Prediction of the heat transfer coefficient with film cooling by a row of holes over a flat surface

الملخص EN

A numerical scheme is described and its capability for predicting the heat transfer coefficient associated with film cooling by a transverse row of discrete holes over a flat surface is tested.

The computer scheme uses an elliptic three-dimensional calculation procedure which solves the differential equations expressing the physical laws of conservation of mass, momentum and energy employing methods of numerical mathematics.

The turbulent stresses and heat fluxes are simulated by a k-e turbulence model based on a modified log-law that uses the turbulent kinetic energy as the characteristic velocity scale rather than the friction velocity.

This allows calculation in regions of flow reversal and flow separation from the wall, as in locations near injection.

Comparisons with measurements obtained for injection angles of 35* and 90*, coolant-to-main stream density ratio of 1.0 and 1.5, and di-mensionless blowing rates in the range 0.5 to 1.5 show fairly satisfactory agreement within the majority of the cases.

Discrepancies are however observed at the conditions of large density ratios and large blowing rates close to the holes.