scholarly journals Measurements on Fully Wetted and Ventilated Ring Wing Hydrofoils

1967 ◽  
Vol 89 (3) ◽  
pp. 445-455 ◽  
Author(s):  
A. J. Acosta ◽  
T. Kiceniuk ◽  
E. R. Bate
Keyword(s):  
Pressure Distribution ◽  
Flat Plate ◽  
Cone Angle ◽  
Leading Edge ◽  
Water Tunnel ◽  
Force Measurements ◽  
Lift Curve ◽  
Made In ◽  
Visual Observations

Force measurements and visual observations were made in a water tunnel on fully wetted and ventilated flows past a family of conical ring wings having a flat plate section geometry. The diameter chord ratio was varied from one to three, at a fixed total included cone angle of 12 deg. The fully wetted flows all exhibited separation from the leading edge except for the largest diameter-chord ratio, a result which has been attributed to excessive cone angle. The effect of ventilation is to reduce markedly the lift curve slope. Pressure distribution measurements were also made under ventilating conditions for one member of this series. The effect of ventilation over only a portion of the circumference of the ring was also briefly investigated; large cross forces were developed by such ventilation.

Heat Transfer in the Separated and Reattached Flow on a Blunt Flat Plate

1974 ◽  
Vol 96 (4) ◽  
pp. 459-462 ◽  
Author(s):  
Terukazu Ota ◽  
Nobuhiko Kon
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Coefficient ◽  
Transfer Coefficient ◽  
Flat Plate ◽  
Leading Edge ◽  
Two Dimensional ◽  
Separated And Reattached Flow ◽  
The Heat Transfer Coefficient ◽  
Blunt Leading Edge ◽  
Made In

Heat transfer measurements are made in the separated, reattached, and redeveloped regions of the two-dimensional air flow on a flat plate with blunt leading edge. The flow reattachment occurs at about four plate thicknesses downstream from the leading edge and the heat transfer coefficient becomes maximum at that point and this is independent of the Reynolds number which ranged from 2720 to 17900 in this investigation. The heat transfer coefficient is found to increase sharply near the leading edge. The development of flow is shown through the measurements of the velocity and temperature in the separated, reattached, and redeveloped regions.

Two-dimensional planing at high Froude number

1958 ◽  
Vol 4 (5) ◽  
pp. 466-478 ◽  
Author(s):  
E. Cumberbatch
Keyword(s):  
Integral Equation ◽  
Pressure Distribution ◽  
Flat Plate ◽  
Froude Number ◽  
Water Surface ◽  
Flow Characteristics ◽  
Iteration Process ◽  
Leading Edge ◽  
Two Dimensional ◽  
High Froude Number

This paper examines the flow characteristics of a body of small slope planing at high Froude number over a water surface. An equation is obtained relating the slope of the planing surface to an integral containing the pressure distribution on the planing surface. The equation is expanded for large Froude number and a solution is obtained by an iteration process. At each stage of the iteration process the integral equation of ordinary thin aerofoil theory is solved. The pressure distribution on the planing surface is derived as a series in inverse powers of the Froude number F, as far as the F−4 term. Computations are performed for the planing of a flat plate, a parabolic surface, and a suitable linear combination of these shapes which results in a flow without a splash at the leading edge.

A Separated and Reattached Flow on a Blunt Flat Plate

1976 ◽  
Vol 98 (1) ◽  
pp. 79-84 ◽  
Author(s):  
Terukazu Ota ◽  
Masaaki Itasaka
Keyword(s):  
Flat Plate ◽  
Finite Thickness ◽  
Flow Characteristics ◽  
Leading Edge ◽  
Reattachment Length ◽  
Reattachment Point ◽  
Separated And Reattached Flow ◽  
Velocity Pressure ◽  
Blunt Leading Edge ◽  
Made In

Velocity, pressure, and turbulence measurements were made in the separated, reattached, and redeveloped regions of a two-dimensional incompressible flow over a flat plate with finite thickness and blunt leading edge. Flow characteristics, such as the reattachment length and the flow pattern in the separated region, were determined. The boundary layer characteristics of the flow downstream of the reattachment point are presented through various experimental results.

