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A Study Of Nonlinear Combustion Instability, Eric J. Jacob

Doctoral Dissertations

Combustion instability (CI) has been persistent in all forms of propulsion since their inception. CI is characterized by pressure oscillations within the propulsion system. If even a small fraction of the dense energy within the system is converted to acoustic oscillations the system vibrations can be devastating. The coupling of combustion and fluid dynamic phenomena in a nonlinear system poses CI as a significant engineering challenge.

Drawing from previous analysis, second order acoustic energy models are taken to third order. Second order analysis predicts exponential growth. The addition of the third order terms capture the nonlinear acoustic phenomena (such as …

Development And Testing Of A Self-Contained, Portable Instrumentation System For A Fighter Pilot Helmet, Michael Anthony Kamp

Masters Theses

A self-contained, portable, inertial and positional measurement system was developed and tested for an HGU-55 model fighter pilot helmet. The system, designated the Portable Helmet Instrumentation System (PHIS), demonstrated the recording of accelerations and rotational rates experienced by the human head in a flight environment. A compact, self-contained, “knee-board” sized computer recorded these accelerations and rotational rates during flight. The present research presents the results of a limited evaluation of this helmet-mounted instrumentation system flown in an Extra 300 fully aerobatic aircraft. The accuracy of the helmet-mounted, inertial head tracker system was compared to the aircraft-mounted referenced system. The ability …

Integral Formulation Of The Compressible Flowfield In Solid Rocket Motors, Michel Henry Akiki

Masters Theses

In this thesis, a semi-analytical formulation is provided for the rotational, steady, inviscid, compressible motion in a solid rocket motor that is modeled as a slender porous chamber. The analysis overcomes some of the deficiencies encountered in previous work on the subject. The method that we employ consists of reducing the problem’s mass, momentum, energy, ideal gas, and isentropic relations into a single integral equation that can be solved numerically. Furthermore, Saint-Robert’s power law is used to link the pressure to the sidewall mass injection rate. At the outset, results are presented for the axisymmetric and planar porous chambers and …

An Experimental Analysis Of The Laminar Separation Bubble At Low Reynolds Numbers, Karla Marie Swift

Masters Theses

This paper is an investigation into the laminar separation bubble that frequently plagues airborne vehicles operating in the low Reynolds number regime – experimentally found to be typically present in flows with Reynolds numbers below 10⁶ (Lissaman 1983). The specific application driving the present investigation is the fixed wing performance of unmanned micro air vehicles (MAVs), defined by their maximum chord length of 6 inches and current cruising speeds of 10-20 meters per second (Mueller 2001). A basic generic model was chosen for this investigation: a circular arc (section of 16 inch diameter PVC pipe) with sharp leading and …

Computational Investigations Of Characteristic Performance Improvements For Subkilogram Laser Micropropulsion, Richard Joel Thompson

Masters Theses

Experimental investigations have evaluated the feasibility of using laser-driven plasma microthrusters for small-thrust, high-specific-impulse space maneuvers, particularly for micro- and nanosatellite missions. Recent work made use of the Mach2 hydromagnetics code for the construction of an adequate computational model of the micro-thruster opera- tion. This thesis expounds on this previous work by extending the computational modeling capabilities, allowing for the determination of plasma plume properties and characteristic performance assessment of the microthruster; this allows for further computational investi- gation of the performance improvements achieved by new design considerations. Two par- ticular design changes are implemented and measured: (i) the simulation …

Multiple Axisymmetric Solutions For Axially Traveling Waves In Solid Rocket Motors, Nadim Yaacoub Zgheib

Masters Theses

In this article, we consider the vorticoacoustic flowfield arising in a rightcylindrical porous chamber with uniform sidewall injection. Such configuration is often used to simulate the internal gaseous environment of a solid rocket motor (SRM). Assuming closed-closed acoustic conditions at both fore and aft ends of the domain, the introduction of small disturbances in the mean flow give rise to an axially traveling vortico-acoustically dominated wave structure that our study attempts to elucidate. Although this problem has been formulated before, it is reconsidered here in the context of WKB perturbation expansions in the reciprocal of the crossflow Reynolds number. This …

Development And Flight Test Of A Real-Time Energy Management Display, Isaac Atuahene

Masters Theses

A real-time energy management display is developed and evaluated, and the feasibility and utility of the display in providing real-time guidance and information on the aircraft’s energy state was investigated. Flight simulations were conducted with the UTSI Aviation Systems research flight simulator to validate the display and evaluate its utility for flying along constant specific excess power contours, and directly obtaining specific excess power contours from level acceleration flight test. The display was evaluated for flying optimal paths. This study considered the energy state of the aircraft from the point of view of the relation that exists between specific excess …

Flight Test And Evaluation Of A Low-Cost, Compact, And Reconfigurable Airborne Data Acquisition System Based On Commercial Off-The-Shelf Hardware, Christopher George Ludwig

Masters Theses

Digitization of physical parameters for the display and recording by computers is the essential aspect of any airborne data acquisition system. The objective of this thesis was to develop a data acquisition system for General Aviation research and certification flight testing based on a low-cost Commercial Off-The- Shelf (COTS) hardware, in particular, a common glass cockpit system for experimental aircraft. A kneeboard computer was used to monitor data communications between the various devices of the Grand Rapids Technology (GRT) Electronic Flight Information System (EFIS). The monitored data was then displayed for use in-flight, and recorded aboard the aircraft for post-flight …

Adapting A Tier 2 Unmanned Aerial Vehicle To Provide An Electronic Surveillance And Geolocation Capability, Ward Andrew Huffine

Masters Theses

The purpose of this thesis was to investigate if it would be possible to integrate a developmental Radar Warning Receiver named “The Puffer” onto a Tier 2 Unmanned Aerial Vehicle, and incorporate the Multifunctional Information Display System/Low Volume Terminal into the UAV‟s ground control station. This integration of systems would become a low cost platform that could provide an Electronic Surveillance and geolocation capability of known mobile threat systems. The results of this investigation showed that the Puffer could be integrated on to the Tier 2 UAV with minor modifications. To control and fully integrate the downlink messages from …

Airplane Piston Engine Dynamics As An Aeronca E-113 Case Study, Michael Charles Leigh

Masters Theses

Kinematic equations were developed to describe the dynamic motions of the aircraft piston engine components in terms of time dependent position, velocity, and acceleration relationships. Using the Aeronca E-113 engine as a case study, the brake mean effective pressure (BMEP) rating was used to model the cylinder gas pressure profile. The moments of inertia of the dynamic components including connecting rod, crankshaft, and propeller were measured using a pendulum swing method. Representative values were obtained for inertial and gas pressure forces acting on crankshaft journals, connecting rods, and cylinder walls. The resulting model can help in the design of crankshafts …

A Study Of The Cf188 Landing Gear Upgrade, Eric Joseph Grandmont

Masters Theses

A study was undertaken to assess the effectiveness of the CF188 main landing gear upgrade on reducing Planing Link Mechanism failures. Two main landing gear configurations were studied: the prototype configuration and, for comparison purposes, the current configuration referred to as the baseline. Under this study, the flight test data that was analyzed came from key measurements recorded during maintenance rigging procedures, pilot ground handling quality ratings, and from over 80 landings at different descent rates and aircraft attitudes. Landings consisted of touch and go, full stop, cable overrun and cable engagement. The aircraft that was used through the flight …