Chung, Chor Fung. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2007. / Includes bibliographical references (leaves 95-97). / Abstracts in English and Chinese. / Acknowledgements --- p.iv / Table of Contents --- p.v / List of Figures --- p.viii / List of Tables --- p.xiii / Nomenclature --- p.xiv / Chapter Chapter 1 --- Introduction --- p.1 / Chapter 1.1 --- Development of Micro Indoor Surveillance Flyers --- p.1 / Chapter 1.1.1 --- Overview --- p.1 / Chapter 1.1.2 --- Intrinsic Problem of Surveillance Helicopters --- p.2 / Chapter 1.2 --- Proposed Non-moving Parts and Noiseless Flyers --- p.2 / Chapter 1.3 --- Organization of the remaining dissertation --- p.5 / Chapter Chapter 2 --- The Basic Structure of the Ionic Flyers --- p.7 / Chapter 2.1 --- The Components and the Structural Parameters of the Ionic Flyers --- p.7 / Chapter 2.2 --- Proposed Operational Principles --- p.8 / Chapter 2.2.1 --- The Electrohydrodynamic Effect --- p.9 / Chapter 2.2.2 --- The Biefeld-Brown Effect --- p.10 / Chapter Chapter 3 --- Overview of Corona Discharge --- p.11 / Chapter 3.1 --- The Gaseous Discharge --- p.11 / Chapter 3.2 --- "Uniform Fields, Electrical Breakdown" --- p.12 / Chapter 3.3 --- "Non-uniform Fields, Corona Discharge" --- p.12 / Chapter 3.3.1 --- Positive Corona Discharge --- p.13 / Chapter 3.3.2 --- Negative Corona Discharge --- p.14 / Chapter 3.4 --- Conclusion --- p.15 / Chapter Chapter 4 --- Electrical Current-Voltage Model --- p.16 / Chapter 4.1 --- Experimental Setup and Measurement --- p.17 / Chapter 4.2 --- Basic Current to Voltage Relationship --- p.18 / Chapter 4.2.1 --- The Three Electrical Stages of the Ionic Flyers --- p.20 / Chapter 4.2.2 --- Proposed Quadratic Equation for the Current to Voltage Relationship --- p.22 / Chapter 4.3 --- Determination of the Current Gain C and the Onset Voltage V0 by the Structural Parameters of the Ionic Flyers --- p.22 / Chapter 4.3.1 --- The Electrode Length (L) --- p.24 / Chapter 4.3.2 --- The Gap Distance between the Wire-emitter and the Plate-collector (d) --- p.27 / Chapter 4.3.3 --- The Wire-emitter Radius (rw) --- p.31 / Chapter 4.3.4 --- The Plate-collector Height (h) --- p.36 / Chapter 4.3.5 --- The Electrode Enclosed Area (A) --- p.38 / Chapter 4.3.6 --- The Electrical Environmental Constant (Ke) --- p.43 / Chapter 4.4 --- Summary of the Experimental Derived Current-Voltage Model --- p.45 / Chapter Chapter 5 --- Mechanical Lift-force Models --- p.46 / Chapter 5.1 --- Experimental Setup and Measurement --- p.47 / Chapter 5.2 --- Basic Lift-force to Voltage Relationship --- p.49 / Chapter 5.2.1 --- The Initial Power Dissipation (IPD) --- p.50 / Chapter 5.2.2 --- The Maximum Lift-force --- p.51 / Chapter 5.2.3 --- Proposed Third-order Equation for the Lift-force to Power Relationship --- p.52 / Chapter 5.3 --- Determination of the Voltage Gain J and the Barrier Voltage Vfby the Structural Parameters of the Ionic Flyers --- p.54 / Chapter 5.3.1 --- The Electrical Length (L) --- p.55 / Chapter 5.3.2 --- The Gap Distance between the Wire-emitter and the Plate-collector (d) --- p.59 / Chapter 5.3.3 --- The Wire-emitter Radius (rw) --- p.63 / Chapter 5.3.4 --- The Plate-collector Height (h) --- p.66 / Chapter 5.3.5 --- The Electrode Enclosed Area (A) --- p.67 / Chapter 5.3.6 --- The Lift-force Environmental Constant (Kf) --- p.71 / Chapter 5.4 --- Summary of the Experimental Derived Lift-force Model --- p.73 / Chapter 5.5 --- Analysis on the Force/Power Ratio of the Ionic Flyers --- p.74 / Chapter Chapter 6 --- Further development of the Ionic Flyers --- p.76 / Chapter 6.1 --- Multi-directional Force Generation --- p.76 / Chapter 6.1.1 --- Linear Motion --- p.77 / Chapter 6.1.2 --- Rotation Motion --- p.78 / Chapter 6.2 --- Application of MEMS Motion Sensors and Wireless Signal Transmission --- p.80 / Chapter Chapter 7 --- Future Work --- p.84 / Chapter 7.1 --- Single-Emitter-Multiple-Collector Ionic Flyers --- p.84 / Chapter 7.2 --- Development of Miniaturized High-voltage Power Supply --- p.88 / Chapter Chapter 8 --- Conclusion --- p.90 / Chapter 8.1 --- The Electrical Current to Voltage Model --- p.90 / Chapter 8.2 --- The Mechanical Lift-force to Power Model --- p.91 / Chapter 8.3 --- The Force/Power Ratio Model --- p.91 / Appendix A --- p.92

