FORCE AND PRESSURE CHARACTERISTICS FOR A SERIES OF NOSE INLETS AT MACH NUMBERS FROM 1.59 TO 1.99 Ⅳ – CONICAL-SPIKE EXTERNAL-INTERNAL COMPRESSION INLET UTILIZING PERFORATED COWL

摘要

As part of a general investigation of supersonic inlets in the NACA Lewis 8- by 6-foot supersonic wind tunnel, tests were conducted to determine the force and pressure-recovery characteristics of a model utilizing a single-shock spike-type inlet with a perforated cowl. External and internal pressure distributions, pressure recovery, and lift, drag, and pitching moment were measured for a range of mass-flow ratios at angles of attack from 0° to 10° for free-stream Mach numbers of 1.59, 1.79, and 1.99. The average Reynolds number based on the inlet diameter was approximately 2.4X106.nThe use of a perforated cowl resulted in the attainment of. a high pressure recovery at zero angle of attack, but was accom¬panied by a relatively large increase in external drag as compared with nonperforated inlets of the same proportions. Throughout the range of stable operation, the total-pressure recovery decreased with increasing angle of attack, particularly at Mach numbers of 1.79 and 1.99.nStable flow was observed at the design Mach number of 1.79 for the higher mass flows at zero angle of attack. The range of mass-flow ratios with stable operation decreased with increasing angle of attack and at 10°, shock oscillation was observed for all but the supercritical mass flow.nThe calculated average subsonic-flow coefficient of the perforations for a free-stream Mach number of 1.79 and zero angle of attack was 0.53.