Turbulent Axisymmetric Near-Wake at Mach Four with Base Injection

Introduction F the early experiments by Cortright and Schroeder, and the theoretical and experimental investigation by Korst, Page, and Childs, it was apparent that the base drag of supersonic vehicles could be controlled effectively by the injection of small quantities of gas into the turbulent nearwake. Experimental investigations of the effect of mass injection into the turbulent near-wake of axisymmetric bodies with blunt bases have been reported in Refs. 1 and 3-7. Most of these previous investigations have been hampered either by model support effects (cf. Refs. 1,4), or by inconsistent zero mass injection data (cf. Refs. 5-7). As a consequence of this apparent lack of detailed data, particularly at Mach numbers higher than two, a systematic investigation of base pressure variation caused by mass injection into a turbulent supersonic axisymmetric near-wake was conducted. The major results of this study are summarized in this Note.