Engineering Commons^™

Experimental Investigation And Cfd Simulation Of Active Damping Mechanism For Propellant Slosh In Spacecraft Launch Systems, Dhawal Leuva

Doctoral Dissertations and Master's Theses

Motion of propellant in the liquid propellant tanks due to inertial forces transferred from actions like stage separation and trajectory correction of the launch vehicle is known as propellant slosh. If unchecked, propellant slosh can reach resonance and lead to complete loss of the spacecraft stability, it can change the trajectory of the vehicle or increase consumption of propellant from the calculated requirements, thereby causing starvation of the latter stages of the vehicle. Predicting the magnitude of such slosh events is not trivial. Several passive mechanisms with limited operating range are currently used to mitigate the effects of slosh. An …

Innovative Double Bypass Engine For Increased Performance, Sanjivan Manoharan

Doctoral Dissertations and Master's Theses

Engines continue to grow in size to meet the current thrust requirements of the civil aerospace industry. Large engines pose significant transportation problems and require them to be split in order to be shipped. Thus, large amounts of time have been spent in researching methods to increase thrust capabilities while maintaining a reasonable engine size. Unfortunately, much of this research has been focused on increasing the performance and efficiencies of individual components while limited research has been done on innovative engine configurations. This thesis focuses on an innovative engine configuration, the High Double Bypass Engine, aimed at increasing fuel efficiency …

The Propulsive Design Aspects On The World’S First Direct Drive Hybrid Airplane, Ankit Nanda

Doctoral Dissertations and Master's Theses

The purpose of this thesis is to design a safe technology demonstrator by implementing a direct drive propulsion system for a gas-electric hybrid aircraft. This system was integrated on the Embry-Riddle Eco-Eagle for the Green Flight Challenge 2011. The aim of the system is to allow the pilot to use the electric motor as an independent power source to fly the aircraft once at cruise altitude, while having a gas engine to allow for higher power capability.

The system was designed to incorporate the motor and the motor control unit provided by Flight Design and Drivetek AG alongside a Rotax …

Integration Of Unmanned Aerial Systems In Class E Airspace: The Effect On Air Traffic Controller Workload, Jeeja S. Vengal

Doctoral Dissertations and Master's Theses

As technology rapidly advances and our imagination is no longer fantasy but instead reality, the aviation community needs to concentrate on the harsh truth of airspace safety. In the situation of integrating unmanned aerial systems (UASs) into the National airspace, UASs outside of terminal areas would generally be permitted to fly their preferred routes, and self-separate, with minimal intervention from air traffic control. From an air traffic control perspective, the integration could raise a number of human performance problems including workload extremes and passive-monitoring demands. One fundamental requirement for operation in the National Air Space is to preserve the safety …

Development Of A Higher-Order Navier-Stokes Solver For Transient Compressible Flows, Arjun Vijayanarayanan

Doctoral Dissertations and Master's Theses

A higher‐order density based Navier‐Stokes solver was developed for 2‐Dimensional flows using the finite volume approach. The Van leer flux‐splitting technique was used to calculate the fluxes. The second‐order spatial accuracy was achieved using the variable extrapolation method developed by Van leer called the Montone Upstream Centered Scheme for Conservation Laws (MUSCL) approach. The code development was done using Matlab. The code was verified using two validation cases. Firstly, subsonic, transonic, and supersonic flows over the 2‐D bump were simulated, and the results of the code were compared to the results from Fluent. Secondly, the shock‐tube problem was chosen, and …

Numerical Analysis Of Gun Barrel Pressure Blast Using Dynamic Mesh Adaption, Sathish Xavier

Doctoral Dissertations and Master's Theses

A Computational Fluid Dynamics (CFD) method has been applied to simulate the pressure blast of the projectile which is launched from a barrel and to investigate the pressure distribution and sound pressure level (dB) along different positions away from the gun axis and towards the fuselage of the aircraft. Fluent was employed to simulate the unsteady flow using dynamic mesh with moving boundary. Most CFD based ballistics-model requires additional thermodynamic functions which must be derived from the Noble-Abel equation of state. The unsteady, axisymmetric Navier Stokes equation systems were numerically solved using the Advection Upstream Splitting Method (AUSM) scheme; with …

An Automated Test Station Design Used To Verify Aircraft Communication Protocols, Joshua Berrian

Master's Theses

Requirements verification is typically the costliest part of the systems engineering design process. In the commercial aircraft industry, as the software and hardware design evolves, it must be verified to conform to requirements. In addition, when new design releases are made, regression analysis must be performed which usually requires repeat testing. To streamline verification, a suite of automated verification tools is described in this document which can reduce the test effort. This test suite can be qualified to be used to verify systems at any DO-178B design assurance level. Some of the software tools are briefly described below.

