On Spectral Exponent Over Inertial Range in a Turbulent Square Jet

This paper reports a study that investigates the effects of the large-scale intermittency factor γ and the mean shear S on the inertial range spectral exponent m in the far field of a turbulent square jet (γ is defined as the fraction of time when the flow is turbulent at a specific location.). The exit Reynolds number is Re = 50,000. The turbulent energy recognition algorithm (TERA) method proposed by Falco and Gendrich (1990) is applied to estimate γ from velocity signals. It is found that γ has a strong impact on m while the influence of S is negligible. More specifically, m varies with γ following the relationship of m = m _t  + (lnγ ^−0.0173)^1/2, where m _t denotes the scaling exponent in full turbulence. Moreover, self-similarity of γ is observed in the far field of the jet.