A theory of circulation control by slot-blowing, applied to a circular cylinder

1968 ◽  
Vol 33 (3) ◽  
pp. 495-514 ◽  
Author(s):  
J. Dunham
Keyword(s):  
Boundary Layer ◽  
Circular Cylinder ◽  
Flow Field ◽  
Lift Force ◽  
Air Flow ◽  
Inviscid Flow ◽  
Boundary Layer Theory ◽  
Experimental Results ◽  
Circulation Control ◽  
Narrow Slot

Lift can be generated on a circular cylinder with its axis normal to an air flow by blowing a sheet of air tangentially round the upper surface from a narrow slot or slots. This lift force may be estimated by matching the external inviscid flow field with separation points calculated by Spalding's unified boundary-layer theory. The theory reproduces experimental results reasonably well, except in certain special conditions fully discussed.

Boundary-layer theory for blast waves

1975 ◽  
Vol 71 (1) ◽  
pp. 65-88 ◽  
Author(s):  
K. B. Kim ◽  
S. A. Berger ◽  
M. M. Kamel ◽  
V. P. Korobeinikov ◽  
A. K. Oppenheim
Keyword(s):  
Heat Transfer ◽  
Boundary Layer ◽  
Flow Field ◽  
Classical Problem ◽  
Outer Region ◽  
Inviscid Flow ◽  
Boundary Layer Theory ◽  
Blast Waves ◽  
Matched Asymptotic Expansion ◽  
Flow Equations

The necessity for developing a boundary-layer theory in the case of blast waves stems from the fact that inviscid flow solutions often yield physically unrealistic results. For example, in the classical problem of the so-called non-zero counterpressure explosion, one obtains infinite temperature and zero density in the centre at all times even after the shock front deteriorates into a sound wave. In reality, this does not occur, as a consequence, primarily, of heat transfer that modifies the structure of the flow field around the centre without drastically affecting the outer region. It is profitable, therefore, to consider the blast wave as a flow field consisting of two regions: the outer, which retains the properties of the inviscid solution, and the inner, which is governed by flow equations including terms expressing the effects of heat transfer and, concomitantly, viscosity. The latter region thus plays the role of a boundary layer. Reported here is an analytical method developed for the study of such layers, based on the matched asymptotic expansion technique combined with patched solutions.

scholarly journals UNSTEADY FLOW AROUND A VERTICAL CIRCULAR CYLINDER IN A WAVE

1988 ◽  
Vol 1 (21) ◽  
pp. 68
Author(s):  
Kenjirou Hayashi ◽  
Toshiyuki Shigemura
Keyword(s):  
Boundary Layer ◽  
Circular Cylinder ◽  
Unsteady Flow ◽  
Incident Wave ◽  
Lift Force ◽  
Boundary Layer Separation ◽  
Long Time ◽  
Unsteady Characteristics ◽  
Vertical Cylinders ◽  
The Relationship

The unsteady characteristics of flow around a vertical circular cylinder in a typical wave, under which the lift force acting on it is very stable and has a frequency which is twice that of the incident wave, have been investigated experimentally. The relationship between the fluctuating flow velocities near the boundary layer separation points and the lift force acting on a sectional part of the cylinder has been understood quantitatively. To clarify the region where the appearance of stable lift force occurs, the long time records of lift forces acting on vertical cylinders in waves are also performed.

Note on the Flow past a Circular Cylinder

1935 ◽  
Vol 31 (4) ◽  
pp. 585-588
Author(s):  
L. Howarth
Keyword(s):  
Boundary Layer ◽  
Circular Cylinder ◽  
Experimental Results ◽  
Turbulent Motion ◽  
Flow Past ◽  
Method Of Solution

Buri's method of solution of the equations of turbulent motion in a boundary layer has been used extensively in a previous paper. Since the results of that investigation have not been compared with experiment, nor has any other application of Buri's method been checked experimentally, it seems advisable to apply this method to a problem for which the experimental results are known.

scholarly journals Phase-Averaged Method Applied to Periodic Flow Between Shrouded Corotating Disks

