A real need exists for a sensor capable of detecting flow-field separation on an airplane wing during routine flight operations. A sensor of this type could lead to both improved flight safety and increased performance. It would also contribute to future separation control technologies. A new idea is presented for a sensor that is cost effective, easy to maintain, durable, and highly effective. The system, known as a Thermal Grid, works by using a grid of heaters and temperature sensors to trace out the streamlines closest to the surface. Specific singularities in these streamlines are excellent indicators of flow separation. This paper addresses many of the necessary principles that are necessary to making the Thermal Grid an operational device. An analytic design is presented that details the system requirements and potential performance, including heater/sensor spacing, heater power requirements, sensor time response and sensitivity needs and the effects of changes in flow conditions. / Master of Science

Stability and progress are among the most important factors for study in an economic analysis of the aircraft manufacturing industry. Stability of an industry of such critical importance reduces the extreme dislocations associated with a free enterprise economy during business cycle fluctuations. Stability contributed to the maintenance of a high level of gross national product, employment, and income at local, regional and national levels of the economy. In addition, stability is essential to progress and is, therefore, of vital concern to the aircraft manufacturing industry, individual firms, the Federal Government, and the economy as a whole. Progress is required at a pace sufficient to maintain the healthy competitive situation existing within the industry at the present time. In addition, progress is necessary to assure the highest attainable degree of national security. Furthermore progress, as measured by the gross national product, should annually advance rapidly enough to insure adequate investment opportunities and unhindered expansion of the national economy. In a dynamic free enterprise economy, attainment of stability and progress simultaneously is exceedingly difficult to achieve. This nation’s economic well-being and national security dictate that stability and progress be maximized in the foreseeable future.

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A procedure for generating and using polynomial approximations to the range or to the cruise drag components in terms of 29 design variables for the High Speed Civil Transport (HSCT) configuration and performance design is presented. Response surface model methodology is used to fit quadratic polynomials to data gathered from a series of numerical analyses of different HSCT designs. Several techniques are employed to minimize the number of required analyses and to maintain accuracy. Approximate analysis techniques are used to find regions of the design space where reasonable HSCT designs could occur and response surface models are built using higher fidelity analysis results of the designs in this "reasonable" region. Regression analysis and analysis of variance are then used to reduce the number of polynomial terms in the response surface model functions. Optimizations of the HSCT are then carried out both with and without the response surface models, and the effect of the use of the response surface models is discussed. Results of the work showed that considerable reduction of the amount of numerical noise in optimization is achieved with response surface models and the convergence rate was slightly improved. Careful attention was required to keep the accuracy of the models at an acceptable level. NOTE: (07/2012) An updated copy of this ETD was added after there were patron reports of problems with the file. / Master of Science

A computational investigation was performed to assess the effectiveness of Detached-Eddy Simulation (DES) as a tool for predicting icing effects. The AVUS code was employed to compute solutions for an iced wing configuration using DES and steady-state Reynolds Averaged Navier-Stokes (RANS) equation methodologies. The model wing was an extruded GLC305/944-ice shape section with a rectangular planform. Unstructured grids were generated using VGRID/GRIDTOOL. The one-equation Spalart-Allmaras turbulence model was used for all steady state RANS and DES computations. The numerical results were evaluated by comparison with experimental data. RANS solutions significantly under-predicted the lift and drag even after mesh refinement. The time-averaged DES computations showed some improvement in lift and drag coefficients, when compared to experimental data near stall at a 6 deg angle of attack. No significant improvement was observed at lower angles of attack. The DES computations were determined to be valid, since significant changes in the flow field were not observed after both mesh refinement and time step refinement.

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This work discusses the algorithms and implementation of a multi-robot system for locating radioactive sources. The estimation algorithm presented in this work is able to fuse measurements collected by γ-ray spectrometers carried by an unmanned aerial and unmanned ground vehicle into a single consistent estimate of the probability distribution over the position of a point source in an environment. By constructing a set of hypotheses on the position of the point source, this method converts a non-linear problem into many independent linear ones. Since the underlying model is probabilistic, candidate paths may be evaluated by their expected reduction in uncertainty, allowing the algorithm to select good paths for vehicles to take. An initial hardware test conducted at Savannah River National Laboratory served as a proof of concept and demonstrated that the algorithm successfully locates a radioactive source in the environment, and moves the vehicle to that location. This approach also demonstrated the capability to utilize radiation data collected from an unmanned aerial vehicle to aid the ground vehicle’s exploration. Subsequent numerical experiments characterized the performance of several reward functions and different exploration algorithms in scenarios covering a range of source strengths and region sizes. These experiments demonstrated the improved performance of planning-based algorithms over the myopic method initially tested in the hardware experiments. / Doctor of Philosophy / This work discusses the use of unmanned aerial and ground vehicles to autonomously locate radioactive materials. Using radiation detectors onboard each vehicle, they are commanded to search the environment using a method that incorporates measurements as they are collected. A mathematical model allows measurements taken from different vehicles in different positions to be combined together. This approach decreases the time required to locate sources by using previously collected measurements to improve the quality of later measurements. This approach also provides a best estimate of the location of a source as data is collected. This algorithm was tested in an experiment conducted at Savannah River National Laboratory. Further numerical experiments were conducted testing different reward functions and exploration algorithms.