NC State Theses and Dissertations

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A Low-Order Aerodynamic Prediction Approach for Fuselage Forces and Wakes.
(2017-08-15) Gupta, Utkarsh Bibhas; Ashok Gopalarathnam, Chair; Kenneth Granlund, Member; Gregory Buckner, Member
A New Hybrid LES/RANS Model with Eddy Viscosity Transport (EVT) Based Outer-layer Length Scale.
(2017-08-15) Shen, Minao; Jack Edwards, Chair; Ashok Gopalarathnam, Member; Hong Luo, Member; Carl Kelley, Minor
A Non-Invasive Technique for Acoustic Resonance Measurement in Supersonic Cavity Flows Using Shadowgraph Imaging and Data Processing.
(2025-05-05) Srivastava, Tushar Eric; Laura Paquin, Chair; Marie Muller, Member; Jack Edwards, Member
A p-adaptive Discontinuous Galerkin Method for Single- and Multi-material Hydrodynamics with Load Balancing.
(2023-05-10) Li, Weizhao; Hong Luo, Chair; Jack Edwards, Member; Chi-An Yeh, Member; Zhilin Li, Minor
A Parallel Implicit Reconstructed Discontinuous Galerkin Method for Compressible Turbulent Flows on 3D Hybrid Grids.
(2016-07-08) Liu, Xiaodong; Hong Luo, Chair; Jack Edwards, Member; Hassan Hassan, Member; Zhilin Li, Member
A Parametric Study on the Laser-Forced Ignition of Laminar and Turbulent Round Jets in Non-Ideal Environments.
(2020-03-25) Ley, Kevin Michael; Venkateswaran Narayanaswamy, Chair; Kenneth Granlund, Member; Kevin Lyons, Member; Alexei Saveliev, Member; Phillip Westmoreland, Graduate School Representative
A Robust and Efficient Finite Volume method for Compressible Two-Phase Flows at All Speeds on Unstructured Grids.
(2018-08-13) Pandare, Aditya Kiran; Hong Luo, Chair; Jack Edwards, Member; Pramod Subbareddy, Member; Pierre Gremaud, Member
Accelerating Reactive Flow Simulations with Deep Operator Networks: Integration of DeepONets with PeleLMeX.
(2025-05-12) Sachdeva, Kunal; Tarek Echekki, Chair; Chi-An Yeh, Member; Srinath Ekkad, Member
Actuation and Control Strategies for Miniature Robotic Surgical Systems
(2002-08-12) Stevens, Jason Michael; Dr. Edward Grant, Committee Member; Dr. Gregory Buckner, Committee Chair; Dr. M.K. Ramasubramanian, Committee Member
Over the past 20 years, tremendous advancements have been made in the fields of minimally invasive surgery (MIS) and minimally invasive robotic assisted (MIRA) surgery. Benefits from MIS include reduced pain and trauma, reduced risks of post-operative complications, shorter recovery times, and more aesthetically pleasing results. MIRA approaches have extended the capabilities of MIS by introducing three-dimensional vision, eliminating tremors, and enabling the precise articulation of smaller instruments. These advancements come with their own drawbacks, however. Robotic systems used in MIRA procedures are large, costly, and do not offer the miniaturized articulation necessary to facilitate tremendous advancements in MIS. This research tests the hypothesis that miniature actuation can overcome some of the limitations of current robotic systems by demonstrating accurate, repeatable control of a small end-effector. A 10X model of a two link surgical manipulator is developed, using antagonistic shape memory alloy (SMA) wires as actuators, to simulate motions of a surgical end-effector. Artificial neural networks (ANNs) are used in conjunction with real-time visual feedback to "learn" the inverse system dynamics and control the manipulator endpoint trajectory. Experimental results are presented for indirect, on-line learning and control. Manipulator tip trajectories are shown to be accurate and repeatable to within 0.5 mm. These results confirm that SMAs can be effective actuators for miniature surgical robotic systems, and that intelligent control can be used to accurately control the trajectory of these systems.
