TRANSITION CORRELATIONS IN 3-DIMENSIONAL BOUNDARY-LAYERS

The stability and transition characteristics of three-dimensional boun dary-layer flows are examined. First, the flow over a rotating cone is considered computationally. An increase of stagnation temperature is found to be only slightly stabilizing. Parameter studies on the simple rotating-cone geometry provide a large database of three-dimensional boundary-layer profiles and associated stability characteristics. To d etermine the possibility of correlating transition location with param eters based purely on basic-state three-dimensional boundary-layer pro file characteristics, an empirical transition location of N = 9 is ass umed. Transition location does not correlate with the traditional cros sflow Reynolds number. A more appropriate definition for crossflow Rey nolds number is found and termed R(cf)(new). This new parameter appear s to correlate for transition location when plotted against maximum cr ossflow velocity. Then, the flow over a yawed cone is considered exper imentally. The correlation results obtained from the rotating-cone wor k are applied to the actual measured transition locations on two diffe rent yawed-cone models under various angle-of-attack conditions in two different experimental facilities and are verified. This correlation is only suggested as a tool for preliminary transition prediction and design in three-dimensional boundary layers; once a preliminary shape is selected, further linear stability theory or parabolized stability equation calculations are strongly urged.