Passive venting technique for shallow cavities

A device is introduced for reducing drag and store separation difficulties caused by shallow cavities on aircraft in supersonic flight consisting of a group of hollow pipes the same length as the cavity. The pipes are attached to the cavity floor so as to allow air to flow through the pipes. This device allows air to flow through the pipes opposite to the direction of flow outside the pipes. This results in reduced drag and improved store separation characteristics

Supersonic axial-force characteristics of a rectangular-box cavity with various length-to-depth ratios in a flat plate

A wind-tunnel investigation has been conducted at Mach numbers of 1.50, 2.16, and 2.86 to obtain axial-force data on a metric rectangular-box cavity with various length-to-depth ratios. The model was tested at angles of attack from -4 deg to -2 deg. The results are summarized to show variations in cavity axial-force coefficient for deep- and shallow-cavity configurations with detached and attached cavity flow fields, respectively. The results of the investigation indicate that for a wide range of cavity lengths and depths, good correlations of the cavity axial-force coefficients (based on cavity rear-face area) are obtained when these coefficients are plotted as a function of cavity length-to-depth ratio. Abrupt increases in the cavity axial-force coefficients at an angle of attack of 0 deg. reflect the transition from an open (detached) cavity flow field to a closed (attached) cavity flow field. Cavity length-to-depth ratio is the dominant factor affecting the switching of the cavity flow field from one type to the other. The type of cavity flow field (open or closed) is not dependent on the test angles of attack except near the critical value of length-to-depth ratio

Experimental cavity pressure distributions at supersonic speeds

An investigation was conducted to define pressure distributions for rectangular cavities over a range of free-stream Mach numbers and cavity dimensions. These pressure distributions together with schlieren photographs are used to define the critical values of cavity length-to-depth ratio that separate open type cavity flows from closed type cavity flows. For closed type cavity flow, the shear layer expands over the cavity leading edge and impinges on the cavity floor, whereas for open type cavity flow, the shear layer bridges the cavity. The tests were conducted by using a flat-plate model permitting the cavity length to be remotely varied from 0.5 to 12 in. Cavity depths and widths were varied from 0.5 to 2.5 in. The flat-plate boundary layer approaching the cavity was turbulent and had a thickness of approximately 0.2 in. at the cavity front face for the range of test Mach numbers from 1.5 to 2.86. Presented are a discussion of the results and a complete tabulation of the experimental data

Wind-tunnel measurements and comparison with flight of the boundary layer and heat transfer on a hollow cylinder at Mach 3

The wind tunnel tests were conducted both with and without boundary layer trips at Mach 3 and nominal free stream Reynolds numbers per meter ranging from 3.3 x 10 the 6th power. Instrumentation consisted of pressure orifices, thermocouples, a boundary layer pitot pressure rake, and a floating element skin friction balance. Measurements from both wind tunnel and flight were compared with existing engineering prediction methods

A simplified method for calculating temperature time histories in cryogenic wind tunnels

Average temperature time history calculations of the test media and tunnel walls for cryogenic wind tunnels have been developed. Results are in general agreement with limited preliminary experimental measurements obtained in a 13.5-inch pilot cryogenic wind tunnel

Sweep effect on the drag of rows of perpendicular circular cylinders in a laminar boundary layer at supersonic free-stream velocities

Drag measurements were obtained for circular cylinders attached perpendicularly to a flat-plate surface. Measurements were obtained for a single cylinder and for rows of cylinders. The cylinders were alined at various sweep angles relative to the free-stream velocity vector and at spacings appropriate for roughness elements used as boundary layer trips. The drag measurements were obtained for Mach numbers of 3.95 and 4.60, ratios of cylinder height to an undisturbed laminar boundary layer displacement thickness of approximately 1.0 to 3.0, a cylinder height-to-diameter ratio of approximately 2, and sweep angles up to 60. A complete presentation of the experimental results is given. A discussion of the more significant findings, including the most appropriate parameters for correlating the experimental results, is presented

