The data files on this tape contain reduced mean flow data and Reynolds averaged data from Amy Alving's experimental investigation of boundary layer relaxation from convex curvature. The investigation was performed at Pršceton University's Gasdynamics Laboratory. All measurements were made in a subsonic, open-return wind tunnel driven by a suction fan located downstream of the test section. The flow entered the tunnel through a bell-mouth, passed through a honeycomb flow-straightener and into a settling chamber containing a series of five screens placed perpendicular to the flow. The flow exited the settling chamber, passed through a two-dimensional 6:1 contraction and entered the 0.15m x 1.22m test section. At the contraction exit, a 1.0mm trip wire provided a uniform transition site for the boundary layer on all four walls. The boundary layer on the test wall developed on a flat plate in zero pressure gradient, with a nominal freestream velocity of 31m/s and a freestream turbulence intensity of 0.3%. At a distance of 1.5m downstream of the trip wire, the boundary layer thickness was 22.7mm, and the momentum thickness Reynolds number was approximately 6000. At this point, the test wall was subjected to 90 degrees of convex curvature with a constant radius of 300mm. In an attempt to isolate curvature effects from pressure gradient effects, the wall opposite the test wall was contoured to minimize the imposed pressure gradient on the test wall, and the boundary layer on this wall was removed by suction. In addition, sidewall jets were used to minimize the strength of the secondary flow. After passing through the curved section, the boundary layer was allowed to relax on a flat plate in zero pressure gradient. This recovery region was 4.9m long. At the end of the recovery region, the flow passed through a diffuser, through the fan and a series of baffles, and exited into the room. Several ports were located along the length of the test wall to provide access for measurement probes. The port centers were located as follows: Port # s (distance in m from the end of curvature) 1 -0.646 (Upstream of the entrance of the curved section) 2 0.098 (Just downstream of the exit from the curved section) 3 0.238 4 0.379 5 0.529 6 0.799 7 1.099 8 1.600 9 2.100 10 2.600 11 3.200 12 3.830 13 4.404 Only ports 1 through 9 were actually used, due to the inability to obtain a zero pressure gradient beyond port 9. A series of static pressure taps along the centerline of the test wall was used to measure the pressure coefficient along the length of the test wall. All static pressure measurements were referenced to a tap located on the test wall 0.36m downstream of the trip wire. A pitot-static tube located 0.86m downstream of the trip wire was used to measure the reference freestream velocity. Using a pitot probe, mean velocity profiles were measured at ports 1 through 9. These profiles were used to calculate all integral parameters of the boundary layer. The skin friction coefficient was determined by fitting the velocity profiles to the law-of-the-wall. Measurements of the instantaneous velocity were made at ports 1 and 3 through 9. These mesurements were made using constant-temperature hot-wire anemometry. A single normal wire, placed perpendicular to the flow and parallel to the test wall, was used to measure the instantaneous streamwise velocity (u). A pair of crossed-wires oriented perpendicular to both the test wall and the mean flow was used to measure instantaneous streamwise (u) and normal (v) velocities simultaneously. A pair of crossed-wires oriented parallel to the test wall and perpendicular to the mean flow was used to measure instantaneous streamwise (u) and spanwise (w) velocities simultaneously. All wires were calibrated using a dynamic calibration technique described in Alving (1988). For those who desire more detatiled information, the investigation is thoroughly documented in the following publications: 1) Alving, A.E. Ph.D. thesis, Princeton University, 1988. 2) Alving, A.E., Smits, A.J., & Watmuff, J.H. 1990, "Turbulent Boundary Layer Relaxation from Convex Curvature," J. Fluid Mech. 211, 529-556. 