11,597 research outputs found

    High Reynolds number tests of a NASA SC(3)-0712(B) airfoil in the Langley 0.3-meter transonic cryogenic tunnel

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    A wind tunnel investigation of a NASA 12-percent-thick, advanced-technology supercritical airfoil was conducted in the Langley 0.3-Meter Transonic Cryogenic Tunnel (TCT). This investigation represents another in the series of NASA/U.S. industry two-dimensional airfoil studies to be completed in the Advanced Technology Airfoil Tests program. Test temperature was varied from 220 K to 96 K at pressures ranging from 1.2 to 4.3 atm. Mach number was varied from 0.60 to 0.80. These variables provided a Reynolds number range from 4,400,000 to 40,000,000 based on a 15.24-cm (6.0-in.) airfoil chord. This investigation was designed to test a NASA advanced-technology airfoil from low to flight-equivalent Reynolds numbers, provide experience in cryogenic wind tunnel model design and testing techniques, and demonstrate the suitability of the 0.3-m TCT as an airfoil test facility. The aerodynamic results are presented as integrated force and moment coefficients and pressure distributions. Data are included which demonstrate the effects of fixed transition, Mach number, and Reynolds number on the aerodynamic characteristics. Also included are remarks on the model design, the model structural integrity, and the overall test experience

    Force, moment, and flow-field characteristics of two wing-body-nacelle combinations at mach numbers 2 and 3

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    Force, moment, and flow field characteristics of two wing body nacelle combinations at Mach 2 and

    Pressure distribution from high Reynolds number tests of a NASA SC(3)-0712(B) airfoil in the Langley 0.3-meter transonic cryogenic tunnel

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    A wind tunnel investigation of a NASA 12-percent-thick, advanced-technology supercritical airfoil was conducted in the Langley 0.3-Meter Transonic Cryogenic Tunnel (TCT). This investigation represents another in the series of NASA/U.S. industry two-dimensional airfoil studies to be completed in the Advanced Technology Airfoil Tests program. Test temperature was varied from 220 K to 96 K at pressures ranging from 1.2 to 4.3 atm. Mach number was varied from 0.50 to 0.80. This investigation was designed to: (1) test a NASA advanced-technology airfoil from low to flight equivalent Reynolds numbers, (2) provide experience in cryogenic wind-tunnel model design and testing techniques, and (3) demonstrate the suitability of the 0.3-m TCT as an airfoil test facility. All the test objectives were met. The pressure data are presented without analysis in tabulated format and as plots of pressure coefficient versus position on the airfoil. This report was prepared for use in conjunction with the aerodynamic coefficient data published in NASA-TM-86371. Data are included which demonstrate the effects of fixed transition. Also included are remarks on the model design and fabrication

    Preliminary Report on a Stratified Late Archaic-Woodland Era Rockshelter in Rogers County, Oklahoma

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    In northeastern Oklahoma, very little is known about the transition from the Late Archaic to the Woodland period (Wyckoff and Brooks, 1983: 55). To date, most of the archeological evidence documenting this time period has been derived from sites with mixed or otherwise uncertain components. In this report, we present a preliminary description of a small rockshelter, 34RO252, which has a Late Archaic deposit stratigraphically below a Woodland era cultural deposit. These two deposits are unmixed, discrete, and are physically separated by an apparently sterile clay soil horizon. It is anticipated that the stratified cultural deposits at this site will help characterize the transition from the Late Archaic to the Early Woodland period along the Verdigris River in northeast Oklahoma. This site was first reported in April 1994 by two men who had discovered partially exposed human skeletal remains located in the rear remnant of a rockshelter at Oologah Lake in Rogers County, Oklahoma. The two men illegally excavated the remains and removed them from the site. 1 The rockshelter where the remains originated was subsequently examined by the authors and additional skeletal material was identified, in situ, in an exposed soil profile. A series of three radiocarbon assays, described below, placed the cultural deposit and the human remains within the Late Archaic-Woodland period (circa 780 B.C. to A.O. 900).2 This site is provisionally classified as corresponding to a cultural sequence that includes the old Grove C described by Purrington and Vehik

    High Reynolds number tests of a Boeing BAC I airfoil in the Langley 0.3-meter transonic cryogenic tunnel

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    A wind tunnel investigation of an advanced-technology airfoil was conducted in the Langley 0.3-Meter Transonic Cryogenic Tunnel (TCT). This investigation represents the first in a series of NASA/U.X. industry two dimensional airfoil studies to be completed in the Advanced Technology Airfoil Test program. Test temperature was varied from ambient to about 100 K at pressures ranging from about 1.2 to 6.0 atm. Mach number was varied from about 0.40 to 0.80. These variables provided a Reynolds number (based on airfoil chord) range from about .0000044 to .00005. This investigation was specifically designed to: (1) test a Boeing advanced airfoil from low to flight-equivalent Reynolds numbers; (2) provide the industry participant (Boeing) with experience in cryogenic wind-tunnel model design and testing techniques; and (3) demonstrate the suitability of the 0.3-m TCT as an airfoil test facility. All the objectives of the cooperative test were met. Data are included which demonstrate the effects of fixed transition, Mach number, and Reynolds number on the aerodynamic characteristics of the airfoil. Also included are remarks on the model design, the model structural integrity, and the overall test experience

