Mechanical Engineering Commons^™

Performance And Emissions Study Of N+3 And N+4 Engine Models With Several Fuel Types Using Npss, Abel Solomon

McKelvey School of Engineering Theses & Dissertations

The aviation industry is known to be one of the major contributors to greenhouse gases accounting for 4.9% of the global greenhouse emissions. With the ever-increasing threat of climate change to the overall survival of the planet, the exploration of new technologies and alternative energy sources that minimize greenhouse gas emissions are of paramount importance. In this regard, the development of propulsion systems well suited for the performance and emissions requirements of future commercial aircraft plays a crucial role. This thesis investigates N+3 and N+4 technology-level propulsion systems that are proposed by NASA as possible propulsion systems for advanced single-aisle …

Foundations For Finite-State Modelling Of A Two-Dimensional Airfoil That Reverses Direction, Jake Michael Oscar Welsh

McKelvey School of Engineering Theses & Dissertations

Current 3-D finite-state wake models are incapable of simulating a maneuver in which the sign of the free-stream velocity changes direction and the rotor enters its own wake -- as might occur in the case of a helicopter which ascends and then descends. It is the purpose of this work to create a 2-D finite-state wake model which is capable of handling changes in free-stream direction as a precursor to development of a 3-D model that can do the same.

The 2-D finite-state model used for reentry modifications is an existing model created by Peters, Johnson, and Karunamoorthy. By the …

Numerical Simulation Of Flow Past An Airfoil With Ice Accretion On Leading Edge, Boyu Wang

McKelvey School of Engineering Theses & Dissertations

The focus of this research is on aerodynamic simulation of flow past NACA 23012 airfoil with clean surface and with ice accretion on its leading edge by using the commercial CFD solver ANSYS Fluent. Reynolds-Averaged Navier-Stokes (RANS) computations are performed using Spalart-Allmaras (SA) and Wray-Agarwal (WA) turbulence models. ANSYS mesh package ICEM is used to model the geometry and generate the mesh. The computations are performed at 0, 2, 4, 6, 8, 10, and 12 degrees angle of attack which are compared with experimental data. For the case of ice accretion at the leading edge, the physical geometry becomes more …

Development And Application Of Elliptic Blending Lag K-Omega Sst Standard And Wall-Distance-Free Turbulence Model, Wenjie Shang

McKelvey School of Engineering Theses & Dissertations

In recent decades, Computational Fluid Dynamics (CFD) has become the most widely used technology to understand the fundamental complex fluid dynamics of turbulent flows as well as for modeling of turbulent flows in industrial applications. In industrial applications, the widely used methodology is to solve Reynolds-Average Navier-Stokes Equations (RANS) equations in conjunction with a turbulence model since it strikes a balance between accuracy and computational cost compared to other high fidelity approaches namely the Large Eddy Simulation (LES) and Direct Numerical Simulation (DNS), There are a large number of turbulence models proposed in past five decades, majority of them are …

Computation Of Flow Fields Due To Single- And Twin-Jet Impingement, Xiang Zhang

McKelvey School of Engineering Theses & Dissertations

The thesis consists of two parts. The first part focuses on numerical simulations and their comparison with experimental data for single-jet impingement on ground. Angles between the axisymmetric jet and impingement surface considered are 15, 30 and 90 degree. It is shown that both the k-epsilon and Wray-Agarwal (WA) model can predict the flow fields in good agreement with the experimental results. The second part extends the first part to twin-jet normal impingement on the ground. It focuses on numerical simulation of fountains formed by the twin-jet impingement. The fountains can be normal straight upward when the two jets are …

Development Of A One-Equation Turbulence Model Based On K-Ε Closure And Its Extension For Computing Transitional Flows By Including An Intermittency Transport Equation, Cheng Peng

McKelvey School of Engineering Theses & Dissertations

No abstract provided.

Development Of A Multi-Probe Kelvin Scanner Device For Industrially-Relevant Characterization Of Surface-Activated Carbon Fiber Reinforced Thermoplastic Composites, Kirby Simon

McKelvey School of Engineering Theses & Dissertations

Carbon fiber reinforced thermoplastic (CFRTP) composites are becoming increasingly attractive materials in manufacturing due to their lightweight nature, mechanical strength, and corrosion resistance. Surface activation of these materials is usually required during processing to increase the bond strength of assemblies (aerospace and automotive industries) or improve adhesion with implants (biomedical industry). Industrially-relevant, nondestructive quality control methods for assessing the activation state of these materials do not currently exist, however. Applying principles discovered through the use of scanning probe microscopy, a multiple-probe Kelvin scanning (MPKS) device has been developed that can assess the uniformity of the activation state of plasma-treated CFRTP …

Numerical Simulation Of A High Strain Rate Biaxial Compression Apparatus, Michael Lagieski

McKelvey School of Engineering Theses & Dissertations

Few experimental methods today are capable of exploring the strength of materials at high strain rates (10⁵ s^-1). Those that are capable, such as the Split Hopkinson Bar, Taylor Anvil and Plate Impact suffer from instability and are generally limited to one dimensional wave propagation. Of particular interest is material response under biaxial compression, similar to that seen in inertial confinement fusion. Laser fusion fuel pellets typically undergo large strain rates as well as plastic deformation and non-linear behavior. This work briefly outlines an experimental procedure designed to replicate these large strain rates under biaxial compression using …

Minimum Induced Power For A Helicopter In High-Speed Forward Flight, Junsoo (Sean) Hong

McKelvey School of Engineering Theses & Dissertations

A dynamic inflow model is used to calculate minimum induced power for a helicopter in high-speed forward flight with infinite and finite number of blades. Comparisons between analytical and numerical results are shown and they show good agreement. Different flow conditions (such as with and without reverse flow or inflow feedback) are used to show how each condition affects optimum induced power. Several results confirm the findings of earlier investigations such as a singularity in rotor power in reverse flow and induced power reduction with increase in blade number. Some of the new findings are that greater inflow feedback (due …

Semi-Empirical Modeling Of Two-Dimensional And Three-Dimensional Dynamic Stall, Ramin Modarres

McKelvey School of Engineering Theses & Dissertations

Helicopters are generally limited in their performance by the phenomenon of dynamic stall. The purpose of this work is to develop a method for modeling dynamic stall that is appropriate to preliminary design and flight simulator applications. Unlike other semi-empirical dynamic stall models, the model developed in this thesis, not only counts for the well-known, three-dimensional flow effects on the stalled loads but also captures the secondary vortex-shedding phenomenon that has been seen in experiments. The fundamental physics that modify dynamic-stall behavior and that have been extended from two-dimensional to three-dimensional flow are, namely: 1.) yawed flow, 2.) time-varying velocity, …

Evaluation Of The Performance Of Various Turbulence Models For Accurate Numerical Simulation Of A 2d Slot Nozzle Ejector, Colin Graham

McKelvey School of Engineering Theses & Dissertations

With the development over the last several decades, accurate Computational Fluid Dynamics (CFD) modeling has now become an essential part in the analysis and design of various industrial products where the fluid flow plays an important role. The goal of this thesis is to apply the CFD technology to the analysis of a 2D slot nozzle ejector which has application in Short Take-off and Landing (STOL) aircraft and other future aerospace vehicles. In the nozzle-ejector configuration, the high speed air flow from the nozzle entrains the ambient air into a mixing chamber (ejector) as a means to create additional thrust …