A nonintrusive laser interferometer method for measurement of skin friction

TLDR: In this article, a method is described for monitoring the changing thickness of a thin oil film subject to an aerodynamic shear stress using two focused laser beams, which is then simply analyzed in terms of the surface skin friction of the flow, including the effects of arbitrarily large pressure and skinfriction gradients, gravity, and time-varying oil temperature.

Abstract: A method is described for monitoring the changing thickness of a thin oil film subject to an aerodynamic shear stress using two focused laser beams. The measurement is then simply analyzed in terms of the surface skin friction of the flow. The analysis includes the effects of arbitrarily large pressure and skinfriction gradients, gravity, and time-varying oil temperature. It may also be applied to three-dimensional flows with unknown direction. Applications are presented for a variety of flows including two-dimensional flows, three-dimensional swirling flows, separated flows, supersonic high-Reynolds-number flows, and delta-wing vortical flows.

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NASA Technical Memorandum 84300
NASA-TM-84300 19830004123
A NonintrusiveLaserInterferometer
Methodfor Measurementof
SkinFriction
Daryl J. Monson
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October 1982
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NASA Technical Memorandum 84300
A NonintrusiveLaserInterferometer
Methodfor Measurementof
SkinFriction
Daryl J. Monson, Ames ResearchCenter, Moffett Field, California
NASA
NationalAeronautics and
SpaceAdministration
Ames ResearchCenter
MoffettField,California94035
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Abstract
A method is described for monitoring the changing thickness of a thin oil film
subject to an aerodynamic shear stress using two focused laser beams. The measure-
ment is then simply analyzed in terms of the surface skin friction of the flow.
The analysis includes the effects of arbitrarily large pressure and skin-friction
gradients, gravity, and time-varying oil temperature. It may also be applied to
three-dimensional flows with unknown direction. Applications are presented for a
variety of flows including two-dlmensional flows, three-dimensional swirling flows,
separated flows, supersonic high Reynolds number flows, and delta-wing vortical
flows.