Turbulence Measurements in a Two-Dimensional Compressible Wake,
Abstract
This report describes turbulence measurements in a compressible, two-dimensional wake of a slender, adiabatic model. The constant-current hot-wire anemometer was used to map the axial and lateral variations of the following properties: velocity and density (temperature) fluctuations, their cross correlation coefficient, their one-dimensional spectral functions and their longitudinal integral scales. The results are generally in agreement with predictions of the Dynamic Equilibrium Hypothesis by which scaling laws the wake structure behind vehicles at all speeds and altitudes might be predicted. In particular, the axis values of the velocity and density fluctuations asymptotically become constant fractions of the velocity and density deficits, and they become anti-correlated; however the lateral distributions are somewhat different from the equivalent distributions at low speeds. The off-axis maxima of the fluctuations are not located at the region of maximum shear. The integral scales of velocity proportional to the wake growth. The one-dimensional spectra were not followed beyond a frequency limited by the system, but since the Reynolds number of turbulence is low, no spectral activity was expected beyond the integral scale. Between the axis and the wake edge the spectra are distorted by a peak with a wavelength slightly smaller than the wake width, which is more prominant in the density rather than the velocity and which is probably indicative of a non-random turbulent front. (Author)
Document Details
- Document Type
- Technical Report
- Publication Date
- Jun 01, 1969
- Accession Number
- AD0854497
Entities
People
- A. Demetriades