The rapid air travel growth during the last three decades, has resulted in runway congestion at major airports. The current airports infrastructure will not be able to support the rapid growth trends expected in the next decade. Changes or upgrades in infrastructure alone would not be able to satisfy the growth requirements, and new airplane concepts such as the NASA proposed Super Short Takeo and Landing and Extremely Short Takeo and Landing (ESTOL) are being vigorously pursued. Aircraft noise pollution during Takeoff and Landing is another serious concern and efforts are aimed to reduce the airframe noise produced by Conventional High Lift Devices during Takeoff and Landing. Circulation control technology has the prospect of being a good alternative to resolve both the aforesaid issues. Circulation control airfoils are not only capable of producing very high values of lift (Cl values in excess of 8.0) at zero degree angle of attack, but also eliminate the noise generated by the conventional high lift devices and their associated weight penalty as well as their complex operation and storage. This will ensure not only satisfying the small takeoff and landing distances, but minimal acoustic signature in accordance with FAA requirements. The Circulation Control relies on the tendency of an emanating wall jet to independently control the circulation and lift on an airfoil. Unlike, conventional airfoil where rear stagnation point is located at the sharp trailing edge, circulation control airfoils possess a round trailing edge, therefore the rear stagnation point is free to move. The location of rear stagnation point is controlled by the blown jet momentum. This provides a secondary control in the form of jet momentum with which the lift generated can be controlled rather the only available control of incidence (angle of attack) in case of conventional airfoils. The use of Circulation control despite its promising potential has been limited only to research applications due to the lack of a simple prediction capability. This research effort was focused on the creation of a rapid prediction capability of Circulation Control Aerodynamic Characteristics which could help designers with rapid performance estimates for design space exploration. A morphological matrix was created with the available set of options which could be chosen to create this prediction capability starting with purely analytical physics based modeling to high fidelity CFD codes. Based on the available constraints, and desired accuracy metamodels has been created around the two dimensional circulation control performance results computed using Navier Stokes Equations (Computational Fluid Dynamics). DSS2, a two dimensional RANS code written by Professor Lakshmi Sankar was utilized for circulation control airfoil characteristics. The CFD code was first applied to the NCCR 1510-7607N airfoil to validate the model with available experimental results. It was then applied to compute the results of a fractional factorial design of experiments array. Metamodels were formulated using the neural networks to the results obtained from the Design of Experiments. Additional validation runs were performed to validate the model predictions. Metamodels are not only capable of rapid performance prediction, but also help generate the relation trends of response matrices with control variables and capture the complex interactions between control variables. Quantitative as well as qualitative assessments of results were performed by computation of aerodynamic forces and moments and flow field visualizations. Wing characteristics in three dimensions were obtained by integration over the whole wing using Prandtl's Wing Theory. The baseline Super STOL configuration was then analyzed with the application of circulation control technology. The desired values of lift and drag to achieve the target values of Takeoff and Landing performance were compared with the optimal configurations obtained by the model. The same optimal configurations were then subjected to Super STOL cruise conditions to perform a tradeoff analysis between Takeoff and Cruise Performance. Supercritical airfoils modified for circulation control were also thoroughly analyzed for Takeoff and Cruise performance and may constitute a viable option for Super STOL and STOL Designs. The prediction capability produced by this research effort can be integrated with the current conceptual aircraft modeling and simulation framework. The prediction tool is applicable within the selected ranges of each variable, but methodology and formulation scheme adopted can be applied to any other design space exploration.

