NASA SBIR Phase I: Development of a Plasma Injector for Supersonic Drag Reduction

Spark driven by EHT solid-state power system

Methods to reduce the turbulent viscous skin friction stand out as paramount to increasing the energy efficiency, and therefore the aerodynamic efficiency of supersonic aircraft. Eagle Harbor Technology (EHT) proposes to develop and optimize a MHD plasma injector, which will be used to efficiently reduce the viscous skin friction in supersonic aircraft. EHT has developed similar MHD plasma injection technologies, which have been applied to a number of different fusion energy science, aerospace thruster, and basic research investigations. Here, we aim to computationally investigate and verify the dominant physical mechanisms for MHD plasma drag reduction; develop a proof of concept plasma injector demo, which conforms to necessary power and efficiency requirements for an onboard flight-relevant system; and use insights gained through our computational investigations to optimize the performance of our MHD plasma injector for maximum aerodynamic efficiency. This investigation will focus on flight-relevant Reynolds and magnetic Reynolds numbers at low supersonic (M<~3) speeds. Phase II research will couple the plasma injector to a scale model airframe for detailed in-situ supersonic wind tunnel testing. The Phase II research will produce a fully-realized working plasma injector prototype that conform to power requirements of an on-board power system.

Energy deposition drag reduction technologies came to the forefront over a decade ago following several decades of previous work in Russia. Despite its long history, questions remain regarding the detailed physical mechanism of plasma drag reduction and the optimal actuator design. Though predominantly a thermodynamic mechanism, few CFD studies have investigated the process beyond using a single fluid with ideal thermodynamics. Additionally, a simple and robust hardware solution is still required for potential implementation on commercial aircraft. To address these issues EHT will utilize both novel numerical modeling techniques and newly developed actuator technology during a Phase I SBIR program.

The computational portion of the project will employ the Mach2/3 extended magnetohydrodynamics (MHD) package to model the plasma actuator and its effects on supersonic (Ma ~2-3) drag reduction. The Mach package has the capability to model neutral air and multiple charge states with atomic physics capabilities and thermodynamic closures beyond ideal MHD. Initial modeling will inform the design of the plasma source for optimal drag reduction.

Temperature profile of Mach 3 flow over a rounded cylindrical airfoil with hot plasma injected at the fore.

The EHT Integrated Power Module (IPM) brings new capabilities that will significantly increase the capabilities of plasma actuators. The IPM solid switching technology allows for precision plasma injector control on fast time scales (~ 20 ns). The IPM technology allows for a wide range of plasma injector parameters including high peak power levels (> 10 MW) and adjustable average power with pulse length and duty cycle control. Since the microsecond time scale of Joule heating occurs much faster than conductive and convective heating, the IPM allows for precise control of the plasma injector, which will allow for careful comparison to the numerical model.

This research was supported by NASA.