Sting Effects in Hypersonic Base Pressure Measurements
DAVID W TAYLOR NAVAL SHIP RESEARCH AND DEVELOPMENT CENTER BETHESDA MD AVIATION AND SURFACE EFFECTS DEPT
Pagination or Media Count:
Sting interference effects were investigated at nominal Mach numbers of 6.3 and 9.9. Sting mounted and instrumented free flight sharp cone mocels were used at a unit Reynolds number of about 1,000,000ft. Measurements showed that the base pressure distribution changes little below angle of attack 15 degrees but becomes highly nonuniform and sensitive to angle of attack changes at high angles of incidence. Sting interference effects are not very severe at M 6.3 when angle of attack less than 20 degrees, but as the angle of attack increases, the flow becomes progressively more distorted. Consequently, the base pressure values of the sting mounted model deviate from the free flight interference free model measurements. Beyond about 40 degrees, due to the severe effects of sting interference, no steady base pressure value could be reached with the sting mounted model in either of the tested Mach numbers. For the free flight model at Mach number 9.9, the magnitude of the measured base pressure ratios at corresponding flow conditions and angles of attack were about 70 percent above the sting mounted model showing how serious sting interference can be.
- Test Facilities, Equipment and Methods
- Fluid Mechanics