This thesis presents a decentralized electromagnetic formation flying (EMFF) control method using frequency-multiplexed sinusoidal control signals. We demonstrate the EMFF control approach in open-loop and closed-loop control experiments using a single-degree-of-freedom testbed with an electromagnetic actuation system (EAS). The EAS sense the relative position and velocity between satellites and implement a frequency-multiplexed sinusoidal control signal. We use a laser-rangefinder device to capture the relative position and an ARM-based microcontroller to implement the closed-loop control algorithm. We custom-design and build the EAS that implements the formation control in one dimension. The experimental results in this thesis demonstrate the feasibility of the decentralized formation control algorithm between two satellites.

ABSTRACT Multidisciplinary Design Optimization of an Extreme Aspect Ratio HALE UAV Bryan J. Morrisey Development of High Altitude Long Endurance (HALE) aircraft systems is part of a vision for a low cost communications/surveillance capability. Applications of a multi payload aircraft operating for extended periods at stratospheric altitudes span military and civil genres and support battlefield operations, communications, atmospheric or agricultural monitoring, surveillance, and other disciplines that may currently require satellite-based infrastructure. Presently, several development efforts are underway in this field, including a project sponsored by DARPA that aims at producing an aircraft that can sustain flight for multiple years and act as a pseudo-satellite. Design of this type of air vehicle represents a substantial challenge because of the vast number of engineering disciplines required for analysis, and its residence at the frontier of energy technology. The central goal of this research was the development of a multidisciplinary tool for analysis, design, and optimization of HALE UAVs, facilitating the study of a novel configuration concept. Applying design ideas stemming from a unique WWII-era project, a “pinned wing” HALE aircraft would employ self-supporting wing segments assembled into one overall flying wing. The research effort began with the creation of a multidisciplinary analysis environment comprised of analysis modules, each providing information about a specific discipline. As the modules were created, attempts were made to validate and calibrate the processes against known data, culminating in a validation study of the fully integrated MDA environment. Using the NASA / AeroVironment Helios aircraft as a basis for comparison, the included MDA environment sized a vehicle to within 5% of the actual maximum gross weight for generalized Helios payload and mission data. When wrapped in an optimization routine, the same integrated design environment shows potential for a 17.3% reduction in weight when wing thickness to chord ratio, aspect ratio, wing loading, and power to weight ratio are included as optimizer-controlled design variables. Investigation of applying the sustained day/night mission requirement and improved technology factors to the design shows that there are potential benefits associated with a segmented or pinned wing. As expected, wing structural weight is reduced, but benefits diminish as higher numbers of wing segments are considered. For an aircraft consisting of six wing segments, a maximum of 14.2% reduction in gross weight over an advanced technology optimal baseline is predicted.

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 for the modulation field. The ROM is validated by considering the acoustically-excited premixed methane/air flames in conical and M-shape configurations. To test the model availability to practical burners, a confined flame configuration is also employed for model evaluation. Furthermore, to investigate the generality of the ROM to the burner flame, the performance of the ROM with respect to the V-shape and the swirled V-shape is investigated. The model accuracy is evaluated concerning flame geometrical features and flame describing function, and assessed by comparing the ROM results with both experimental measurements and direct- numerical-simulation results. It is found that the flame describing/transfer functions predicted by the ROM compare well with reference data, and are more accurate than those obtained from the conventional kinematic model built upon heuristically-presumed modulation fields.

Small electric uninhabited aerial vehicles (UAV) represent a rapidly expanding market requiring optimization in both efficiency and weight; efficiency is critical during cruise or loiter where the vehicle operates at part power for up to 99% of the mission time. Of the four components (battery, motor, propeller, and electronic speed controller (ESC)) of the electric propulsion system used in small UAVs, the ESC has no accepted performance model and almost no published performance data. To collect performance data, instrumentation was developed to measure electrical power in and out of the ESC using the two wattmeter method and current sense resistors; data was collected with a differential simultaneous data acquisition system. Performance of the ESC was measured under different load, commanded throttle, bus voltage, and switching frequency, and it was found that ESC efficiency decreases with increasing torque and decreasing bus voltage and does not vary much with speed and switching frequency. The final instrumentation was limited to low-voltage systems and error propagation calculations indicate a great deal of error at low power measurements; despite these limitations, an understanding of ESC performance appropriate for conceptual design of these systems was obtained. MODELING AND TEST OF THE EFFICIENCY OF ELECTRONIC SPEED CONTROLLERS FOR BRUSHLESS DC MOTORS

