- Author
- Marshall, R. D.
- Title
- Surface Pressure Fluctuations Near an Axisymmetric Stagnation Point. Technical Note.
- Coporate
- National Bureau of Standards, Washington, DC
- Report
- NBS TN 563, August 1971,
- Distribution
- Available from National Technical Information Service
- Keywords
- turbulent flow, pressure; axisymmetric flow; stagnation point; disks (shapes); analysis of variance; turbulence; surface properties; blunt bodies
- Abstract
- Surface pressure fluctuations on a circular disk placed normal to a turbulent air stream were investigated. Turbulence intensities of approximately 10% were produced by a coarse grid installed at the test-section entrance. The turbulent field in the neighborhood of the disk was homogeneous and nearly isotropic. Experimental results indicate that existing linear theories which do not consider distortion of the flow fail to predict the nature of surface pressure fluctuations on a bluff body. Only for wavelengths which are large compared to the body do these theories yield satisfactory results. A strong attenuation of the high frequency components occurs as the flow stagnates. This is accompanied by a transfer of energy from short to long wavelengths. The opposite effect is observed as the flow attains a radial direction and approaches the edge of the disk. A neutral wavelength which undergoes little change in energy was observed. Integral scales of surface pressure fluctuations are much larger than the lateral integral scale of the free-stream turbulence. (Author)