A COMPARISON OF EXPERIMENTAL AND THEORETICALLY PREDICTED PRESSURE DISTRIBUTIONS AND FORCE AND STABILITY COEFFICIENTS FOR A SPHERICALLY BLUNTED CONE AT M ~ 18 AND ANGLES OF ATTACK

摘要

Analysis of experimental pressure distributions and force and moment coefficients for a 9-deg half-angle spherically blunted cone at MM - 18 and a = 0 to 20 deg is presented based on an ideal gas (y = 1.4) three-dimensional characteristics solution developed by General Applied Sciences Laboratory (GASL). Comparisons are also made with pre¬dictions based on modified Newtonian theory. Pressure distributions along the windward and leeward streamlines were well predicted by the results from the GASL, program at a ~ 10 deg. For a 10 deg, comparison with the experimental data indicated differences attributed to viscous effects. For a > 10 deg the numerical results were affected by necessary program modifications on the leeward side. Radial pressure distribu¬tions along the body surface from the GASL results showed the develop¬ment of low pressure "wells" in the leeward region at a > 10 deg . Similar distributions along a constant entropy surface within the inviscid shock layer indicated substantial delay in the formation of the low pressure "wells". CN and Cm were found to be in good agreement with the experi¬mental data when based on the GASL surface pressure distribution. Predicted values of CA were about 40 percent below the experimental data over the entire range, a = 0 to 20 deg, in agreement with a previous Newtonian based analysis. The difference is attributed to the viscous -induced drag increment. Computed slopes, CNA and Cma , were found to be well predicted by the integrated GASL results, whereas the modified Newtonian prediction was in poorer agreement with the trends of the experimental data.