An Adaptive Grid Algorithm for Air Quality Modeling
(1998-09-29) Srivastava, Ravi K; Dr. D. Scott McRae, Chair; Dr. F. DeJarnette, Member; Dr. Robert White, Member; Dr. M. Talat Odman, Member
The physical and chemical processes responsible for air pollution span a wide range of spatial scales. For example, there may be point sources, such as power plants that are characterized by relatively small spatial scales compared to the size of the region that may be impacted by such sources. To obtain accurate distributions of pollutants in an air quality simulation, the pertinent spatial scales can be resolved by varying the physical grid node spacing.A new dynamic adaptive grid algorithm, the Dynamic Solution Adaptive Grid Algorithm - PPM (DSAGA-PPM), is developed for use in air quality modeling. Given a fixed number of grid nodes, DSAGA-PPM distributes these nodes in response to spatial resolution requirements of the solution field and then updates the solution field based on the resulting distribution of nodes. DSAGA-PPM is implemented dynamically to resolve any evolving solution features. Tests with model problems demonstrate that DSAGA-PPM calculates advection much more accurately than the corresponding static grid algorithm (SGA-PPM) and, therefore, would assure more accurate starting concentrations for chemistry calculations. For example, after one revolution of four rotating cones, 87% of each of the cone peaks is retained using DSAGA-PPM while only 63% is retained using SGA-PPM. The root-mean-square errors in DSAGA-PPM results are about 4-5 times lower than those in the corresponding SGA-PPM results. Tests with reacting species and sources demonstrate that DSAGA-PPM provides the needed solution resolution. In simulations of a rotating and reacting conical puff, the root-mean-square errors in DSAGA-PPM results are about 4-6 times lower than those in the corresponding SGA-PPM results. In simulations of a power plant plume, the DSAGA-PPM solution reflects the early, the intermediate, and the mature stages of plume development; these stages are not seen in the corresponding SGA-PPM solution. Finally, it is demonstrated that DSAGA-PPM provides an accurate description of the ozone production resulting due to dynamic interactions between emissions from two power plants and an urban area. In general, these results reflect that DSAGA-PPM is able to provide accurate spatial and temporal resolution of rapidly changing and complex concentration fields. Performance achieved by DSAGA-PPM in model problem simulations indicates that it can provide accurate air quality modeling solutions at costs 10 times less than those incurred in obtaining equivalent static grid solutions.
Additively Manufactured Sacrificial Tooling for Carbon Fiber-Reinforced Polymer Composite Fabrication.
(2016-06-23) Lakshman, Narender Shankar; Mark Pankow, Chair; John Strenkowski, Member; Binil Starly, Member
Advancements in Aerodynamic Technologies for Airfoils and Wings
(2006-12-08) Jepson, Jeffrey Keith; Dr. Jeffrey A. Joines, Committee Member; Dr. Charles E. Hall, Committee Member; Dr. Hassan A. Hassan, Committee Member; Dr. Ashok Gopalarathnam, Committee Chair
Although aircraft operate over a wide range of ﬂight conditions, current fixed geometry aircraft are optimized for only a few of these conditions. By altering the shape of the aircraft, adaptive aerodynamics can be used to increase the safety and performance of an aircraft by tailoring the aircraft for multiple light conditions. Of the various shape adaptation concepts currently being studied, the use of multiple trailing-edge ﬂaps along the span of a wing offers a relatively high possibility of being incorporated on aircraft in the near future. Multiple trailing-edge ﬂaps allow for effective spanwise camber adaptation with resulting drag beneﬁts over a large speed range and load alleviation at high-g conditions. The research presented in this dissertation focuses on the development of this concept of using trailing-edge ﬂaps to tailor an aircraft for multiple liight conditions. One of the major tasks involved in implementing trailing-edge ﬂaps is in designing the airfoil to incorporate the ﬂap. The ﬁrst part of this dissertation presents a design formulation that incorporates aircraft performance considerations in the inverse design of low-speed laminar-ﬂow adaptive airfoils with trailing-edge cruise ﬂaps. The beneﬁt of using adaptive airfoils is that the size of the low-drag region of the drag polar can be effectively increased without increasing the maximum thickness of the airfoil. Two aircraft performance parameters are considered: level-ﬂight maximum speed and maximum range. It is shown that the lift coefficients for the lower and upper corners of the airfoil low-drag range can be appropriately adjusted to tailor the airfoil for these two