Numerical investigation of twin-nozzle rocket plume phenomenology

Abstract

The generalized implicit e ow solver (GIFS)computerprogram has been modie ed and applied fortheanalysis of three-dimensionalreactingtwo-phasee owsimulationproblems.TheintentoftheoriginalGIFSdevelopmenteffort was to provide the joint Army, Navy, NASA, Air Force community with a standard computational methodology to simulate the complete e owe eld of propulsion systems including multiple nozzle/plume e owe eld phenomena and other three-dimensional effects. The Van Leer e ux splitting option has been successfully implemented into the existing GIFS model and provides a more robust solution scheme, making application of the model more reasonable for engineering applications. Signie cant results of several twin-nozzle/plume simulations using the GIFS code are reported. Eight simulations of Titan II plume e owe elds have been completed to assess the effects of three dimensionality, turbulent viscosity, afterburning, near-e eld shock structure, e nite rate kinetic chemistry, internozzlegeometricspacing,nozzleexitplaneproe le,andmissilebodyonthesubsequentplumeexhauste owe eld. The results of these calculations indicate that the viscous stress model; kinetic chemistry, particularly at lower altitudes; and nozzle exit proe le may be important parameters that should be considered in the analyses and the interpretation of radar signature calculations. Three dimensionality is also an important ine uence, which can substantially ine uence the interpretation of the results. If three-dimensional effects are oversimplie ed in the model, analyses of the spatial results can be misinterpreted and misapplied. In addition, the missile body effect and internozzle geometric spacing ine uence the expansion shock ree ection location that can signie cantly affect the plume/plume impingement shock location, inviscid shock structure, and shear-layer growth.