SOME EFFECTS OF BLUNTNESS HEAT TRANSFER By SUMMARY ON BOUNDARY-LAYER TRANSITION AND AT SUPERSONIC SPEEDS 1

Large doumtream nwvementa of tran8i&rn obst%wedwhen the leading edge of a)iOUowqlinder or a jlzt pti i-s 81i9h#Jy blunted are czpluined in &ma of h redudion in Rqrnolde number at tlw outm edge of the boundary layer due to the de-tuched shock wave. The magnitude of this rechtion ti com-puted for cones and wedgesfor Mach numbem to 90. Concur-rent changtx in outer-edgeMach number and tempera.twe occur in the direction that would hcreuse the 8tu.bi. @ of the laminar boundary layer. The hypothmis ti made thai tra?urdiunReynolds number h substanti.dy unchanged when a 8harp leading edge or tip is blunted. This hypotlwi.s law % to the conclusion that the downstream movement of transition is inver8eJyproportti to the ratw of suq%ce Reynoldx number with bluntd tip or lead-ing edge to surface Reynolds number with slump tip or leading edge. TILis conclwian ix in good agreement with the hoUow-cylinder result at Mach 3.1. Application of this hypothemk to other Mach numbw8 yie.?d8 the rewlt that blunting h tip of a dender cone or the leading edge of a thin wedge 8h4nddproduce o%wnstreammomments of tram”tion ~jactors rangingfiom 2?at Mach 3.0 to 30 at Mach 16, Tb tignifikance of this result is dimnsed wdh regard to the possibh reduc+ionin over-allheut-tramj%rrate and friction dragfor aircra~$~”ng at h~h supersonic speeds. Mach number pro % near the suq%eeaof blunted cones and weo?gtxare computed for an amunwd shupe of the detuehed shock wave a.t$ight Mach numbers to 90. The dimipti and stabiiity qf these proms are discu88ed, and a method h de-scribedfor estimating the amount of blunting requwed to produce the maximum possible downstream move-mW of tram3i$i5n