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- All Subjects: Mechanical Engineering
- Genre: Masters Thesis
- Resource Type: Text
Description
Derived from the necessity to increase testing capabilities of hybrid rocket motor (HRM) propulsion systems for Daedalus Astronautics at Arizona State University, a small-scale motor and test stand were designed and developed to characterize all components of the system. The motor is designed for simple integration and setup, such that both the forward-end enclosure and end cap can be easily removed for rapid integration of components during testing. Each of the components of the motor is removable allowing for a broad range of testing capabilities. While examining injectors and their potential it is thought ideal to obtain the highest regression rates and overall motor performance possible. The oxidizer and fuel are N2O and hydroxyl-terminated polybutadiene (HTPB), respectively, due to previous experience and simplicity. The injector designs, selected for the same reasons, are designed such that they vary only in the swirl angle. This system provides the platform for characterizing the effects of varying said swirl angle on HRM performance.
ContributorsSummers, Matt H (Author) / Lee, Taewoo (Thesis advisor) / Chen, Kangping (Committee member) / Wells, Valana (Committee member) / Arizona State University (Publisher)
Created2013
Description
This thesis examines themodeling, analysis, and control system design issues for scramjet powered hypersonic vehicles. A nonlinear three degrees of freedom longitudinal model which includes aero-propulsion-elasticity effects was used for all analyses. This model is based upon classical compressible flow and Euler-Bernouli structural concepts. Higher fidelity computational fluid dynamics and finite element methods are needed for more precise intermediate and final evaluations. The methods presented within this thesis were shown to be useful for guiding initial control relevant design. The model was used to examine the vehicle's static and dynamic characteristics over the vehicle's trimmable region. The vehicle has significant longitudinal coupling between the fuel equivalency ratio (FER) and the flight path angle (FPA). For control system design, a two-input two-output plant (FER - elevator to speed-FPA) with 11 states (including 3 flexible modes) was used. Velocity, FPA, and pitch were assumed to be available for feedback. Aerodynamic heat modeling and design for the assumed TPS was incorporated to original Bolender's model to study the change in static and dynamic properties. De-centralized control stability, feasibility and limitations issues were dealt with the change in TPS elasticity, mass and physical dimension. The impact of elasticity due to TPS mass, TPS physical dimension as well as prolonged heating was also analyzed to understand performance limitations of de-centralized control designed for nominal model.
ContributorsKhatri, Jaidev (Author) / Rodriguez, Armando Antonio (Thesis advisor) / Tsakalis, Konstantinos (Committee member) / Wells, Valana (Committee member) / Arizona State University (Publisher)
Created2011
Description
Identifying and tracking the location of the fluid interface is a fundamental aspect of multiphase flows. The Volume of Fluid (VOF) and Level Set methods are widely used to track the interface accurately. Analyzing the liquid structures such as sheets, ligaments, and droplets helps understand the flow physics and fluid breakup mechanism, aids in predicting droplet formation, improves atomization modeling and spray combustion. The thesis focuses on developing a new method to identify these liquid structures and devise a sphere model for droplet size prediction by augmenting concepts of linear algebra, rigid body dynamics, computational fluid mechanics, scientific computing, and visualization. The first part of the thesis presents a new approach to classify the fluid structures based on their length scales along their principal axes. This approach provides a smooth tracking of the structures' generation history instead of relying on high-speed video imaging of the experiment. A droplet is observed to have three equal length scales, while a ligament has one and a sheet has two significantly larger length scales. The subsequent breakup of ligaments and droplets depends on the atomizer geometry, operating conditions, and fluid physical properties. While it's straightforward to apply DNS and estimate this breakup, it is proven to be computationally expensive. The second part of the thesis deals with developing a sphere model that would essentially reduce this computational cost. After identifying a liquid structure, the sphere model utilizes the level set data in the domain to quantify the structure using spheres. By using the evolution information of these spheres as they separate from each other, the subsequent droplet size distribution can be evaluated.
ContributorsKashetty, Sindhuja (Author) / Herrmann, Marcus (Thesis advisor) / Wells, Valana (Committee member) / Kim, Jeonglae (Committee member) / Arizona State University (Publisher)
Created2021