Langley Research Center Turbulence Modeling Resource

Exp: CFDVAL2004 Case 1 Experimental Data

Return to: CFDVAL2004 Case 1 - Intro Page

Using PIV, experimental data for Case 1 are available in the following file:

These data include the following:

• Phase-averaged data every 5 deg (0, 5, 10,..., 350, 355) of u, v, u', v', u'v' at z=0 over an array of (x,y) from approximately -2.74 < x < 3.93mm and 0.122 < y < 8.37mm
• Long-time-averaged data of u, v over same (x,y) array

Using hot wire, experimental data for Case 1 are available in the following file:

These data include the following:

• Phase-averaged data every 1.6 deg (0, 1.6, 3.2, ..., 356.8, 358.4) of v and v' at x=0, z=0 over the centerline from 0 < y < 40 mm
• Long-time-averaged data of v over same y range

Note: Case 1 experimental data are being reported in the following coordinate system: x-direction across the slot (narrow-wise), y-direction up, z-direction parallel to the slot. The coordinate system's origin (0,0,0) is at the center of the slot, in line with the floor of the box into which the jet issues.

Sample plot of long-time-averaged data (left-hand plot is from PIV):

Sample plots of phase-averaged data from PIV (contours plotted are -20 m/s through 30 m/s, in increments of 1 m/s, with negative contours plotted as dashed lines and positive contours plotted as solid lines):

The following figure compares PIV phase-averaged v-velocity with those from hot wire at several stations along the center line:

Newer Experimental Data:

More recent experimental data is available using PIV, hot wire, and LDV. These data are at different conditions(!!) than the workshop data conditions described above and on the Details and Submissions Guidelines page, because the diaphragm was replaced in the newer experiments. The cavity dimensions were identical, the diaphragm frequency was the same, and the ambient conditions were all the same as for the workshop case. But the diaphragm displacement was somewhat larger (and thus cavity pressure was larger), so this newer data produced a somewhat stronger jet than the case used for the workshop. Although there are still differences, the three different measurement techniques generally agree better for this dataset than for the original workshop dataset. The new data are given in the following file:

These data include the following:

• PIV long-time-averaged u and v data, and phase-averaged data every 5 deg (0, 5, 10,..., 350, 355) of u, v, u', v', u'v' at z=0 over an array of (x,y) from approximately -3.1 < x < 3.5mm and 0.3 < y < 8.7mm
• Hotwire long-time-averaged v data, vmax and vmin data, and phase-averaged data every 1.6 deg (0, 1.6, 3.2, ..., 356.8, 358.4) of v at x=0, z=0 over the centerline from 0 < y < 50 mm
• LDV long-time-averaged v data, vmax and vmin data, and phase-averaged data every 10 deg (0-10, 10-20, ... 350-360) of v at x=0, z=0 over the centerline from 0 < y < 70 mm
• Broader-view PIV long-time-averaged data (with coarse resolution so best used only for qualitative comparisons) in the usual x-y plane (across the slot) as well as in the z-y plane (along the LONG axis of the slot)

The following plot shows measured phase-averaged vertical velocity over the center of the slot as a function of phase for the newer data (note that the LDV data has been scaled as described in the write-up that accompanies the data). Compare this plot with the workshop-case plot on the Details and Submission Guidelines page.

It is also important to note that the newer experimental data explored 3-D end effects. The following plot shows velocity contours along the slot, and indicates that end effects intrude toward the center region as you move away from the wall. The experimentalists interpret this plot to mean that 3-D end effects cannot be ignored above z=10 mm or so. This means that both 2-D CFD and 3-D CFD that does not account for end effects are likely poor approximations above that height. 3-D effects were likely very similar to this for the original case 1 data.
 

Return to: CFDVAL2004 Case 1 - Intro Page

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Last Updated: 05/15/2021