Grid turbulence exhibiting a peak in the spectrum
Abstract
A quasi-homogeneous turbulent flow is generated by a propeller-equipped grid, and the homogeneity of the mean velocity distribution and the Reynolds stress tensor is determined. To assure the aerodynamic stability and avoid the torch effects, the battery of 100 triple propellers mounted on the rectangular-bar grid are counterrotating. The quality of test jets is controlled by measuring the development of the boundary layers, which are limited in thickness to 5 cm. With or without propeller rotation, the transversal components present weak periodic amplitude inhomogeneities, with spatial periods twice that of the grid. Measurements were made for a turbulent velocity spectrum extending to 4 kHz, and the propeller rotation speed coincides with the frequency of the principal peak. Auxiliary peaks, seen primarily at 60 Hz, correspond to second and third order harmonics. The expected peak is detected in the fluctuating velocity field spectrum.
- Publication:
-
Academie des Sciences Paris Comptes Rendus Serie Sciences Mathematiques
- Pub Date:
- February 1986
- Bibcode:
- 1986CRASM.302..501M
- Keywords:
-
- Flow Measurement;
- Homogeneous Turbulence;
- Turbulent Flow;
- Flow Velocity;
- Kinetic Energy;
- Propellers;
- Reynolds Stress;
- Fluid Mechanics and Heat Transfer