What is it about?
Hypersonic vehicles fly extremely fast, at speeds five times the speed of sound, but steering them is challenging because traditional control surfaces like rudders can overheat or require complex mechanics. This experimental investigation involves shooting a jet of air from a curved slot on a model's trailing edge to control direction without moving parts. Using high-speed cameras and force sensors, we found the jet creates shock waves and expanding air flows that act like virtual steering surfaces, boosting thrust by 17%, turning ability by 18%, and lift by 9% at the optimal jet pressure.
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Photo by Oo Jiflip on Unsplash
Why is it important?
This investigation is one of the earliest experimental explorations of curved-surface jets for attitude control in hypersonic flows (Mach 5), addressing a critical gap left by prior research, which primarily focused on lower speeds, opposing jets, or the transverse Jet. Amid surging global investments in hypersonics—from U.S. DoD budgets emphasizing advanced control systems in 2026 to ongoing AI-driven flow predictions at institutions—our 2022 work remains timely, revealing an optimal pressure ratio that enhances thrust, pitching moment, and lift by up to 18% via virtual shockwave rudders. It could revolutionize hypersonic vehicle design, enabling lighter, heat-resistant alternatives to traditional mechanics and boosting maneuverability for space, defense, and commercial applications.
Perspectives
After more than a decade in aerodynamics, this research on Mach 5 curved-surface jet control still makes my heart leap as if witnessing a shock wave for the first time. It is far more than striking schlieren images; it is a mirror reflecting the shared agony and rekindled passion of every researcher who has faced the hypersonic thermal barrier. Seeing a single jet "sculpt" a virtual rudder amidst five-times-sonic turbulence—boosting control moment by nearly 18%—is a moment of pure technical elegance. It turns out that the invisible air we often overlook can, with such ingenuity, be tamed into precise authority, offering a silent comfort to those of us who have gritted our teeth through countless failed calculations. Even in the face of Mach 5 gales, what carries us forward is an unquenchable curiosity and a stubborn love for the unknown. May this spark warm your journey, just as it has reignited the fire in mine.
Dr. Zhikun Sun
Nanjing University of Aeronautics and Astronautics
Read the Original
This page is a summary of: Experimental investigation of flow control of a curved-surface jet at Mach 5 hypersonic flow, Physics of Fluids, June 2022, American Institute of Physics,
DOI: 10.1063/5.0094555.
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