Effect of Counterflowing Jet on Supersonic Slender-Body Configurations: A Numerical Study

Previous studies have demonstrated that the use of counterflowing supersonic jets operating in the long penetration mode (LPM), directed from the nose of blunt bodies against a supersonic/hypersonic freestream, can greatly reduce the drag and heat loads on the vehicle. However, the benefits of LPM for slender bodies of revolution operating at low supersonic speeds, applicable to supersonic transport applications, remain largely unknown. This Paper conducts a systematic parametric study for the effects of a counterflowing jet on two slender body models (cone-cylinder and quartic body of revolution, respectively) operating at a freestream Mach number of 1.6, using time-accurate computations performed with an unstructured Navier-Stokes solver. Different ranges of jet flow rates, jet exit Mach numbers, nozzle exit diameters, and jet-to-base diameter ratios are examined systematically. The jet-to-base diameter ratio is determined to be the most important parameter to facilitate the establishment of the LPM regime. Depending on the geometry of the slender body, longer jet penetration (thus larger shock-standoff distance) associated with the LPM does not always result in larger drag reduction. Furthermore, current results indicate that inclusion of an LPM jet is likely to cause large oscillations of surface pressure and drag on these slender geometries.