The Distribution of Pressure on an Aerofoil, in a Stream with a Spanwise Velocity Gradient

1955 ◽  
Vol 6 (1) ◽  
pp. 1-12 ◽  
Author(s):  
W. A. Mair
Keyword(s):  
Wind Tunnel ◽  
Drag Coefficient ◽  
Pressure Distribution ◽  
Flat Plate ◽  
Velocity Gradient ◽  
Lift Coefficient ◽  
Leading Edge ◽  
Pressure Measurements ◽  
Form Drag ◽  
Spanwise Velocity

SummaryPressure measurements were made at one section of an aerofoil of constant chord spanning a wind tunnel. A flat plate was mounted in the tunnel upstream of the aerofoil, so that the wake from the plate produced a spanwise velocity gradient at the aerofoil. By traversing the plate across the tunnel the position of the wake could be altered relative to the pressure holes in the aerofoil, so that the complete pressure distribution over the aerofoil in the neighbourhood of the wake could be found. The results showed that, because of the secondary flow produced by the interaction between the aerofoil and the wake, the variation of pressure across the wake for a given chordwise position was very small, except close to the leading edge. Thus the lift coefficient, based on the velocity outside the wake, was nearly constant across the wake. The form drag coefficient, based on the same velocity, was considerably reduced in the wake. Even when the form drag coefficient was based on the local velocity of the stream, a considerable reduction was found in the wake.

One-Dimensional Contact Pressure Distribution of Radial Tires in Motion

1995 ◽  
Vol 23 (2) ◽  
pp. 116-135 ◽  
Author(s):  
H. Shiobara ◽  
T. Akasaka ◽  
S. Kagami ◽  
S. Tsutsumi
Keyword(s):  
Pressure Distribution ◽  
Contact Pressure ◽  
Experimental Studies ◽  
Rolling Resistance ◽  
Leading Edge ◽  
Forward Direction ◽  
Contact Pressure Distribution ◽  
Support Ring ◽  
One Dimensional ◽  
Lowered Pressure

Abstract The contact pressure distribution and the rolling resistance of a running radial tire under load are fundamental properties of the tire construction, important to the steering performance of automobiles, as is well known. Many theoretical and experimental studies have been previously published on these tire properties. However, the relationships between tire performances in service and tire structural properties have not been clarified sufficiently due to analytical and experimental difficulties. In this paper, establishing a spring support ring model made of a composite belt ring and a Voigt type viscoelastic spring system of the sidewall and the tread rubber, we analyze the one-dimensional contact pressure distribution of a running tire at speeds of up to 60 km/h. The predicted distribution of the contact pressure under appropriate values of damping coefficients of rubber is shown to be in good agreement with experimental results. It is confirmed by this study that increasing velocity causes the pressure to rise at the leading edge of the contact patch, accompanied by the lowered pressure at the trailing edge, and further a slight movement of the contact area in the forward direction.

Experimental study of heat transfer in the boundary layer of a flat plate with the impact of weak shock waves on the leading edge

2020 ◽  
Author(s):  
V. L. Kocharin ◽  
A. A. Yatskikh ◽  
D. S. Prishchepova ◽  
A. V. Panina ◽  
Yu. G. Yermolaev ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Boundary Layer ◽  
Experimental Study ◽  
Shock Waves ◽  
Flat Plate ◽  
Leading Edge ◽  
Weak Shock ◽  
The Impact

Maximizing the efficiency of a flexible propulsor using experimental optimization

2015 ◽  
Vol 767 ◽  
pp. 430-448 ◽  
Author(s):  
Daniel B. Quinn ◽  
George V. Lauder ◽  
Alexander J. Smits
Keyword(s):  
Leading Edge ◽  
The Body ◽  
Phase Lag ◽  
Force Measurements ◽  
Experimental Optimization ◽  
Image Velocimetry ◽  
Flexible Panel ◽  
Gradient Based ◽  
Power Scale ◽  
Effective Angle

AbstractExperimental gradient-based optimization is used to maximize the propulsive efficiency of a heaving and pitching flexible panel. Optimum and near-optimum conditions are studied via direct force measurements and particle image velocimetry (PIV). The net thrust and power scale predictably with the frequency and amplitude of the leading edge, but the efficiency shows a complex multimodal response. Optimum pitch and heave motions are found to produce nearly twice the efficiencies of optimum heave-only motions. Efficiency is globally optimized when (i) the Strouhal number is within an optimal range that varies weakly with amplitude and boundary conditions; (ii) the panel is actuated at a resonant frequency of the fluid–panel system; (iii) heave amplitude is tuned such that trailing-edge amplitude is maximized while the flow along the body remains attached; and (iv) the maximum pitch angle and phase lag are chosen so that the effective angle of attack is minimized. The multi-dimensionality and multi-modality of the efficiency response demonstrate that experimental optimization is well-suited for the design of flexible underwater propulsors.

