3 edition of Development of a new instrument for direct skin friction measurements found in the catalog.
Development of a new instrument for direct skin friction measurements
by Gas Dynamics Division, The University of Tennessee Space Institute, National Aeronautics and Space Administration, National Technical Information Service, distributor in Tullahoma, TN, [Washington, DC, Springfield, Va
Written in English
|Statement||by A.D. Vakili, J.M. Wu|
|Series||NASA contractor report -- NASA CR-176818|
|Contributions||Wu, Cheng-ming, 1945-, United States. National Aeronautics and Space Administration|
|The Physical Object|
for determination unit skin friction for driven piles. Finally, based on the test results, a simple relation was proposed to relate the N70 value and interface friction of silty clay soils for a range of N70 between 12 and Keywords: undisturbed, O.C., silty clay، soil-concrete skin friction, direct . 5. The skin friction is generated with the increment of pile shaft displace m ent and the m axim um skin friction is obs erve d at 5 ~ 15mm displacement. Then it reduces to residual strength when the displacement continues. The maximum skin friction is con firm ed as the param eter of shear strengt h of soi l an d as show n in table 1 and figs.
Direct Measurements of Skin Friction. By Satish Dhawan. Get PDF (21 MB) Abstract. A device has been developed to measure local skin friction on a flat plate by measuring the force exerted upon a very small movable part of the surface of the flat plate. These forces, which range from about 1 milligram to about milligrams, are measured by. The standard penetration test (SPT) supplemented with the measurement of torque (SPT-T) may be used to obtain a direct measurement of unit skin friction (f s) between the sampler and the surrounding test is performed after the standard SPT procedure and does not compromise conventional SPT results.
Summary. This paper presents comparative skin-friction measurements obtained by a Preston tube, a surface fence, a single film and a McCROSKEY hot-film probe, and a wall pulsed wire in two- and three-dimensional highly turbulent flows (near wall turbulence level > . A stainless steel ball was pressed on to the skin with at a pre-set load and then moved across the skin at a constant velocity of 5 mm/min. The UMT continuously monitored the friction force of the skin and the normal force of the ball to calculate the friction coefficient in real-time.
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A device developed for the direct measurement of wall shear stress generated by flows is described. Simple and symmetric in design with optional small moving mass and no internal friction, the features employed in the design eliminate most of the difficulties associated with the traditional floating element balances.
The device is basically small and can be made in various by: 2. Development of a new instrument for direct skin friction measurements: final report for NASA grant NAG [A D Vakili; J M Wu; United States. National Aeronautics and Space Administration.]. In hypervelocity, the skin friction is proportional to the product of the gas density multiplied by the square of the flight velocity.
Related research results  show that the skin friction drag accounts for almost 50 % of the total drag in hypersonic vehicles with : Lv Zhiguo, Lv Zhiguo, Li Guojun, Zhao Rongjuan, Jiang Hua, Liu Jichun, Huang Jun, Liu Shiran.
The principal objective of this technology development program was to design, build, and test a new class of direct-measuring skin friction sensors capable of performing favorably under a standard hypersonic flow test program at AEDC Hypervelocity Wind Tunnel 9, located at White Oak, Maryland.
Fully understanding and optimizing these complex flows requires knowledge of the Author: Ryan J. Meritt, Joseph A. Schetz, Eric C.
Marineau, Daniel R. Lewis, Derick T. Daniel. The instrument has three major parts: casing, pressure cell, and cantilever. The casing protects the pressure cell which measures lateral earth pressure. Strain gages on the cantilever, which screws into the back of the casing, measure skin friction.
The instrument has been tested by embedding it in a precast concrete pile driven in natural by: 3. Joseph A. Schetz. A new type of direct-measuring skin-friction gauge was developed for the high-speed, high-temperature environment of turbulent boundary-layer flows in supersonic combustion.
The feasibility of measuring the skin friction from the movement of interference fringes of a thin oil ﬁlm was ﬁrst realized by Tanner and Blows (). Oil-ﬁlm interferometry is the only direct method for skin-friction measurement apart from ﬂoating-element balances.
