This study is a qualitative documentation of the main flow features that affect the aerodynamic performance under steady and unsteady maneuver conditions. The relevant fluid flow physics is not available presently and, hence, this thesis concentrated on generating those critical details. Towards this goal, model studies were conducted on the United States Air Force (USAF) geometry, described as same UCAV 1303, which is essentially a flying wing in the Naval Postgraduate School (NPS) water tunnel using dye-flow visualization technique. This study adapted the UCAV model 1303 for the NPS water tunnel by incorporating multiple ports for dye injection and was manufactured using rapid prototyping techniques. To obtain conditionally sampled flow images, especially for unsteady flow conditions, special phase locking circuitry was designed, fabricated and integrated with high resolution digital cameras and tunnel flow monitoring software. Flow visualization images at various Reynolds numbers, model attitudes and pitch rates were obtained. Strong vortical flow was observed as expected for a 47 degree delta-wing. The shallow sweep angle and tail-less geometry seemed to present some unusual aerodynamic characteristics in regard to vortex bursting.

The unsteady aerodynamic performance of a maneuvering 1/72nd scale model of an unmanned combat air vehicle (UCAV) 1303 geometry has been studied in the Naval Postgraduate School water tunnel. Despite the numerous past publications on UCAV flows, none pertains to the UCAV maneuvering characteristics. Due to its nonslender wing, the flow features over the chosen aircraft are unique in that both features of highly yawed wings and of delta wings are present. Even though the speeds and Reynolds numbers are low in a water tunnel, the results of the present studies attest to the suitability of a water tunnel for performing such studies. Force measurements taken at various Reynolds numbers, model attitudes and maneuvering rates for comparison proved to be valid for data comparison to potential flight scenarios. The UCAV 1303 model has a 47 degrees leading edge sweep and a cranked trailing edge delta wing with a fuselage. Pitching and rolling maneuvers were performed in various combinations to demonstrate the real flight conditions of a maneuvering UCAV. A five-component strain-gage and flow monitoring software were used to determine force and moment coefficients in real time. These coefficients were analyzed and compared to previous flow visualization tests to correlate the various flow features recorded during that phase of the study, and to determine the overall stability of a delta wing UCAV. These plots demonstrate what is seen visually at Reynolds numbers from 1.17x104 to 2.94x104. Where the pitch break occurs on the wings during maneuvers is correlated and dependent on Reynolds number, as initially suspected. Performing unsteady maneuvers helped in retaining the approximate linear variation of lift coefficient to higher angles of attack. Roll maneuvers produced oscillatory side forces and moments at high angles of attack and roll, indicating potentially serious unsteady forces.

This study generated new information through qualitative documentation of the main flow features and direct measurements of the aerodynamic performance of a tailless, unmanned combat air vehicle (UCAV) 1303 configuration under both steady and unsteady maneuvering conditions. Photographic evidence of flow features, measurements of large-scale flow effects, and that of forces and aerodynamic coefficients during static and dynamic pitch, roll and yaw maneuvers were obtained. Flow visualization images and force measurements were taken at various Reynolds numbers, model attitudes and pitch rates for comparison. A 1/72nd-scale model with a 47-degree leading edge sweep and a cranked trailing edge delta wing with a fuselage was investigated in the NPS water tunnel. Phase locked, high-resolution flow images were obtained using a five color dye injection system over the maneuvering model. Both static and dynamic pitch-up, roll and yaw maneuvers were considered. Additionally, a five-component strain gage and flow monitoring software were employed to record, in real time, yawing, pitching and rolling moment information and derive the aerodynamic force and moment coefficients for selected maneuver conditions. Flow visualization revealed the presence of a strong spanwise flow at low angles of attack and strong vortical flow structures at larger angles of attack, as can be expected, but not clearly established earlier, for such low sweep angle wings. It also indicated that the vortical structures and reverse flow were highly Reynolds-number dependent. Normal force and pitching moment load data correlated well with trends observed for low sweep angle delta wings, but unexpected side force, yawing moment and rolling moment variations were observed, which were attributable to asymmetrical vortical flow behavior on the tailless UCAV geometry.

This is the 2nd edition of the book, Flow Visualization: Techniques and Examples, which was published by Imperial College Press in 2000. Many of the chapters have been revised and updated to take into consideration recent changes in a number of flow visualization and measurement techniques, including an updated high quality flow gallery. Unique among similar publications, this book focuses on the practical rather than theoretical aspects. Obtaining high quality flow visualization results is, in many ways, more of an art than a science, and experience plays a key deciding role. The depth and breadth of the material will make this book invaluable to readers of all levels of experience in the field.

With contributions from some of the world's leading experts, the second edition of this classic reference compiles all major techniques of flow visualization and demonstrates their applications in all fields of science and technology. A new chapter has been added that covers flow visualization applications in large wide tunnels for airplane and automobile testing. Several important examples of applications are included. A second new chapter details the use of infrared (IR) cameras for detecting and observing the boundary layer transition in industrial wind tunnels and flight testing of commercial transport airplanes. A final new chapter has been added on multiphase flow and pulsed-light velocimetry.

Over the last decade, flow visualization has advanced in step with the progress in laser and computer technologies. The scope of the International Symposium on Flow Visualiza- tion will be broader than ever, covering the range of infor- mation generally thought of as nonvisual and reflecting the inclusion of computer - aided methodologies. The Sixth In- ternational Symposium on Flow Visualization aims to attract the participation of experts and users of flow viualizing techniques on furthering an advanced philosophy for the de- velopment of the methods and their applications.

Flow Visualization, Second Edition focuses on developments, applications, and results in the field of flow visualization. Organized into four chapters, this book begins with the principles of flow visualization and image processing. Subsequent chapters describe the methods of flow visualization, particularly the addition of foreign material to the flowing fluid that might be gaseous or liquid; certain optical methods that are sensitive to changes of the index of refraction; and flow field marking by heat and energy addition.