Superposition effect of the laidback fan-shaped film cooling hole on a gas turbine vane.

The superposition effect of optimized laidback fan-shaped film cooling holes on a vane was experimentally investigated. The film cooling experiments were conducted using a linear cascade with five vanes and the blow-down cascade facility of the Korea Aerospace University. The Reynolds number calculated using the velocity of cascade exit and chord length of vane was 1.1×106. The film cooling effectiveness (FCE) was investigated by applying a pressure sensitive paint technique with a density ratio of 1.5 (DR) and four different blowing ratios (BR). To focus the superposition of the coolant, each coolant cavity had only a single-row holes and the flow rate for each cavity was separately controlled. Also, test vanes were designed so that the flow disturbance by the upstream non-injecting holes was excluded. The dimensions of the laidback fan-shaped (LBF) hole installed on the vane was derived from a series of experimental optimization processes using a flat plate test section at the DR of 1.5 and BR of 2.0 conditions. The cascade test results presented that FCE of the optimized LBF hole increased as the BR increased and FCE of suction side (SS) showed superior film cooling performance compared to the pressure side (PS). Generally, the FCE obtained by superposing the single-row injection case was well-matched with FCE of multi-row injection cases. The difference between the two results enlarged toward downstream, however, the maximum difference was only 0.03 units. [ABSTRACT FROM AUTHOR]