Thesis (M.S.)--California Polytechnic State University, 2010. / Title from PDF title page; viewed on May 20, 2010. Major professor: David Marshall, Ph.D. "Presented to the faculty of California Polytechnic State University, San Luis Obispo." "In partial fulfillment of the requirements for the degree [of] Master of Science in Aerospace Engineering." "April 2010." Includes bibliographical references (p. 80-82).

Newtonian theory was applied, in this analysis, to the elliptic cone segment at angles of attack and sideslip. Closed form expressions for the aerodynamic coefficients and static stability derivatives were obtained. Expressions for the full and half conic bodies were given and approximate expressions were given for the half cone case. The circular cone results were obtained as a special case of the general results. Comparisons of the theoretical calculations with experimental results at hypersonic speeds were made of the aerodynamic coefficients and static derivatives for several conic segments. Generally, good agreement was observed for specified ranges of fineness ratios and angles of attack. / Master of Science

Simulation and modelling of turbulent flows under influence of streamline curvature and system rotation have been considered. Direct numerical simulations have been performed for fully developed rotating turbulent channel flow using a pseudo-spectral code. The rotation numbers considered are larger than unity. For the range of rotation numbers studied, an increase in rotation number has a damping effect on the turbulence. DNS-data obtained from previous simulations are used to perform a priori tests of different pressure-strain and dissipation rate models. Furthermore, the ideal behaviour of the coefficients of different model formulations is investigated. The main part of the modelling is focused on explicit algebraic Reynolds stress models (EARSMs). An EARSM based on a pressure strain rate model including terms that are tensorially nonlinear in the mean velocity gradients is proposed. The new model is tested for a number of flows including a high-lift aeronautics application. The linear extensions are demonstrated to have a significant effect on the predictions. Representation techniques for EARSMs based on incomplete sets of basis tensors are also considered. It is shown that a least-squares approach is favourable compared to the Galerkin method. The corresponding optimality aspects are considered and it is deduced that Galerkin based EARSMs are not optimal in a more strict sense. EARSMs derived with the least-squares method are, on the other hand, optimal in the sense that the error of the underlying implicit relation is minimized. It is further demonstrated that the predictions of the least-squares EARSMs are in significantly better agreement with the corresponding complete EARSMs when tested for fully developed rotating turbulent pipe flow. / QC 20100825

Mémoire (M.Eng.)-- Université du Québec à Chicoutimi, 1993. / Document électronique également accessible en format PDF. CaQCU

Mémoire (M.Sc.A.)-- Université du Québec à Chicoutimi, 1993. / Document électronique également accessible en format PDF. CaQCU