There are …

A Fixed Robotic Mars Base Architecture, Christie Angunette Alston

Mechanical & Aerospace Engineering Theses & Dissertations

This thesis proposes a fixed Mars base architecture consisting of the following interconnected elements: landing area, power generation, in-situ resource utilization (ISRU), robotic repair and assembly, and a scientific research laboratoiy. The base architecture that has been put forward can be expanded readily to include future elements such as a sustainable human habitat. The base architecture approach was developed assuming that serial Earth-launched lander missions were too expensive and too slow going forward in effecting the systematic exploration of a planet whose surface area constitutes nearly the same area as the land mass of Earth. The fixed base architecture facilitates …

Radiation Effects Basics For 7750, Robert J. Twiggs

Robert "Bob" Twiggs STEM Education Collection

A PowerPoint presentation created by Professor Bob Twiggs on "Radiation Effects Basics for 7750" on September 25, 2011.

Evaluation Of Nanocomposites For Shielding Electromagnetic Interference, Kenneth Y. Chong

Theses and Dissertations

Numerous efforts are ongoing to research and develop nanocomposite materials for space applications. Current composite spacecraft materials are nonconductive and require costly shielding materials to be applied in order to protect spacecraft from the harmful effects caused by electromagnetic interference (EMI), which is a by-product of exposure to the space environment. Conductive fillers (nanofibers) are being employed in composites to produce nanocomposites to reduce the dry weight of space vehicles while providing sufficient protection against EMI. This eliminates the need to apply secondary shielding materials to spacecraft. This thesis studied a nanocomposite consisting of Cycom 5575-2 glass with multi-walled carbon …

Stochastic Real-Time Optimal Control: A Pseudospectral Approach For Bearing-Only Trajectory Optimization, Steven M. Ross

Theses and Dissertations

A method is presented to couple and solve the optimal control and the optimal estimation problems simultaneously, allowing systems with bearing-only sensors to maneuver to obtain observability for relative navigation without unnecessarily detracting from a primary mission. A fundamentally new approach to trajectory optimization and the dual control problem is developed, constraining polynomial approximations of the Fisher Information Matrix to provide an information gradient and allow prescription of the level of future estimation certainty required for mission accomplishment. Disturbances, modeling deficiencies, and corrupted measurements are addressed with recursive updating of the target estimate with an Unscented Kalman Filter and the …

Increasing The Performance Of A Sliding Discharge Actuator Through The Application Of Multiple Potentials, Steven D. Seney Jr.

Theses and Dissertations

This work encompasses a comparison between a sliding discharge DBD actuator with grounded and AC biased sliding electrode driven at kHz frequency. The induced velocity in the bulk flow was recorded with PIV and compared for multiple potential splits between two test configurations and a baseline sliding discharge actuator over three test phases. In the first test phase, varying potential splits were examined between the primary and secondary electrode with the sliding electrode grounded. The potential splits induced a thicker induced jet than the baseline case with similar peak velocities on the order of 1.25 m/s at the 61 mm …

Two-Dimensional, Time-Dependent Plasma Structures Of A Hall Effect Thruster, David Liu

Theses and Dissertations

The Hall thruster is a type of electric propulsion utilized by satellites to perform a wide variety of missions ranging from station keeping, orbital maneuvers, and even deep space propulsion. In order to accommodate the multitude of missions it also has a wide assortment of sizes and power configurations which can range from approximately an inch in diameter at 20 W to a couple of feet in diameter at 1.5 kW. Additionally, this electro-static device provides high specific impulse without the added weight penalty associated with conventional chemical thrusters. It supplies this high specific impulse by ionizing a gas such …

Design And Control Of Flapping Wing Micro Air Vehicles, Michael L. Anderson

Theses and Dissertations

Flapping wing Micro Air Vehicles (MAVs) continues to be a growing field, with ongoing research into unsteady, low Re aerodynamics, micro-fabrication, and fluid-structure interaction. However, research into flapping wing control of such MAVs continues to lag. Existing research uniformly consists of proposed control laws that are validated by computer simulations of quasi-steady blade-element formulae. Such simulations use numerous assumptions and cannot be trusted to fully describe the flow physics. Instead, such control laws must be validated on hardware. Here, a novel control technique is proposed called Bi-harmonic Amplitude and Bias Modulation (BABM) which can generate forces and moments in 5 …

Effect Of The Thickness Of Undoped Gan Interlayers Between Multiple Quantum Wells And The P-Doped Layer On The Performance Of Gan Light-Emitting Diodes, T. Lu, S. Li, K. Zhang, C. Liu, Y. Yin, L. Wu, H. Wang, Xiaodong Yang, G. Xiao, Y. Zhou