    Pressure distributions from high Reynolds number tests of a Boeing BAC 1 airfoil in the Langley 0.3-meter transonic cryogenic tunnel

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    A wind-tunnel investigation designed to test a Boeing advanced-technology airfoil from low to flight-equivalent Reynolds numbers has been completed in the Langley 0.3-Meter Transonic Cryogenic Tunnel. This investigation represents the first in a series of NASA/U.S. industry two-dimensional airfoil studies to be completed in the Advanced Technology Airfoil Test program. Test temperature was varied from ambient to about 100 K at pressures ranging from about 1.2 to 6.0 atm. Mach number was varied from about 0.40 to 0.80. These variables provided a Reynolds number (based on airfoil chord) range from 4.4 X 10 to the 6th power to 50.0 X 10 to the 6th power. All the test objectives were met. The pressure data are presented without analysis in plotted and tabulated formats for use in conjunction with the aerodynamic coefficient data published as NASA TM-81922. At the time of the test, these pressure data were considered proprietary and have only recently been made available by Boeing for general release. Data are included which demonstrate the effects of fixed transition. Also included are remarks on the model design, the model structural integrity, and the overall test experience

    Data from tests of a R4 airfoil in the Langley 0.3-meter transonic cryogenic tunnel

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    Aerodynamic data for the DFVLR R4 airfoil are presented in both graphic and tabular form. The R4 was tested in the Langley 0.3-Meter Transonic Cryogenic Tunnel (TCT) at Mach number from 0.60 to 0.78 at angles of attack from -2.0 to 8.0 degrees. The airfoil was tested at Reynolds numbers of 4, 6, 10, 15, 30, and 40 million based on the 152.32 mm chord

    Functional Movement Screentm Scores in Collegiate Track and Field Athletes in Relation to Injury Risk and Performance

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    Purpose: The purpose of this study was to examine the relationship between Functional Movement Screentm (FMS) scores, injury rate, and performance in collegiate track and field athletes. Methods: Forty seven male (n=17) and female (n=30) competitive track and field athletes at an NCAA Division I university volunteered for this study. As part of their regular team assessment, the athletes were evaluated on three separate occasions using the FMS tool: in August, one week prior to the start of university organized practice for the fall (T1); in December, one week prior to the end of the fall academic semester (T2); and in March, the week following the conclusion of the indoor competition season (T3). The FMS consists of the performance of seven fundamental movement patterns that are evaluated and scored by a trained professional. For each time point, athletes were divided into two categories based on total FMS score (≤14 and ≥15). Throughout the competitive season, injuries were tracked and categorized as either mild (no loss of practice or competition time) or moderate/severe (loss of practice or competition time). As part of an ongoing injury prevention program, athletes performed generalized corrective exercises for 15 min 2-3 times per week. The performance in the last event of the season (conference meet) was also recorded. Results: Average FMS scores significantly (p\u3c0.05) decreased across the three time points (Mean ± SD, T1: 15.5 ± 2.2, T2: 14.9 ± 1.8, T3: 14.7 ± 1.6) despite that generalized corrective exercises were performed. Analyses of results found no association between FMS scores and likelihood to sustain a moderate/severe injury. Athletes with a score of ≤14 on the FMS at T1 were 3.1 times more likely not to place in the top 8 at the conference meet. 53% of the athletes who had a score of ≥15 at T1 placed in the top 8 at the meet while only 27% of athletes with a score of ≤14 at T1 placed in the top 8 at the meet. Conclusion: FMS scores ≤14 indicate reduced performance ability but not increased likelihood of injury in track and field athletes

    The "recoil" correction of order mα6m \alpha^6 to hyperfine splitting of positronium ground state

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    The "recoil" correction of order mα6m \alpha^6 to the hyperfine splitting of positronium ground state was found. The formalism employed is based on the noncovariant perturbation theory in QED. Equation for two-particle component of full (many-body) wave function is used, in which effective Hamiltonian depends on the energy of a system. The effective Hamiltonian is not restricted to the nonrelativistic region, so there is no need in any regularization. To evaluate integrals over loop momenta, they are divided into "hard" and "soft" parts, coming from large and small momenta respectively. Soft contributions were found analytically, and hard ones are evaluated by numerical integration. Some soft terms due to the retardation cancel each other. To calculate the "hard" contributions, a great number of noncovariant graphs is replaced by only a few covariant ones. The hard contribution was found in two ways. The first way is to evaluate contributions of separate graphs, using the Coulomb gauge. The second one is to calculate full hard contribution as a whole using the Feynman gauge. The final result for the "recoil" correction is 0.381(6) m\al^6 and agrees with those of previous papers. Diagram-to-diagram comparison with the revised results of Adkins&Sapirstein was done. All the results agree, so the "recoil" correction is now firmly established. This means a considerable disagreement with the experimental data.Comment: 28 pages, latex including latex figure
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