight conditions of an aircraft that utilizes an airbreathing propulsion system necessitates a method to account for the increase in energy introduced into the flow. Current methods for modeling engines either assign fixed conditions on flat faces on the intake and exhaust through a manual process with the use of external models or attempt to model the flow through the engine within the simulation using complex and computationally expensive geometry and solvers. The method presented attempts to provide an intermediate option to model airbreathing engines through coupling the intake and exhaust boundary conditions with a parametric engine model. …

A Study Of Pressure Probe Response In Steady And Unsteady Flows, Michael T. Charonnat

Master's Theses

The objective of this thesis is two-fold: to analyze the directional calibration of a 3-hole probe in steady flow and to develop a method for the interpretation of measurements recorded with a novel, fast-response Pitot-type probe in unsteady, turbulent flow. Calibration data for the 3-hole probe’s two side ports was taken in the steady, non-turbulent region of a free jet and was evaluated for symmetry. In addition, data that was recorded using one side port in two independent calibration runs was compared to study repeatability. Misalignment was found between the nominally symmetric data sets, which may be the result of …

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 …

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 …

Characterization, Design, And Optimization Of Dual-Purpose Wind Turbines And Frost Protection Fans, Ethan Narad

Master's Theses

This thesis report outlines the creation of a MATLAB tool to design reversible machines that can function as both wind turbines and as agricultural frost protection fans. Frost protection fans are used to prevent crop loss during radiative freeze events during which a temperature inversion is present. Such a dual-purpose machine fundamentally has the constraint that it must use symmetric airfoils, so a suite of tools for automatically designing an optimized wind turbine blade with symmetric airfoils using the Blade Element Momentum (BEM) theory approach is presented. The BEM code is then re-derived and adapted for use with a frost …

Integral Boundary Layer Methods In Python, Malachi Joseph Edland

Master's Theses

This thesis presents a modern approach to two Integral Boundary Layer methods implemented in the Python programming language. This work is based on two 2D boundary layer methods: Thwaites' method for laminar boundary layer flows and Head's method for turbulent boundary layer flows. Several novel enhancements improve the quality and usability of the results. These improvements include: a common ordinary differential equation (ODE) integration framework that generalizes computational implementations of Integral Boundary Layer methods; the use of a dense output Runge-Kutta ODE solver that allows for querying of simulation results at any point with accuracy to the same order as …

A Flat Plate Skin Friction Correlation Including Transition, Jaret M. Wedow

Master's Theses

Many existing boundary layer models treat transition as a rapid switch from laminar to turbulent flow, with correlations defining properties in each respective region. Natural transition, however, is not always a very spanwise uniform process, with the onset of transition varying somewhat between different streamwise paths of fluid flow. Thus, a spanwise average of natural transition can result in a more gradual, extended transition region than many existing models predict. Modern applications, such as aircraft wings and fuselages, are extremely streamlined and smooth, allowing for natural transition to occur rather than flow tripping to turbulent near the leading edge. Under …

Analytical, Numerical, And Computational Methods To Analyze The Time To Empty Open, Closed, And Variable-Topped Inverted Bottles, Callen Schwefler

Master's Theses

Recent unexpected experimental observations of the emptying of inverted bottles with perforations has generated interest in modeling and simulation of this phenomenon. It was observed that as a perforation, i.e., a small hole at the "top" of the inverted bottle, is added and enlarged, the overall emptying time first increases to a maximum value and then decreases until it reaches a lower limit. The change in emptying time is associated with a transition from jetting, where only water exits the neck, to glugging, a competition between air and water flows at the neck of the bottle.

This paper develops analytical …

Development Of An Infrared Thermography System To Measure Boundary Layer Transition In A Low Speed Wind Tunnel Testing Environment, Damien Horton

Master's Theses

The use of infrared thermography for boundary layer detection was evaluated for use in the Cal Poly Low Speed Wind Tunnel (LSWT) and recommendations for the successful use of this technique were developed. In cooperation with Joby Aviation, an infinite wing model was designed, manufactured and tested for use in the LSWT. The wing was designed around a custom airfoil profile specific for this project, where the nearly-flat pressure gradient at a zero pitch angle would delay the chordwise onset of boundary layer transition. Steady-state, RANS numerical simulations predicted the onset of transition to occur at 0.75 x/c for the …

Development Of A Hybrid Particle Continuum Solver, Anthony J. Gay

Master's Theses

When simulating complex flows, there are some physical situations that exhibit large fluctuations in particle density such as: planetary reentry, ablation due to arcing, rocket exhaust plumes, etc. When simulating these events, a high level of physical accuracy can be achieved with kinetic methods otherwise known as particle methods. However, this high level of physical accuracy requires large amounts of computation time. If the simulated flow is in collisional equilibrium, then less computationally intensive continuum methods, otherwise known as fluid methods, can be utilized. Hybrid Particle-Continuum (HPC) codes attempt to blend particle and fluid solutions in order to reduce computation …

Ram Air-Turbine Of Minimum Drag, Raymond Akagi

Master's Theses

The primary motivation for this work was to predict the conditions that would yield minimum drag for a small Ram-Air Turbine used to provide a specified power requirement for a small flight test instrument called the Boundary Layer Data System. Actuator Disk Theory was used to provide an analytical model for this work.