Mechanical and Aerospace Engineering Faculty Research & Creative Works

InGaN based light-emitting diodes (LEDs) with undoped GaN interlayer of variant thicknesses grown by metal-organic chemical vapor deposition technique have been investigated. It was found that the thickness of undoped GaN interlayers affected LEDs' performance greatly. The LED with 50 nm undoped GaN interlayer showed higher light output power and lower reverse-leakage current compared with the others at 20 mA. Based on electrical and optical characteristics analysis and numerical simulation, these improvements are mainly attributed to the improvement of the quality of depletion region by inserting an undoped GaN layer, as well as reduction of the Shockley-Read-Hall recombination in InGaN/GaN …

Space Environment-Iii Lecture - Powerpoint Presentation, Robert J. Twiggs

Robert "Bob" Twiggs STEM Education Collection

Professor Bob Twiggs' lecture on Space Environment-III PowerPoint presentation delivered on September 2, 2011.

Space Environment - A Review, Robert J. Twiggs

Robert "Bob" Twiggs STEM Education Collection

A PowerPoint presentation created by Professor Bob Twiggs on "Space Environment" on September 2, 2011.

Mission Performance Considered As Point Performance In Aircraft Design, Robert A. Mcdonald

Aerospace Engineering

The cruise or loiter performance of an aircraft is intimately tied to its wing loading and its thrust-to-weight ratio. Paradoxically, mission performance is often not considered when these fundamental aircraft parameters are determined in conceptual design. In this paper, the traditional constraint diagram is extended to include contours of range or endurance parameter. These performance metrics represent the mission-performance capability of the aircraft without sizing the aircraft to a particular mission. This gives the designer an immediate and intuitive understanding of the tradeoff between the point and mission performance of the aircraft. The potential freedom for the designer to choose …

Designing Propulsion Systems For Future Aerospace Applications, Nihad E. Daidzic

Aviation Department Publications

No abstract provided.

Advances In Hydrogen Compression Ignition Internal Combustion Engines, Alberto Boretti

Mechanical and Aerospace Engineering Faculty Research & Creative Works

The turbocharged direct injection lean burn Diesel engine is the most efficient engine now in production for transport applications within heavy duty trucks applications full load brake engine thermal efficiencies up to 45% and reduced penalties in brake engine thermal efficiencies reducing the load by the quantity of fuel injected. the secrets of this engine's performances are the high compression ratio and the lean bulk combustion mostly diffusion controlled in addition to the partial recovery of the exhaust energy to boost the charging efficiency. the major downfalls of this engine are the carbon dioxide emissions and the depletion of natural …

Stoichiometric H2ice With Water Injection And Exhaust And Coolant Heat Recovery Through Organic Rankine Cycles, Alberto Boretti

Mechanical and Aerospace Engineering Faculty Research & Creative Works

High power density, stoichiometric, turbocharged, directly injected engines with water injection and a three-way catalytic converter after treatment have been proposed as one of the most promising H2ICE [1]. These throttle-controlled engines have top brake efficiencies exceeding 40%, but large penalties in efficiency reducing the load with 1 bar BMEP values approaching 10%. Recovery of the large amount of fuel energy lost in the coolant especially at low loads as well as the fuel energy lost in the exhaust that is significant at high loads and speeds may push not only the top brake efficiencies to exceed the 45% mark, …

Flow Characteristics Of The Renovated Cal Poly 3 X 4 Ft Subsonic Wind Tunnel, Mathew L. Thomas, Dorian V. Pandey, Jason N. Nguyen

Aerospace Engineering

This paper investigates the flow characteristics of the renovated Cal Poly 3 x 4 ft subsonic wind tunnel. The IFA 300 constant-temperature anemometer along with a cross-plane X-wire dual-sensor probe was used to measure the mean velocity and turbulence intensity of the tunnel flow and part of the turbulent boundary layer at one section of the tunnel. Because of the malfunction of one channel of the IFA 300, only one wire of the dual sensor probe was calibrated for the measurements. The probe was then placed in a streamlined probe holder mounting on the traverse inside the wind tunnel. The …

Vibration-Based Health Monitoring Of Multiple-Stage Gear Train And Differential Planetary Transmission Involving Teeth Damage And Backlash Nonlinearity, Andrew Patrick Sommer

Master's Theses

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 …

Femtosecond Laser Fabricated All-Optical Fiber Sensors With Ultrahigh Refractive Index Sensitivity: Modeling And Experiment, Lan Jiang, Longjiang Zhao, Sumei Wang, Jinpeng Yang, Hai Xiao

