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Boundary layer receptivity to free-stream turbulence and surface roughness over a swept flat plate
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10.1063/1.3562843
/content/aip/journal/pof2/23/3/10.1063/1.3562843
http://aip.metastore.ingenta.com/content/aip/journal/pof2/23/3/10.1063/1.3562843

Figures

Image of FIG. 1.
FIG. 1.

(a) Coordinate system of the test section with its corresponding velocity components. (b) Configuration of X-probe allowing for all three velocity component to be measured.

Image of FIG. 2.
FIG. 2.

(a) Sketch of the leading edge and plate along with coordinate systems. (b) Photo of the leading edge. (c) Side view of the setup at the test section centerline with the displacement body placed on the ceiling in black and the plate in gray. (d) Top view of the setup with side walls in black and the plate in gray. The lengths and are used to scale the streamwise and spanwise coordinates, respectively.

Image of FIG. 3.
FIG. 3.

Free-stream velocity distributions for the streamwise and spanwise velocity components. (a) and (b) correspond to and velocity distributions, respectively. .

Image of FIG. 4.
FIG. 4.

(a) Streamwise and (b) spanwise velocity in normal coordinates. The solid line in (a) corresponds to the power-law relation, Eq. (1), fitted to the data. .

Image of FIG. 5.
FIG. 5.

Spanwise variation of the (a) streamwise and (b) spanwise velocity in normal coordinates for increasing .

Image of FIG. 6.
FIG. 6.

Spanwise variation of the Hartree parameter, .

Image of FIG. 7.
FIG. 7.

Parameter values of integral length scale and turbulence intensity measured at the leading edge for the grids (cf. Table I for symbols).

Image of FIG. 8.
FIG. 8.

(a) Sketch of the location of the roughness elements. , , and denote the wavelength or spacing, the height and the diameter of the cylindrical roughness elements. (b) The parameters investigated in the experiments. Filled squares indicate traversing was done in full planes, whereas circles indicate wider spans at one wall-normal position.

Image of FIG. 9.
FIG. 9.

(a) Free-stream velocity variation in normal coordinates along the centerline for all grids. The gray line represents a fit to the data with . (b) All wall-normal profiles plotted together with the theoretical (gray line) Falkner–Skan–Cooke profile in tunnel coordinates with .

Image of FIG. 10.
FIG. 10.

(a) Two-point velocity correlation functions in the spanwise direction around the disturbance peak for all grids at . (b) The spanwise variation of the mean velocity around the disturbance peak at . (c) Amplitude of the stationary mode taken from (b). (d) Averaged spanwise length scale for all grids for both the traveling and stationary modes in open and filled symbols respectively. See Table I for symbols.

Image of FIG. 11.
FIG. 11.

Evolution of wall-normal disturbance profiles in the downstream direction for grids (a) , (b) , (c) , (d) , (e) , and (f) all profiles with subtracted free-stream disturbance levels and normalized with its maximum value. .

Image of FIG. 12.
FIG. 12.

(a) Phase shift at different spanwise distances for . (b) Resulting phase speed, for all the grids.

Image of FIG. 13.
FIG. 13.

(a) Growth of the integrated disturbance profiles for each grid, in absolute terms. (b) Growth of the integrated disturbance profiles for each grid, normalized with the value at . (c) Derivative of N using central difference. (d) Same as (b) plotted with spline curves through the data points to emphasize the locations of regions I, II, and III. See Table I for symbols.

Image of FIG. 14.
FIG. 14.

The spanwise variation of the fluctuating velocity for all grids. See Table I for symbols.

Image of FIG. 15.
FIG. 15.

(a) Energy levels for all grids at , 0.50, and 0.55 as a function of . Solid line represents a quadratic fit to the data. (b) Growth of the integrated disturbance profiles for each grid, normalized with the square of the free-stream turbulence level measured at the leading edge. See Table I for symbols.

Image of FIG. 16.
FIG. 16.

Energy spectra for all grids at the location of the disturbance peak at (a) and (b) . The legend identifying the different grids is below figure (b). Some amount of aliasing error can be seen for at but does not affect the behavior of the peak. (c) Evolution of the premultiplied energy spectra at the disturbance peak in the streamwise direction for grid .

Image of FIG. 17.
FIG. 17.

Base flow for the stationary disturbance experiments along the fit to the power law. .

Image of FIG. 18.
FIG. 18.

Base flow mean velocity profiles, relative to the streamline, without any disturbance for the stationary disturbance experiments at all streamwise and spanwise locations. .

Image of FIG. 19.
FIG. 19.

Spanwise variation of the velocity along with their energy spectra for and . (a), (b), and (c) correspond to the downstream positions , 0.5, and 1.0 respectively.

Image of FIG. 20.
FIG. 20.

Spanwise variation of the velocity along with their FFTs for and . (a), (b), and (c) correspond to the downstream positions , 0.5, and 1.0 respectively.

Image of FIG. 21.
FIG. 21.

The disturbance development of the stationary modes, , for two roughness heights, normalized with the for (gray) and (black). —–: mode 1, – – –: mode 2, : mode 3. (a) With linear axes. (b) In a semilog plot to show the exponential behavior.

Image of FIG. 22.
FIG. 22.

Contour plots of the streamwise disturbances for and in the -plane taken at the -position with the maximum disturbance level. Low speed areas are in white, high-speed areas are in black.

Image of FIG. 23.
FIG. 23.

Contour plots of the streamwise disturbances for and at (a) , (b) , (c) , (d) , (e) , (f) , (g) , (h) , (i) , and (j) . The values at the wall are extrapolated to 0. Low speed areas are in white, high-speed areas are in black.

Image of FIG. 24.
FIG. 24.

Contour plots of the spanwise disturbances for and . The -locations are identical to Fig. 23. The values at the wall are extrapolated to 0. Negative velocities are in white, positive velocities are in black.

Tables

Generic image for table
Table I.

The five turbulence generating grids used in this investigation. Bar width, mesh width and grid solidity are denoted , , and , respectively. The streamwise integral length scale, , and the turbulence intensity, , are measured at the leading edge in the center of the wind tunnel.

Generic image for table
Table II.

Cylindrical surface roughness parameters studied during the experiment.

Generic image for table
Table III.

Free-stream variation of parameters [cf. Eq. (1)] determined in a least square fit sense to the data for each grid.

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/content/aip/journal/pof2/23/3/10.1063/1.3562843
2011-03-31
2014-04-23
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752b84549af89a08dbdd7fdb8b9568b5 journal.articlezxybnytfddd
Scitation: Boundary layer receptivity to free-stream turbulence and surface roughness over a swept flat plate
http://aip.metastore.ingenta.com/content/aip/journal/pof2/23/3/10.1063/1.3562843
10.1063/1.3562843
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