ISSN Online: 2377-424X
ISBN Print: 0-89116-299-2
International Heat Transfer Conference 7
THE EFFECT OF COLD AIR JET INJECTION UPON THE FILM COOLING EFFECTIVENESS OF COMBUSTION CHAMBER WALLS FOR DIFFERENT INJECTION GEOMETRIES
Abstract
The influence of cold air jet injection upon the effectiveness of the combustion chamber wall film cooling is investigated theoretically in dependence of several flow conditions and geometrical parameters. The equation used for the calculations has been verified by extensive experimental investigations.
The results indicate that the film cooling effectiveness is improved by larger injection velocities and mass flow rates of the jet as well as by smaller distances between two adjacent jets. Larger diameters of the injection hole decrease the cooling effectiveness for constant mass flow rate of the jets, but cause an increase of the cooling
effectiveness for constant injection velocity. All
these parameters strongly effect the turbulence level and the turbulent heat exchange downstream of the jet injection point. The investigations show also that an additional improvement of the film cooling effectiveness can be achieved when using oval-shaped injection holes instead of circular holes.