Mechanical and Aerospace Engineering Faculty Research & Creative Works

All-optical fiber sensors based on ultracompact fiber inline Mach-Zehnder interferometer (MZI) are fabricated by side-ablating a Ushape microcavity in a single-mode optical fiber with the fiber core partially removed using femtosecond (fs) laser pulses, in which the two light paths are accordingly formed in the remaining D-type fiber core and the U-shape microcavity. Beam propagation method (BPM) analysis is utilized to illustrate the dependences of good transmission spectra on parameters including the ablation depth, ablation length and the refractive index of Ushape microcavity, which gives some guidelines to optimize parameters for fs laser micromachining and predicts RI (refractive index) sensitivities …

Sitting In The Pilot's Seat: Optimizing Human-Systems Interfaces For Unmanned Aerial Vehicles, Steven Michael Queen, Kurt Sanner

STAR Program Research Presentations

One of the pilot-machine interfaces (the forward viewing camera display) for an Unmanned Aerial Vehicle called the DROID (Dryden Remotely Operated Integrated Drone) will be analyzed for optimization. The goal is to create a visual display for the pilot that as closely resembles an out-the-window view as possible. There are currently no standard guidlines for designing pilot-machine interfaces for UAVs. Typically, UAV camera views have a narrow field, which limits the situational awareness (SA) of the pilot. Also, at this time, pilot-UAV interfaces often use displays that have a diagonal length of about 20". Using a small display may result …

Simulation Of Wing Tip Vortices, Ryan Termath, Jason Lechniak, Keerti Bhamidipati

STAR Program Research Presentations

Modeling and Simulation (M&S) computational fluid dynamics (CFD) techniques were used to better understand wing tip vortices about a wing section. The CFD results were compared to experimental wind tunnel data derived from the University of Iowa (Ref. 2). The experiment used Stereoscopic Particle Image Velocimetry (SPIV) to measure the flow field. The SPIV data from the experiment illustrates the vortex core development and behavior downstream of the trailing edge of the wing section. Three CFD simulations using various mesh sizes and time steps were completed and compared to the experimental results. Two dimensional plots of modeled local flow field …

Thermal Expansions In Wurtzite Aln, Gan, And Inn: First-Principle Phonon Calculations, L.-C. Xu, R.-Z. Wang, Xiaodong Yang, H. Yan

Mechanical and Aerospace Engineering Faculty Research & Creative Works

Using the first-principle phonon calculations under the quasiharmonic approximation, thermal expansions in III-nitrides with wurtzite AlN, GaN, and InN are reported. The results showed that it is different for each thermal expansion of three III-nitrides at low temperatures, which is consistent with their Grneisen parameters as the function of temperature. Below 50 K, negative thermal expansions occur in InN, while GaN and AlN follow the rule of positive thermal expansion. To seek the origin of positivenegative thermal expansion distinction, the mode Grneisen parameters and the phonon spectra are investigated. They indicate that different low-frequency phonon vibration modes correspond to the …

Unsteady Total Pressure Measurement For Laminar-To-Turbulent Transition Detection, Akane Sharon Karasawa

Master's Theses

This thesis presents the use of an unsteady total pressure measurement to detect laminar-to-turbulent transition. A miniature dynamic pressure transducer, Kulite model XCS-062-5D, was utilized to measure the total pressure fluctuations, and was integrated with an autonomous boundary layer measurement device that can withstand flight test conditions. Various sensor-probe configurations of the Kulite pressure transducer were first examined in a wind tunnel with a 0.610 m (2.0 ft) square test section with a maximum operational velocity of 49.2 m/s (110 mph), corresponding dynamic pressure of 1.44 kPa (30 psf). The Kulite sensor was placed on an elliptical nose flat plate …

The Future Of Aerospace Propulsion: Visco-Elastic Non-Newtonian Liquids, Nicole Arockiam

The Journal of Purdue Undergraduate Research

Aerospace propulsion often involves the spray and combustion of liquids. When a liquid is sprayed, large drops form first, in a process known as primary atomization. Then, each drop breaks up into smaller droplets, in a process known as secondary atomization. This determines final drop sizes, which affect the liquid’s evaporation and mixing rates and ultimately influence combustor efficiency. Little has been published concerning the secondary atomization of visco-elastic non-Newtonian liquids, such as gels. These substances have special potential as aerospace propellants, because they are safer to handle than their Newtonian liquid counterparts, such as water. Additionally, they can be …

Comparison Of Best Economy And Best Power Mixture Settings In The Purdue University Training Fleet, Charles G. Chrisman

Purdue Polytechnic Directed Projects

Purdue University operates a fleet of Cirrus SR20s as training aircraft. Standard operating procedures for the cruise portion of cross country training flights call for 65% power with a best power mixture, also called rich of peak, as opposed to a best economy setting, also called lean of peak. Previous work demonstrated that fuel consumption rates, cylinder head temperatures, and true airspeeds are lower when best economy is employed compared to best power for the same power output. This study confirmed that best economy is associated with a lower fuel consumption rate and lower cylinder head temperatures but was unable …