3) Smits, A.J., et al. 1989, "A Comparison of the Turbulence Structure of Subsonic and Supersonic Boundary Layers," Phys. Fluids A 1 (11), 1865-1875. The contents of the files on this tape are as follows: Filename: Description of contents: INFO.DAT Information about where each survey was made, the pressure coefficient and skin friction coefficient, reference velocity and friction velocity for each survey. CP1.DAT Pressure coefficient measured at static pressure taps along the centerline of the test wall. CP2.DAT Pressure coefficient measured at the center of each port. P1MEAN.DAT Pitot survey at Port 1 P2MEAN.DAT Pitot survey at Port 2 P3MEAN.DAT Pitot survey at Port 3 P4MEAN.DAT Pitot survey at Port 4 P5MEAN.DAT Pitot survey at Port 5 P6MEAN.DAT Pitot survey at Port 6 P7MEAN.DAT Pitot survey at Port 7 P8MEAN.DAT Pitot survey at Port 8 P9MEAN.DAT Pitot survey at Port 9 P1U.DAT Single normal wire hotwire data at Port 1 P1UV.DAT u and v crossed wire data at Port 1 P1UW.DAT u and w crossed wire data at Port 1 P3U.DAT Single normal wire hotwire data at Port 3 P3UV.DAT u and v crossed wire data at Port 3 P3UW.DAT u and w crossed wire data at Port 3 P4U.DAT Single normal wire hotwire data at Port 4 P4UV.DAT u and v crossed wire data at Port 4 P4UW.DAT u and w crossed wire data at Port 4 P5U.DAT Single normal wire hotwire data at Port 5 P5UV.DAT u and v crossed wire data at Port 5 P5UW.DAT u and w crossed wire data at Port 5 P6U.DAT Single normal wire hotwire data at Port 6 P6UV.DAT u and v crossed wire data at Port 6 P6UW.DAT u and w crossed wire data at Port 6 P7U.DAT Single normal wire hotwire data at Port 7 P7UV.DAT u and v crossed wire data at Port 7 P7UW.DAT u and w crossed wire data at Port 7 P8U.DAT Single normal wire hotwire data at Port 8 P8UV.DAT u and v crossed wire data at Port 8 P8UW.DAT u and w crossed wire data at Port 8 P9U.DAT Single normal wire hotwire data at Port 9 P9UV.DAT u and v crossed wire data at Port 9 P9UW.DAT u and w crossed wire data at Port 9 RDCP.FOR RDMEAN.FOR These four files are described below. RDHW.FOR RDINFO.FOR The file INFO.DAT is composed of six columns of data. The first column is a filename corresponding to one of the other data files listed above (excluding CP1.DAT and CP2.DAT). The second column is the streamwise position, s, of the probe tip for each data survey, measured in meters, relative to the end of curvature. A negative value is a position upstream from the end of curvature, a positive value is downstream from the end of curvature. The third column contains the static pressure coefficient, Cp, interpolated from the data in CP1.DAT and CP2.DAT. To perform the interpolation, a linear variation in Cp between adjacent points was assumed. The fourth column contains the skin friction coefficient, Cf, which was calculated by fitting the velocity profile data from P1MEAN.DAT, P2MEAN.DAT, etc... to the logarithmic portion of the law of the wall. The values of s and Cp are the same for each of the four data surveys at each port. Likewise, the value of Cf is assumed to be the same for each of the four surveys at each port. (A blank entry in INFO.DAT means that the value is the same as the first non-blank entry above it.) The fifth column contains the value of the reference velocity, Uref, as measured by the upstream pitot-static tube, for each survey. The sixth column contains the value of the friction velocity, Utau, for each survey. The procedure used to calculate Utau is as follows. For the pitot probe surveys (P*MEAN.DAT files), the local freestream velocity , Ue, is calculated from the velocity profile data, as is the skin friction coefficient (as described above). The value of Utau for these surveys was calculated by multiplying the freestream velocity by the squareroot of one-half the skin friction coefficient. For the three hot-wire surveys at each port, the value of Utau was calculated by the value of Utau from the pitot survey at that port multiplied by the reference velocity from the particular hot-wire survey and divided by the freestream velocity from the pitot survey. Thus, (Utau)pitot = (Ue)pitot * sqrt(Cf/2) (Utau)hotwire = (Utau)pitot * (Uref)hotwire / (Uref)pitot The static pressure data files (CP1.DAT, CP2.DAT) each have a header at the beginning of the file, which contains brief descriptive information about the data, and the values of both the reference dynamic head and the average temperature during the survey. The header is followed by four columns of numerical data. The first column is simply an index. In CP1.DAT this corresponds to the number of the static pressure tap. In CP2.DAT the index corresponds to the port number. The second column contains the streamwise position of the static tap, in meters, referenced to the end of curvature. As stated before, a positive position is downstream of the end of curvature, while a negative position corresponds to a location upstream of the end of curvature. Note that no measurements were made in the curved section