Experimental Characterization of the Drag and Velocity Flow field of Fish-like motion

REU Student: Jeremy Diaz, Rice University

Faculty Mentor: Dr. Sharath S. Girimaji

The objective of this study was to use Particle Image Velocimetry (PIV) techniques in a water tunnel experiment to characterize the velocity flow field associated with carangiform locomotion.  In this report, the basics of PIV are explained and the outline for our specific setup is illustrated.  The calibration process of the force balance with known imposed loads is described.  Then, the flow past a circular cylinder is visualized.  The results show a promising agreement between the expected and measured flows.  Finally, we will outline the future work necessary to construct a three-plate model that mimics carangiform locomotion.  The flow pattern and forces associated with this motion are discussed.

FireFlight: Thermal Management of an Unmanned Air Vehicle

REU Student: Alexander C. Hansen, Texas A&M University

Faculty Mentor: Dr. James G. Boyd

The goal is to develop an unmanned air vehicle (UAV) that can fly over a fire to inspect damages in oil and gas facilities, chemical plants, and nuclear reactors. As an initial feasibility study, this project concerns the thermal management of a UAV. A heat transfer model was created in Excel that approximates the heat that raises the internal temperature of the UAV from the heat generated by the electrical components, the heat from the exterior, and the heat absorbed by heat sinks, phase change materials (PCMs), or endothermic reactions. First, a library of materials was created so that the user can select which material would be used for each component of the UAV. Batteries, insulation, and heat absorption methods were specifically studied. Using a PCM as a heat absorber was selected for the UAV. The model is a 1D heat transfer problem that has developed into a representation that includes wires and motor shafts that penetrate the insulation walls as well as a vacuum and fiber suspension between the electronics, which are surrounded by a PCM, and the insulation walls. The temperature of the fire was also expressed as an altitude to better communicate with engineers the density the UAV will be flying in.

Flutter Characterization through Linear and Nonlinear Aeroelasticity Experiments in Subsonic Flow

REU Student: Joseph Huy Phan, Texas A&M University

Faculty Mentor: Dr. Thomas W. Strganac

Grad Student Mentors: Yogesh Babbar and Vishvas S. Suryakumar

This research examines the adverse interaction of aerodynamics, structures and motion, and such interaction a.k.a. “Aeroelasticity” is possible in all aircraft. Such interaction leads to flutter and Limit Cycle Oscillations which may lead to structural failure. For these studies, a flexible wing is placed in a wind tunnel and subjected to disturbances, which are representative of gust loads. The experimental setup and methodology of data acquisition are described. The measured responses serve as a characterization of flutter in the linear and nonlinear regimes. The nonlinear responses are compared to linear data. Eventually, a system with gust excitation will be integrated into the effort to develop control to suppress and alleviate gust loads. 

Verification and Validation of the Numerical Accuracy of a 3D Unstructured Finite Volume Flow Solver

REU Student: Francois Rice, University of Maryland - Baltimore County

Faculty Mentor: Dr. Paul Cizmas

Grad Student Mentor: Raymond Fontenot

An unstructured 3D flow solver is evaluated in this work. The flow solver uses a finite volume dual cell-vertex method of discretization. This method of analysis gives the flow solver flexibility in the different cases that can be analyzed, without loss of numerical accuracy. The purpose of this work was to validate and verify the numerical solutions of the flow solver. The flow solver was used to analyze a benchmark test case using both first and second order discretization. Four levels of mesh refinement were analyzed. The solution of the finest mesh was used as an exact solution for the case. The solutions of the other meshes were compared to the solution of the finest mesh to calculate their respective L2 error norms. The L2 error norms were then plotted to determine the order of accuracy for the flow solver’s solutions.

Hydrodynamics of Undulatory Fish Locomotion

REU Student: Nicholas Taluzek, Illinois Institute of Technology

Faculty Mentor: Dr. Sharath Girimaji

Grad Student Mentor:  Brian Rodgers

While fish utilize their complex musculature to propel themselves through water, simplifying the complex motions of fish locomotion into simpler mechanical systems will allow us to design more efficient propulsion devices for neutrally buoyant craft such as submarines and airships. In this study the hydrodynamics of fish locomotion is modeled using a three-dimensional (3D) computational fluid dynamics simulation of a thin undulatory plate. The rectangular plate model mimics the waveform of carangiform swimming by dividing the model into thirds along the axial flow direction with each section moving in a synchronized fashion. The Strouhal number (St) is a dimensionless parameter that is a function of oscillation frequency, fin tip amplitude, and flow velocity. Fish are found to naturally swim within a limited range of St that result in high propulsive efficiency. In this study, parameters of flow velocity, tail angular frequency, and amplitude of fin displacement were varied to investigate the thrust production and efficiency of the thin plate fin model. The results of this study show that this fish model achieves maximum propulsive efficiencies within the range of 0.3 = St = 0.5 and that there is a dependence of the thrust production and efficiency on the St similar to the fish locomotion upon which it is based.

Virtual Space Camera

REU Student: Chelsea E. Williams, University of Oklahoma

Faculty Mentor: Dr. Daniele Mortari

Grad Student Mentor:  Francesco de Dilectis

Space travel is an intricate process in which every step requires a high level of accuracy. The preliminary planning phase of each mission involves analysis of trajectories and orbits using navigational software. New tools are constantly being developed to provide further validation of these estimations. The purpose of this project is to develop one of these tools by writing a MATLAB program that functions as a virtual space camera. When given a point in time and the necessary camera information, this program will produce a synthetic image showing the field-of-view of the particular camera. The virtual space camera can function as a preliminary validation tool, but could also be developed further and used for various other applications. 

Experimental Method to Measure Moments of Inertia for Unmanned Aircraft Systems

REU Student: Nicholas Zias, Texas A&M University

Faculty Mentors: Dr. John Valasek

The objective of this research project is to design and build a test rig which will find the moments of inertia of unmanned aircraft systems (UAS) by spinning it. The reason this project was completed is because by having the moments of inertia of UAS’s, non-parametric models of flight can be created, the dynamics of the UAS can be further analyzed, a database relating weight to moment of inertia of UAS’s can be created, and it can be used as a tool to educate students. The method chosen to find the moments of inertia was to utilize a bifilar pendulum. A bifilar pendulum is a pendulum which oscillates horizontally from two cables. The first step was to understand the theory of the bifilar pendulum. By relating the energy of the system to its angular motion, an equation was found which could find the moment of inertia from the angular motion of the bifilar pendulum. The next step was to simulate the bifilar pendulum based off our equation to ensure that the equation accurately represented it. Along with this, simulation was also used to gain an understanding of how the tests will be conducted and how to create an accurate method to find the moment of inertia. After this, the test rig was built with an accelerometer as the device to measure the angular motion. From there, the moment of inertia will be calculated. With this process, the overall goals of the project will be accomplished.