The aerodynamic performance of low aspect ratio wings at low Reynolds numbers applicable to micro air vehicle design was studied in this thesis. There is an overall lack of data for this low Reynolds number range, particularly concerning details of local flow behavior along the span. Experiments were conducted to measure the local pressure distributions on a wing at various spanwise locations in a Reynolds number range 30000 < Re < 90000. The model wing consisted of numerous wing sections and had a rectangular planform with NACA0012 airfoil shape with aspect ratio of one. One wing section, with pressure ports at various chordwise locations, was placed at different spanwise locations on a wing to effectively obtain the local pressure information. Integration of the pressure distributions yielded the local lift coefficients. Comparison of the local lift distributions to optimal elliptic lift distribution was conducted. This comparison showed a sharply peaked lift distribution near the wing tip resulting in a drastic deviation from the equivalent elliptic lift distributions predicted by the finite wing theory. The local lift distributions were further analyzed to determine the total lift coefficients vs angle of attack curves, span efficiency factors and the induced drag coefficients. Measured span efficiency factors, which were lower than predictions of the elliptic wing theory, can be understood by studying deviations of measured lift from the elliptic lift distribution. We conclude that elliptic wing theory is not sufficient to predict these aerodynamic performance parameters. Overall, these local measurements provided a better understanding of the low Reynolds number aerodynamics of the low aspect ratio wings.

This thesis explains how the classified design parameters of existing passenger jets can be determined. The classified design parameters are; the maximum lift coefficient for landing and take-off, the maximum aerodynamic efficiency and the specific fuel consumption. The entire concept is based on the preliminary sizing of jet powered civil aeroplanes. This preliminary sizing is explained in detail because it is the foundation of the final result. The preliminary sizing is combined using reverse engineering which is not a strict method. Therefore, only the basics are explained. By applying reverse engineering on the preliminary sizing and aiming for the classified design parameters as output, formulas are derived to calculate the maximum lift coefficients, the maximum aerodynamic efficiency and the specific fuel consumption. The goal is to calculate these parameters, using only aircraft specifications that are made public by the manufacturer. The calculations are complex with mutual relations, iterative processes and optimizations. Therefore, it is interesting to integrate everything in a tool. The tool is built in Microsoft Excel and explained in detail adding operating instructions. The program is executed for miscellaneous aeroplanes, supported with the necessary comments. Investigated aeroplanes are: Caravelle 10B (Sud-Aviation), Boeing 707-320C, BAe 146-200 (British Aerospance), A320-200 (Airbus), "The Rebel" (based on A320), Boeing SUGAR High, Boeing 747-400, Blended Wing Body VELA 2 (VELA) and Dassault Falcon 8X.

Purpose - The paper presents a theoretical framework that describes the aerodynamics of a falling maple (Acer pseudoplatanus) seed. --- Methodology - A semi-empirical method is developed that provides a ratio stating how much longer a seed falls in air compared to freefall. The generated lift is calculated by evaluating the integral of two-dimensional airfoil elements using a preliminary falling speed. This allows for the calculation of the definitive falling speed using Blade Element Momentum Theory (BEMT); hereafter, the fall duration in air and in freefall are obtained. Furthermore, the input-variables of the calculation of lift are transformed to require only the length and width of the maple seed. Lastly, the method is applied to two calculation examples as a means of validation. --- Findings - The two example calculations gave percentual errors of 5.5% and 3.7% for the falling speed when compared to measured values. The averaged result is that a maple seed falls 9.9 times longer in air when released from 20 m; however, this result is highly dependent on geometrical parameters which can be accounted for using the constructed method. --- Research limitations - Firstly, the coefficient of lift is unknown for the shape of a maple seed. Secondly, the approximated transient state is yet to be verified by measurement. --- Originality / Value - The added value of this report lies in the reduction of simplifications compared to BEMT approaches. In this way a large amount of accuracy is achieved due to the inclusion of many geometrical parameters, even though simplicity is maintained. This has been accomplished through constructing a simple three-step method that is fundamental and essentially non-iterative.