Abstract
The study of heat transfer and film effectiveness of film cooling on rotating components of turbomachinery is becoming of great significance for engineers because of its potential applications in industry. In modern high efficiency gas turbines, an extremely large thermal stress on turbine blade surface occurs due to the high entry temperature of around 2000k. Film cooling on the blade surface plays an important role in protecting the turbine blades. In literature, film cooling researches are available for stationary blades or cylinders only. This results can apply on the stator for the design of film cooling technology, on the contrary, it is a big problem for the rotor's application. In view of this, this project will be investigate the film cooling on the rotating body. There are adequately two aspects of factors that affect the performance of film cooling. One is the geometric parameter, the other is flow condition of the field. Such as velocity of mainstream, turbulence intensity, the arrangement of injected hole, the geometric of injected hole, spacing between holes, angle of the injected flow, coolant-to-mainstream density ratio and coolant-to-mainstream blowing ratio, etc. Therefore how to analyze the heat transfer mechanism in film cooling for different physical configurations, promote its efficiency, and prolong the blade life expectancy are the main objectives of the film cooling research. Therefore, this project study the film cooling on the rotating cylinder at first, and to extend the investigation of film cooling on the rotating cylinder in future. In real engine, the leading edge of blade which is impinged in hot gas is similar to circular cylinder, and the leading edge is most hot that need to cooling. So it is very important to study the film cooling on the rotating cylinder. For fully understanding of the heat transfer effect on rotating flow field, one designed the test cylinder with film holes were inclined outwards at an injection angle of 35°, and the secondary air was injected though four rows of inclined holes locating at ±15° and ±40° from the stagnation line. In general, it is evident that an increase in blowing ratio causes larger interactions between injected air and free-stream flow, and produces an augmentation in the turbulence at the exit of the film holes to enhance the heat transfer.