Kinetic Theory of the Sharp Leading Edge Problem in Supersonic Flow

Estimates for pressures on the surface of a given delta wing at zero incidence in a steady uniform stream of air are obtained by numerically integrating two semi-characteristic forms of equations which govern the inviscid supersonic flow of an ideal gas with constant specific heats. In one form of the equations coordinate surfaces are fixed in space so that the surface of the wing, which has round sonic leading edges, is a coordinate surface. In the other, two families of coordinates are chosen to be stream-surfaces. For each form of the equations, a finite difference method has been used to compute the supersonic flow around the wing. Convergence of the numerical results, as the mesh is refined, is slow near the leading edge of the wing and an extrapolation procedure is used to predict limiting values for the pressures on the surface of the wing at two stations where theoretical and experimental results have been given earlier by another worker. At one station differences between the results given here and the results given earlier are significant. The two methods used here produce consistent values for the pressures on the surface of the wing and, on the basis of this numerical evidence together with other cited numerical results, it is concluded that the pressures given here are close to the true theoretical values.

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Application Of Elastic Layers To Register Pressure Field On The Model Surface In Supersonic Flow

Siberian Journal of Physics ◽

10.54362/1818-7919-2016-11-1-23-33 ◽

2016 ◽

Vol 11 (1) ◽

pp. 23-33

Author(s):

Maxim Golubev ◽

Andrey Shmakov

Keyword(s):

Surface Waves ◽

High Frequency ◽

High Speed ◽

Pressure Pulsation ◽

Pressure Field ◽

Leading Edge ◽

Supersonic Wind Tunnel ◽

Register Pressure ◽

Elastic Layers ◽

Sharp Leading Edge

The work presents the results of application of panoramic interferential technique which is based on elastic layers (sensors) usage to obtain pressure distribution on the flat plate having sharp leading edge. Experiments were done in supersonic wind tunnel at Mach number M = 4. Sensitivity and response time are shown to be enough to register pressure pulsation against standing and traveling sensor surface waves. Applying high-frequency image acquiring is demonstrated to make possible to distinguish at visualization images high-speed disturbances propagating in the boundary layer from low-speed surface waves

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Fan Stability With Leading Edge Damage: Blind Prediction and Validation

10.1115/gt2021-59495 ◽

2021 ◽

Author(s):

E. J. Gunn ◽

T. Brandvik ◽

M. J. Wilson ◽

R. Maxwell

Keyword(s):

Supersonic Flow ◽

High Speed ◽

Leading Edge ◽

Rotating Stall ◽

Stall Inception ◽

Blind Prediction ◽

Edge Damage ◽

The Impact ◽

Operating Points ◽

Relative Flow

Abstract This paper considers the impact of a damaged leading edge on the stall margin and stall inception mechanisms of a transonic, low pressure ratio fan. The damage takes the form of a squared-off leading edge over the upper half of the blade. Full-annulus, unsteady CFD simulations are used to explain the stall inception mechanisms for the fan at low- and high-speed operating points. A combination of steady and unsteady simulations show that the fan is predicted to be sensitive to leading edge damage at low speed, but insensitive at high speed. This blind prediction aligns well with rig test data. The difference in response is shown to be caused by the change between subsonic and supersonic flow regimes at the leading edge. Where the inlet relative flow is subsonic, rotating stall is initiated by growth and propagation of a subsonic leading edge flow separation. This separation is shown to be triggered at higher mass flow rates when the leading edge is damaged, reducing the stable flow range. Where the inlet relative flow is supersonic, the flow undergoes a supersonic expansion around the leading edge, creating a supersonic flow patch terminated by a shock on the suction surface. Rotating stall is triggered by growth of this separation, which is insensitive to leading edge shape. This creates a marked difference in sensitivity to damage at low- and high-speed operating points.

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