Aerodynamic Measurements on the Interaction of Secondary Jets and Separation Bubble

2012 ◽  
Author(s):  
A. Samson ◽  
S. Sarkar
Keyword(s):  
Flat Plate ◽  
Large Scale ◽  
Separation Bubble ◽  
Three Dimensional ◽  
Leading Edge ◽  
Bubble Interactions ◽  
Separated Shear Layer ◽  
Bubble Length ◽  
Flow Visualizations ◽  
Turbulence Generation

The dynamics of separation bubble under the influence of continuous jets ejected near the semi-circular leading edge of a flat plate is presented. Two different streamwise injection angles 30° and 60° and velocity ratios 0.5 and 1 for Re = 25000 and 55000 (based on the leading-edge diameter) are considered here. The flow visualizations illustrating jet and separated layer interactions have been carried out with PIV. The objective of this study is to understand the mutual interactions of separation bubble and the injected jets. It is observed that flow separates at the blending point of semi-circular arc and flat plate. The separated shear layer is laminar up to 20% of separation length after which perturbations are amplified and grows in the second-half of the bubble leading to breakdown and reattachment. Blowing has significantly affected the bubble length and thus, turbulence generation. Instantaneous flow visualizations supports the unsteadiness and development of three-dimensional motions leading to formation of Kelvin-Helmholtz rolls and shedding of large-scale vortices due to jet and bubble interactions. In turn, it has been seen that both the spanwise and streamwise dilution of injected air is highly influenced by the separation bubble.

An experimental investigation of resonant interaction of a rectangular jet with a flat plate

2015 ◽  
Vol 779 ◽  
pp. 751-775 ◽  
Author(s):  
K. B. M. Q. Zaman ◽  
A. F. Fagan ◽  
J. E. Bridges ◽  
C. A. Brown
Keyword(s):  
Mach Number ◽  
Flat Plate ◽  
Cross Section ◽  
Leading Edge ◽  
Resonant Interaction ◽  
Trailing Edge ◽  
Resonant Condition ◽  
Direction Parallel ◽  
Rectangular Jet ◽  
Axis Switching

The interaction between an 8:1 aspect ratio rectangular jet and a flat plate, placed parallel to the jet, is addressed in this study. At high subsonic conditions and for certain relative locations of the plate, a resonance takes place with accompanying audible tones. Even when the tone is not audible the sound pressure level spectra are often marked by conspicuous peaks. The frequencies of these peaks, as functions of the plate’s length, its location relative to the jet as well as jet Mach number, are studied in an effort to understand the flow mechanism. It is demonstrated that the tones are not due to a simple feedback between the nozzle exit and the plate’s trailing edge; the leading edge also comes into play in determining the frequency. With parametric variation, it is found that there is an order in the most energetic spectral peaks; their frequencies cluster in distinct bands. The lowest frequency band is explained by an acoustic feedback involving diffraction at the plate’s leading edge. Under the resonant condition, a periodic flapping motion of the jet column is seen when viewed in a direction parallel to the plate. Phase-averaged Mach number data on a cross-stream plane near the plate’s trailing edge illustrate that the jet cross-section goes through large contortions within the period of the tone. Farther downstream a clear ‘axis switching’ takes place for the time-averaged cross-section of the jet that does not occur otherwise for a non-resonant condition.

scholarly journals Microtubule-organizing centers and cell migration: effect of inhibition of migration and microtubule disruption in endothelial cells.

1983 ◽  
Vol 96 (5) ◽  
pp. 1266-1272 ◽  
Author(s):  
A I Gotlieb ◽  
L Subrahmanyan ◽  
V I Kalnins
Keyword(s):  
Endothelial Cells ◽  
Cell Migration ◽  
Cytochalasin B ◽  
Leading Edge ◽  
Wound Edge ◽  
Microtubule Organizing Centers ◽  
Migration Effect ◽  
Microtubule Disruption ◽  
Made In ◽  
Experimentally Induced

We have previously shown that microtubule-organizing centers (MTOC's) become preferentially oriented towards the leading edge of migrating endothelial cells (EC's) at the margin of an experimentally induced wound made in a confluent EC monolayer. To learn more about the mechanism responsible for the reorientation of MTOC's and to determine whether a similar reorientation takes place when cell migration is inhibited, we incubated the wounded cultures with colcemid (C) and cytochalasin B (CB), which disrupt microtubules (MT's) and microfilaments (MF's), respectively. The results obtained showed that the MTOC reorientation can occur independent of cell migration since MTOC's reoriented preferentially toward the wound edge in the CB-treated cultures, even though forward migration of the EC was inhibited. In addition, the MTOC reorientation is inhibited by C, indicating that it requires an intact system of MT's and/or other intracellular structures whose distribution is dependent on that of MT's.

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