Computational control of flexible aerospace systems

The main objective of this project is to establish a distributed parameter modeling technique for structural analysis, parameter estimation, vibration suppression and control synthesis of large flexible aerospace structures. This report concentrates on the research outputs produced in the last two years. The main accomplishments can be summarized as follows. A new version of the PDEMOD Code had been completed based on several incomplete versions. The verification of the code had been conducted by comparing the results with those examples for which the exact theoretical solutions can be obtained. The theoretical background of the package and the verification examples has been reported in a technical paper submitted to the Joint Applied Mechanics & Material Conference, ASME. A brief USER'S MANUAL had been compiled, which includes three parts: (1) Input data preparation; (2) Explanation of the Subroutines; and (3) Specification of control variables. Meanwhile, a theoretical investigation of the NASA MSFC two-dimensional ground-based manipulator facility by using distributed parameter modeling technique has been conducted. A new mathematical treatment for dynamic analysis and control of large flexible manipulator systems has been conceived, which may provide an embryonic form of a more sophisticated mathematical model for future modified versions of the PDEMOD Codes

Computational Control of Flexible Aerospace Systems

The main objective of this project is to establish a distributed parameter modeling technique for structural analysis, parameter estimation, vibration suppression and control synthesis of large flexible aerospace structures. This report concentrates on the research outputs produced in the last two years of the project. The main accomplishments can be summarized as follows. A new version of the PDEMOD Code had been completed. A theoretical investigation of the NASA MSFC two-dimensional ground-based manipulator facility by using distributed parameter modelling technique has been conducted. A new mathematical treatment for dynamic analysis and control of large flexible manipulator systems has been conceived, which may provide a embryonic form of a more sophisticated mathematical model for future modified versions of the PDEMOD Codes

Improvements to the RV Waste-transfer Station Design to Reduce Contaminated Storm Runoff

Mammoth Cave in Central Kentucky is the world’s longest cave system and has been designated an international biosphere. It has unique organisms that live in the cave system and they are dependant upon high quality water supplied through rain recharge. We have documented quaternary ammonia compounds (QAC) levels ranging from 0.2 to 22 mg/L in storm fl ow, as well as, other chemicals coming from the RV waste-transfer station. The objective of this project was to re-design the drain system around the dump station to prevent spillage from washing down into the cave. The first design feature is a v-trench to catch storm runoff and redirect it into the sanitary sewer. The second feature is a gently elevated barrier that will impede the fl ow of runoff from the impacted area. The designs presented in this paper incorporate both features

A piecewise continuous Timoshenko beam model for the dynamic analysis of tapered beam-like structures

Distributed parameter modeling offers a viable alternative to the finite element approach for modeling large flexible space structures. The introduction of the transfer matrix method into the continuum modeling process provides a very useful tool to facilitate the distributed parameter model applied to some more complex configurations. A uniform Timoshenko beam model for the estimation of the dynamic properties of beam-like structures has given comparable results. But many aeronautical and aerospace structures are comprised of non-uniform sections or sectional properties, such as aircraft wings and satellite antennas. This paper proposes a piecewise continuous Timoshenko beam model which is used for the dynamic analysis of tapered beam-like structures. A tapered beam is divided into several segments of uniform beam elements. Instead of arbitrarily assumed shape functions used in finite element analysis, the closed-form solution of the Timoshenko beam equation is used. Application of the transfer matrix method relates all the elements as a whole. By corresponding boundary conditions and compatible conditions a characteristic equation for the global tapered beam has been developed, from which natural frequencies can be derived. A computer simulation is shown in this paper, and compared with the results obtained from the finite element analysis. While piecewise continuous Timoshenko beam model decreases the number of elements significantly; comparable results to the finite element method are obtained

The Effects of Coolant Pipe Geometry and Flow Conditions on Turbine Blade Film Cooling

The performance of gas turbine engines can be improved by increasing the inlet gas temperature. Turbine blades can be damaged by high gas temperature, unless additional cooling mechanisms are incorporated to maintain the blades below an acceptable temperature limit. Film cooling techniques are often used to cool the blades to avoid damages. The performance of film cooling depends on several parameters, however. In this paper past research on film cooling is reviewed and areas in need of further investigation are identified. Computational fluid dynamics (CFD) simulations are then conducted on the widely-used single-hole film cooling arrangements in which coolant jets are injected into air flows inside a straight channel before issuing onto the blades. Cooling pipe-blade configurations and flow conditions are varied and the resulting flow hydrodynamics are examined. Counter rotating vortex pairs (CRVPs) formed in the flow strongly influence the film cooling performance. Small coolant inclination angles, exit holes enlargement in span wise direction, higher injected fluid density, and higher injectedambient fluid velocity ratios are all found to maintain the CRVPs away from each other and close to wall - both of which promote cooling. Pipe curvature can be used for enhancing cooling by exploiting the centrifugal force effect

