Modeling of the interaction of a side jet with a rarefied atmosphere

Abstract

The interaction of a jet from a 3000-N-class thruster positioned on the side of a small rocket, with the raree ed atmosphere at 100 and 80 km, is studied numerically. The direct simulation Monte Carlo method was applied to model the three-dimensional jet-atmosphere interaction. Chemical reactions between freestream and plume species were included in the simulations. A two-stage numerical strategy was used, with sequential computations of an axisymmetric plume core e ow and three-dimensional plume-freestream interaction. The impact of altitude, angle of attack, rocket velocity, and thrust on e owe elds and surface mass e uxes is examined. PACEvehiclesoftenusedivertandattitudereactioncontrolsys- tems (RCS) to perform maneuvers during e ight. The forward and aft RCS engines provide the thrust for attitude (rotational) ma- neuvers(pitch, yaw, and roll ) and for small velocity changes along the vehicle trajectory (translation maneuvers ). The application of RCS is particularly important at high altitudes where the efe ciency of the control surfaces decreases signie cantly as a result of the low density of the freestream. It is therefore needed to predict the ef- fects of the interaction of RCS jets with the raree ed atmosphere accurately. The experimental study of jet-atmosphere interaction is hardly able to match similarity parameters of such an interaction, 1 making a detailed numerical simulation indispensable. The descrip- tion of the interaction of RCS jets with the raree ed atmosphere is cone guration specie c. 2 That means that the available experimental data for the Space Shuttle Orbiter 3 and the sharp leading-edge jet- interaction measurements 4 are not applicable to other vehicle types. Computations of RCS jet interactions in raree ed atmospheres were undertaken by various authors. 5i8 The modeling efforts were concentrated on different aerodynamic aspects of the RCS: freestream interaction and different vehicle types in a perfect gas environment. The direct simulation Monte Carlo (DSMC) method was used 1 to compute the three-dimensional jet interaction for a corner e ow cone guration; the results were compared with experi- mental data of surface-pressure distributions. A sharp leading-edge cone guration 2;7 was also used where both the kinetic (DSMC) and continuum approaches were utilized to model in detail the inter- action between a continuum jet and the raree ed atmosphere. The e ow separation effects were studied 6 for a biconic atmospheric in- terceptor geometry and near-continuum atmosphere conditions of 65 km. The recent work 8 examines transient effects associated with jet interactions at 20 and 35 km for a generic interceptor missile cone guration. The previous results obtained by continuum and kinetic ap- proaches showed the importance of an accurate and detailed mod- eling of the jet-atmosphere interaction to obtain a credible solution