A novel technique for skin friction measurement in short duration and unsteady flows [microform]
- Bib ID:
- 3283416
- Format:
- Book and Microform
- Author:
- O'Brien, Scott Adrian
- Description:
- 137 p.
- Summary:
-
A new method for measurement of skin friction in short duration and unsteady flows has been developed. Initially studied for use in hypersonic shock tunnel instrumentation, further investigation has shown wider application is possible. The method combines techniques from two other measurement schemes: Particle Image Velocimetry (PIV) and thin film thickness measurement techniques. A thin continuous film of oil is applied to the surface in the area under investigation. When sheared by an external flow, a Couette-like flow forms within the oil. Analysis of the transient response of oil film motion shows that, in the absence of heat transfer, pressure gradient and surface slope, a linear velocity profile is rapidly established in the microsecond time frame in which the applied external shear stress can be directly related to surface velocity, thickness and viscosity of the oil film. Application of the technique requires the measurement of film thickness and surface velocity of the oil.
Micro-particles are placed on the film surface and imaged through a microscope external to the flow field allowing non-intrusive visualization of the oil surface motion. Microscopic PIV allows both high spatial resolution and directional information of wall shear stress to be obtained. Certain aspects of the oil flow, external flow and position of the micro-particles introduce errors into the velocity measurement. These errors are discussed along with an analysis of the effects of aerodynamic heating on the surface velocity, relevant to application of the technique to hypersonic or combustion testing devices. Methods for determination of film thickness are discussed and include ellipsometric, capacitance and mechanical methods.
Demonstration of the technique by measurement of skin friction on a flat plate in a short duration supersonic wind tunnel is described. For these experiments, polystyrene latex microspheres 1 $\mu
- Notes:
-
- (UnM)AAI9409350
- Source: Dissertation Abstracts International, Volume: 54-10, Section: B, page: 5277.
- Chairperson: Walter H. Christiansen.
- Thesis (Ph.D.)--University of Washington, 1993.
- Reproduction:
- Microfiche. Ann Arbor, Mich.: University Microfilms International.
- Subject:
- Other authors/contributors:
- University of Washington
- Copyright:
-
In Copyright
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Copyright status was determined using the following information:
- Material type:
- Literary Dramatic Musical
- Published status:
- Unpublished
- Creation date:
- 1993
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