Nose blowing for side force control on slender cones at high incidence

Vortex asymmetry on axisymmetric pointed forebodies at high angles of incidence results in side forces and adverse yawing moments even in symmetric flight. An experimental investigation has been carried out at low speeds to study the effectiveness of axial nose blowing against the oncoming flow for side force control on two slender cones. Tests were made on the 8 and 12 deg cone models with (circular)jet flow over a Reynolds number range of 0.4 x 10(6) to 5.4 x 10(6). Jet-to-freestream velocity ratio was varied up to 2.0, and the blowing diameter was varied as well. Force measurements were carried over the incidence range of 0 to 45 deg, and limited surface pressure distributions were obtained on the 12 deg cone model. The results explicitly show the effectiveness of nose blowing for side force control over a wide range of Reynolds numbers, and minimum side force was reached around a jet velocity ratio of 1.0. An important result is that the side force reduction correlates with jet velocity ratio in the range of parameters studied. Broad similarities in the trend of side force reduction with the nose blowing and the nose bluntness suggest that the interaction of axial jet with freestream flow results, possibly, in what we may call "fluid dynamic blunting."