Department of Mechanical Engineering

Film cooling in high pressure gas turbine blades

Experimental facility investigating the fluid dynamics of different film cooling geometries through use of state-of-the-art flow visualisation techniques.

Engine designers are continually striving to increase the air turbine-entry temperate of their engines to benefit from improved specific fuel consumption. The corollary of this is that first-stage turbine blades are the components exposed to the highest working temperatures and stresses in the engine.

Film and internal cooling strategies are employed in the blades to ensure that metal temperatures stay within acceptable limits. Given that the bleed off of cooling air from the compressor stage reduces the efficiency of the engine, engine designers want reliable data and models to allow the design of effective and efficient cooling strategies.

State-of-the-art flow visualisation techniques

The film cooling rig is a new Turbomachinery Research Centre test bench for studying film cooling flows with state-of-the-art flow visualization techniques: Plane Laser-Induced Fluorescence (PLIF) and Volumetric 3 Component Velocimetry (V3V).

A CAD model showing the new TRC test bench for studying film cooling flows with state-of-the-art PLIF and V3V flow visualization techniques.PLIF is an optical technique which uses a camera to track light emissions from fluorescing carbon dioxide species within a laser light sheet. V3V is a 3D version of classical Particle Imaging Velocimetry (PIV), which comprises the use of 3 cameras to track tracers introduced in a flow illuminated by a laser cone. PLIF will allow the trajectory of the carbon dioxide coolant flow to be traced out of the film cooling holes, whilst V3V will deliver 3-component plots of velocity in 3D space.

The rig’s modular design allows different flow conditions and film cooling geometries to be tested. Pressure, temperature, turbulence, boundary layer profiling, mass flow and concentration measurements will take place in addition to the PLIF and V3V measurements. The suite of measurements will allow a full characterisation of the film cooling geometries under test in the rig, providing essential information to engine designers.