Partners in Water Quality Monitoring at Mammoth Cave National Park, Kentucky

Water resources are essential to landscape development and maintenance of the extraordinary ecosystem at Mammoth Cave National Park, Kentucky. The National Park Service has implemented many policies and management practices in an effort to maintain and improve the water quality in the park. As part of their resources management, the Park evaluates current hydrologic conditions, as well as, anticipates and responds to emerging issues. With regards to that goal, Mammoth Cave National Park Service partnered with Tennessee State University, the Mammoth Cave International Center for Science and Learning, and the U.S. Geological Survey on a series of water-related projects from 2007-2013. The objective of this paper is to highlight some of the findings and lessons learned from the past 6 years. Many of the results presented in this paper have been presented at other conferences or published in other reports. Collaborative projects included storm-water runoff from parking lots and roads, evaluating storm-water filters, and transport of chemicals in the caves. These projects purposefully engaged students to provide professional experience and educational outreach opportunities. Over 50 student presentations related to these monitoring activities have been made at regional and national conferences in the past 6 years, resulting in numerous awards and publications. Major funding or in-kind services were provided by the partnering agencies and institutions. Additional funding for supplies and student support was provided by the National Science Foundation (Opportunity for Enhancing Diversity in Geoscience, 2007-8; Undergraduate Research and Mentoring, 2009-13), and, the Department of Energy (Massey Chair – NNSA, 2007-13). The following summaries are excerpts from previously published student papers (West et al., 2010; Diehl et al., 2012, Embry, et al., 2012, West et al., 2012)

Three Examples of Chemical Transport in Storm Runoff at Mammoth Cave National Park, Kentucky

The karst landscape at Mammoth Cave National Park, Kentucky, was formed by water through the dissolution of soluble rocks forming sinkholes, disappearing streams, emerging springs, closed depressions, and a combination of wet and dry caves. The Park’s cave streams and pools provide a home to unique organisms. Surface waters in the Park tend to rapidly drain into subsurface geologic features and caves. This rapid infiltration makes the subsurface vulnerable to contamination. The objective of this investigation was to characterize chemical transport from the surface into the cave. The preliminary results were achieved by tracer studies and monitoring water chemistry along known flowpaths. The results presented in this paper are the outcome of several studies occurring between 2009-2012 in a partnership between Mammoth Cave National Park, Tennessee State University, Mammoth Cave International Center for Science and Learning, and U.S. Geological Survey. Processes that influenced chemical transport included storm intensity, time between storms, epikarst saturation, dispersion, dilution, and complex fl ow paths in the geology

Numerical Analysis of Heat and Mass Transfer From Bubbles, Drops, and Rigid Spheres

62 p.Thesis (Ph.D.)--University of Illinois at Urbana-Champaign, 1980.Steady state heat or mass transfer from spherical objects at low values of the Reynolds number is investigated. Heat or mass transfer to a drop in an electric field; to single translating bubbles, drops, and rigid spheres; and to rigid and fluid spheres in shear flow is considered. The energy equation is solved using finite difference techniques. A method known as upwind differencing is used in approximating the convective terms. Far from the sphere, a 'transmitting' boundary condition is introduced; the dimensionless temperature is held zero for inward radial flow and the dimensionless temperature gradient is held zero for outward radial flow at a fixed distance from the sphere's surface. Heat transfer results are obtained for the creeping flow for Peclet numbers up to 10('3).U of I OnlyRestricted to the U of I community idenfinitely during batch ingest of legacy ETD

TiO2 Assisted Photodegradation for Low Substrate Concentrations and Transition Metal Electron Scavengers

Some contaminants of emerging concern (CECs) are known to survive conventional wastewater treatment, which introduces them back to the environment, allowing them to potentially cycle into drinking water. This is especially concerning because of the inherent ability of some CECs to induce physiological effects in humans at very low doses. Advanced oxidation processes (AOPs) such as TiO2-based photocatalysis are of great interest for addressing CECs in aqueous environments. Natural water resources often contain dissolved metal cation concentrations in excess of targeted CEC concentrations. These cations may significantly adversely impact the degradation of CECs by scavenging TiO2 surface generated electrons. Consequently, simple pseudo-first-order or Langmuir-Hinshelwood kinetics are not sufficient for reactor design and process analysis in some scenarios. Rhodamine Basic Violet 10 (Rhodamine B) dye and dissolved [Cu2+] cations were studied as reaction surrogates to demonstrate that TiO2-catalyzed degradation for very dilute solutions is almost entirely due to the homogeneous reaction with hydroxyl radicals, and that in this scenario, the hole trapping pathway has a negligible impact. Chemical reaction kinetic studies were then carried out to develop a robust model for RB-[Cu2+] reactions that is exact in the electron pathways for hydroxyl radical production and electron scavenging