Transonic Flow (2nd Edition)

Dear Colleagues,

Transonic flow research has been of critical importance since the development of high-speed propellor aeroplanes and turbojet engines in the mid-1940s. The transonic flow regime has been, and remains, a challenge both for computational prediction and experimental simulation. The close coupling of shock waves, arising from the compressibility of air, and the effects of viscous flow on aircraft surfaces lead to highly unsteady and complicated flows that often involve detrimental flow separations. These can result in unsteady loading, potentially causing structural vibrations of aircraft components. An understanding of unsteady transonic flow is therefore fundamental to the safe design of high-speed aircraft.

Today’s aircraft industry is required to develop revolutionary new aircraft concepts to address the aviation impact on climate change and noise. This involves driving reassessments in design philosophy to achieve step changes in aerodynamic and propulsive efficiency, involving a much closer coupling of aircraft fuselage, wings, and engines. Emerging data on the transonic performance of these revolutionary designs have revealed how different the flows are to those associated with conventional tube and swept-wing designs.

Transonic flow research therefore remains critical to the development of high-speed aircraft today, and it is fitting that this Special Issue of Aerospace is devoted to this important topic.

Prof. Dr. Simon Prince
Guest Editor

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• transonic flow
• shock wave
• buffet
• boundary layer interaction
• computational fluid dynamics
• wind tunnel testing

• Transonic Flow in Aerospace (3 articles)

Title: Coupling analysis between the transonic buffeting flow and a heaving supercritical airfoil based on dynamic mode decomposition
Authors: Wei Kang; Binzhou Chen; Shilin Hu
Affiliation: School of Astronautics, Northwestern Polytechnical University, Shaanxi Province, 710072, P.R.China
Abstract: The coupling between the transonic buffeting flow and the supercritical airfoil with harmonic heave motion. An in-house finite volume solver is used to compute the flow dynamcis around the heaving airfoil at transonic flow. A parametric space of the heave frequency and amplitude is investigated using a verified fluid-structural interaction framework. The results indicate that there is a sharp deteriorate of the time-averaged lift and drag coefficient at f=fbuffet while the variance of the aerodynamic loading increases significantly at f≥fbuffet and higher heave amplitudes. Spatial-temporal flow pattern around the transonic airfoil is studied using dynamic mode decomposition (DMD) to unveil the coupling physical mechanism. The flow response under the heave motion is categorized into three types: a) Buffet frequency response with λ-shape shock wave structure and recirculation zone at the shock foot; b) Transitional response with a weaken shock and enhanced boundary layer; c) Heaving frequency lock-in response with the dominant heave motion. The driving motion of the airfoil transfers the energy of the buffet mode to boundary layer with more evenly energy balance by the energy contribution analysis of the DMD modes.