Effect of Coolant Jet Holes Direction on Film Cooling Performance

  • H. Yousif,.Amer University of Technology, Baghdad, Iraq
  • M. Al-Dabaghand University of Technology, Baghdad, Iraq
  • Muwafag Sh. Alwan University of Technology, Baghdad, Iraq
Keywords: Film cooling, Blowing ratio, Effectiveness, Jet holes direction


The film cooling effectiveness and local heat transfer coefficient for coolant jet
holes direction (orientation angle), have been investigated. Experimental investigations were
done on a flat plate by using a single test transient IR thermograph technique. Evaluation of
the cooling performance is obtained by estimated both film cooling effectiveness and heat
flux ratios. Three models of coolant jet holes are investigated, each model consists of two
rows of holes arranged in a staggered way with different orientation angles. Model (1)
downstream row with acute angle and the upstream row with obtuse angle; model (2) both
rows with obtuse angles, while model (3) both rows with acute angles. The holes diameter is
4mm, the longitudinal distance between the upstream and downstream rows (X/D) is 4D, and
the span distance between two neighboring holes (S/D) is 3D. Three blowing ratios of (BR=
0.5, 1.0, and 1.5) were used in the investigation program. In order to predict the flow behavior
numerically for the cases under investigation CFD code is introduced. The numerical
investigation shows two large vortices, pair of counter rotating vortex and horseshoe vortices,
both vortices have major effects on cooling performance. The experimental results showed
that the film cooling effectiveness increases as blowing ratio increases for models (1 and 2),
while decreases for model (3), and model (1) provide better performance than the others at
high blowing ratios.