The SRB nozzle erosion related flow analysis

A study was performed to define the solid rocket booster (SRB) nozzle throat flow field, and to investigate one possible mechanism for the severe erosion which occurred on a recent flight. The flow field in the vicinity of the eroded area was not found to be exceptional, and the presence of a notch or scored area near the imbedded region nose did not appear to produce sufficient flow fluctuations to exacerbate the erosion characteristics of the throat liner. An interesting fluctuating mechanism was found in the imbedded cavity, but that mechanism (while of possible importance for erosion of the seal region) did not seem to adversely affect the region of concern. On the basis of this analysis, the conclusion can be drawn that the anomalous erosion did not result from a single mechanical defect (pit, or gouge) since the flow fluctuations which result seem insufficient to induce a repetitive pattern downstream. It further appears that the emission pattern exhibited did not result from a steady flow phenomena in the throat region. This does not rule out acoustic phenomena or severe start-up transients.