 distribut three-dimension rough surfac cool boundari layer transit later spread turbul superson speed distribut three-dimension rough surfac cool boundari layer transit later spread turbul superson speed investig langlei 4 4-foot superson pressur tunnel mach number 1 61 2 01 determin 1 distribut rough boundari-layer transit model surfac adiabat wall temperatur cool 2 surfac cool later spread turbul distribut granular-type singl spheric rough particl transit boundari layer determin hot-wire anemomet transit-trigger mechan three-dimension rough superson speed appear observ subson speed fact critic rough reynold number paramet turbul spot initi rough superson subson speed complet local condit top rough includ densiti viscos consid formul rough reynold number three-dimension rough reynold number critic rough introduc disturb suffici magnitud influenc transit surfac cool provid theoret increas stabil small disturb increas extent critic rough reynold number three-dimension rough particl cool boundari-layer thick densiti viscos promot transit exist three-dimension surfac rough mach reynold number measur later spread turbul boundari layer appear unaffect increas laminar stabil deriv surfac cool 