Paper 7: The Measurement of Skin Friction in Pressure Gradients Using a Static Hole Pair

1967 ◽  
Vol 182 (8) ◽  
pp. 76-83 ◽  
Author(s):  
J. Duffy ◽  
J. F. Norbury
Keyword(s):  
Pressure Gradient ◽  
Skin Friction ◽  
Pressure Difference ◽  
Static Pressure ◽  
Hole Pair ◽  
Pressure Gradients ◽  
Friction Measurement ◽  
Local Skin ◽  
Small Pressure ◽  
Local Skin Friction

Two wall static holes of different sizes will give different readings of static pressure and the observed pressure difference is a function of the local skin friction. The static hole pair has, therefore, been proposed as a skin friction measurement device. This paper describes experiments which have been carried out to assess the accuracy of the static hole pair for the measurement of skin friction in favourable pressure gradients. The holes were formed in the wall of a pipe so that the device could easily be calibrated, and the favourable pressure gradient was then generated by inserting a central fairing. The skin friction values obtained from the device were compared with those measured by a Preston tube. Results showed that the static hole pair is capable of measuring skin friction within about 2 per cent, but a number of practical difficulties are involved, including the necessity to measure very small pressure differences. Brief consideration is given to the use of the static hole pair in adverse pressure gradients.

The Static Hole Pair as a Skin Friction Meter

1967 ◽  
Vol 71 (673) ◽  
pp. 55-56 ◽  
Author(s):  
J. Duffy ◽  
J. F. Norbury
Keyword(s):  
Skin Friction ◽  
Pressure Difference ◽  
Static Pressure ◽  
Technical Note ◽  
Hole Diameter ◽  
Hole Pair ◽  
Local Skin ◽  
Local Skin Friction ◽  
The Difference ◽  
Test Hole

In a recent technical note Rajaratnam has pointed out the possibility of using the pressure difference measured between two static pressure holes of different diameter as a means of determining skin friction. The device exploits the fact that for any hole there is an error in measurement of static pressure which depends both on the hole diameter and on local skin friction, as Shaw has demonstrated. Consequently the difference in pressure measured between two adjacent holes of different diameter will be a function of the skin friction. In this note the device will be called a “static hole pair”. The larger hole will be referred to as the “test” hole, and the smaller hole as the “reference” hole.

Direct total skin-friction measurement of a flat plate in zero-pressure-gradient boundary layers

2009 ◽  
Vol 41 (2) ◽  
pp. 021406 ◽  
Author(s):  
Kiyoto Mori ◽  
Hiroki Imanishi ◽  
Yoshiyuki Tsuji ◽  
Tomohiro Hattori ◽  
Masaharu Matsubara ◽  
...  
Keyword(s):  
Pressure Gradient ◽  
Flat Plate ◽  
Skin Friction ◽  
Boundary Layers ◽  
Friction Measurement

Global and local skin friction diagnostics from TSP surface patterns on an underwater cylinder in crossflow

2016 ◽  
Vol 28 (12) ◽  
pp. 124101 ◽  
Author(s):  
Massimo Miozzi ◽  
Alessandro Capone ◽  
Fabio Di Felice ◽  
Christian Klein ◽  
Tianshu Liu
Keyword(s):  
Skin Friction ◽  
Local Skin ◽  
Local Skin Friction ◽  
Surface Patterns ◽  
Global And Local

An Experimental Study of the Viscous Resistance of a 0,564-CB Form

1979 ◽  
Vol 23 (02) ◽  
pp. 140-156
Author(s):  
P. N. Joubert ◽  
P. H. Hoffmann
Keyword(s):  
Experimental Study ◽  
Reynolds Number ◽  
Skin Friction ◽  
Resistance Coefficient ◽  
Viscous Resistance ◽  
Local Skin ◽  
Friction Resistance ◽  
Local Skin Friction ◽  
The University ◽  
Resistance Coefficients

Wind tunnel tests were performed to determine the viscous resistance and its components for a 0.564-CB model from the BSRA Trawler Series. It was found that the sum of the pressure and skin friction resistance coefficients agreed well with the viscous resistance coefficient determined from drag balance tests. The range of Reynolds number examined was from 1.15 × 106 to 5.17 × 106. The results for the viscous resistance and its components were fitted using least-squares methods to various equations. The results were also compared with the results of previous tests done at the University of Melbourne on models of Lucy Ash-. ton and a 0.80-CB tanker. It was found that the skin friction and viscous resistance coefficients had curves of quite different position and slope. Local skin friction distribution showed noteworthy differences, especially at the stern, with high values at the keel and low values approaching the waterline.

Coupled fields in inhomogeneous warm plasmas with static pressure gradients. I

1972 ◽  
Vol 72 (2) ◽  
pp. 285-297
Author(s):  
R. Burman
Keyword(s):  
Pressure Gradient ◽  
Acoustic Waves ◽  
Wave Equations ◽  
Static Pressure ◽  
Pressure Gradients ◽  
Coupling Region ◽  
Electron Plasmas ◽  
Coupled Wave Equations ◽  
Electron Acoustic ◽  
The Waves

Abstract.This paper deals with small amplitude waves in inhomogeneous warm electron plasmas. The waves are coupled electromagnetic and electron-acoustic waves, and are described by Maxwell's equations together with single-fluid hydrodynamical equations. Here, previous work is generalized by including the effect of a static pressure gradient. Coupled wave equations are obtained and specialized to the case of a planar stratified plasma. Then, as a preliminary to a treatment of wave coupling, the behaviour of the solutions of the uncoupled wave equations in a coupling region is investigated. The static pressure gradient complicates the behaviour of the uncoupled field components; singularities occur at two points which coalesce as the static pressure gradient is allowed to tend to zero.

