EXPERIMENTAL SURVEY ON HEAT TRANSFER IN AN INTERNAL CHANNEL OF A TRAILING EDGE COOLING SYSTEM

AN EXPERIMENTAL INVESTIGATION WAS CONDUCTED TO INVESTIGATE THE COOLING PERFORMANCE OF A TRAILING EDGE (TE) COOLING SYSTEM OF A GAS TURBINE BLADE. PRESENT WORK IS THE FIRST STEP OF AN EXPERIMENTAL SURVEY ON EFFECTS OF ROTATION IN AN INTERNAL TRAILING EDGE COOLING SYSTEM. THE GEOMETRY CONSISTS OF A 30:1 SCALED MODEL REPRODUCING THE TYPICAL SHAPE OF A HIGH PRESSURE TURBINE BLADE TE, WITH ONE ROW OF ENLARGED PEDESTALS. THE AIRFLOW PATTERN INSIDE THE TEST RIG SIMULATES THE ROTOR BLADE COOLING SCHEME WITH A 90 DEG TURNING FLOW FROM THE HUB INLET TO THE TE OUTLET. HEAT TRANSFER COEFFICIENT MEASUREMENTS WERE MADE VARYING REYNOLDS NUMBER FROM 10000 TO 20000 IN THE HUB INLET SECTION. THE EFFECT OF A VARYING TIP MASSFLOW RATE WAS ALSO INVESTIGATED EJECTING 0% AND 12.5% OF THE TRAILING EDGE MASSFLOW THROUGH THE TIP OUTLET. DETAILED HEAT TRANSFER COEFFICIENT MEASUREMENTS WERE MADE USING A STEADY STATE TECHNIQUE WITH A THIN INCONEL HEATING FOIL AND WIDE BAND THERMO-CHROMIC LIQUID CRYSTALS APPLIED ON A TRANSPARENT PMMA TEST ARTICLE. FINALLY, EXPERIMENTAL RESULTS WERE COMPARED WITH A 3D RANS CFD SIMULATION PERFORMED WITH AN OPEN SOURCE CODE.