This thesis aims to uncover preliminary design relationships for an inlet of a split-wing electric distributed propulsion regional airliner. Several aspects of the inlet design were investigated, including: the overall thickness of the airfoil section with respect to the chord, inlet throat area, and lip radius. These parameters were investigated using several angles of attack and mass flow rates through the fan. Computational fluid dynamics, with a 2nd Order turbulence model was used and validated against World War II era data from NACA, as those studies were the most pertinent wind tunnel data available. Additionally, other works by Boeing, Empirical Systems Aerospace (ESAero), Rolling Hills Research, and the Air Force Research Laboratories (AFRL) were considered as part of this design tool tradespace. Future work considerations include utilizing an airfoil section designed for M = 0.6 or 0.65 cruise conditions as opposed to a symmetrical airfoil section, extruding the 2-D airfoil section discussed in this thesis for 3-D effects, and incorporating fan rotational physics into the simulations to better account for inlet Mach number effects.

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. Because swirl and losses due to the effects of viscosity have real and significant impacts on existing turbines, there is a strong motivation to develop models which can provide generalized results about the performance of an energy-extractor, such as a turbine, with the inclusion of these effects. A model with swirl and a model with losses due to the effects of viscosity were incorporated into CADT which yielded equations that predicted the performance of an energy-extractor for both un-ducted and ducted cases. In both of these models, for this application, additional performance parameters were analyzed including the drag, drag coefficient, power output, power coefficient, force coefficient, and relative efficiency. For the un-ducted CADT, it is well known that the wake-to-freestream velocity ratio of 1/3 will give the maximum power extraction efficiency of 59.3%; this result is called the Betz limit. However, the present analysis shows that reduced drag for a desired power extraction will occur for wake-to-freestream velocity ratios higher than the value of 1/3 which results in maximum power extraction efficiency. This in turn means that a turbine with a larger area than the smallest possible turbine for a specified power extraction will actually experience a lower drag. The model with the inclusion of swirl made use of the Moment of Momentum Theorem applied to a single-rotor actuator disk with no stators, in addition to the laws of Conservation of Mass, Momentum, and Energy from the CADT. The results from the model w/swirl showed that drag remains unchanged while power extracted decreases with the addition of swirl, with swirl effects becoming more severe for tip speed ratios below about 5. As for CADT, reduced drag for a specified power extraction can be achieved when the wake-to-freestream velocity ratio is higher that than which provides maximum power extraction efficiency. The model w/losses due to viscosity incorporated the losses into the Conservation of Energy relationship. The results from the model w/losses showed that there is a distinct wake-to-freestream velocity ratio at which minimum drag for a specified power output is achieved, and that this velocity ratio is usually—but not always—higher than that for which the power extraction efficiency is a maximum. It was concluded that a lower drag for a specified power output of an energy-extractor can usually be achieved at a wake-to-freestream velocity ratio higher than that which produces the v maximum power extraction efficiency. The latter condition, known as the Betz limit for CADT, and which defines the minimum size for a turbine to provide a specified power extraction, is therefore not the correct target design condition to achieve lowest drag for a small Ram-Air Turbine to power BLDS.

In this work, the data analysis of oscillating flapping fins is conducted for mathematical model. Data points of heave and surge force obtained by the CFD (Computational Fluid Dynamics) for different geometrical kinds of flapping fins. The fin undergoes a combination of vertical and angular oscillatory motion, while travelling at constant forward speed. The surge thrust and heave lift are generated by the combined motion of the flapping fins, especially due to the carrier vehicle’s heave and pitch motion will be investigated to acquire system identification with CFD data available while the fin pitching motion is selected as a function of fin vertical motion and it is imposed by an external mechanism. The data series applied to model unsteady lifting flow around the system will be employed to develop an optimization algorithm to establish an approximation transfer function model for heave force and obtain a predicting black box system with nonlinear theory for surge force with fin motion control synthesis.

