The theoretical prediction of the boundary-layer-blockage and external flow choking at moving aircraft in ground effects

2021 ◽  
Vol 33 (3) ◽  
pp. 036108
Author(s):  
V. R. Sanal Kumar ◽  
Vignesh Saravanan ◽  
Vivek Srinivasan ◽  
S. Ganesh Shankar ◽  
Sivabalan Mani ◽  
...  
Keyword(s):  
Boundary Layer ◽  
Theoretical Prediction ◽  
External Flow ◽  
Flow Choking ◽  
Ground Effects

Correction: Studies on 2D and 3D Boundary layer Blockage and External Flow Choking at Moving Wing in Ground Effect

2018 ◽  
Author(s):  
VR Sanal Kumar ◽  
Vignesh Saravanan ◽  
Vivek Srinivasan ◽  
Ganesh Shankar S ◽  
Sivabalan Mani ◽  
...  
Keyword(s):  
Boundary Layer ◽  
Ground Effect ◽  
External Flow ◽  
Flow Choking ◽  
2D And 3D ◽  
Wing In Ground Effect

Studies on 2D and 3D Boundary layer Blockage and External Flow Choking at Moving Wing in Ground Effect

2018 ◽  
Author(s):  
VR Sanal Kumar ◽  
Vignesh Saravanan ◽  
Vivek Srinivasan ◽  
Ganesh Shankar S ◽  
Sivabalan Mani ◽  
...  
Keyword(s):  
Boundary Layer ◽  
Ground Effect ◽  
External Flow ◽  
Flow Choking ◽  
2D And 3D ◽  
Wing In Ground Effect

Boundary-Layer Flow Between the Attachment Lines on a Flat Plate Delta Wing at Incidence

1962 ◽  
Vol 13 (1) ◽  
pp. 1-16
Author(s):  
J. C. Cooke
Keyword(s):  
Boundary Layer ◽  
Delta Wing ◽  
Three Dimensional ◽  
External Flow ◽  
Two Dimensional ◽  
Conical Flow ◽  
Slender Body Theory ◽  
Layer Flow ◽  
Body Theory ◽  
Transition Fronts

SummaryA three-dimensional laminar-boundary-layer calculation is carried out over the area concerned. The external flow is simplified, being calculated by slender-body theory assuming conical flow, with two point vortices above the wing, their positions and strength being determined by experiment. Attempts are made to draw transition fronts both for two-dimensional and sweep instability from this calculation. The combination of these gives fronts similar to those observed in some experiments. Because there is little or no pressure gradient over the area in question it is suggested that it is a region where distributed suction might usefully be applied in order to maintain laminar flow and reduce drag.

External Flow Choking at the Landing Phase of Aircraft and Re-entry Vehicles

2019 ◽  
Author(s):  
Dhanalakshmi Krishnamoorthy ◽  
Deepak Natarajan ◽  
Amrith Mariappan ◽  
Kiridharan R ◽  
VR Sanal Kumar
Keyword(s):  
External Flow ◽  
Flow Choking

Instability in a viscous flow driven by streamwise vortices

2001 ◽  
Vol 432 ◽  
pp. 127-166 ◽  
Author(s):  
K. W. BRINCKMAN ◽  
J. D. A. WALKER
Keyword(s):  
Boundary Layer ◽  
Numerical Solutions ◽  
Three Dimensional ◽  
Wall Layer ◽  
External Flow ◽  
Three Dimensional Flow ◽  
Dimensional Flow ◽  
Wall Flow ◽  
Turbulent Wall ◽  
Near Wall

Unsteady separation processes at large finite, Reynolds number, Re, are considered, as well as the possible relation to existing descriptions of boundary-layer separation in the limit Re → ∞. The model problem is a fundamental vortex-driven three-dimensional flow, believed to be relevant to bursting near the wall in a turbulent boundary layer. Bursting is known to be associated with streamwise vortex motion, but the vortex/wall interactions that drive the near-wall flow toward breakdown have not yet been fully identified. Here, a simulation of symmetric counter-rotating vortices is used to assess the influence of sustained pumping action on the development of a viscous wall layer. The calculated solutions describe a three-dimensional flow at finite Re that is independent of the streamwise coordinate and consists of a crossflow plane motion, with a developing streamwise flow. The unsteady problem is constructed to mimic a typical cycle in turbulent wall layers and numerical solutions are obtained over a range of Re. Recirculating eddies develop rapidly in the near-wall flow, but these eddies are eventually bisected by alleyways which open up from the external flow region to the wall. At sufficiently high Re, an oscillation was found to develop in the streamwise vorticity field near the alleyways with a concurrent evolution of a local spiky behaviour in the wall shear. Above a critical value of Re, the oscillation grows rapidly in amplitude and eventually penetrates the external flow field, suggesting the onset of an unstable wall-layer breakdown. Local zones of severely retarded streamwise velocity are computed which are reminiscent of the low-speed streaks commonly observed in turbulent boundary layers. A number of other features also bear a resemblance to observed coherent structure in the turbulent wall layer.

The Laminar Boundary Layer on a Hot Cylinder Fixed in a Fluctuating Stream

1961 ◽  
Vol 28 (3) ◽  
pp. 339-346 ◽  
Author(s):  
R. J. Gribben
Keyword(s):  
Boundary Layer ◽  
Mach Number ◽  
Laminar Boundary Layer ◽  
Small Amplitude ◽  
External Flow ◽  
Low Speed ◽  
Boundary Layer Equations ◽  
Special Cases ◽  
Exact Calculations ◽  
Small Amplitude Oscillation

The equations for nonsteady, two-dimensional low-speed compressible flow in the laminar boundary layer are solved approximately by use of the Pohlhausen technique with the assumption of quartic profiles for the velocity and temperature. The external flow considered is of the form of a steady basic velocity with a superimposed small amplitude oscillation such as may arise, for example, when a sound wave is present in a uniform incident stream. The analysis is then applicable to the case of a hot cylinder fixed in such a stream. Terms of the order of the incident stream Mach number are neglected in the expressions for external flow quantities (whereas the low-speed boundary-layer equations involve errors of the order of only the square of this Mach number). Two special cases are worked out—the flow over a flat plate for which there is fair agreement with available exact calculations, and the flow over a circular cylinder.

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