Experimental pressure distributions for a family of blunt bodies at Mach numbers from 2.49 to 4.63 and angles of attack from 0 deg to 15 deg

Pressure distributions for blunt body wind tunnel models at supersonic speeds and angles of attack from 0 to 15 degree

Correspondence: August 30, 1960, Letter to Reverend Robert John Gisler - Jacksonville Ministerial Alliance from Florida House Representative Stallings

A letter to Reverend Gisler declining the invitation to participate on a bi-racial committee of local citizens to solve the tense racial situation in Jacksonville, Florida. John E. Mathews Jr. Collection -Series 206 - Box 49 - Folder 379

Early School Leaving: A Narrative Inquiry of the School Dropout

In the field of education, student performance has become an integral component when determining the effectiveness of schools, levels of student engagement, and a measure of the learning that is occurring in schools. In particular, certain criteria have been identified as appropriate measures for monitoring the effectiveness of school systems, individual school programs, and teacher merit. Included in these specific areas to be monitored are graduation and or dropout rates. While these have become a part of the major focus of those monitoring the effectiveness of schools across the country, it seems that little has been done to investigate what may be contributing to the phenomenon.;Thus far, most studies of the phenomenon of early school leaving, otherwise known as school dropout, seems to have become complacent and has therefore settled on merely identifying labels for the characteristics and or symptoms of this growing silent epidemic, Milliken (2007). While being able to identify or recognize such things as what symptoms may foretell the possibility that students in danger of academic failure may decide to dropout, I posit that a great deal more can be learned about the growing disparity between graduation and school dropout rates. This can be done by investigating the phenomenon through the lens of those who have actually made the decision to drop out.;My personal belief is that there is much to be said about discovering what may be contributing to those symptoms which may be contributing to early school leaving beyond the labeling of characteristics. I further believe that it will require attention from more than the classroom teachers\u27 attempt to respond to the emotional needs of their students; however, this is an important step to the process.;My study is the result of my personal convictions that more needs to be understood about the underlying contributors to such things as poor attendance, inappropriate behavior, and or coursework failure. Therefore, the following questions have guided my research: (1) What contributes to an individual\u27s decision to leave school early? and (2) How does the decision to leave school early affect the later life of the school dropout?;This research is framed in social constructivism and employed audio-taped interview sessions and transcripts of stories shared by participants pertaining to their experiences prior to enrolling in school, while attending school as well as what life has been like since each actually dropped out. The individual\u27s constructed understandings of the complicating actions, evaluations of those action and subsequent resolutions have been used to reveal each person\u27s positioning as a result of those experiences.;This research has provided evidence of what may be contributing to such things as feelings of marginalization, abandonment and disequilibrium from a very young age through the present. Using this information may be useful when reflecting on policy and practice that may need to be more sensitive to those factors that actually may be contributing to decision to leave school early. In addition, this information may be useful when rethinking the current trend that continues the operation of a deficit model wherein blaming the victim seems to be the typical response to the growing dilemma of school dropout. Further, this information has implications for teacher education, professional development and community awareness training practices that could serve the individual needs of our students as well as needs of the community at large. However, the responsibilities for these initiatives can only be addressed in a cooperative, collaborative fashion

Effect of Reynolds number on stability characteristics of a cruciform wing-body

An experimental investigation was conducted to determine the effect of Reynolds number on the stability characteristics of a body with cruciform wings at large angles of attack. Pressure distributions and force and moment data (axial force not measured) are presented for Mach 1.60 and 2.70, Reynolds numbers based on body diameter from approximately 130,000 to 2,800,000, and angles of attack from 0 deg to 50 deg. In general, the data show only small effects of Reynolds number throughout the range of test condition. Also discussed are force balance and pressure data that suggest a direct relationship between wind choking and the onset of a nonlinear stability variaton with angle of attack