Analysis of the effects of positive ions and boundary layer temperature at various hypersonic speeds on boundary layer density

(1) North Creek High School, Bothell, Washington, USA, (2) Karpagam University, Coimbatore, India

Vehicles traveling at hypersonic speeds ionize the air around them. This ionization leads to the possibility of utilizing an induced positive surface charge to lower the density of the boundary layer flow electrostatically. Reducing the boundary layer's density would have several positive effects, such as lowering the drag and heat transfer. The study's goal was to identify the Mach numbers for which the electrostatic drag and heat transfer manipulation would be most applicable inside the stratosphere. We hypothesized that the potential to use induced positive surface charge repulsion to lower boundary layer density would increase with speed, and there will be greater (>10%) potential to decrease boundary layer density at a lower bound estimate of Mach 18-19. We also explored the extent to which extrapolation through a quadratic model based on Dr. Jesse R. Maxwell's data in Morphing Waveriders for Atmospheric Entry could be used to approximate maximum boundary layer temperature values. The experiments were conducted using computational fluid dynamics software. The study demonstrated that, on average, higher Mach speeds resulted in a considerably higher potential decrease in density. Also, as predicted by the hypothesis, a significant potential reduction in density occurred near Mach 19. The study also supported using the quadratic model based on Maxwell's data for approximating the maximum boundary layer temperature up to at least Mach 26. This study highlights that further research on the surface charge method is warranted as we seek to explore higher hypersonic speeds within the stratosphere.

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