Coefficient of Drag with CVG
Effect of the addition of a CVG to the Coefficient of Drag on a wing with a slat in transonic flight. The solution is 3D DES, and is for the B737 wing at Mach 0.78. The red line is the standard wing with a slat only, and it shows the high frequency variations from the shedding off the back of the slat, and the lower frequency but larger amplitude changes to drag are from the shock wave response to the shedding of the flow off the back of the slat step. The green line is the same section and slat, with a CVG applied. The suppression of vibration, unsteadiness and the large alteration in drag is evident in the test case, The test is of a series of CFD runs, that take 50,000 iterations of the model to achieve convergence, and then each step is then run for 50,000 further runs to provide the complete outcome. The total time from start of the run to the end of the run in stable terms is 0.3 seconds, with about 0.2 seconds in the stable operating condition for the slat only outcome.
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