Experimental and numerical investigations of vacuum plume interaction for dual hydrogen/oxygen thrusters

• The pressure field of the vacuum plume from a hydrogen/oxygen thruster was measured.
• A CFD-DSMC simulation method was employed and validated by the experimental data.
• The plume interaction of dual hydrogen/oxygen thrusters was numerically studied.
• The secondary jet was evaluated by the separation distance and angle of the thrusters.

In spacecrafts such as high-altitude rockets and lunar landers, multiple thrusters or engines operate simultaneously with a small separation distance. Thus, the plume interaction may cause a different three-dimensional flow field with a single plume or plumes separated by a large distance. To study the flow field of the plume interaction, a hydrogen/oxygen sample thruster with a thrust of 60 N with the same propellant, mixing ratio, and shrunken bell-nozzle profile as an actual engine was first designed and tested in the Vacuum Plume Effects Experimental System (PES). The pressure field of the plume was determined using a pitot-tube array. The experimental data were compared with the results from a numerical solution that combined both computational fluid dynamics (CFD) and direct simulation Monte Carlo (DSMC) analyses, and a favorable agreement was obtained, demonstrating the application ability of the CFD-DSMC method to predict the plume flow field. Subsequently, two identical sample thrusters were modeled with a separation distance ranging from 1.0 to 3.0 times the diameter of the nozzle exit and a deflection angle ranging from 0° to 20°, and the plume interactions were numerically investigated.