Temperature fluctuations and heat flux in gridgenerated isotropic turbulence with streamwise and transverse meantemperature gradients
Abstract
A screen of closely spaced, parallel, thin wires was placed downstream of a grid generating nearly isotropic turbulence. The screen was normal to the flow and was heated in one of two modes: (1) periodically in time, to generate a train of transversely uniform streamwise thermal ramps, each with a uniform streamwise gradient, and (2) steadily, with transverse nonuniformity, to generate a uniform transverse thermal ramp. The simple temperature and temperaturegradient fluctuation statistical properties in both cases were found to be comparable to those encountered in earlier works with a steadily heated grid producing a uniform transverse thermal ramp. In both modes of heating the temperature fluctuations decreased initially behind the screen and then increased monotonically. The turbulent heattransfer correlation coefficient attained an asymptotic magnitude between 0.7 and 0.8 for both modes of heating. The skewness of the temperature fluctuation derivative in the direction of the mean gradient was found to be nonzero despite the absence of mean shear.
 Publication:

Journal of Fluid Mechanics
 Pub Date:
 April 1985
 DOI:
 10.1017/S0022112085001331
 Bibcode:
 1985JFM...153..441B
 Keywords:

 Aerothermodynamics;
 Heat Flux;
 Isotropic Turbulence;
 Turbulent Flow;
 Temperature Gradients;
 Turbulent Heat Transfer;
 Wind Tunnel Tests;
 Fluid Mechanics and Heat Transfer