2003 ◽  
Vol 9 (4) ◽  
pp. 293-301 ◽  
Author(s):  
Shen-Chun Wu ◽  
Yau-Ming Chen
Keyword(s):  
Boundary Layer ◽  
Flow Field ◽  
Dynamic Behavior ◽  
Outer Region ◽  
Experimental Results ◽  
Periodic Flow ◽  
Vortical Structures ◽  
Boundary Layer Region ◽  
Layer Region ◽  
Inner Region

This study investigates the coherent flow fields between corotating disks in a cylindrical enclosure. By using two laser velocimeters and a phase-averaged technique, the vortical structures of the flow could be reconstructed and their dynamic behavior was observed. The experimental results reveal clearly that the flow field between the disks is composed of three distinct regions: an inner region near the hub, an outer region, and a shroud boundary layer region. The outer region is distinguished by the presence of large vortical structures. The number of vortical structures corresponds to the normalized frequency of the flow.

Effects of a Source-Type Hypersonic Free Stream on the Flow Field about an Axisymmetric Cone

1966 ◽  
Vol 17 (2) ◽  
pp. 161-176
Author(s):  
Stuart B. Savage
Keyword(s):  
Boundary Layer ◽  
Flow Field ◽  
Layer Thickness ◽  
Surface Pressure ◽  
Shock Layer ◽  
Boundary Layer Thickness ◽  
Free Stream ◽  
Inviscid Flow ◽  
Source Type ◽  
Displacement Thickness

SummaryMost hypervelocity tunnels presently make use of conical or wedge type nozzles which produce source-type flow non-uniformities in the test section. The present paper considers the effects of such free-stream non-uniformities on the flow fields about slender axisymmetric cones. The inviscid flow is considered within the framework of the Newtonian expansion procedure of Cole and simple expressions are obtained for the flow field properties in the shock layer. This inviscid analysis predicts that a free-stream gradient of a magnitude typical of present hypervelocity test facilities can cause sizeable reductions in surface pressure and increased shock-layer thickness at the aft end of long slender conical models. The cone pressure, accounting for the viscous-inviscid interaction, is obtained by applying the inviscid analysis in tangent-cone fashion to the effective body (i.e. physical cone plus boundary-layer displacement thickness). Cheng’s simple equation is used to approximate the hypersonic boundary-layer development. Large increases in the boundary-layer thickness at the aft end of the model are predicted as a consequence of the source flow effects. The analyses agree well with experimental measurements of surface pressure and boundary-layer thickness made on a 5° half-angle cone tested in the Republic 24 inch Longshot I hypervelocity shock tunnel.

A note on interior vs. boundary-layer damping of surface waves in a circular cylinder

1998 ◽  
Vol 364 ◽  
pp. 319-323 ◽  
Author(s):  
J. W. MILES ◽  
D. M. HENDERSON
Keyword(s):  
Boundary Layer ◽  
Reynolds Number ◽  
Circular Cylinder ◽  
Surface Waves ◽  
Contact Line ◽  
Present Note ◽  
Experimental Results ◽  
Clean Surface ◽  
Irrotational Flow ◽  
Comparable Accuracy

Martel et al. (1998) have shown that interior damping may be comparable with boundary-layer damping for surface waves in small cylinders and that its incorporation yields predictions in agreement with the experimental results of Henderson & Miles (1994) for non-axisymmetric waves on a clean surface with a fixed contact line. In the present note, Henderson & Miles's boundary-layer calculation is supplemented by a calculation of interior damping based on Lamb's dissipation integral for an irrotational flow. The analysis, which omits second-order boundary-layer effects, is simpler than that of Martel et al. (which includes these effects and is based on an expansion in an inverse Reynolds number), but yields results of comparable accuracy within the parametric domain of the experiments. The corresponding calculations for a fully contaminated (inextensible) surface reduce the discrepancy between calculation and experiment but, in contrast to the results for a clean surface, leave a significant residual discrepancy. An unexplained discrepancy also remains for axisymmetric waves on either a clean or a contaminated surface.

Sign in / Sign up

Export Citation Format

Share Document