aircraft performance parameters. The design problem is posed as a part of a multidimensional Newton iteration in an existing conformal-mapping based inverse design code, PROFOIL. This formulation automatically adjusts the lift coefficients for the corners of the low-drag range for a given ﬂap deﬂection as required for the airfoil-aircraft matching. Examples are presented to illustrate the ﬂapped-airfoil design approach for a general aviation aircraft and the results are validated by comparison with results from post-design aircraft performance computations. Once the airfoil is designed to incorporate a TE ﬂap, it is important to determine the most suitable ﬂap angles along the wing for different flight conditions. The second part of this dissertation presents a method for determining the optimum flap angles to minimize drag based on pressures measured at select locations on the wing. Computational ﬂow simulations using a panel method are used "in the loop" for demonstrating closed-loop control of the ﬂaps. Examples in the paper show that the control algorithm is successful in correctly adapting the wing to achieve the target lift distributions for minimizing induced drag while adjusting the wing angle of attack for operation of the wing in the drag bucket. It is shown that the "sense-and-adapt" approach developed is capable of handling varying and unpredictable inﬂow conditions. Such a capability could be useful in adapting long-span ﬂexible wings that may experience signiﬁcant and unknown atmospheric inﬂow variations along the span. To further develop the "sense-and-adapt" approach, the method was tested experimentally in the third part of the research. The goal of the testing was to see if the same results found computationally can be obtained experimentally. The North Carolina State University subsonic wind tunnel was used for the wind tunnel tests. Results from the testing showed that the "sense-and-adapt" approach has the same performance experimentally as it did computationally. The research presented in this dissertation is a stepping stone towards further development of the concept, which includes modeling the system in the Simulink environment and flight experiments using uninhabited aerial vehicles.
Advancements in Low-Order Modeling of Unsteady Airfoil Flows.
(2024-11-07) Lee, Yi Tsung; Ashok Gopalarathnam, Chair; Jack Edwards, Member; Mohammad Farazmand, Member; Matthew Bryant, Member
The Aerodynamic Analysis and Aeroelastic Tailoring of a Forward-Swept Wing
(2006-05-08) Roberts, David William; Dr. Kara Peters, Committee Member; Dr. Charles E. Hall, Committee Chair; Dr. James Selgrade, Committee Member
The use of forward-swept wings has aerodynamic benefits at high angles of attack and in supersonic regimes. These consist of reduction in wave drag, profile drag, and increased high angle of attack handling qualities. These increased benefits are often offset due to an increase in structural components, to overcome flutter and wing tip divergence due to high loading of the wing tips at high angles of attack. The use of composite materials and aeroelastic tailoring of the structures eliminates these instabilities without a significant increase in weight. This work presents the design of an aeroelastic wing structure for a highly forward-swept wing, and the verification of the aerodynamic and structural finite element analysis through experimental testing.
Aerodynamic Analysis of a Coaxial Turbine in Yaw for Hydrokinetic Energy Harvesting
(2018-03-27) Nand Kishore Khatri, Dheepak; Kenneth Granlund, Chair; Ashok Gopalarathnam, Member; Matthew Bryant, Member
Aerodynamic Fuselage Design and Engine Integration for the Vampire Light Sport Aircraft.
(2013-03-26) Armes, Robert James; Charles Hall, Chair; James Selgrade, Minor; Ashok Gopalarathnam, Member
Aerodynamic Validation using MER and Phoenix Entry Flight Data.
(2011-02-25) Thomas, Casey; Robert Tolson, Committee Chair; Fred DeJarnette, Committee Member; Lawrence Silverberg, Committee Member
Aerothermodynamic Design Sensitivities for a Reacting Gas Flow Solver on an Unstructured Mesh Using a Discrete Adjoint Formulation.
(2017-03-17) Thompson, Kyle Bonner; Hassan Hassan, Co-Chair; Peter Gnoffo, Co-Chair; Jack Edwards, Member; John Griggs, Graduate School Representative; Hong Luo, Member
Airfoil Flow Characteristics in a Pure Surge Environment at Constant Incidence.
(2018-07-02) Barrier, Adron Thomas; Kenneth Granlund, Chair; Ashok Gopalarathnam, Member; Matthew Bryant, Member
Airfoil Flow-Separation and Stall Detection Using Surface-Mounted Pitot Tubes.
(2017-08-28) Aleman Chona, Maria Auxiliadora; Ashok Gopalarathnam, Chair; Kenneth Granlund, Member; Matthew Bryant, Member

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Browsing NC State Theses and Dissertations by Discipline "Aerospace Engineering"