Studies on Vortex Tubes : 2nd Report, Reynolds Number. The Effects of the Cold Air Rate and the Partial Admission of Nozzle on the Energy Separation

Abstract

The authors tried to explain the effects of the dimensions of a vortex tube (especially the rate of partial admission of nozzle) on the energy separation of gas flowing through it. They tried also to explain the influence of the cold air rate on the flow and thermal fields in a vortex tube with the optimum proportion of the total area of nozzle openings (F_n) to the cross-sectional area of main tube (F_t). From these researches the following results have been obtained : (1) The maximum efficiency of energy separation is obtained when F_n≒0.17F_t. (2) The values of turbulent diffusivity calculated from the tangential velocity profiles nearly coincide with the values computed from Keyes'empirical formula. Reynolds number of jet from the nozzle, R_et=(0.5∼3.0)×10⁶. (3) For the case of large axial velocity, the modified formulae including the axial velocity terms (36) and (37) should be used to predict the stagnation temperature profile in the cross-section at the cold end of the tube.