Multi-Physics Modeling of Hypersonics

Apollo 11 Postdoctoral Fellowships at Purdue - Proposal
Kyle Hanquist, Assistant Professor 

Research Goals

The postdoctoral appointment will focus on advancing computational high-speed aerothermodynamics, particularly in the context of hypersonic flight and atmospheric re-entry. This research involves the development and implementation of multi-physics models—encompassing fluid dynamics, plasma physics, and material response—within high-performance computing environments to simulate and analyze extreme flow conditions.

Hypersonics is complex, multi-disciplinary, and is best investigated by diverse collaborations. While aerothermodynamics is a defining attribute of hypersonics, it is coupled to other areas such as propulsion, GNC, structures, and signals. A key motivation for this work stems from the limitations of current experimental facilities, which typically offer either flight-like enthalpy for short durations (missing material response physics) or flight-like testing times at lower enthalpy (missing high-enthalpy gas effects like chemical reactions and thermal nonequilibrium). These constraints highlight the need for robust computational approaches that can be integrated with experimental data to provide deeper insight into high-speed aerothermodynamic phenomena under flight-relevant conditions.

 

A diagram of a multi-physics modeling framework for hypersonics

 

The Hanquist Group’s approach to modeling hypersonic physics represents this multi-physics nature as represented in the diagram above. As shown by the functional boxes, we have excellent capabilities for approaching chemical kinetics, flow, and structural response. The Postdoctoral Fellow (Fellow) would expand this into two new regimes that fittingly had significant engineering impacts on the Apollo missions:

Plasma radio blackout mitigation. At the high Mach numbers encountered during hypersonic flight and atmospheric re-entry, the surrounding flow can become ionized, forming a plasma sheath that may block radio signals—a phenomenon known as radio blackout. This occurs when the plasma frequency exceeds the communication signal frequency, preventing transmission. Radio blackout is a critical concern for planetary entry missions. Fittingly, the Apollo missions—after which this Fellowship is named—experienced ionization blackouts lasting approximately three minutes, with Apollo 13 enduring a six-minute blackout due to its unique re-entry trajectory. To address this challenge, the Fellow will integrate the magnetohydrodynamics equations into the existing multi-physics framework to explore mitigation strategies. One such approach involves applying magnetic fields to manipulate the plasma and potentially open communication pathways during blackout periods.

Thermal protection systems. In hypersonic and atmospheric re-entry flows, aerodynamic heating is so intense that it often dictates the overall vehicle configuration. Effectively managing these extreme thermal loads is essential for mission success. The high-speed flow interacts with the vehicle surface through mechanisms such as in-depth conduction, ablation, and complex gas-surface chemistry. To investigate these phenomena, the Fellow will couple a material response solver with the flow field solver, enabling detailed simulations of the aerothermodynamic environment during hypersonic entry. A precise understanding of these interactions is critical—not only to ensure mission safety, but also to avoid overdesigning thermal protection systems, which can add unnecessary mass and cost.

Design of Experiment. A strong synergy between modeling and experimentation is essential to address the complex physical phenomena in hypersonics. Purdue University hosts state-of-the-art hypersonic testing facilities, including tw​o particularly relevant to this work: 1) HYPULSE, a shock tunnel capable of replicating plasma flowfields, and 2) an ablation torch facility that can simulate sustained aerodynamic heating on materials over several minutes. The Fellow will design an experiment in at least one of these facilities towards validating the modeling approaches described above.

Expected Deliverables

  1. Present and submit a peer-reviewed paper to an international conference such as the International Symposium on Shock Waves (ISSW) or Rarefied Gas Dynamics (RGD).
  2. Deliver a technical talk at the Ablation Workshop, showcasing recent advancements and findings.
  3. Develop and publish a publicly accessible tutorial on the multi-physics framework, aimed at facilitating broader adoption and reproducibility.
  4. Co-author at least one journal article in a high-impact publication related to multi-physics modeling of hypersonics.

Affiliated Faculty

Assistant Professor in Defense Innovation Kyle Hanquist
School of Aeronautics and Astronautics, Purdue University

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