Currently, the South Pole has a large data problem. It is estimated that 1.2 TB of data is being produced every day, but less than 500 GB of that data is being uploaded via aging satellites to researchers in other parts of the world. This requires those at the South Pole to analyze the data and carefully select the parts to send, possibly missing out on vital scientific information. The South Pole Carrier Pigeon will look to bridge this data gap. The Carrier Pigeon will be a small unmanned aerial vehicle that will carry a 30 TB solid-state hard drive from the South Pole to various destinations in the Southern Hemisphere, but it has been designed to y to Christchurch, New Zealand. This 87 lb. UAV will be able to y 3,650 nmi. up to 25,000 ft., using a 5.7 hp. engine. It will feature an de-icing system on the leading edge of its 8 ft. span wing to allow it to y through cold, moist climates. It will have a 39 in. long fuselage with a tail boom of 33 in. The aircraft has been designed to be made out of composites, thus reducing both the weight of the aircraft as well as its drag. It has been designed to come apart in order to be shipped successfully to the South Pole. There, it will be assembled and launched via a custom pneumatic launcher. It will y autonomously to 15,000 ft. and cruise climb throughout the flight to 25,000 ft., before descending to its destination. There, it will be caught by a net restraint system, where the hard drive will be extracted. The Carrier Pigeon is truly a unique vehicle for its size, range, and robustness.

The objective of this thesis is to develop vibration-based fault detection strategies for on-line condition monitoring of gear transmission systems. The study divides the thesis into three sections. First of all, the local stresses created by a root fatigue crack on a pinion spur gear are analyzed using a quasi-static finite element model and non-linear contact mechanics simulation. Backlash between gear teeth which is essential to provide better lubrication on tooth surfaces and to eliminate interference is included as a defect and a necessary part of transmission design. The second section is dedicated to fixed axis power trains. Torsional vibration is shown to cause teeth separation and double-sided impacts in unloaded and lightly loaded gearing drives. The transient and steady-state dynamic loading on teeth within a two stage crank-slider mechanism arising from backlash and geometric manufacturing errors is investigated by utilizing a non-linear multi-body dynamics software model. The multi-body model drastically reduces the computation time required by finite element methods to simulate realistic operation. The gears are considered rigid with elastic contact surfaces defined by a penalty based non-linear contact formulation. The third section examines a practical differential planetary transmission which combines two inputs and one output. Planetary gears with only backlash errors are compared to those containing both backlash and tooth defects under different kinematic and loading conditions. Fast Fourier Transform (FFT) analysis shows the appearance of side band modulations and harmonics of the gear mesh frequency. A joint time-frequency analysis (JTFA) during start-up reveals the unique vibration patterns for fixed axis gear train and differential planetary gear, respectively, when the contact forces increase during acceleration.

Collision with orbital debris poses a serious threat to spacecraft and astronauts. Hypervelocity impacts resulting from collisions mean that objects with a mass less than 1g can cause mission-ending damage to spacecraft. A means of shielding spacecraft against collisions is necessary. A means of testing candidate shielding methods for their efficacy in mitigating hypervelocity impacts is therefore also necessary. Cal Poly’s Electromagnetic Railgun was designed with the goal of creating a laboratory system capable of simulating hypervelocity (≥ 3 km/s) impacts. Due to several factors, the system was not previously capable of high-velocity (≥ 1 km/s) tests. A deficient projectile design is revised, and a new design is tested. The new projectile design is demonstrated to enable far greater performance than the previous design, with a muzzle velocity ≥ 1 km/sbeing verified during testing, and an energy conversion efficiency of 2.7%. A method of improving contact and controlling wear at the projectile/rail interface using silver plating and conductive silver paste is validated. A mechanism explaining the problem of internal arcing within the railgun barrel is proposed, and design recommendations are made to eliminate arcing on the basis of the work done during testing. The primary structural members are found to be deficient for their application and a failure analysis of a failed member, loading analysis of the railgun barrel, and design of new structures is undertaken and presented.