| Autor: |
Jay Fox, Harald Rungaldier |
| Rok vydání: |
1972 |
| Předmět: |
|
| Zdroj: |
Society of Naval Architects and Marine Engineers, and U.S. Navy, Advanced Marine Vehicles Meeting. |
| DOI: |
10.2514/6.1972-673 |
| Popis: |
The popular underdense scattering spectrum that was used by Salpeter and Treiman (1964) is compared for the first time with experimental measurements. The form of the spectrum is F(KA) = 15.5A3(1 + K2A2)~11/6, where A is the turbulent scale and K is the electron density spectrum wavenumber. (K is twice the radar wavenumber in backscatter calculations.) Direct measurements of the three-dimensional spectrum in turbulent Mach 16 wakes behind sphere projectiles are obtained with fine-wire electron-collection probes operating in a free-molecule electronsaturation mode. The power-law slopes of the experimental spectrum are always steeper than the — -^ slope of the prediction, which is consistent with the low Reynolds number character of these high Mach number experiments. When compared with the prediction, the experimental spectrum varies from +3 db to — 8 db. A zone of high dissipation spectra is found near breakthrough where the probes were 25% off-axis. Similar results are found in Mach 9 spectra but not in Mach 6 spectra, the latter being farther off-axis. |
| Databáze: |
OpenAIRE |
| Externí odkaz: |
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