Supersonic retropropulsion enables human-scale Mars entry, but predicting multijet aerodynamic interference forces and moments remains a challenge. Existing high-fidelity models are computationally prohibitive for trajectory analysis, while prior reduced-order models assume a single unified plume and therefore miss the topological transition between isolated and merged plumes. This work presents a topology-adaptive reduced-order model that removes this limitation, predicting heatshield forces during multijet operation at zero degrees angle of attack. The framework employs a shared-cap control volume coupled to an annular throat, using an axisymmetric method of characteristics solver to resolve individual plume boundaries. A blockage model adjusts according to whether plumes act as separate jets or merge into a single structure, resolving the ambiguity in identifying the contact surface for noninteracting nozzles, particularly in annular configurations. Comparisons against NASA wind-tunnel data for single-, three-, four-, and eight-jet configurations across a range of freestream Mach numbers and mass flow rates demonstrate that the model reproduces shielding onset and high-thrust force plateaus, reducing the mean squared error by more than 50% relative to a single-jet baseline. At approximately 1 s per prediction on one CPU, the model facilitates rapid design trade studies and characterizes the coupling between nozzle canting and control-volume topology.
Hypersonic vehicles are constrained by severe aerodynamic heating and drag, which limit both their performance and operational safety. To mitigate these critical issues, this study introduces an integrated aerospike configuration incorporating opposing and lateral jets, designed to achieve simultaneous drag and thermal load reduction. The proposed design was evaluated using Reynolds-averaged Navier-Stokes simulations with the shear-stress transport k-omega turbulence model, supported by comparative analyses of flow structures, surface heat flux, and aerodynamic performance. Results show that, compared to an unprotected blunt body, the integrated configuration reduces peak surface heat flux by 94.80% and decreases the total drag coefficient by 80.46%. Additionally, it was observed that an increase in the angle of attack intensifies the windward recompression shock, resulting in a moderate decline in drag reduction efficiency. Overall, the proposed configuration demonstrates strong potential for advancing active thermal protection systems in hypersonic vehicle applications.
In this study, a quasi-steady pulsed magnetic field system combining a pulse forming network (PFN) and an air-core coil was developed for magnetohydrodynamic aerobraking experiments in an expansion tube. The system was developed to overcome limitations of permanent magnets in magnetic field strength and spatial distribution. The two models differed in curvature, and their magnetic field distributions were evaluated using the finite element magnetic analysis software FEMM. The system was applied to expansion-tube experiments, in which the magnetic field was synchronized with a shock wave propagating at 7.7 km/s. A pulsed current of approximately 1 kA generated a magnetic flux density of up to 1.5 T near the stagnation point, and the quasi-steady duration exceeded twice the effective test time. High-speed imaging showed that the thickness of the self-emission region increased by approximately 15.7% and 16.2% for the two models, respectively. The observed increases were consistent with theoretical predictions and trends reported in previous studies. Changes were also observed in the emission spectra measured inside the shock layer. The present results demonstrate that the developed system enables strong magnetic fields and flexible field distributions under short-duration expansion-tube conditions and provides an experimental approach for investigating MHD aerobraking.
The paper highlights major outcomes from nearly a decade of research surrounding the three Boundary Layer Transition/Turbulence flight experiments (BOLT-1A, BOLT-2, and BOLT-1B) and associated preflight and postflight research related to those flights. The intent here is to summarize key findings to date through a review of associated literature from the BOLT program and to highlight the progress made in our present understanding of transition and turbulence from these flight programs. Major topics addressed include outcomes from wind-tunnel testing of this common geometry in many facilities over the years, key advancements in numerical simulation techniques motivated by the need to model physics on the complex BOLT geometry, progress in flight experimentation methodologies, the importance of combining hypersonic flight experiments with atmospheric measurements, and the value of programs like BOLT for accelerating workforce experience. A list of suggested focus areas for future work is provided.
