Turbulence generation in homogeneous particle-laden flows

The generation of turbulence by uniform flutes of monodisperse spherical pa rticles moving through a uniform dosing gas was studied experimentally, Pha se velocities, moments, probability density functions, and energy spectra s ere measured within a counterflowing particle/gas sind tunnel using phase-d iscriminating laser velocimetry. Test conditions included particle Reynolds numbers of 106-990, particle volume fractions less than 0.003% , direct ra tes of dissipation of turbulence by particles less than 4%, and turbulence generation rates sufficient to yield relative turbulence intensities in the range 0.2-5.0% . Velocity records showed that the dos consisted of randoml y arriving sake disturbances within a turbulent interwake region and that t he particle wake properties corresponded to recent observations of laminarl ike turbulent sakes for spheres at intermediate Reynolds numbers in turbule nt environments. Probability density functions of velocities were peaked fo r streamwise velocities due to contributions from mean streamwise velocitie s in particle sakes but sere Gaussian for cross stream velocities that only involve contributions from the turbulence in the wakes. Relative intensiti es of streamwise and cross stream velocity fluctuations were roughly correl ated in terms of a dimensionless rate of turbulence dissipation factor. Fin ally, energy spectra exhibited prominent -1 and -5/3 power decay regions as sociated with contributions from mean velocities in particle wakes and part icle and interwake turbulence, respectively.