Recent experimental assessment of cruise performance for supersonic transport has led to reevaluation of some time-honored techniques for trip drag correction. Two wind-tunnel tests were conducted on a wing/body configuration at Mach 2.4 and Reynolds number 6.4 x 106. A method for determining corrections to the drag near the cruise angle of attack is presented. These corrections account for the trip drag associated with attempts to induce boundary-layer transition and for the effect of any laminar flow that persists on the model. Extensive flow visualization using a subliming chemical revealed that the boundary-layer trip was not consistently effective. Flow over a portion of the upper wing surface exhibited delayed transition for even the largest trip heights tested. Laminar run corrections based on measured transition locations were computed using flat-plate skin-friction formulas. Once corrected for laminar run, the drag was constant for small trip heights ('drag plateau') before linearly increasing with trip height. Therefore, a trip drag correction is required only for those trip heights beyond the plateau. It is concluded that correction for laminar run is essential and must precede evaluation of trip drag. Neither correction is negligible at the level of accuracy desired.
Accounting for laminar run and trip drag in supersonic cruise performance testing
Berücksichtigung der laminaren Grenzschicht und des Einflusses von Turbulenzerzeugern bei der Messung des Widerstands von Überschallflugzeugen im Modellmaßstab
AIAA Journal ; 42 , 11 ; 2225-2233
2004
9 Seiten, 14 Bilder, 2 Tabellen, 22 Quellen
Aufsatz (Zeitschrift)
Englisch
Accounting for Laminar Run and Trip Drag in Supersonic Cruise Performance Testing
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