It has a high spatial resolution and is capable of measuring reverse. Direct measurement of the skin friction with a skin friction drag balance, under the same aerodynamic conditions, lets us correlate the skin friction with optical transmission. This provides a unique technique for the direct measurement of skin friction from the transmitted light intensity.
The results are in excellent agreement with the model. The first part is an introduction to skin friction and to current knowledge on skin friction. The second part presents the RevoltST, the tribometer that was specially developed for skin friction research and which meets the objectives described in the thesis.
The third part presents the results of the skin friction measurements obtained with. A study was conducted on the measurement of skin friction, the least under-stood component of drag.
Skin friction is considered the “last frontier” in drag reduc-tion for supersonic flight, but to understand skin friction, it must be accurately mea s-ured. This study utilized the direct measuring technique for skin friction.
A small de. An emerging area of application for skin friction measurements is as critical and sensitive inputs for flow control systems. Since skin friction (or wall shear) measurement is an important topic, there is a long history of work in the area starting with Froude ().
There are two broad classes of methods – indirect and direct measurements. Skin friction and oil-film development.
Quantitative skin friction measurements were made by using image-based interferometry for determining the thickness of an oil drop on a surface. Data processing in interferometric oil-film skin friction meter is based on a local similarity solution of the thin-oil-film equation providing.
A device has been developed to measure local skin friction on a flat plate by measuring the force exerted upon a very small movable part of the surface of a flat plate.
These forces, which range from about 1 milligram to about milligrams, are measured by means of a reluctance measuring device. The apparatus was first applied to measurements in the low-speed range, both for laminar and.
A simple instrument for skin-friction measurements in adiabatic turbulent compressible boundary-layers is described. Its small size makes its use possible in very thin boundary layers. A universal calibration relation is given. et al. , in order to measure in vivo skin friction for different anatomical sites, experiments were carried out using a multiaxial load cell that allows the simultaneous measurement of the normal and tangential forces.
The tests consist of sliding the skin surface on a glass disc and simultaneously. Measurement Approach i. The Skin Friction Measurement Technique The FISF technique permits a non-obstructive direct measurement of skin friction on a surface in a three-dimensional flow field. This method is described in great detail in references 1–7.
In short, drops (or short line. MEMS-based skin friction sensors are used to measure and validate skin friction and its distribution, and their advantages of small volume, high reliability, and low cost make them very important for vehicle design. Aiming at addressing the accuracy problem of skin friction measurements induced by existing errors of sensor fabrication and assembly, a novel fabrication technology based on.
New techniques for the direct measurement of skin friction using nematic liquid crystal layers are demonstrated. Skin friction measurements can be made using a molecular rotation time technique or an equilibrium orientation technique.
A mathematical model describing the molecular dynamics of the nematic liquid crystal layer has been introduced. This paper presents the development of a floating-element shear stress sensor that permits the direct measurement of skin friction based on geometric Moiré interferometry.
A new class of wall. The skin-friction and heat-transfer data are compared with other data obtained by direct measurement of surface shear with balances and accompanied by boundary-layer surveys.
The use of momentum-thickness Reynolds number in the skin-friction comparison avoids the need for arbitrary location of the. DEVELOPMENT AND GROUND TESTING OF DIRECT MEASURING SKIN FRICTION GAGES FOR HIGH ENTHALPY SUPERSONIC FLIGHT TESTS Theodore B.
Smith Dr. Joseph Schetz, Chairman Aerospace Engineering (ABSTRACT) A series of direct-measuring skin friction gages were developed for a high-speed.Another application for skin friction measurement is as a sensitive input signal for flow control systems.
From a basic viewpoint, local skin friction values are central to all data-correlating techniques for turbulent flows, and these correlations form the basis for the development of all turbulence models used in computational fluid dynamics.An instrument for the measurement of wall shear stress in two-phase flows is described.
The device, termed a Laser Interferometer Skin Friction (LISF) meter, determines the wall shear by optically measuring the time rate of thinning of a thin oil film placed on the wall of the flow channel.