Berechnung der Störung der Brennkammer-Filmkühlung durch Einblasen von Luftstrahlen mit Hilfe einer Analogiebetrachtung zwischen Strahl und Zylinder

The influence of cold air jet injection upon the film cooling of combustion chamber walls is investigated theoretically and experimentally. Considering the cold air jet acting like a cylinder in the combustion gas and film cooling streams, an equation can be derived theoretically which describes the disturbance of the film cooling effectiveness downstreams of the air jet injection. The experiments, where single cold air jets are injected normal to the film cooled test chamber wall, show considerable decreases of the film cooling effectiveness downstream of the injection points. The same effect is noted in real combustion chambers of aircraft gas turbine engines. Additional experiments with cylinders simulating the disturbance effect of the air jets prove the analogy consideration between jet and cylinder. The theoretically predicted cooling effectiveness is in agreement with own experiments as well as other test results.