Sustainable In-Space Manufacturing through Rapid Prototyping Technology

The goal of this research investigation is to advance the state of the art for the performance analysis of planetary entry systems equipped with magnetohydrodynamic (MHD) energy generator and flow control devices. This goal is advanced through three primary contributions, summarized below. Contribution I: Magnetohydrodynamic Energy Generation and Lorentz Force Drag Augmentation Performance Characterization Calculating the energy reclaimed through MHD energy generation during planetary entry is challenging, with previous investigations employing full-field numerical analysis of the hypersonic flow-field, chemical and ionizing reactions, and detailed design of the MHD energy generator at specific boundary conditions. The additional drag potential due to the presence of the Lorentz force is similarly challenging to compute without a full-field numerical simulation. These calculations are made even more challenging during mission design, as the specific entry vehicle trajectory, geometry, and energy storage system may be unknown, and trade studies can become computationally expensive. Thus, there is a need for tools and techniques that are more applicable to conceptual design. In comparison to the current state of the art, this contribution represents methodologies by which the energy available for extraction through MHD energy generation and additional drag due to the Lorentz force can be calculated in a manner suitable for conceptual design. With respect to the state of the art, these methodologies do not require detailed knowledge of the MHD generator or flow control system, and depend on only on parameters such as the planetary body, entry vehicle diameter, drag coefficient, entry vehicle mass, and applied magnetic field strength, enabling rapid iterations and trades useful for identifying planetary entry mission architectures that may benefit from the inclusion of MHD energy generation and flow control. Contribution II: Experimental Demonstration of Magnetohydrodynamic Energy Generation in Conditions and Configurations Relevant to Planetary Entry The number of experimental investigations of MHD interaction for conditions relevant to planetary entry is limited. There are a few experimental investigations dating back to the late 1950s and 1960s, mainly concerned with the effects MHD interaction has on shock standoff distance. More recent studies describe various experimental campaigns aimed at investigating drag enhancement, heat-flux mitigation, artificial ionization, and energy generation through MHD interaction. From all of these experiments, it is apparent that creating and testing MHD interaction in conditions relevant to planetary entry is a challenging task requiring specialized equipment. As compared to the current state of the art, the principal contribution made in this area is the design and execution of an experimental campaign to demonstrate MHD energy generation for a nonchannel type MHD energy generation on a simulated blunt-body reentry vehicle. The overall structure of the experiment involves a gas source accelerated to supersonic speed, which is artificially ionized to create a supersonic plasma, and allowed to pass over a permanently magnetized ceramic model with electrodes for current generation. The proposed experimental design has been demonstrated with limited configurations, and appears to show a positive effect for current through the MHD generator model when the supersonic plasma discharge is present. In comparision with previous MHD experiments, the experimental campaign will be expanded to include additional diagnostics and larger data sets focused around flight relevant conditions in order to better inform parametric dependencies for theoretical models used in conceptual design. Contribution III: Impact of Magnetohydrodynamic Energy Generation and Lorentz Force Drag Augmentation on Planetary Entry Architectures Previous literature concerning MHD and planetary entry has usually focused on one entry vehicle configuration at one or a few entry conditions, limiting the analysis capability for rapid trade studies with the limited entry vehicle design and trajectory specifics available in conceptual design. In comparison with the state of the art, this contribution develops systems analysis capabilities for entry systems equipped with MHD generators and flow control devices. These capabilities aim to quantify the additional system mass required for MHD systems, as well as their potential performance for energy generation and flow control across a wide variety of vehicles. Currently, a conceptual analysis capability for MHD generator equipped entry descent and landing systems has been developed. This methodology integrates models for flight dynamics, MHD energy generation, energy storage, atmosphere, and post-shock chemical equilibrium to compute the potential for generation and storage of energy through MHD interaction. In addition, the application of the methodology has been demonstrated for various case studies in which the entry mass, entry conditions, and energy storage system technologies were varied. A benefit of this methodology for space systems conceptual design is the ability to conduct rapid iteration across many design parameters without detailed generator and vehicle design information, thus allowing the identification of mission configurations amenable to MHD energy generation and storage. For a majority of the cases analyzed, storage of the available energy with an electrical energy storage (EES) system that had a medium or higher TRL was deemed possible. As such, MHD energy generation and storage is deemed a potential useful technology for future planetary exploration missions. In addition, a systems analysis capability for the effect of MHD flow interaction on a planetary entry vehicle equipped with a MHD energy generation system has been developed. The analysis techniques employed and the associated results demonstrate that MHD flow interaction effects can be computed for a variety of entry vehicles using fundamental functional relationships between flow properties. The results show that MHD flow interaction for the magnetic field configuration presented causes a significant increase in overall entry vehicle deceleration and trajectory given appropriate alkali metal seed and magnetic field strength. The effect of the flow interaction is similar to a decrease in the ballistic coefficient of a particular vehicle, essentially causing the vehicle to decelerate higher in the atmosphere. Consideration of active control of the magnetic field orientation and magnitude for inducing lift and moments on the vehicle will be considered in future work. This aspect of the MHD flow interaction could prove particularly interesting because the majority of the additional drag occurs at much higher altitudes than the aerodynamic drag. Summary and Conclusions To conclude, MHD energy generation and drag augmentation has the potential to significantly benefit planetary entry system performance and should be considered for future development. There are significant amounts of energy that can be reclaimed, which may have applicability to future Mars missions, as demonstrated in peer-reviewed publication and NIAC collaboration. This research effort has advanced the state of the art for MHD energy generation and flow control as applied to the design and development of planetary entry systems.