of the tunnel. The third column contains the measured pressure difference , in Pa, between the static tap at the position indicated and the reference static tap. The fourth column contains the calculated pressure coefficient. The mean data files from pitot surveys (P1MEAN.DAT, etc.) also have a header at the beginning of the file. The header contains descriptive information about the data, the pitot probe outside diameter, and all pertinent measured and calculated parameters of the freestream flow and the boundary layer. The header is followed by 7 columns of numerical data. The first column is an index. The second column is the height of the probe, in mm, above the test wall. This height has been corrected to account for the inside and outside diameters of the pitot probe. The third column contains the measured value of U (average velocity in the freestream direction) normalized by the local freestream velocity. The fourth column contains the nondimensional quantity formed by the product of the local freestream velocity and the height above the wall divided by the kinematic viscosity. The fifth column contains the nondimensional height from the wall in wall units, Y+. The sixth column contains the measured velocity normalized by the friction velocity, U+. The seventh column contains the calculated deviation of the measured value of U+ from the value predicted by the law of the wall. As mentioned earlier, the value of the skin friction coefficient is determined by fitting the measured velocity profile to the law of the wall. The friction velocity is computed from the skin friction coefficient and the local freestream velocity, as described above. The hotwire data files (P1U.DAT, etc.) begin with a file header, which contains the friction velocity (determined from the formulas given above) and boundary layer thickness (calculated from the pitot survey data), the index of the first line of data in the file, the index of the last line of data in the file, the number of wires, and the number of probes. (Thus the single normal wire data will indicate 1 wire and 1 probe, while the crossed-wire data will indicate 2 wires and 1 probe.) In the normal wire data files, the header is followed by 6 columns of numerical data. The first column is the index of the data point. The second column is the height, in mm, above the test wall, of the center of the active length of the wire. The third column is the calculated average streamwise velocity (U), in m/s. The fourth, fifth, and sixth columns are the calculated variance, skewness and kurtosis, respectively, of the fluctuating component of the streamwise velocity (u'). In the P*UV.DAT crossed-wire data files, the header is followed by 12 columns of numerical data. The first column is the index of the data point. The second column is the height, in mm, above the test wall, of the center of the active lenghts of the two wires. The third column is the calculated average streamwise velocity (U), in m/s. The fourth column is the calculated average velocity (V), in m/s, normal to the wall and perpendicular to the freestream velocity. Columns 5, 8 and 12, contain, respectively, the variance, skewness and kurtosis of the fluctuating component of velocity in the freestream direction (u'). Columns 7 and 11 contain, respectively, the variance and skewness of the fluctuating component of V (v'). The sixth column contains the average value of the product u'v'. Columns 9 and 10 contain, respectively, the average values of the products (u'**2)(v') and (u')(v'**2). The structure of the P*UW.DAT files is exactly the same as that of the P*UV.DAT files. Simply replace V by W and v' by w'. In this case, W is the velocity parallel to the test wall and normal to the freestream flow direction. w' is the fluctuating component of W. The four files RDCP.FOR, RDMEAN.FOR, RDHW.FOR, and RDINFO.FOR contain FORTRAN program listings of code that can be compiled and linked and used to read in data from each of the three types of data files on this tape. Use RDCP.FOR to read in data from the files containing static pressure data. Use RDMEAN.FOR to read in data from the files containing mean flow data from pitot surveys. Use RDHW.FOR to read in data from the files containing hotwire data. Use RDINFO.FOR to read in the data in INFO.DAT. If there are any questions about the contents of this tape or the experimental investigation described above, please contact: Prof. A.J. Smits Dept. of Mech. and Aerospace Engineering D302 E-Quad Olden Street Princeton University Princeton, NJ 08544 Phone: (609) 258-5117