Measurement of the Wall Shear Stress With Sublayer Thin Plate of Thermochromic Liquid Crystal

2015 ◽  
Author(s):  
Takashi Kodama ◽  
Shinsuke Mochizuki
Keyword(s):  
Shear Stress ◽  
Liquid Crystal ◽  
Friction Coefficient ◽  
Wall Shear Stress ◽  
Skin Friction ◽  
Channel Flow ◽  
Skin Friction Coefficient ◽  
Local Skin ◽  
Local Skin Friction ◽  
Wall Shear

New optical method for measurement of the local wall shear stress has been developed by using thermo-chromic liquid crystal temperature measurement based on hue [1], [2] of the camera view. The flow field is the fully developed turbulent channel flow. Thin film made of thermo-chromic liquid crystal is placed on the wall. A rectangular shaped obstacle is glued on the film. The obstacle is within a region of buffer layer with height from the wall. Temperature of the film and the obstacle are slightly raised by a heater below the wall. The air flow makes non-uniform temperature distribution and non-uniform color distribution appears on the surface of the film. Relations between hue and local skin friction coefficient were examined in a turbulent air channel flow. It is indicated that a certain hue of a point is varying linearly against the corresponding local skin friction coefficient.

scholarly journals Effects of Slip and Heat Generation/Absorption on MHD Mixed Convection Flow of a Micropolar Fluid over a Heated Stretching Surface

2010 ◽  
Vol 2010 ◽  
pp. 1-20 ◽  
Author(s):  
Mostafa Mahmoud ◽  
Shimaa Waheed
Keyword(s):  
Nusselt Number ◽  
Friction Coefficient ◽  
Mixed Convection ◽  
Skin Friction ◽  
Heat Generation ◽  
Local Nusselt Number ◽  
Skin Friction Coefficient ◽  
Convection Flow ◽  
Local Skin ◽  
Local Skin Friction

A theoretical analysis is performed to study the flow and heat transfer characteristics of magnetohydrodynamic mixed convection flow of a micropolar fluid past a stretching surface with slip velocity at the surface and heat generation (absorption). The transformed equations solved numerically using the Chebyshev spectral method. Numerical results for the velocity, the angular velocity, and the temperature for various values of different parameters are illustrated graphically. Also, the effects of various parameters on the local skin-friction coefficient and the local Nusselt number are given in tabular form and discussed. The results show that the mixed convection parameter has the effect of enhancing both the velocity and the local Nusselt number and suppressing both the local skin-friction coefficient and the temperature. It is found that local skin-friction coefficient increases while the local Nusselt number decreases as the magnetic parameter increases. The results show also that increasing the heat generation parameter leads to a rise in both the velocity and the temperature and a fall in the local skin-friction coefficient and the local Nusselt number. Furthermore, it is shown that the local skin-friction coefficient and the local Nusselt number decrease when the slip parameter increases.

The Effects of Small Changes of Prandtl Number and the Viscosity-Temperature Index on Skin Friction

1964 ◽  
Vol 15 (4) ◽  
pp. 392-406 ◽  
Author(s):  
A. D. Young
Keyword(s):  
Boundary Layer ◽  
Prandtl Number ◽  
Pressure Gradient ◽  
Skin Friction ◽  
Laminar Boundary Layer ◽  
Wall Temperature ◽  
External Pressure ◽  
Main Stream ◽  
Pressure Gradients ◽  
Temperature Index

SummaryThe analytic simplifications in boundary-layer analysis that result from the assumptions that the Prandtl number σ and the viscosity-temperature index ω are unity make it desirable to be able to assess the effects of the departures of the actual values of these parameters from unity. In this paper only the effects on skin friction are considered. Formulae of acceptable validity and wide application are first used to produce generalised curves for these effects for given main-stream Mach numbers and wall temperature conditions for the case of zero external pressure gradient for both laminar and turbulent boundary layers (Figs. 1 and 2).A number of calculated results for the laminar boundary layer with favourable and adverse pressure gradients is then analysed (Figs. 3, 4 and 5) and it is shown that these results are consistent with the assumption that, for a given wall temperature, the effects of small changes of σ and ω on skin friction are independent of the external gradient, so that the appropriate curves of Figs. 1 and 2 apply. Where the change of a- is associated with a change of wall temperature (e.g. if the heat transfer is specified as zero) then the interaction between pressure gradient and this temperature change can be significant in its effects on skin friction for the laminar boundary layer and can only be assessed if the effects of changes of wall temperature with constant σ and ω have been separately determined for the pressure distribution considered. It is inferred that in all cases, except with large adverse pressure gradients and imminent separation, the effects of changes of ω and σ for the turbulent boundary layer are reliably predicted by the zero pressure gradient curves of Figs. 1 and 2 and the effect of any associated change of wall temperature can then be reliably inferred from the zero pressure gradient formula (equation (15)) in the absence of more specific calculations covering a range of wall temperatures.

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