A Study on Double Concentric Jets : 1st Report, Experimental Results of Air-Air Flow

Abstract

Concerning double concentric jets, the authors performed experimental studies on influences of nozzle conditions such as thickness of nozzle wall or boundary layers on the inside and outside walls of a nozzle on the characteristics of jets in the main region. And the following results are obtained. (1) In the main region, the dimensionless radial velocity profile fits the cosine curve independently of values of δ^^-, λ and χ^^-. (2) The velocity decay on the central axis and the intensity of turbulence are hardly affected by the value of δ^^- for small values of λ. But for large values of λ, the tendency of velocity decay becomes remarkable and the intensity of turbulence is affected heavily by the wake behind the nozzle wall with an increase in the value of δ^^-. (3) Values of ι^^- and ε^^- vary in radial and axial directions and these values are different respectively in both cases of large and small values of λ.