Classic Actuator Disk Theory (CADT) or Froude’s Momentum Theory was initially established for quasi-one-dimensional flows and inviscid fluids to predict the power output, drag, and efficiency of energy-extracting devices as a function of wake and freestream velocities using the laws of Conservations of Mass, Momentum, and Energy. …

Field Testing The Effects Of Low Reynolds Number On The Power Performance Of The Cal Poly Wind Power Research Center Small Wind Turbine, John B. Cunningham

Master's Theses

This thesis report investigates the effects of low Reynolds number on the power performance of a 3.74 m diameter horizontal axis wind turbine. The small wind turbine was field tested at the Cal Poly Wind Power Research Center to acquire its coefficient of performance, C­_p, vs. tip speed ratio, λ, characteristics. A description of both the wind turbine and test setup are provided. Data filtration and processing techniques were developed to ensure a valid method to analyze and characterize wind power measurements taken in a highly variable environment. The test results demonstrated a significant drop in the …

Hypersonic Heat Transfer Load Analysis In Star-Ccm+, Robert Comstock

Master's Theses

This thesis investigates the capabilities of STAR-CCM+, a Computational Fluid Dynamics (CFD) software owned by Siemens, in predicting hypersonic heat transfer loads on forward-facing surfaces. Results show that STAR-CCM+ predicted peak heat transfer loads within +/- 20% of experimental data on the leading edge of a delta wing design from the X-20 Dyna-Soar program with 73^o of sweep. Steady-state laminar simulations were run as replications of wind tunnel tests documented in NASA CR-535, a NASA technical report that measured and studied the hypersonic pressure and heat transfer loads on preliminary X- 20 wing designs across a wide range of …

Numerical Analysis Of A Circulation Control Wing, Luke W. Bodkin

Master's Theses

The objective of this thesis was to develop an experimental method to research circulation control wings using numerical analysis. Specifically, it is of interest to perform 3D wind tunnel testing on a circulation control wing in the Cal Poly Low Speed Wind Tunnel (CPLSWT). A circulation control wing was designed and analyzed to determine the feasibility of this testing.

This study relied on computational fluid dynamics (CFD) simulations as a method to predict the flow conditions that would be seen in a wind tunnel test. A CFD simulation was created of a wing model in a wind tunnel domain. Due …

A Parametric Study Of Formation Flight Of A Wing Based On Prandtl's Bell-Shaped Lift Distribution, Kyle S. Lukacovic

Master's Theses

The bell-shaped lift distribution (BSLD) wing design methodology advanced by Ludwig Prandtl in 1932 was proposed as providing the minimum induced drag. This study used this method as the basis to analyze its characteristics in two wing formation flight. Of specific interest are the potential efficiency savings and the optimal positioning for formation flight. Additional comparison is made between BSLD wings and bird flight in formation.

This study utilized Computational Flow Dynamics (CFD) simulations on a geometric modeling of a BSLD wing, the Prandtl-D glider. The results were validated by modified equations published by Prandtl, by CFD modeling published by …

A Study Of The Design Of Adaptive Camber Winglets, Justin J. Rosescu

Master's Theses

A numerical study was conducted to determine the effect of changing the camber of a winglet on the efficiency of a wing in two distinct flight conditions. Camber was altered via a simple plain flap deflection in the winglet, which produced a constant camber change over the winglet span. Hinge points were located at 20%, 50% and 80% of the chord and the trailing edge was deflected between -5° and +5°. Analysis was performed using a combination of three-dimensional vortex lattice method and two-dimensional panel method to obtain aerodynamic forces for the entire wing, based on different winglet camber configurations. …

A Study Of The Utilization Of Panel Method For Low Aspect Ratio Wing Analysis, William Barton D. Newey

Master's Theses

This study demonstrates the applicability of using a modified application strategy of panel method to analyze low aspect ratio wings at preliminary design phases. Conventional panel methods fail to capture the leading edge vortex (LEV) that is shed by wings with low aspect ratios, typically below 2 depending on planform. This aerodynamic phenomenon contributes to a significant amount of the lift of these wings and the result is a drastic underestimation of the lift characteristics when analyzed by conventional panel method. To capture the effect of the leading edge vortex, a panel method code was used with an extended definition …