Numerical investigation of twin-nozzle rocket plume phenomenology

The generalized implicit how solver (GIFS) computer program has been modifi ed and applied for the analysis of three-dimensional reacting two-phase flo w simulation problems. The intent of the original GIFS development effort w as to provide the joint Army, Navy, NASA, Air Force community with a standa rd computational methodology to simulate the complete flowfield of propulsi on systems including multiple nozzle/plume flowfield phenomena and other th ree-dimensional effects. The Van Leer flux splitting option has been succes sfully implemented into the existing GIFS model and provides a more robust solution scheme, making application of the model more reasonable for engine ering applications. Significant results of several twin-nozzle/plume simula tions using the GIFS code are reported. Eight simulations of Titan II plume flowfields have been completed to assess the effects of three dimensionali ty, turbulent viscosity, afterburning, near-field shock structure, finite r ate kinetic chemistry, internozzle geometric spacing, nozzle exit plane pro file, and missile body on the subsequent plume exhaust flowfield, The resul ts of these calculations indicate that the viscous stress model; kinetic ch emistry, particularly at lower altitudes; and nozzle exit profile may be im portant parameters that should be considered in the analyses and the interp retation of radar signature calculations. Three dimensionality is also an i mportant influence, which can substantially influence the interpretation of the results. If three-dimensional effects are oversimplified in the model, analyses of the spatial results can be misinterpreted and misapplied. In a ddition, the missile body effect and internozzle geometric spacing influenc e the expansion shock reflection location that can significantly affect: th e plume/plume impingement shock location, inviscid shock structure, and she ar-layer growth.