The influence of density gradients on the effectiveness of film cooling

Abstract

New measurements of the impervious-wall effectiveness are presented in the range of the velocity ratio ... These measurements were carried out using hydrogen, air, argon and Arcton 12 as the injected gas: the resulting range of density ratios was ... The measurements demonstrate, quantitatively, that an increase in the density ratio leads to an increase in effectiveness for the same velocity ratio. The prediction method proposed by S. V. Patankar and D. B. Spalding has been tested against the present measurements and shown to be a convenient method in the region downstream of the immediate vicinity of the slot exit. The predictions are reasonable but it is concluded that further experimental work is necessary to establish the appropriate distribution of the effective Schmidt (or Prandtl) number.