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Supercritical airfoils feature four main benefits: they have a higher drag-divergence Mach number, [21] they develop shock waves farther aft than traditional airfoils, [22] they greatly reduce shock-induced boundary layer separation, and their geometry allows more efficient wing design (e.g., a thicker wing and/or reduced wing sweep, each of which may allow a lighter wing).
The Convair 990 had bumps called antishock bodies added to the top surface of the wing with the intent of achieving the required cruise speed. However, the area distribution in the channels formed by the nacelle/pylon/wing surfaces also caused supersonic velocities and was the source of significant drag.
Transonic (or transsonic) flow is air flowing around an object at a speed that generates regions of both subsonic and supersonic airflow around that object. [1] The exact range of speeds depends on the object's critical Mach number, but transonic flow is seen at flight speeds close to the speed of sound (343 m/s at sea level), typically between Mach 0.8 and 1.2.
Conical shockwave with its hyperbola-shaped ground contact zone in yellow The abruptness of change in the features of the medium, that characterize shock waves, can be viewed as a phase transition : the pressure–time diagram of a supersonic object propagating shows how the transition induced by a shock wave is analogous to a dynamic phase ...
The supercritical airfoil is a type that results in reasonable low speed lift like a normal airfoil, but has a profile considerably closer to that of the von Kármán ogive. All modern civil airliners use forms of supercritical aerofoil and have substantial supersonic flow over the wing upper surface.
Anti-shock body is the name given by Richard T. Whitcomb to a pod positioned on the upper surface of a wing. [1] Its purpose is to reduce wave drag while travelling at transonic speeds (Mach 0.8–1.0), which includes the typical cruising range of conventional jet airliners.
Years of research and experience with the unusual conditions of supersonic flow have led to some interesting conclusions about airfoil design. Considering a rectangular wing, the pressure at a point P with coordinates (x,y) on the wing is defined only by the pressure disturbances originated at points within the upstream Mach cone emanating from point P. [3] As result, the wing tips modify the ...
In thermodynamics, the Frenkel line is a proposed boundary on the phase diagram of a supercritical fluid, separating regions of qualitatively different behavior. [1] Fluids on opposite sides of the line have been described as "liquidlike" or "gaslike", and exhibit different behaviors in terms of oscillation, excitation modes, and diffusion.